Urogenital Infections and Inflammations

T.E. Bjerklund Johansen, F. M.E. Wagenlehner, Y.-H. Cho, T. Matsumoto, J. N. Krieger, D. Shoskes, K. Naber

Urinary microbiota analyzed by extended microbiology in subjects with and without urological disorders

Yulia Naboka 1
 Michael Kogan 2


1 Department of Microbiology, Rostov State Medical University, Rostov on Don, Russia
2 Department of Urology, Rostov State Medical University, Rostov-on-Don, Russia

Abstract

A healthy person’s urine is not a sterile environment, and its microbiota contain a wide range of Gram-positive and Gram-negative aerobic and anaerobic bacteria, with Gram-positive aerobic microorganisms predominating. There are significant differences between the urinary microbiota of healthy men and women. The composition of healthy women’s urinary microbiota depends on age and sexual activity. Non-clostridial anaerobic bacteria (NAB) predominate Enterobacteriaceae in case of acute obstructive pyelonephritis with bacteriuria of 104 CFU/ml and higher. Experiments have shown that obstructive pyelonephritis can be caused by various species of NAB (Peptococcus spp., Bacteroides spp., Eubacterium spp.). In every third case of recurrent symptomatic uncomplicated lower urinary tract infection (UTI) Enterobacteriaceae with low level bacteriuria of ≤103 CFU/ml are found and every third case of acute cystitis is not associated with typical uropathogens. Low levels of bacteriuria (102–103 CFU/ml) correlate with symptoms of upper and lower UTI and thus cannot be considered contamination. Asymptomatic bacteriuria is normal in healthy individuals.


Summary of recommendations

  1. A sample of urine for bacteriological examination should be collected minimizing contamination of the material, and culture of urine should be conducted on an expanded set of culture media. To identify the facultative anaerobic bacteria it is advisable to use MacConkey Agar, HiCrome Candida Differential Agar, HiCrome Enterococci Agar, HiCrome Aureus Agar Base, Blood Agar prepared according to Mueller, Hinton agar added with sheep erythrocytes, and in order to identify non-clostridial anaerobic bacteria to use Anaerobic Agar, Broth Shaedler, Shaedler Agar, Bacteroides Bile Esculinum Agar, MRS Agar.
  2. Culture medium for the cultivation of anaerobic and microaerophilic bacteria should be used for bacteriological urine culture in acute and chronic infections of the upper and lower urinary tracts.
  3. In acute obstructive pyelonephritis, a level of bacteriuria for Enterobacteriaceae equal to 103–104 CFU/ml should be considered clinically significant.
  4. In the experimental obstruction of the ureter, several taxons of non-clostridial anaerobic bacteria (Peptococcus spp., Bacteroides spp., Eubacterium spp.) 105 CFU/ml lead to the development of acute suppurative lesions of the kidney. In this regard, non-clostridial anaerobic bacteria should be considered as an etiological factor of acute obstructive pyelonephritis.
  5. Difficult to cultivate microorganisms at a level of bacteriuria <104 CFU/ml should be considered etiologic for acute obstructive pyelonephritis if typical uropathogens are absent.
  6. If non-clostridial anaerobic bacteria are isolated at a level of ≤103 CFU/ml and typical uropathogens are absent in the urine of patients with uncomplicated infection of the lower urinary tract, their causative role cannot be ruled out.
  7. Gram-positive microorganisms and non-clostridial anaerobic microorganisms in voided or catheterized urine samples at levels of 102–103 CFU/ml, should not be considered contamination.
  8. Asymptomatic bacteriuria is normal in healthy individuals.

1 Introduction

Standard microbiological protocols for investigation of urine include microscopic examination with Gram stain and urine culture using media such as Blood and MacConkey Agar incubated at aerobic conditions (35°С, 24 hours) [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]. Such investigations aim to identify microorganisms in the urine known to cause urinary tract infection (UTI). These are mainly species of Enterobacteriaceae (Escherichia coli, Klebsiella spp., Proteus spp., et al.), Pseudomonas spp. and some selective Gram-positive species (Staphylococcus aureus, S. saprophyticus, Enterococcus spp., et al.). These standard protocols, however, narrow down the possible spectrum of uropathogens. Based on the ensuing results new antibacterial agents are developed and manufactured. Common knowledge about uropathogens remained unchanged until recently, when some studies showed, that some microorganisms, so far unknown as uropathogens, may also cause UTI [12], [13], [14], [15], [16], [17], [18].

As early as 1939 Schulte et al. [19] isolated Bacteroides spp. and anaerobic streptococci in patients with unilateral pyelonephritis. Later in 1976 Japanese authors [20] created an experimental model of acute pyelonephritis caused by B. fragilis, proving morphologically the etiologic role of this organism in inflammatory kidney lesions. Sapico et al. [21] isolated some taxons of non-clostridial anaerobic bacteria (NAB), such as Bifidobacterium spp. and Veillonella spp., from the bladder urine of patients with permanent indwelling urethral catheter. Brook [22] isolated Bacteroides spp., Peptococcus spp., and Bifidobacterium spp. from the urine of children with acute pyelonephritis and cystitis and as early as 1980 indicated the necessity of using anaerobic bacteriological studies. Apostolopoulo et al. [23] also noticed the relationship between NAB and development of kidney infections, because NAB were identified in 24.4% of kidney pathology samples after nephrectomy and 22.2% of the kidney bioptates and bladder urine with the predominance of Bacteroides spp. DuPrey et al. [24] described a case of acute pyelonephritis caused by Lactobacillus delbrueckii with a level of bacteriuria of >1010 CFU/mL. The patient had a history of type II diabetes mellitus and hypothyreoidism.

In the 1990s our investigators’ group extended the spectrum of culture media, including anaerobic culturing techniques in order to increase the isolation of a wider spectrum of aerobic and anaerobic bacteria. Those media were previously used to study vaginal and bowel microbiota [1], [2], [3], [10]. We could show [25], [26], [27], [28], [29], [30] that urine of healthy men, women and children and urine of patients with UTI contains a wide spectrum of aerobic and anaerobic bacteria and also virus-bacteria associations.

Finally the realization of the Project to Study the Human Microbiome (2008–2012) became a serious breakthrough in proving that urine of healthy individuals and of patients with UTI is colonized by many different microorganisms with different levels of bacteriuria [4], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40]. New impulses for a modern view on urinary microbiota were generated by Brubaker [7]. He stated that “the standard urine culture protocol was not designed to detect bacteria that require special nutrients, grow slowly, cannot tolerate oxygen, or are present in small numbers (<103 CFU/mL). Some of these organisms may be involved in urinary disorders”. Aagaard [41] critised standards even sharper: “Even if a single microbe is the etiologic agent of infection, the pathogenesis and pathophysiology of infection can be viewed within the context of the microbiome and human biology”, and further “Connections among microbiomes in different body sites may help us to understand patterns of human infections”.

Now, we have entered a new era to investigate the urinary microbiota of healthy subjects and patients suffering from UTI. This will lead us to a new understanding of etiology, pathophysiology and management of UTI in human.

2 Methods

A systematic literature search was performed for the last 10 years in MEDLINE, PubMed, ClinicalKey, Cochrane for the following key words: microbiota urine, urine culture, culture urine, culture medium for the examination of the urine, urinary tract infection and the following limitations: age, children, pregnant women, clinical studies, English, abstract available, only peer reviewed.

A total of 1,189 publications was found and screened by title and abstract. After exclusion of duplicates a total of 50 publications was included into the review.

