Microbial population diversity in the urethras of healthy males and males suffering from nonchlamydial, nongonococcal urethritis

Microbiota of Urine, Glans and Prostate Biopsies in Patients with Prostate Cancer Reveals a Dysbiosis in the Genitourinary System

Prostate cancer (PCa) is the most common malignant neoplasm with the highest worldwide incidence in men aged 50 years and older. Emerging evidence suggests that the microbial dysbiosis may promote chronic inflammation linked to the development of PCa. Therefore, this study aims to compare the microbiota composition and diversity in urine, glans swabs, and prostate biopsies between men with PCa and non-PCa men. Microbial communities profiling was assessed through 16S rRNA sequencing. The results indicated that α-diversity (number and abundance of genera) was lower in prostate and glans, and higher in urine from patients with PCa, compared to non-PCa patients. The different genera of the bacterial community found in urine was significantly different in PCa patients compared to non-PCa patients, but they did not differ in glans and prostate. Moreover, comparing the bacterial communities present in the three different samples, urine and glans show a similar genus composition. Linear discriminant analysis (LDA) effect size (LEfSe) analysis revealed significantly higher levels of the genera Streptococcus, Prevotella, Peptoniphilus, Negativicoccus, Actinomyces, Propionimicrobium, and Facklamia in urine of PCa patients, whereas Methylobacterium/Methylorubrum, Faecalibacterium, and Blautia were more abundant in the non-PCa patients. In glans, the genus Stenotrophomonas was enriched in PCa subjects, while Peptococcus was more abundant in non-PCa subjects. In prostate, Alishewanella, Paracoccus, Klebsiella, and Rothia were the overrepresented genera in the PCa group, while Actinomyces, Parabacteroides, Muribaculaceae sp., and Prevotella were overrepresented in the non-PCa group. These findings provide a strong background for the development of potential biomarkers with clinical interest.

Malignant Prostate Tissue Is Associated with Different Microbiome Gene Functions

Specific microorganisms and changes in the constituents of the microbiome are linked with pathologies in humans, such as malignancy. Within the prostate, certain bacterial communities may locate advantageous conditions and establish themselves, thus outperforming alternative species. In this study, a comparison of malignant (MT) and benign prostate tissues (BT) or benign prostate hyperplasia (BPH) was performed in order to delineate the respective microbiomes in each sample type and to determine their pertinence to prostatic tumourigenesis. Specimens of MT (n = 26) and PT (n = 13)/BPH (n = 10) were acquired from patients. No variations in the make-up of the microbiome were seen when MT and PT specimens were compared. Changes in the bacterial constituents and functional genes were seen in the specimens obtained from patients with MT when contrasted against samples from those with BPH. Pelomonas was the genus with the highest abundance in MT specimens. It is proposed that dissimilar microbiome gene functions are present in the contexts of MT and PT samples.

Choice of 16S Ribosomal RNA Primers Impacts Male Urinary Microbiota Profiling

Accessibility to next-generation sequencing (NGS) technologies has enabled the profiling of microbial communities living in distinct habitats. 16S ribosomal RNA (rRNA) gene sequencing is widely used for microbiota profiling with NGS technologies. Since most used NGS platforms generate short reads, sequencing the full-length 16S rRNA gene is impractical. Therefore, choosing which 16S rRNA hypervariable region to sequence is critical in microbiota profiling studies. All nine 16S rRNA hypervariable regions are taxonomically informative, but due to variability in profiling performance for specific clades, choosing the ideal 16S rRNA hypervariable region will depend on the bacterial composition of the habitat under study. Recently, NGS allowed the identification of microbes in the urinary tract, and urinary microbiota has become an active research area. However, there is no current study evaluating the performance of different 16S rRNA hypervariable regions for male urinary microbiota profiling. We collected urine samples from male volunteers and profiled their urinary microbiota by sequencing a panel of six amplicons encompassing all nine 16S rRNA hypervariable regions. Systematic comparisons of their performance indicate V1V2 hypervariable regions better assess the taxa commonly present in male urine samples, suggesting V1V2 amplicon sequencing is more suitable for male urinary microbiota profiling. We believe our results will be helpful to guide this crucial methodological choice in future male urinary microbiota studies.

Microbiome Compositions From Infertile Couples Seeking In Vitro Fertilization, Using 16S rRNA Gene Sequencing Methods: Any Correlation to Clinical Outcomes?

Background

Bacterial infections are usually suspected in infertile couples seeking IVF with no clear understanding of the microbial compositions present in the seminal fluids and vaginal niche of the patients. We used next-generation sequencing technology to correlate microbiota compositions with IVF clinical outcomes.

Methods

Thirty-six couples were recruited to provide seminal fluids and vaginal swabs. Bacterial DNA was extracted, and V4 region of the 16S rRNA was amplified and sequenced in a pair-end configuration on the Illumina MiSeq platform rendering 2 × 150 bp sequences. Microbial taxonomy to species level was generated using the Greengenes database. Linear discriminant analysis (LDA) effect size (LEfSe) was used to identify biologically and statistically significant differences in relative abundance.

Results

Seminal fluid microbiota compositions had lower bacterial concentrations compared with the vagina, but species diversity was significantly higher in seminal fluid samples. Azoospermic subjects had more relative abundance of Mycoplasma and Ureaplasma. In Normospermic semen, Lactobacillus (43.86%) was the most abundant, followed by Gardnerella (25.45%), while the corresponding vaginal samples, Lactobacillus (61.74%) was the most abundant, followed by Prevotella (6.07%) and Gardnerella (5.86%).

Conclusions

Semen samples with positive IVF were significantly colonized by Lactobacillus jensenii (P=0.002), Faecalibacterium (P=0.042) and significantly less colonized by Proteobacteria, Prevotella, Bacteroides, and lower Firmicutes/Bacteroidetes ratio compared with semen samples with negative IVF. Vaginal samples with positive IVF clinical outcome were significantly colonized by Lactobacillus gasseri, less colonized by Bacteroides and Lactobacillus iners. This study has opened a window of possibility for Lactobacillus replenishments in men and women before IVF treatment.

The bacterial microbiota in first-void urine from men with and without idiopathic urethritis

Background

Non-gonococcal urethritis (NGU) is a common syndrome in men. NGU may have several causes, but many cases are caused by sexually transmitted infections that may also cause complications in their female partners. Chlamydia trachomatis and Mycoplasma genitalium are the most common causes of NGU, but in up to 35% of the cases, none of the known viral or bacterial causes are found. Traditionally, pathogens have been detected using various culture techniques that may not identify all species present in the urethra. To address this, we used culture-independent methods for analysis of the male urethral microbiota.

Methods

This case-control study analysed first void urine samples, collected at STD clinics in Stockholm, Sweden from men with idiopathic urethritis (IU), i.e. negative for Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma genitalium, Ureaplasma urealyticum, Trichomonas vaginalis, adenovirus, and herpes simplex virus type 1 and -2 together with samples from men without urethritis. Forty-six controls and 39 idiopathic urethritis patients were analysed.

Results

The microbiota was highly diverse: None of the 302 operational taxonomic units (OTUs) found in negative controls and IU patients were found in all of the samples or even in all of the samples in one group. More than 50% of the OTUs were only found in one or two of the total of 85 samples. Still the most dominant 1/6 of the genera constituted 79% of the sequences.

Hierarchical clustering in a heatmap showed no specific clustering of patients or controls.

A number of IU patient samples were dominated by a single genus previously related to urethritis (Gardnerella, Haemophilus, Ureaplasma).

Conclusion

The male urethra contain a very diverse composition of bacteria, even in healthy controls. NGU may be caused by a number of different bacteria but more studies including a higher number of samples are needed for elucidation of the role of each species.

The Microbiome of the Prostate Tumor Microenvironment

BACKGROUND

The advent of molecular-based methods of identification and characterization of complex microbial populations has led to a new era of microbial discovery. A detailed and comprehensive analysis of the microbial ecosystem of the pathologic and healthy prostate tissues has not been yet reported.