3 Results

3.1 Urinary microbiota of healthy women

The paradigm on the sterility of a healthy person’s urine was based for more than half a century only on the bacteriological methods to investigate urine samples. We have changed this approach by using both, the conventional culture media (blood and MacConkey agar) and also a wide range of additional culture media to detect also facultative anaerobic bacteria (FAB) and non-clostridial anaerobic bacteria (NAB). These media are commonly used for identification of microorganisms derived from colon and vagina. For the FAB cultivation we used MacConkey Agar, HiCrome Candida Differential Agar, HiCrome Enterococci Agar, HiCrome Aureus Agar Base, Blood Agar, prepared according to Mueller Hinton agar with addition of sheep red blood cells. For the NAB cultivation we used Anaerobic Agar, Shaedler Broth, Shaedler Agar, Bacteroides Bile Esculinum Agar, MRS Agar. Nutritional media were purchasedfrom HiMedia (India). The culture media were incubated with the test material under aerobic (24–48 hours) and anaerobic (48–72 hours) conditions (10% СО2, 10% Н2, 80% N2).

To study the microbiota of normal urine, 66 healthy women were divided into three groups:

  • group I – 22 not sexually active women (18–25 years)
  • group II – 24 sexually active women (18–25 years)
  • group III – 20 sexually active women in the postmenopause (52–65 years)

All women were healthy according to medical history, general physical examination, and vital signs. Especially they had no urological and gynecological disorders including ultrasound examination of the internal genitalia. They had no infectious diseases during the last year, and were without medication for the last 2 months. In group III the menopause occurred before 5 years or earlier, without any pelvic organ prolapse, with the uterus still present and with at least two deliveries without abortion in the history. Complete blood count and urinalysis were normal in all women.

From each subject midstream samples of morning urine were collected for bacteriological examination, which was repeated three times with an interval of 3 days. The urine samples were collected in a way to minimize the risk of contamination with microorganisms from the skin, periurethral area and vagina. A total of 198 urine samples was studied.

After a threefold bacteriological examination of urine samples from healthy women of the groups I, II, III, no sterile sample was found in any case. Microorganisms were detected in all urine samples with different species at different proportions between FAB and NAB (Table 1).

Table 1: Urinary microbiota of healthy women
Microorganisms   group I group II group III
% CFU/mL
% CFU/mL % CFU/mL
Facultative anaerobic bacteria (FAB)
CNS 90.9 102 83.8 103 60.0* 102
Corynebacterium spp. 90.9 102 75.0* 102 50.0* 102
Enterococcus spp. 36.4 102 12.5* 102 70.0* 102
Micrococcus spp. 18.2 102 12.5 102 20.0* 102
Klebsiella spp. 18.2 102 0 0 0 0
S. aureus 18.2 102 16.7 102 0 0
Streptococcus spp. 9.1 102 8.3 102 0 0
Candida spp. 9.1 102 33.3* 102 0 0
Bacillus spp. 0 102 20.8 102 0 0

E. coli

0 102 16.7 102 20.0 104
Non-clostridial anaerobic bacteria (NAB)
Lactobacillus spp. 81.8 104 83.3 104 10.0* 102
Peptococcus spp. 72.7 103 75.0 103 45.0* 102
Propionibacterium spp. 72.7 103 58.3* 104 50.0 102
Eubacterium spp. 54.5 104 41.7* 105 50.0 102
Peptostreptococcus spp. 45.5 103 41.7 103 60.0* 102
Bacteroides spp. 18.2 103 25.0 104 0
Veillonella spp. 0 0 16.7 103 40.0* 102
Prevotella spp. 0 0 12.5 102 15.0 102
Actinomyces spp. 0 0 8.3 102 0
Megasphaera 0 0 0 0 55.0 102
Mobiluncus spp. 0 0 0 0 20.0 103
Fusobacterium spp. 0 0 0 0 20.0 102

Note:
% – frequency of detection (%)
CFU/mL – the average level of bacteriuria (CFU/ml)
* – statistical significant difference between groups (р<0.05)

For urine of healthy women of all age groups, the dominance of coagulase-negative staphylococci (CNS), Corynebacterium spp., Peptococcus spp., Propionibacterium spp., Eubacterium spp., and Peptostreptococcus spp. was typical. In the urine of postmenopausal women, Enterococcus spp. are more frequent (p<0.05). The dominance of Lactobacillus spp. in urine of young women (group I and II) is opposed by their rare (10%) detection in urine of postmenopausal women. E. coli, Veillonella spp., Prevotella spp. appeared more frequently in the urine of sexually active women and postmenopausal women than in the urine of sexually not active young women. Some FAB species were not found in the urine of healthy postmenopausal women. The lowest detectable degree of FAB bacteriuria (102 CFU/ml) was found for almost all microorganisms, except for E. coli in postmenopausal women (104 CFU/ml). On the contrary, the level of bacteriuria for most of NAB for young women was between 103 and 105 CFU/ml and for postmenopausal women this level was reduced to the lowest detectable level (102 CFU/ml).

In an unpublished study we conducted a study comparing three midstream urine samples obtained at 8.00, 12.00, 16.00 hours in a single day from 20 healthy, sexually active women aged 18–20 years. In general insignificant daily fluctuations of frequencies and levels of bacteriuria were found (Figure 1) with the exception of certain genera, as confirmed by cluster analysis.

Figure 1: Frequency of detection (%) and average number (lg CFU/ml) of microorganisms detected from healthy women’s urine.

In conclusion, the urine of healthy women of all age groups is not sterile and is dominated by Gram-positive and not Gram-negative species of FAB and NAB.

3.2 Urinary microbiota of healthy men

Midstream morning urine samples were collected three times with an interval of 3 days from 20 sexually active, healthy (criteria see above) men aged 20–25 years and cultivated on the expanded set of culture media as mentioned above (Table 2).

Table 2: Urinary microbiota of healthy men
Microorganisms Frequency of detection (%)   The average level of bacteriuria (CFU/ml)
Facultative anaerobic bacteria (FAB)    
CNS 89.3 102
Corynebacterium spp. 78.6 102
Enterococcus spp. 50.0 102
E. coli 10.7 102
S. aureus 10.7 102
Non-clostridial anaerobic bacteria (NAB)
Eubacterium spp. 78.6 103
Peptostreptococcus spp. 50.5 102
Bacteroides spp. 21.4 103
Peptococcus spp. 21.4 102
Megasphaera 21.4 102
Propionibacterium spp. 10.7 102
Veillonella spp. 10.7 102
Mobiluncus spp. 10.7 103
Fusobacterium spp. 10.7 102

In the urine of healthy men there is a prevalence of CNS, Corynebacterium spp., and Enterococcus spp. among the FAB, and Eubacterium spp., and Peptostreptococcus spp. among the NAB. The NAB patterns ranged twice as wide as compared with the FAB patterns. The levels of bacteriuria for FAB and NAB were at the lower level of detection.

3.3 Comparison between urinary microbiota of healthy women and men

The comparison was conducted for the young sexually active groups. The urinary microbiota of men and women were similar in the dominant frequency of CNS and Corynebacterium spp. However, the following differences were found: The FAB range found in men was twice as narrow as that found in women. The spectra of NAB in men and women differed: in men Lactobacillus spp., Actinomyces spp. were absent, but Megasphaera spp., Mobiluncus spp., and Fusobacterium spp. could be detected in contrast to women.

The cluster analysis of the microbiological results revealed typical “female” and “male” urinary microbiota spectra (Figure 2). In mixed clusters men were more similar to men than men to women. The majority of female urinary microbiota (66.6 per cent) were found in mixed clusters, which means higher differences in the urinary microbiota of women than of men.

Figure 2: Hierarchical clustering of urinary microbiota in healthy men and women
Note: m - male; f - female

Our bacteriological results of urinary microbiota in healthy individuals, using an expanded set of culture media, correspond with other studies. Siddiqui et al. [42] found by high throughput sequencing of 16S RNA amplicons 45 different species of microorganisms in the female urine microbiota with predominance of Lactobacillus spp., Prevotella spp., and Gardnerella spp.

Fouts et al. [43] revealed the dominant role of Corynebacterium spp. in the urinary microbiome of healthy men. Lactobacillus spp., Corynebacterium spp., Gardnerella spp., Prevotella spp., and Enterococcus spp. showed differences between both genders. These results suggest that the state of healthy urine is, in fact, one of “asymptomatic bacteriuria”. In our studies presented above urine of healthy sexually active men revealed also a prevalence of FAB with CNS (89.3%) and Corynebacterium spp. (78.6%).

In a study by Wolfe et al. [33] the bacterial spectra of urine collected during normal urination, through a transurethral catheter (TUC) and taken by suprapubic aspiration (SPA) were compared. The presence of bacteria in these samples was assessed by bacterial culture, light microscopy, and 16S rRNA gene sequencing. Fourteen genera out of 321 total (5%) in samples obtained by TUC and SPA were present in different relative abundances. Of those 14 genera, only Lactobacillus represented more than 1% of the total sequences present in either the TUC (26.96%) or SPA (6.94%) samples. The most abundant genera found for TUC samples were similar to those found for SPA urine samples.

From their results the authors concluded that standard clinical microbiological procedures favor detection of fast-growing bacteria only in the presence of oxygen. They consistently underestimate slow-growing bacteria and can detect neither anaerobic bacteria nor those whose preferred growth conditions remain unknown. As an example the authors discussed a clinical observation. that urine, obtained from a participant and determined by standard cultivation procedures to be positive for E. coli, was rich in DNA associated with the fastidious genera Aerococcus (40% and 50% in SPA and TUC, respectively) and Actinobaculum (25% and 17%) yet poor in DNA identified with E. coli (3% and 1%). The disparity between the culture and molecular assays raised the question: are this woman’s clinical symptoms due to the relatively small number of the “typical” uropathogenic E. coli, the numerically superior fastidious bacteria, or a combination of both?

In this context the authors stated further, that “the likelihood that diverse bacteria can exist within the female urinary tract has important implications for urinary tract disorder researchers. These findings should stimulate work to advance our understanding of the roles played by these bacterial communities in the development of UTI and other urinary tract disorders that remain poorly understood. Such studies could make it possible to identify at-risk UTI populations and allow hypothesis-based research of improved targeted treatments and/or prevention efforts”.

These studies, including ours, may provide a new prospect on the concept of “normal (asymptomatic) bacteriuria”, and on additional infectious agents causing inflammatory diseases of the urinary tract.

3.4 Acute complicated (obstructive) pyelonephritis

The majority (>90%) of patients with acute obstructive pyelonephritis present with bacteriuria of ≥105 CFU/ml of Enterobacteriaceae or some Gram-positive species (S. aureus, S. saprophyticus, Enterococcus spp.) as the main etiological pathogens. Since according to our studies urine of healthy individuals does not only contain species of Enterobacteriaceae, but also a wide spectrum of CNS, Corynebacterium spp., and NAB, the involvement of these microorganisms in the development and clinical course of acute obstructive pyelonephritis (AOP) may be of interest. Consequently we studied the urinary microbiota of the renal pelvis immediately after release of the ureter obstruction.

Our research [44] included 72 patients (18–74 years) with AOP, caused by ureteral stone with obstruction lasting 1–14 days. For culture urine from the bladder was obtained by catheterization and from the renal pelvis by ureteral catheter or percutaneous nephrostomy immediately after release of the ureteral obstruction. Bacteriological examination of urine was performed using an expanded set of culture media as mentioned above.

Study results of the microbiota found in the bladder and renal pelvis urine are presented in Table 3.

Table 3: Microbiota of bladder and renal pelvis urine in AOP
Microorganisms   Bladder urine
(n – 72)
Renal pelvis urine
(n – 68)
% CFU/mL (range)   CFU/mL (mean) % CFU/mL (range) CFU/mL (mean)
Enterobacteriaceae 80.5 102–108 104.7 80.8 102–107 104.8
E. coli 52.7 102–108 104.9 52.9 102–107 104.7
Klebsiella spp. 19.4 102–107 104.4 19.1 102–106 104.1
Proteus spp. 6.9 104–105 104.6 7.3 103–105 104.4
Providencia rettgeri 1.3 105 105.0 1.4 103 103.0
Nonfermentative Gram-negative bacteria
Burkholderia cepacia 1.3 106 106.0 1.4 105 105.0
Gram-positive flora 63.8 102–106 102.8 52.9 102–106 102.1
CNS 44.4 102–106 103.2 27.9* 102–106 103.4
Corynebacterium spp. 30.5 102–105 102.7 16.1* 102–104 102.6
Enterococcus spp. 30.5 102–105 103.1 19.1* 102–103 102.4
S. aureus 5.5 102 102.0 7.3 102 102.0
Micrococcus spp. 1.3 102 102.0 - - -
Bacillus sp. 1.3 102 102.0 - - -
NAB 94.4 102–105 102.4 89.7 102–106 103.0
Eubacterium spp. 50.5 102–105 103.1 39.7* 102–105 103.2
Peptococcus spp. 36.1 102–105 102.4 27.9* 102–106 103.5
Peptostreptococcus spp. 30.5 102–105 102.8 22.0* 102–105 103.9
Propionibacterium spp. 29.1 102–105 102.2 17.6* 102–104 103.2
Bacteroides spp. 13.8 102–105 102.3 13.2 102–105 103.3
Fusobacterium spp. - - - 5.8 102 102.0
Veillonella spp. - - - 4.4 102 102.0
Megasphaera spp. 1.3 102 102.0 - - -
Lactobacillus spp. 16.7 102–103 102.5 16.7 102–103 102.5
Fungal flora
Candida tropicalis 1.3 102 102.0 1.4 102 102.0

Note:
* – statistical significant differences between groups (p<0.05)
% – frequency of detection (%)
CFU/mL (range) – range of bacteriuria (CFU/ml)
CFU/mL (mean) – mean level of bacteriuria (CFU/ml)

The study showed a high frequency (81.8%) of Gram-negative bacteria in the bladder urine at AOP, which are common uropathogens. To a lesser extent (63.8%) a wide range of Gram-positive bacteria was identified in the urine. The highest frequency (94.4%) was demonstrated for NAB. It is remarkable that the level of bacteriuria for Enterobacteriaceae had a wide range (102–108 CFU/mL) and only in 30.5% of cases a level of ≥105 CFU/ml, and in 49.2% a level of ≥104 CFU/ml was found. At the same time a high level of bacteriuria (≥104 CFU/ml) was found in 8.8% for Gram-positive bacteria (CNS, Corynebacterium spp., and Enterococcus spp.) and 31.3% for NAB.

The microbiota of the bladder and renal pelvis urine were comparable concerning spectrum, frequency and level of bacteriuria for Enterobacteriaceae. The Gram-positive microflora and NAB, however, showed a significantly reduced frequency in the renal pelvis urine, but concerning the five main NAB species the average level of bacteriuria in the renal pelvis was higher than the level of the bladder bacteriuria. The bacteriuria levels of Gram-positive bacteria were similar for bladder and renal pelvis urine.