OBJECTIVES

To characterize the microbiome possibly associated to the pathologic prostate microenvironment.

DESIGN, SETTING, AND PARTICIPANTS

The microbiome profile of tumor, peri-tumor, and nontumor tissues was assessed on 16 radical prostatectomy-specimens.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Microbiome analysis was assessed by massive ultradeep pyrosequencing. Bacteria load was expressed as a percentage of the total number of bacteria. The statistical significance of differences among specimen-groups was tested with Friedman's test (Dunn posthoc test) and Wilcoxon rank-sum test.

RESULTS AND LIMITATIONS

Three phyla, six classes, nine orders, 14 families, and 11 genera were above the set threshold value of 1%, respectively. Significant differences in specific microbial populations among tumor/peri-tumor and nontumor prostate specimens were observed at certain taxonomic levels. Among genera, Propionibacterium spp. were the most abundant. Staphylococcus spp. were more represented in the tumor/peri-tumor tissues (p<0.05). The restricted number of specimens represents a potential limitation.

CONCLUSIONS

The prostate contains a plethora of bacteria, which set themselves within the gland with a distribution dependent on the nature of the tissue, thus suggesting a possible pathophysiological correlation between the composition of the local microbial niche and the presence of the tumor itself. Future studies will help to clarify the role of these specific bacteria and their potential to be exploited as new biomarkers.

PATIENT SUMMARY

The pathological prostate is populated by specific microbial populations, whose distribution varies according to the nature of the tissue. This finding opens interesting perspectives for the identification of novel therapeutic approaches and biomarkers.

First Trimester Levels of BV-Associated Bacteria and Risk of Miscarriage Among Women Early in Pregnancy

OBJECTIVES

Prior studies have examined the role of bacterial vaginosis (BV) and increased risk of miscarriage; however the risk has been modest and many BV positive pregnant women deliver at term. BV is microbiologically heterogeneous, and thus the identification of specific BV-associated bacteria associated with miscarriage is warranted.

METHODS

We measured the presence and level of seven BV-associated bacteria prior to 14 weeks gestation among urban pregnant women seeking routine prenatal care at five urban obstetric practices at Temple University Hospital in Philadelphia PA from July 2008 through September 2011. 418 Pregnant women were included in this assessment and 74 experienced a miscarriage.

RESULTS

Mean log concentration of BVAB3 was significantly higher among women experiencing a miscarriage (4.27 vs. 3.71, p value = 0.012). Younger women with high levels of BVAB3 had the greatest risk of miscarriage. In addition, we found a significant decreased risk of miscarriage among women with higher log concentrations of Leptotrichia/Sneathia species or Megasphaera phylotype 1-like species early in pregnancy.

CONCLUSIONS FOR PRACTICE

The identification of selected vaginal bacteria associated with an increased risk of miscarriage could support screening programs early in pregnancy and promote early therapies to reduce early pregnancy loss.

First Trimester Levels of BV-Associated Bacteria and Risk of Miscarriage Among Women Early in Pregnancy

OBJECTIVES

Prior studies have examined the role of bacterial vaginosis (BV) and increased risk of miscarriage; however the risk has been modest and many BV positive pregnant women deliver at term. BV is microbiologically heterogeneous, and thus the identification of specific BV-associated bacteria associated with miscarriage is warranted.

METHODS

We measured the presence and level of seven BV-associated bacteria prior to 14 weeks gestation among urban pregnant women seeking routine prenatal care at five urban obstetric practices at Temple University Hospital in Philadelphia PA from July 2008 through September 2011. 418 Pregnant women were included in this assessment and 74 experienced a miscarriage.

RESULTS

Mean log concentration of BVAB3 was significantly higher among women experiencing a miscarriage (4.27 vs. 3.71, p value = 0.012). Younger women with high levels of BVAB3 had the greatest risk of miscarriage. In addition, we found a significant decreased risk of miscarriage among women with higher log concentrations of Leptotrichia/Sneathia species or Megasphaera phylotype 1-like species early in pregnancy.