Thus, the study confirms the validity of the bacteriological evaluation of bladder urine for the detection of pathogens, related to the development of acute pyelonephritis after ureteral obstruction.

In all of the 72 cases the urinary microbiota included three or more taxons of microorganisms. In 94.4% of the cases an aerobic-anaerobic composition was found, but in only 5.6% a purely aerobic one. In 29.2% of the cases, the level of bacteriuria was ≥104 CFU/ml for at least 2 taxons. Considering the wide range of microorganisms found in the urine of the renal pelvis, the question arises, which of the taxons finally initiated or potentiated the pyelonephritis?

3.5 Experimental modeling of acute obstructive pyelonephritis

Using the AOP animal model published by Giamarellos-Bourboulis et al. [45] 60 male rabbits of the New Zealand breed were randomly divided into six groups of 10 animals each. Bacterial suspension of NAB (volume 1 ml containing 105 CFU/ml) obtained from AOP patients were injected into the renal pelvis of the animals:

  • Group 1 – E. coli
  • Group 2 – Peptococcus spp.
  • Group 3 – Eubacterium spp.
  • Group 4 – Propionibacterium spp.
  • Group 5 – Bacteroides spp.
  • Group 6 – E. coli + Peptococcus spp.

The animals were killed on day 1, 3, 7, 14 and 21 of the experiment. Pathomorphologic studies of the kidney samples were performed using tissue preparations stained with hematoxylin-eosin.

Experimental AOP caused by E. coli showed typically morphological alterations [46], [47] and served as control.

All animals in groups 2–6 developed morphological features of acute pyelonephritis. As a result of ureteral obstruction in all animals an acute kidney inflammatory reaction took place already on the first day of the experiment. In group 2 on the first day pyelitis and peripyelitis were observed. On days 2–3 a septic phlebitis and arteritis developed, and on days 3–7 foci of papillomatosis and infarctions of the cortex and medulla were observed.

In group 3 formation of microabscesses was detected on the first day, and on the third day heart attacks, papillary necrosis and contralateral kidney damage occured. In group 4, serofibrinous pelvis inflammation was registered from the 1st day, from 1st–3rd day pyelitis and peri-pyelitis, and from the 3rd–7th day minimum inflammatory reactions of the renal medulla were seen. In group 5, acute inflammation of the renal interstitial tissue (medulla) developed on the 1st day, and on the 3rd–7th day microabscesses of the renal parenchyma were seen. In group 6 from the 1st day onwards, pyelitis, peri-pyelitis, a serious suppurative inflammation of the medulla, and septic thrombophlebitis were noted, on the 3rd–7th days hemorrhagic necroses of the renal parenchyma developed, and all animals died up to the 14th day.

Thus, in experimental animals with ureteral obstruction, NAB inoculated into the renal pelvis reproduced morphological features of acute purulent inflammation of the renal pelvis and renal parenchyma. Strains of Propionibacterium spp. basically provoked pyelitis and peri-pyelitis with a minimal involvement of kidney parenchyma, but Peptococcus spp. provoked the development of inflammatory reactions similar to E.coli. Monovariant Eubacterium spp. and Bacteroides spp. cause more severe alterations of kidney destruction compared to alterations caused by E. coli. Mixed infection E. coli + Peptococcus spp. was responsible for the most severe kidney destruction in form of abscesses, heart attacks, hemorrhagic necrosis and finally animals’ death.

The severity of (ascending) renal damage in the animal experiments could be ranked as shown in Figure 3:

Figure 3: The severity of (ascending)
renal damage in the animal experiment  

3.6 Urine microbiota in women with recurrent uncomplicated lower urinary tract infections (ULUTI)

In 25–30% of cases acute cystitis is caused by Enterobacteriaceae and by some Gram-positive species with a level of bacteriuria <105 CFU/ml [48], [49], [50]. According to the recommendations of the EAU bacteriuria ≥104 CFU/ml is considered diagnostically significant in symptomatic recurrent infections of the lower urinary tract [51]. The same uropathogenic bacteria are considered to cause pyelonephritis.

We performed bacteriological examination of the morning midstream urine from 144 women (20–50 years) with an acute cystitis of recurrent ULUTI (Table 4). Duration of recurrent ULUTI: <1 year (14.3%), 2–4 years (35.4%) and >5 years (50.3 %). All patients had been previously treated repeatedly with antibiotics.

Table 4: Urine microbiota of women with ULUTI
Microorganisms The frequency of detection (%) Range (CFU/ml)   Meanlevel of bacteriuria (CFU/ml)
Enterobacteriaceae    
E. coli 35.5 102–106 104.2
Klebsiella spp. 9.7 102–106 104.0
Enterobacter spp. 9.1 102–105 103.4
Citrobacter spp. 6.9 102–107 103.8
Proteus spp. 4.8 102–107 105.7
Providencia rettgeri 2.1 106 106.0
Nonfermentative gram-negative bacteria
Pseudomonas spp. 4.2 106 106.0
Gram-positive flora
CNS 65.2 102–104 102.7
Corynebacterium spp. 61.1 102–105 102.5
Enterococcus spp. 28.5 102–103 102.4
Streptococcus spp. 12.5 102 102.0
S. aureus 10.4 102–105 103.3
Candida spp. 26.4 102–105 103.0
NAB
Propionibacterium spp. 50.7 102–104 102.6
Peptococcus spp. 48.6 102–106 103.2
Eubacterium spp. 42.4 102–105 103.1
Lactobacillus spp. 40.9 102–105 103.4
Peptostreptococcus spp. 29.2 102–105 103.2
Bacteroides spp. 11.1 102–104 102.7
Actinomyces spp. 7.6 102–104 102.5
Fusobacterium spp. 6.2 102–103 102.3
Prevotella spp. 5.5 103 103.0

The proportion of Enterobacteriaceae in the microbiota was 68.1%, while E. coli was cultured only in 35.5% of the cases. The isolation frequency of Klebsiella spp. and Enterobacter spp. from urine was higher in this than in other studies. Overall, the level of bacteriuria ≤103CFU/ml with Enterobacteriaceae was detected in 36.7% of cases, and that ≥104 CFU/ml in 63.3%. The spectrum of Gram-positive bacteria and NAB were identical with the urine microbiota of healthy women. However, their frequency was lower and the level of bacteriuria significantly higher than in healthy subjects.

Thus, the qualitative composition of the urine microbiota in female patients with acute cystitis was practically identical to that in healthy women with increasing frequency of detection and levels of bacteriuria with Enterobacteriaceae. However, it is not known whether such a low number (≤103 CFU/mL) of Enterobacteriaceae can cause acute cystitis, or whether the infection is caused by organisms of all other taxa in the presence of Enterobacteriaceae. After all in 27.7% of cases with ULUTI such uropathogens (Enterobacteriaceae, Pseudomonas spp., Enterococcus spp., S. aureus, S. saprophyticus) were not found in the urine of these patients. It seems likely that on standard culture media hardly cultivated and/or non-cultivated microorganisms may have been involved in the development of such an acute cystitis episode. With an expanded set of culture media in all cases of ULUTI aerobic-anaerobic bacterial compositions could be identified assuming that such "unproven" bacteria were the pathogens of the recurrent cystitis.

4 Further Research

Further studies are needed to elucidate the role of hardly cultivated microorganisms found in the urine of healthy individuals, in the development of symptomatic infections of upper and lower urinary tract. The levels of bacteriuria of dominant bacterial taxons should be determined and their ability to cause symptomatic infections of the upper and lower urinary tract. It is advisable to improve the standard of the classic bacteriological examination of the urine.