CONCLUSIONS FOR PRACTICE

The identification of selected vaginal bacteria associated with an increased risk of miscarriage could support screening programs early in pregnancy and promote early therapies to reduce early pregnancy loss.

Urinary microbiota in patients with prostate cancer and benign prostatic hyperplasia

INTRODUCTION

Inflammation is associated with promotion of the initiation of various malignancies, partly due to bacterial infection-induced microenvironmental changes. However, the exact association between microbiota in urine, seminal fluid and the expressed prostatic secretions and benign prostatic hypertrophy and prostate cancer is not clear.

MATERIAL AND METHODS

In the present study, we investigated the type of microbiota in the expressed prostatic secretions (EPS) of patients with prostate cancer and benign prostatic hyperplasia (BPH) by the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method using universal bacterial primers. In order to understand the possible association between various bacteria and prostate cancer, quantitative real-time PCR assay was performed to quantify the amount of strains of bacteria in urine, EPS and seminal fluid.

RESULTS

The prostate cancer group had a significantly increased number of Bacteroidetes bacteria, Alphaproteobacteria, Firmicutes bacteria, Lachnospiraceae, Propionicimonas, Sphingomonas, and Ochrobactrum, and a decrease in Eubacterium and Defluviicoccus compared to the BPH group. The number of Escherichia coli in the prostate cancer group was significantly decreased in urine and increased in the EPS and seminal fluid, while the number of Enterococcus was significantly increased in the seminal fluid with little change in urine and EPS.

CONCLUSIONS

Based on these results, we suggest that there are significant changes in the microbial population in EPS, urine and seminal fluid of subjects with prostate cancer and BPH, indicating a possible role for these bacteria in these two conditions.

Bacterial vaginosis-associated bacteria in men: association of Leptotrichia/Sneathia spp. with nongonococcal urethritis

BACKGROUND

Approximately 45% of nongonococcal urethritis cases have no identified etiology. Novel bacteria recently associated with bacterial vaginosis (BV) in women may be involved. We evaluated the association of idiopathic nongonococcal urethritis and 5 newly described BV-associated bacteria (BVAB).

METHODS

Heterosexual men 16 years or older attending a sexually transmitted disease clinic in Seattle, Washington, from May 2007 to July 2011 and negative for Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, Mycoplasma genitalium, and Ureaplasma urealyticum-biovar2 were eligible. Cases had urethral discharge or 5 or more polymorphonuclear leukocytes per high-power field in urethral exudates. Controls had no urethral discharge and less than 5 polymorphonuclear leukocytes per high-power field. Urine was tested for Atopobium spp., BVAB-2, BVAB-3, Megasphaera spp., and Leptotrichia/Sneathia spp. using quantitative taxon-directed polymerase chain reaction.

RESULTS

Cases (n = 157) and controls (n = 102) were of similar age, education, and income, and most were white. Leptotrichia/Sneathia spp. was significantly associated with urethritis (24/157 [15.3%] vs. 6/102 [5.9%], P = 0.03). BVAB-2 was more common in cases than in controls (7/157 [4.5%] vs. 1/102 [1.0%], P = 0.15), and BVAB-3 (n = 2) and Megasphaera spp. (n = 1) were only detected in men with urethritis, but these bacteria were found only in men who also had Leptotrichia/Sneathia spp. Atopobium spp. was not associated with urethritis. The quantity of bacteria did not differ between cases and controls. Among treated cases, doxycycline was more effective than azithromycin for clinical cure of men with Leptotrichia/Sneathia spp. (9/10 vs. 7/12, P = 0.16) and BVAB-2 (3/3 vs. 0/3, P = 0.10).

CONCLUSIONS

Leptotrichia/Sneathia spp. may be urethral pathogens or contribute to a pathogenic microbiota that can also include BVAB-2, BVAB-3, and Megasphaera spp. Doxycycline may be more effective than azithromycin against these newly identified bacteria.