5 Conclusion

Polymicrobial bacteriuria should be considered normal condition of healthy individuals. The concepts of significant bacteriuria (≥105 CFU/ml) as proposed by Kass E. [52], pathogenic bacteriuria, “asymptomatic bacteriuria”, and contamination need to be reconsidered. A number of NAB species are symbiotes in the urine of healthy individuals, but can also cause acute septic renal infection, similarly to E. coli. The proof of two or more bacterial species in the urine of patients with OAP at a concentration of ≥1045 CFU/ml allows to consider them as causative in the development of a renal inflammatory process.

6 Acknowledgement

We thank the staff of the departments of Urology and Microbiology for their help in collecting material, laboratory of bioinformatics, medical statistics and computer modeling for assistance in statistical data processing, as well as the patients for agreeing to participate in research.


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[3] Greenwood D, Barer M, Slack R, Irving W. Medical Microbiology - A Guide to Microbial Infections: Pathogenesis, immunity, laboratory investigation and control. Edinburgh: Churchill Livingstone/Elsevier; 2012.
[4] Hilt EE, McKinley K, Pearce MM, Rosenfeld AB, Zilliox MJ, Mueller ER, Brubaker L, Gai X, Wolfe AJ, Schreckenberger PC. Urine is not sterile: use of enhanced urine culture techniques to detect resident bacterial flora in the adult female bladder. J Clin Microbiol. 2014 Mar;52(3):871-6. DOI: 10.1128/JCM.02876-13
[5] Maskell RM. The natural history of urinary tract infection in women. Med Hypotheses. 2010 May;74(5):802-6. DOI: 10.1016/j.mehy.2009.12.011
[6] Lewis DA, Brown R, Williams J, White P, Jacobson SK, Marchesi JR, Drake MJ. The human urinary microbiome; bacterial DNA in voided urine of asymptomatic adults. Front Cell Infect Microbiol. 2013;3:41. DOI: 10.3389/fcimb.2013.00041
[7] Brubaker L, Wolfe AJ. The new world of the urinary microbiota in women. Am J Obstet Gynecol. 2015 Nov;213(5):644-9. DOI: 10.1016/j.ajog.2015.05.032
[8] Cary EN, Dirita V, Dermody TS. Schaechters Mechanisms of microbial disease. 5th ed. Philadelphia: Wolters Kluwer Lipincott Williams and Wilkins; 2013. p. 360.
[9] Pearce MM, Zilliox MJ, Rosenfeld AB, Thomas-White KJ, Richter HE, Nager CW, Visco AG, Nygaard IE, Barber MD, Schaffer J, Moalli P, Sung VW, Smith AL, Rogers R, Nolen TL, Wallace D, Meikle SF, Gai X, Wolfe AJ, Brubaker L; Pelvic Floor Disorders Network. The female urinary microbiome in urgency urinary incontinence. Am J Obstet Gynecol. 2015 Sep;213(3):347.e1-11. DOI: 10.1016/j.ajog.2015.07.009
[10] Mandell GL. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed. London: Elsevier; 2015.
[11] Wilson ML, Gaido L. Laboratory diagnosis of urinary tract infections in adult patients. Clin Infect Dis. 2004 Apr;38(8):1150-8. DOI: 10.1086/383029
[12] Bank S, Hansen TM, Søby KM, Lund L, Prag J. Actinobaculum schaalii in urological patients, screened with real-time polymerase chain reaction. Scand J Urol Nephrol. 2011 Dec;45(6):406-10. DOI: 10.3109/00365599.2011.599333
[13] Bank S, Jensen A, Hansen TM, Søby KM, Prag J. Actinobaculum schaalii, a common uropathogen in elderly patients, Denmark. Emerging Infect Dis. 2010 Jan;16(1):76-80. DOI: 10.3201/eid1601.090761
[14] Cattoir V. Actinobaculum schaalii: review of an emerging uropathogen. J Infect. 2012 Mar;64(3):260-7. DOI: 10.1016/j.jinf.2011.12.009
[15] Reinhard M, Prag J, Kemp M, Andresen K, Klemmensen B, Højlyng N, Sørensen SH, Christensen JJ. Ten cases of Actinobaculum schaalii infection: clinical relevance, bacterial identification, and antibiotic susceptibility. J Clin Microbiol. 2005 Oct;43(10):5305-8. DOI: 10.1128/JCM.43.10.5305-5308.2005
[16] Darbro BW, Petroelje BK, Doern GV. Lactobacillus delbrueckii as the cause of urinary tract infection. J Clin Microbiol. 2009 Jan;47(1):275-7. DOI: 10.1128/JCM.01630-08
[17] Lawson PA, Falsen E, Akervall E, Vandamme P, Collins MD. Characterization of some Actinomyces-like isolates from human clinical specimens: reclassification of Actinomyces suis (Soltys and Spratling) as Actinobaculum suis comb. nov. and description of Actinobaculum schaalii sp. nov. Int J Syst Bacteriol. 1997 Jul;47(3):899-903. DOI: 10.1099/00207713-47-3-899
[18] Lee YS, Kim JY, Kim JC, Park WH, Choo MS, Lee KS. Prevalence and treatment efficacy of genitourinary mycoplasmas in women with overactive bladder symptoms. Korean J Urol. 2010 Sep;51(9):625-30. DOI: 10.4111/kju.2010.51.9.625
[19] Schulte TL. Bacteroides and anaerobic streptococci in infection of the urinary tract. Proc Mayo Clin. 1939;14:536.
[20] Kumazawa J, Kiyohara H, Momose S. Significance of anaerobic bacteria isolated from the urinary tract. II. Experimental studies. Invest Urol. 1976 Jan;13(4):309-12.
[21] Sapico FL, Wideman PA, Finegold SM. Aerobic and anaerobic flora in bladder urine of patients with indwelling urethral catheters. Urology. 1976 Apr;7(4):382-4. DOI: 10.1016/0090-4295(76)90251-X
[22] Brook I. Urinary tract infection caused by anaerobic bacteria in children. Urology. 1980 Dec;16(6):596-8. DOI: 10.1016/0090-4295(80)90566-X
[23] Apostolopoulou C, Konstantoulaki S, Androulakakis P, Vatopoulou T, Varkarakis M. Isolation of anaerobic organisms from kidney in serious renal infections. Urology. 1982 Nov;20(5):479-81. DOI: 10.1016/0090-4295(82)90117-0
[24] Duprey KM, McCrea L, Rabinowitch BL, Azad KN. Pyelonephritis and Bacteremia from Lactobacillus delbrueckii. Case Rep Infect Dis. 2012;2012:745743. DOI: 10.1155/2012/745743
[25] Nabokova IuL, Gudima IA, Kogan MI, Chernitskaia ML. [Bacterial spectrum of the urine in young healthy women]. Urologiia. 2010 Sep-Oct;(5):7-10.
[26] Naboka IuL, Gudima IA, Ibishev KhS, Miroshnichenko EA, Kogan MI, Vasil'eva LI. [Etiological structure and antibiotic sensitivity of uropathogens in chronic recurrent infection of the lower urinary tract]. Urologiia. 2011 Nov-Dec;(6):12-5.
[27] Kogan MI, Naboka YL, Ibishev KS, Gudima IA, Naber KG. Human urine is not sterile - shift of paradigm. Urol Int. 2015;94(4):445-52. DOI: 10.1159/000369631
[28] Kogan MI, Pasechnik DG, Naboka IuL, Ibishev KhS, Gazaev ZI, Gudima IA. [Non-clostridial anaerobic bacteria can cause acute pyelonephritis (an experimental trial)]. Urologiia. 2012 Mar-Apr;(2):8-13.
[29] Naboka IuL, Kogan MI, Gudima IA, Tchernitskaia ML, Ibishev KhS, Khasigov AV, Mitusova EV. [Role of nonclostridial anaerobes in the development of infectious and inflammatory diseases of the urinary and reproductive systems]. Urologiia. 2013 Nov-Dec;(6):118-21.
[30] Naboka IuL, Kogan MI, Vasil'eva LI, Gudima IA, Miroshnichenko EA, Ibishev KhS. [Bacterial mixed infection in women with chronic recurrent cystitis]. Zh Mikrobiol Epidemiol Immunobiol. 2011 Jan-Feb;(1):8-12.
[31] Pearce MM, Hilt EE, Rosenfeld AB, Zilliox MJ, Thomas-White K, Fok C, Kliethermes S, Schreckenberger PC, Brubaker L, Gai X, Wolfe AJ. The female urinary microbiome: a comparison of women with and without urgency urinary incontinence. MBio. 2014 Jul;5(4):e01283-14. DOI: 10.1128/mBio.01283-14
[32] Wolfe AJ, Brubaker L. "Sterile Urine" and the Presence of Bacteria. Eur Urol. 2015 Aug;68(2):173-4. DOI: 10.1016/j.eururo.2015.02.041
[33] Wolfe AJ, Toh E, Shibata N, Rong R, Kenton K, Fitzgerald M, Mueller ER, Schreckenberger P, Dong Q, Nelson DE, Brubaker L. Evidence of uncultivated bacteria in the adult female bladder. J Clin Microbiol. 2012 Apr;50(4):1376-83. DOI: 10.1128/JCM.05852-11
[34] Groah S, Perez-Losada M, Caldovic L, Ljungberg I, Sprague B, Castro-Nallar E, Shah N, Hsieh M, Pohl H. Pyuria and asymptomatic bacteriuria is associated with novel and specific urine microbiomes. J Urol. 2015;193(4):e226. DOI: 10.1016/j.juro.2015.02.980
[35] Nelson DE, Van Der Pol B, Dong Q, Revanna KV, Fan B, Easwaran S, Sodergren E, Weinstock GM, Diao L, Fortenberry JD. Characteristic male urine microbiomes associate with asymptomatic sexually transmitted infection. PLoS ONE. 2010 Nov;5(11):e14116. DOI: 10.1371/journal.pone.0014116
[36] Nickel JC, Stephens A, Chen J, Melton-Kreft R, Spirk T, Earl J, O'Toole M, Costerton JW, vanBokhoven A, Mullins C, Ehrlich G. Application of state-of-the-art methods to search for microbial contributions to the etiology of urological chronic pelvic pain syndrome (UCPPS). J Urol. 2013;189(4):e468-9. DOI: 10.1016/j.juro.2013.02.782
[37] Dong Q, Nelson DE, Toh E, Diao L, Gao X, Fortenberry JD, Van der Pol B. The microbial communities in male first catch urine are highly similar to those in paired urethral swab specimens. PLoS ONE. 2011;6(5):e19709. DOI: 10.1371/journal.pone.0019709
[38] Hooton TM, Roberts PL, Cox ME, Stapleton AE. Voided midstream urine culture and acute cystitis in premenopausal women. N Engl J Med. 2013 Nov;369(20):1883-91. DOI: 10.1056/NEJMoa1302186
[39] Imirzalioglu C, Hain T, Chakraborty T, Domann E. Hidden pathogens uncovered: metagenomic analysis of urinary tract infections. Andrologia. 2008 Apr;40(2):66-71. DOI: 10.1111/j.1439-0272.2007.00830.x
[40] Khasriya R, Sathiananthamoorthy S, Ismail S, Kelsey M, Wilson M, Rohn JL, Malone-Lee J. Spectrum of bacterial colonization associated with urothelial cells from patients with chronic lower urinary tract symptoms. J Clin Microbiol. 2013 Jul;51(7):2054-62. DOI: 10.1128/JCM.03314-12
[41] Aagaard K, Luna R.A, Versalovic J. The Human Microbiome of Local Body Sites and Their Unique Biology. In: Mandell GL, editor. Principles and Practice of infectious Diseases. 8th ed. London: Elsevier; 2015. p. 11-18.
[42] Siddiqui H, Nederbragt AJ, Lagesen K, Jeansson SL, Jakobsen KS. Assessing diversity of the female urine microbiota by high throughput sequencing of 16S rDNA amplicons. BMC Microbiol. 2011 Nov;11:244. DOI: 10.1186/1471-2180-11-244
[43] Fouts DE, Pieper R, Szpakowski S, Pohl H, Knoblach S, Suh MJ, Huang ST, Ljungberg I, Sprague BM, Lucas SK, Torralba M, Nelson KE, Groah SL. Integrated next-generation sequencing of 16S rDNA and metaproteomics differentiate the healthy urine microbiome from asymptomatic bacteriuria in neuropathic bladder associated with spinal cord injury. J Transl Med. 2012 Aug;10:174. DOI: 10.1186/1479-5876-10-174
[44] Naboka YL, Kogan MI, Mitusova EV, Gudima IA. Microbiota bladder and pelvis urine in complicated infections of the upper urinary tract. European Urology Supplements. 2015;14(2): e259-e259a. DOI: 10.1016/S1569-9056(15)60257-3
[45] Giamarellos-Bourboulis EJ, Adamis T, Laoutaris G, Sabracos L, Koussoulas V, Mouktaroudi M, Perrea D, Karayannacos PE, Giamarellou H. Immunomodulatory clarithromycin treatment of experimental sepsis and acute pyelonephritis caused by multidrug-resistant Pseudomonas aeruginosa. Antimicrob Agents Chemother. 2004 Jan;48(1):93-9.
[46] Zeidan S, El Ghoneimi A, Peuchmaur M, Bingen E, Bonacorsi S. Effect of partial ureteral obstruction and bacterial virulence on the occurrence of renal scarring in a mouse model. Urology. 2012 Aug;80(2):486.e1-7. DOI: 10.1016/j.urology.2012.02.020
[47] Pasechnik DG, Kogan MI, Naboka JL, Ibishev H, Gazaev Z, Gudima I. The experimental model of obstructive acute pyelonephritis induced non-clostridial infection. Plenary Oral Free Paper Sessions. Virchows Archiv. 2011 Aug;459(S1):1–329. DOI: 10.1007/s00428-011-1113-y
[48] Stamm WE, Counts GW, Running KR, Fihn S, Turck M, Holmes KK. Diagnosis of coliform infection in acutely dysuric women. N Engl J Med. 1982 Aug;307(8):463-8. DOI: 10.1056/NEJM198208193070802
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[52] Kass EH. Chemotherapeutic and antibiotic drugs in the management of infections of the urinary tract. Am J Med. 1955 May;18(5):764-81. DOI: 10.1016/0002-9343(55)90190-X

The ZB MED – Information Center for Life Sciences, Germany, together with the European Association of Urology (EAU) provided the opportunity to publish a “Living Textbook” on “Urogenital Infections and Inflammations” in an open access form. This “Living Textbook” represents also an update of the Textbook on Urogenital Infections published 2010 by the International Consultation on Urological Infections and the EAU: http://www.icud.info/urogenitalinfections.html.