Necessity of 16S rRNA gene sequencing for identifying Haemophilus parainfluenzae-like strains associated with opportunistic urinary tract infections

The identification of Haemophilus spp. from urogenital sites can be challenging due to the lack of appropriate media for culturing the organisms and the poor resolution of biochemical methods. By incorporating chocolate agar and 16S rRNA gene sequence analysis in our protocol to identify Haemophilus spp. from urinary specimens, we isolated and characterized 30 genetically homogeneous strains of a cryptic species that is phylogenetically close to, but distinct from, Haemophilus parainfluenzae. Commercial biochemical kits and VITEK 2 could not distinguish between the two species. Over 90 % of the strains were isolated from urine and the urogenital area, made possible with the inclusion of chocolate agar in our urine culture protocol. In contrast, no Haemophilus strains isolated from respiratory specimens were identified as the cryptic genospecies. The cryptic genospecies was associated with urinary tract infections (UTIs) in certain patient populations. Distinct from Haemophilus quentinii that also causes urogenital infection, the cryptic genospecies required V factor (NAD) but not X factor (haemin) to grow. The data indicated that 16S rRNA gene sequencing may be necessary in identifying Haemophilus species and that inaccurate categorization of Haemophilus strains isolated from urogenital specimens based on phenotypic characteristics may prevent accurate diagnosis of UTIs.

Microbiota of the seminal fluid from healthy and infertile men

OBJECTIVE

To explore potential causes of male infertility by determining the composition and structure of commensal bacterial communities in seminal fluids.

DESIGN

Microscopy of Gram-stained semen samples and classification of 16S rRNA gene sequences to determine the species composition of semen bacterial communities.

SETTING

Clinical andrology laboratory and academic research laboratories.

PATIENT(S)

Nineteen sperm donors and 58 infertility patients.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Classification of 16S rRNA gene sequences, clustering of seminal microbial communities, and multiple statistical tests.

RESULT(S)

High numbers of diverse kinds of bacteria were present in most samples of both sperm donors and infertility patients. The bacterial communities varied widely among subjects, but they could be clustered into six groups based on similarities in composition and the rank abundances of taxa. Overall, there were no significant differences between sperm donors and infertility patients. However, multiple statistical tests showed a significant negative association between sperm quality and the presence of Anaerococcus. The results also indicated that many of the bacterial taxa identified in semen also occur in the vaginal communities of some women, especially those with bacterial vaginosis, which suggests that heterosexual sex partners may share bacteria.

CONCLUSION(S)

Diverse kinds of bacteria were present in the human semen, but there were no significant differences between sperm donors and infertility patients. The presence of Anaerococcus might be a biomarker for low sperm quality.

Assessing diversity of the female urine microbiota by high throughput sequencing of 16S rDNA amplicons

Background

Urine within the urinary tract is commonly regarded as "sterile" in cultivation terms. Here, we present a comprehensive in-depth study of bacterial 16S rDNA sequences associated with urine from healthy females by means of culture-independent high-throughput sequencing techniques.

Results

Sequencing of the V1V2 and V6 regions of the 16S ribosomal RNA gene using the 454 GS FLX system was performed to characterize the possible bacterial composition in 8 culture-negative (<100,000 CFU/ml) healthy female urine specimens. Sequences were compared to 16S rRNA databases and showed significant diversity, with the predominant genera detected being Lactobacillus, Prevotella and Gardnerella. The bacterial profiles in the female urine samples studied were complex; considerable variation between individuals was observed and a common microbial signature was not evident. Notably, a significant amount of sequences belonging to bacteria with a known pathogenic potential was observed. The number of operational taxonomic units (OTUs) for individual samples varied substantially and was in the range of 20 - 500.

Conclusions

Normal female urine displays a noticeable and variable bacterial 16S rDNA sequence richness, which includes fastidious and anaerobic bacteria previously shown to be associated with female urogenital pathology.

The microbial communities in male first catch urine are highly similar to those in paired urethral swab specimens

Urine is the CDC-recommended specimen for STI testing. It was unknown if the bacterial communities (microbiomes) in urine reflected those in the distal male urethra. We compared microbiomes of 32 paired urine and urethral swab specimens obtained from adult men attending an STD clinic, by 16S rRNA PCR and deep pyrosequencing. Microbiomes of urine and swabs were remarkably similar, regardless of STI status of the subjects. Thus, urine can be used to characterize urethral microbiomes when swabs are undesirable, such as in population-based studies of the urethral microbiome or where multiple sampling of participants is required.

Characteristic male urine microbiomes associate with asymptomatic sexually transmitted infection

BACKGROUND

The microbiome of the male urogenital tract is poorly described but it has been suggested that bacterial colonization of the male urethra might impact risk of sexually transmitted infection (STI). Previous cultivation-dependent studies showed that a variety of non-pathogenic bacteria colonize the urethra but did not thoroughly characterize these microbiomes or establish links between the compositions of urethral microbiomes and STI.

METHODOLOGY/FINDINGS

Here, we used 16S rRNA PCR and sequencing to identify bacteria in urine specimens collected from men who lacked symptoms of urethral inflammation but who differed in status for STI. All of the urine samples contained multiple bacterial genera and many contained taxa that colonize the human vagina. Uncultivated bacteria associated with female genital tract pathology were abundant in specimens from men who had STI.

CONCLUSIONS

Urine microbiomes from men with STI were dominated by fastidious, anaerobic and uncultivated bacteria. The same taxa were rare in STI negative individuals. Our findings suggest that the composition of male urine microbiomes is related to STI.

Nongonococcal urethritis: new views through the prism of modern molecular microbiology

The rapidly advancing technology of modern molecular microbiology has greatly improved our understanding of the epidemiology of sexually transmitted infections and the etiology and pathogenesis of the diseases they cause. It is now clear that Mycoplasma genitalium accounts for a significant proportion of nonchlamydial nongonococcal urethritis (NGU) cases. DNA sequencing of Ureaplasma spp has revealed a new species, Ureaplasma parvum. This organism may account for much of the colonization observed in asymptomatic men, which confounded many past studies of the role of Ureaplasma spp in NGU. At long last, we can say that Ureaplasma urealyticum is a true pathogen. The use of polymerase chain reaction technology has shown that Trichomonas vaginalis occurs more frequently in men with NGU than had been thought; however, such studies also have demonstrated that it is more prevalent in asymptomatic men. Finally, recent studies have shown that adenovirus should be added to the list of viral causes of NGU.

Molecular Diagnostics and Comparative Genomics in Clinical Microbiology

Initially, the availability of molecular diagnostics was considered a panacea, but replacement of conventional tests for detection and identification of microorganisms by molecular procedures eventually gathered momentum. This chapter describes current state-of-the-art molecular diagnostics and comparative genomics in medical microbiology to provide an understanding of infectious disease over the coming years. Nucleic acid-based tests are being introduced with increasing speed into routine clinical microbiology laboratories. Some of the problems remaining to be solved prior to general acceptance of nucleic acid-mediated detection and identification of microbial pathogens are reviewed. Historic objections are slowly being taken apart, and an accelerated introduction of molecular diagnostics is being pursued in many cases. Clear improvement in clinical testing is achieved by introducing molecular tests. Therefore, swift introduction of such tests into clinical practice is important to be pursued. Several PCR tests show increased sensitivity, excellent specificity, and cost effectiveness highlighting the success of the novel applications in the field of bacterial infections. Finally, some of the problems remaining to be solved prior to general acceptation of nucleic acid-mediated detection and identification of microbial pathogens are also reviewed.