The “Living Textbook” will cover infections and inflammations of the kidney, the urinary tract, as well as the male and female genital tract considering pathogenesis, diagnostics, treatment, prophylaxis and future aspects. The “Living Textbook” will be structured into about 26 Sections each with two section co-chairs responsible for peer review of the chapters of each section. Each chapter should reflect the background to the topic and highlight all of the critical evidence relating to the subject. The intention is to provide an up to date, concise synthesis of the literature on that topic, and for clinical topics also recommendations based on levels of evidence for contemporary clinical practice, as well as suggested research recommendations.

The editors hope that this “Living Textbook” may become a useful instrument for physicians of different specialties taking care about patients suffering from these diseases.

Truls E. Bjerklund Johansen (Norway),

Florian ME Wagenlehner (Germany),

Yong-Hyun Cho (South Korea),

Tetsuro Matsumoto (Japan),

John N Krieger (USA),

Daniel Shoskes (USA),

Kurt G. Naber (Germany).

Publishing at PUBLISSO

Your chapter will be published at the PUBLISSO platform (https://books.publisso.de).

Information for corresponding authors

It is necessary for all corresponding authors to register at PUBLISSO.
To register at PUBLISSO please click the following link: http://books.publisso.de/publisso_gold/register

After registration, please complete your user profile. Information from your user profile will appear in the published chapter and the authors board of the book (http://books.publisso.de/publisso_gold/book/52). If you are displayed in the authors board, you can be contacted by readers and other professionals. You can also contact other authors of the book for exchange and to build a network.
(If you do not want to be displayed in the authors board, but stay registered, you can disable this feature in your profile settings. In this case, your affiliation (publication data) will be displayed in the published chapter only.)

We kindly ask you to provide the co-authors email addresses in the manuscript so that we can contact them in case of queries.

Information for co-authors

After publication of your chapter, your affiliation (publication data) will be displayed in the published chapter.

If you also want to be displayed in the authors board of the book (http://books.publisso.de/publisso_gold/book/52), we kindly ask you to register at PUBLISSO. If you are displayed in the authors board, you can be contacted by readers and other professionals. You can also contact other authors of the book for exchange and to build a network.

To register at PUBLISSO please click the following link: http://books.publisso.de/publisso_gold/register

If you do not want to be displayed in the authors board of the book, you do not have to register. Your affiliation (publication data) will be displayed in the published chapter only.

Support

If you have any further questions please don’t hesitate to contact the PUBLISSO editorial office:

E-Mail: livingbooks@zbmed.de
Phone: +49 221 478-7093

General

The textbook will be structured in sections with two co-chairs each. Each section will start with an introductory chapter written by the two respective co-chairs presented like an editorial commentary in regard to the following chapters (see proposed contents of the book). The two co-chairs of each section will also peer review all chapters in their section and stimulate a consensus discussion within their section together with the authors and the main editors if needed.

Chapters

Each chapter should reflect the background to the topic and highlight all of the critical evidence relating to the subject. The intention is to provide an up to date, concise synthesis of the literature on that topic, and for clinical topics also recommendations based on levels of evidence for contemporary clinical practice, as well as suggested research recommendations.

Manuscript

Each manuscript should have up to approximately 3,000 words (excluding abstract, tables/figures and references). The abstract should count about 300 words.

Structure

The outline of each chapter should be structured as follows (similar as in the edition 2010, which can be downloaded for free: http://www.icud.info/urogenitalinfections.html):

  1. Abstract
  2. Summary of recommendations*/key notes*
    (*which ever term is more appropriate)
  3. Introduction
  4. Methods
  5. Results
  6. Further research
  7. Conclusions
  8. Acknowledgement
  9. Conflict of interest of each author
  10. References

Citation style

As a citation style, the Vancouver style is preferred.

Please mark your references in the text with square brackets ([1], [2], ...).

Summary of recommendations

We would like to have the Summary of recommendations at the beginning after the abstract (as in the edition 2010). However, we do not expect as in the edition 2010, that each recommendation is also specified according to Level of Evidence and Grade of Recommendation, because such a claim would not only need a systematic literature search (see below), but also a structured discussion in a defined group of experts.

Systematic literature search

A systematic literature search should be performed, at least of PUBMED/MEDLINE but ideally of several relevant databases in addition (like Cochrane CENTRAL) to find recent, high quality systematic reviews and/or primary research studies. It is not expected to perform for all chapters a de novo systematic review, if such reviews are already published recently, but it still may be indicated for some items. For questions relating therapy, it should be focused on evidence from (systematic reviews of) randomized controlled trials if available.

The method of the systematic literature search needs to be fully described in the section “Methods”, e.g.:

“A systematic literature search was performed for the last ... (usually 10) years in MEDLINE, Cochrane etc. with the following key words ... and the following limitations: e.g. UTI, age (adult?), ... clinical studies ... English ... abstract available ... only peer reviewed ...

A total of ... publications were identified, which were screened by title and abstract ... After exclusion of duplicates ... a total of ... were included into the review (analysis), supplemented by citations or known to the authors ... ”.

Clinical topics

Clinical topics should be focused on the importance to clinical practice according to the up to date scientific knowledge as presented in the literature. It should relate to questions/complaints/symptoms of patient/population concerning definition, diagnosis, therapy/prevention, intervention, and outcome in comparison, if different approaches are feasible. Please choose patient-important outcomes and focus on those, which you deem critical for decision-making.

Level of evidence and grade of recommendations

Any recommendation should be based on the level of evidence and the grade of recommendation. For this purpose the following system, modified from the Oxford Centre for Evidence-based Medicine should be used (EAU guidelines 2015):

Level of evidence (LE)

Level Type of evidence
1a Evidence obtained from meta-analysis of randomised trials
1b Evidence obtained from at least one randomised trial
2a Evidence obtained from one well-designed controlled study without randomization
2b Evidence obtained from at least one other type of well-designed quasi-experimental study
3 Evidence obtained from well-designed non-experimental studies, such as comparative studies, correlation studies and case reports.
4 Evidence obtained from expert committee reports or opinions or clinical experience of respected authorities.

Grade of Recommendations (GoR)

Grade Nature of recommendations
A Based on clinical studies of good quality and consistency addressing the specific recommendations and including at least one randomised trial
B Based on well-conducted clinical studies, but without randomised clinical trials
C Made despite the absence of directly applicable clinical studies of good quality

Comments (EAU guidelines 2015)

The aim of assigning a LE and grading recommendations is to provide transparency between the underlying evidence and the recommendation given.

It should be noted that when recommendations are graded, the link between the level of evidence and grade of recommendation is not directly linear. Availability of randomized controlled trials may not necessarily translate into a grade “A” recommendation where there are methodological limitations or disparity in published results.

Alternatively, absence of high level evidence does not necessarily preclude a grade A recommendation, if there is overwhelming clinical experience and consensus. In addition, there may be exceptional situations where corroborating studies cannot be performed, perhaps for ethical or other reasons and in this case unequivocal recommendations are considered helpful for the reader. The quality of the underlying scientific evidence - although a very important factor – has to be balanced against benefits and burdens, values and preferences and costs when a grade is assigned.

Since the same rating system should be used in all chapters, for the sake of brevity the same sentence could be used in “Methods” for all manuscripts, because the rating system will be described in details in the Preface of the book:

“The studies were rated according to the level of evidence and the strength of recommendations graded according to a system used in the EAU guidelines modified from the Oxford Centre for Evidence-based Medicine [1].”