Syndromic approach to sexually transmitted infections in Tunisian women: bacteriological validation

The World Health Organization emphasizes an integrated primary care approach using syndromic management of sexually transmitted infections. The objective of our study was to evaluate the quality of care of the syndromic management of sexually transmitted disease in women in Rabta hospital in Tunisia. Algorithms have been developed for: cervicitis due to Neisseria gonorrhoeae or Chlamydia (algorithm 3a), vaginitis due to Trichomonas vaginalis or Chlamydia trachomatis (algorithm 3b) and vaginitis due to Candida (algorithm 3c). A total of 116 women were enrolled in the study during February 2003 to April 2004. The prevalence of each bacterium was Chlamydia (10%), N. gonorrhoeae (1%), Treponema pallidum (1%), T. vaginalis (5%) and Candida (21%). Algorithm '3a' had a sensitivity of 45%, a specificity of 42% and positive predictive value (PPV) of 11.9%. Algorithm '3b' had a sensitivity of 35.7%, a specificity of 68.9% and PPV of 20.8%. Algorithm '3c' had a sensitivity of 12%, a specificity of 88% and PPV of 33.3%. To improve the sensitivity of the syndromic approach, we suggest improving the quality of history taking.

A molecular analysis of prokaryotic and viral DNA sequences in prostate tissue from patients with prostate cancer indicates the presence of multiple and diverse microorganisms

BACKGROUND

Inflammation, both acute and chronic, is a common feature of prostate histology. While inflammation has been proposed to play an important role in both benign and malignant growth of the prostate, the stimuli for this inflammation remain poorly characterized. Infectious pathogens are potential stimuli for prostatic inflammation.

METHODS

Universal eubacterial PCR was used to test 170 prostate tissue core samples from 30 cancer patients for 16S rDNA gene sequences. Positive PCR products (n=64, 37%) were cloned and sequenced. For comparison, tissue samples from 30 patients were cultured using standard clinical microbiological techniques. DNA samples from 200 additional patients were tested by organism-specific PCR for the presence of Chlamydia trachomatis, Propionibacterium acnes, Trichomonas vaginalis, BK virus, Epstein-Barr virus, human cytomegalovirus, human papillomavirus, and xenotropic murine leukemia-related virus.

RESULTS

16S sequencing results indicated the presence of 83 distinct microorganisms. Microbiological culture isolated markedly fewer species. In general, organism-specific PCR failed to detect multiple organisms previously reported as common in the prostate. There was no significant association between the presence of particular species of bacteria and histologic evidence of acute or chronic inflammation.

CONCLUSIONS

Most prostates from men undergoing prostatectomy (87%) contain bacterial DNA from one or more species. However, the majority of individual tissue core samples were negative, suggesting regional heterogeneity in the presence of bacteria and a lack of a generalized or ubiquitous prostatic flora. Culture results suggest either the "unculturable" nature of species present in the prostate or that 16S rDNA sequences were derived from non-viable bacteria.

Coryneform bacteria in semen of chronic prostatitis patients

Our aim was to compare the presence and species composition of coryneform bacteria in chronic prostatitis patients and controls. Semen of 50 men with inflammatory prostatitis and 59 controls (without pelvic pain/discomfort complaints and leukocytospermia) was investigated. First-catch urine was additionally investigated in 36 men (30 with and 6 without prostatitis). Coryneform bacteria were found in semen of 76% men with inflammatory prostatitis and 83% controls. More than half of the isolates were identified as Corynebacterium seminale. Prostatitis patients with severe leukocytospermia (>1 million white blood cells per ml) harboured significantly more Corynebacterium group G (33% vs. 2%, p = 0.0003) and Arthrobacter sp. (17% vs. 2%, p = 0.03) in comparison with controls. Nine species of coryneforms with high concentration (>or=10,000 CFU per ml) were found in prostatitis patients as against only four species in controls. Half of the men harboured corynebacteria in semen as well as in urine, 22% of men in semen only, and 3% in urine only. The total concentration of coryneforms was greater in semen than in urine (median 5000 vs. 100 CFU per ml, p = 0.053). We suggest that although coryneforms are generally considered as saprophytes, they are not uniform and some species (Corynebacterium group G and Arthrobacter sp.) may be associated with inflammatory prostatitis.