References

[1] European Association of Urology. Guidelines. Methodology section. 2015 ed. Arnhem: European Association of Urology; 2015. p. 3. ISBN/EAN: 978-90-79754-80-9. Available from: http://uroweb.org/wp-content/uploads/EAU-Extended-Guidelines-2015-Edn..pdf

The Living Handbook of Urogenital Infections and Inflammations is issued by:

European Association of Urology
att. Maurice Schlief, EAU executive manager business affairs

P.O.Box 30016
NL-6803 AA Arnhem, The Netherlands

Phone: 0031-26-38.90.680
E-mail: m.schlief@uroweb.org

Editor in Chief

responsible for the contents according to § 5 TMG and § 55 Abs. 2 RStV (Germany):

Kurt G. Naber, MD, PhD
Assoc. Professor of Urology

Technical University of Munich
Karl-Bickleder-Str. 44c
94315 Straubing, Germany

E-mail: kurt.naber@nabers.de

John N. Krieger MD, PhD

University of Washington Section of Urology

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Daniel Shoskes MD, PhD

Cleveland Clinic Glickman Urological and Kidney Institute

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Yong-Hyun Cho MD, PhD

St. Mary's Hospital, The Catholic University of Korea Department of Urology

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Tetsuro Matsumoto MD, PhD

University of Occupational and Environmental Health Department of Urology

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Florian M. E. Wagenlehner MD, PhD

Justus-Liebig University of Giessen Clinic of Urology and Andrology

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Truls Erik Bjerklund Johansen MD, PhD

Oslo University Hospital Urology Department

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Kurt G. Naber MD, PhD

Technical University of Munich

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Punit Bansal MD, PhD

R G Stone and Super Specialty Hospital
Department of Urology

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Riccardo Bartoletti

University of Pisa
Department of Translational Research and New Technologies

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Truls Erik Bjerklund Johansen MD, PhD

Oslo University Hospital
Urology Department

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PD Dr. med. Gernot Bonkat

University Basel
alta uro AG, Merian Iselin Klinik, Center of Biomechanics & Calorimetry (COB)

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Prof. Tommaso Cai MD

Santa Chiara Regional Hospital
Dept. of Urology

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Dr Leyland Chuang

Ng Teng Fong Hospital, National University Health System
Department of Medicine

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Prof. Milan Cizman

University Medical Centre
Department of Infectious Diseases

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Alison Crawford MSc

Queen's University
Department of Psychology

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Pfofessor Svetlana Dubrovina MD, PhD

Rostov Medical State University
Obstetrics and Gynaecology

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Dr Valerie Huei Li Gan MBBS (S'pore), MRCS (Edin), MMed (Surg), FAMS (Urology)

Singapore General Hospital
Department of Urology

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Philip Hanno

University of Pennsylvania

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Ass prof MD Gundela Holmdahl

Queen Silvia Childrens Hospital, Sahlgrens Academy
Pediatric surgery and urology

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Udo B. Hoyme

HELIOS Hospital Erfurt Ltd.
Department of Gynecology and Obstetrics

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David Hunstad

Washington University School of Medicine
Pediatrics / Molecular Microbiology

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Gitte M. Hvistendahl

Aarhus University Hospital

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Prof. Michael KOGAN M.D., PhD

Rostov State Medical University
Department of Urology

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Dr Akihiro Kanematsu

Hyogo College of Medicine
Department of Urology

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Frieder Keller

University Hospital Ulm
Department Internal Medicine 1, Nephrology

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Professor Katarzyna Kilis-Pstrusinska PhD, MD

Wroclaw Medical University
Department of Pediatric Nephrology

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MD, PhD Tae-Hyoung Kim

Chung-Ang University
Urology

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John N. Krieger MD, PhD

University of Washington
Section of Urology

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Prof Ekaterina Kulchavenya

Novosibirsk Research TB Institute, Novosibirsk State Medical University

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Dr Christina Kåbjörn Gustafsson

Ryhov Hospital Jönköping
Pathology

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Dr. Bela Köves

South Pest Teaching Hospital
Department of Urology

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Dr. med. Giuseppe Magistro

Ludwig-Maximilians-University of Munich
Department of Urology

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Vittorio Magri

ASST-North
Urologic Clinic

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András Magyar

South-Pest Hospital
Department of Urology

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Professor Emeritus Brian Morris

University of Sydney
School of Medical Sciences

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Baerbel Muendner-Hensen

ICA-Deutschland e.V.

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Stephen F. Murphy

Feinberg School of Medicine, Northwestern University
Department of Urology

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Kurt G. Naber MD, PhD

Technical University of Munich

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Prof. Yulia Naboka

Rostov State Medical University
Department of Microbiology

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Dr. J. Curtis Nickel MD

Queen's University
Department of Urology

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Professor Ralph Peeker MD PhD

University of Gothenburg
Department of Urology

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Tamara Perepanova

N.A. Lopatkin Research Institute of Urology and Interventional Radiology

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Prof. Gianpaolo Perletti M. Clin. Pharmacol.

University of Insubria
Department of Biotechnology and Life Sciences

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Felice Petraglia

Department of Biomedical, Experimental and Clinical Sciences, University of Florence
Obstetrics and Gynecology

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Michel Pontari

Temple University School of Medicine
Department of Urology

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Dr. Jörgen Quaghebeur PhD. Med. Sci.

University Hospital Antwerp and University Antwerp
Department of Urology

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Yazan F. Rawashdeh

Aarhus University Hospital
Paediatric Urology Section, Department of Urology

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Professor Claus Riedl MD

-
Urology

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Matthew Roberts

The University of Queensland
Faculty of Medicine

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PD Dr. med Guido Schmiemann MPH

Institut für Public Health und Pflegeforschung, Universität Bremen
Abteilung Versorgungsforschung

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Caroline Schneeberger MD PhD

Academic Medical Center (AMC)

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Prof. Dr. med. Peter Schneede

Klinikum Memmingen
Department of Urology

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Aaron C. Shoskes

Des Moines University Medical College of Ostheopathic Medicine

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Daniel Shoskes MD, PhD

Cleveland Clinic
Glickman Urological and Kidney Institute

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Prof. Dr. Roswitha Siener

University of Bonn
University Stone Centre, Department of Urology

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Sofia Sjöström

Queen Silvia Childrens Hospital, Sahlgrens Academy
Pediatric surgery and urology

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Mathew Sorensen

University of Washington School of Medicine
Department of Urology

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Prof. Dr. Dr. Walter Ludwig Strohmaier FEBU

Regiomed-Klinikum Coburg. Medical School Regiomed
Urology and Paediatric Urology

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Satoshi Takahashi

Sapporo Medical University School of Medicine
Department of Infection Control and Laboratory Medicine

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Professor Paul Anantharajah Tambyah

Yong Loo Lin School of Medicine, National University Hospital
Department of Medicine

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Peter Tenke

Jahn Ferenc South Pest Teaching Hospital
Department of Urology

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Praveen Thumbikat


Department of Urology

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Dr. Jose Tiran Saucedo

IMIGO / Universidad de Monterrey
Obstetrics and Gynaecology

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Dominic Tran-Nguyen

Des Moines University

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Dean Tripp

Queen's University
Psychology, Anesthesia & Urology

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Prof. SEONGHEON WIE

The Catholic University of Korea, St. Vincent's Hospital
Division of Infectious Diseases, Department of Internal Medicine

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Florian M. E. Wagenlehner MD, PhD

Justus-Liebig University of Giessen
Clinic of Urology and Andrology

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Assoc. Prof. Christian Wejse

Aarhus University, Aarhus University Hospital
Department of Infectious Diseases/Center for Global Health, Dept of Public Health

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Prof. Dr. Mete Çek

Trakya University, School of Medicine
Urology

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