Screening for chronic prostatitis pathogens using high-throughput next-generation sequencing

Genetic insights into gut microbiota and risk of prostatitis: a Mendelian randomization study

Background

The dysbiosis of gut microbiota (GM) is considered a contributing factor to prostatitis, yet the causality remains incompletely understood.

Methods

The genome-wide association study (GWAS) data for GM and prostatitis were sourced from MiBioGen and FinnGen R10, respectively. In the two-sample Mendelian randomization (MR) analysis, inverse variance weighting (IVW), MR-Egger, weighted median, simple mode, weighted mode, and maximum likelihood (ML) methods were utilized to investigate the causal relationship between GM and prostatitis. A series of sensitivity analysis were conducted to confirm the robustness of the main results obtained from the MR analysis.

Results

According to the IVW results, genus Sutterella (OR: 1.37, 95% CI: 1.09-1.71, p = 0.006) and genus Holdemania (OR: 1.21, 95% CI: 1.02-1.43, p = 0.028) were associated with an increased risk of prostatitis. The phylum Verrucomicrobia (OR: 0.76, 95% CI: 0.58-0.98, p = 0.033) and genus Parasutterella (OR: 0.84, 95% CI: 0.70-1.00, p = 0.045) exhibited a negative association with prostatitis, indicating a potential protective effect. Sensitivity analysis showed that these results were not affected by heterogeneity and horizontal pleiotropy. Furthermore, the majority of statistical methods yielded results consistent with those of the IVW analysis.

Conclusions

In this study, we identified two GM taxon that might be protective against prostatitis and two GM taxon that could increase the risk of developing prostatitis. These findings could potentially provide a valuable theoretical basis for the future development of preventive and therapeutic strategies for prostatitis.

Causal effect of gut microbiota on the risk of prostatitis: a two-sample Mendelian randomization study

BACKGROUND

Recent studies demonstrated that chronic prostatitis (CP) is closely related to the gut microbiota (GM). Nevertheless, the causal relationship between GM and CP has not been fully elucidated. Therefore, the two-sample Mendelian randomization (MR) analysis was employed to investigate this association.

METHODS

The summary data of gut microbiota derived from a genome-wide association study (GWAS) involving 18,340 individuals in the MiBioGen study served as the exposure, and the corresponding summary statistics for CP risk, representing the outcome, were obtained from the FinnGen databases (R9). The causal effects between GM and CP were estimated using the inverse-variance weighted (IVW) method supplemented with MR-Egger, weighted median, weighted mode, and simple mode methods. Additionally, the false discovery rate (FDR) correction was performed to adjust results. The detection and quantification of heterogeneity and pleiotropy were accomplished through the MR pleiotropy residual sum and outlier method, Cochran's Q statistics, and MR-Egger regression.

RESULTS

The IVW estimates indicated that a total of 11 GM taxa were related to the risk of CP. Seven of them was correlated with an increased risk of CP, while the remained linked with a decreased risk of CP. However, only Methanobacteria (OR 0.86; 95% CI 0.74-0.99), Methanobacteriales (OR 0.86; 95% CI 0.74-0.99), NB1n (OR 1.16; 95% CI 1.16-1.34), Methanobacteriaceae (OR 0.86; 95% CI 0.74-0.99), Odoribactergenus Odoribacter (OR 1.43; 95% CI 1.05-1.94), and Sutterellagenus Sutterella (OR 1.33; 95% CI 1.01-1.76) still maintain significant association with CP after FDR correction. Consistent directional effects for all analyses were observed in the supplementary methods. Subsequently, sensitivity analyses indicated the absence of heterogeneity, directional pleiotropy, or outliers concerning the causal effect of specific gut microbiota on CP (p > 0.05).

CONCLUSION

Our study demonstrated a gut microbiota-prostate axis, offering crucial data supporting the promising use of the GM as a candidate target for CP prevention, diagnosis, and treatment. There is a necessity for randomized controlled trials to validate the protective effect of the linked GM against the risk of CP, and to further investigate the underlying mechanisms involved.

Gut microbiome in men with chronic prostatitis/chronic pelvic pain syndrome: profiling and its predictive significance

PURPOSE

To investigate the difference in gut microbiome composition between patients with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) and healthy controls, and to assess the potential of gut microbiota as predictive markers for CP/CPPS risk.

METHODS

The present study included 41 CP/CPPS patients and 43 healthy controls in China. Fecal specimen data were obtained and analysed using 16S rRNA gene sequencing. Alpha and beta-diversity indices, relative microbiome abundances, cluster analysis, and linear discriminant analysis effect size (LEfSe) were employed. Microbial biomarkers were selected for the development of a diagnostic classification model, and the functional prediction was conducted using PICRUSt2.

RESULTS

Alpha-diversity measures revealed no statistically significant difference in bacterial community structure between CP/CPPS patients and controls. However, significant differences were observed in the relative abundances of several bacterial genera. Beta-diversity analysis revealed a distinct separation between the two groups. Significant inter-group differences were noted at various taxonomic levels, with specific bacterial genera being significantly different in abundance. The LEfSe analysis indicated that three bacterial species were highly representative and seven bacterial species were low in CP/CPPS patients as compared to the control group. A diagnostic model for CP/CPPS based on microbial biomarkers exhibited good performance. PICRUSt2 functional profiling indicated significant differences in the development and regeneration pathway.

CONCLUSION

Significant differences in the gut microbiome composition were found between groups. The study provided a novel diagnostic model for CP/CPPS based on microbiota, presenting promising potential for future therapeutic targets and non-invasive diagnostic biomarkers for CP/CPPS patients.

Human Male Genital Tract Microbiota

The human body is vastly colonised by microorganisms, whose impact on health is increasingly recognised. The human genital tract hosts a diverse microbiota, and an increasing number of studies on the male genital tract microbiota suggest that bacteria have a role in male infertility and pathological conditions, such as prostate cancer. Nevertheless, this research field remains understudied. The study of bacterial colonisation of the male genital tract is highly impacted by the invasive nature of sampling and the low abundance of the microbiota. Therefore, most studies relied on the analysis of semen microbiota to describe the colonisation of the male genital tract (MGT), which was thought to be sterile. The aim of this narrative review is to present the results of studies that used next-generation sequencing (NGS) to profile the bacterial colonisation patterns of different male genital tract anatomical compartments and critically highlight their findings and their weaknesses. Moreover, we identified potential research axes that may be crucial for our understanding of the male genital tract microbiota and its impact on male infertility and pathophysiology.

Prostate diseases and microbiome in the prostate, gut, and urine

The microbiome in various organs involves a vast network that plays a key role in the health and wellness of the human body. With recent advances in biological technologies such as high-throughput sequencing, transcriptomics, and metabolomics, it appears that the microbial signature varies dynamically among individuals, creating various roles in metabolism, local and systemic inflammation, and host immunity. Urinary and genital organs, including the prostate, seminal vesicles, and urinary bladder, are reservoirs of several bacterial, viral, and fungal communities. Accumulating evidence has suggested profound roles for the gut, urinary, and intraprostate microbiomes in genitourinary benign and malignant diseases. This review article addresses microbiome-related evidence for three major diseases involved in prostate cancer: chronic prostatitis (CP), benign prostatic hyperplasia (BPH), and prostate cancer (PCa). Symptomatic CP is known as CP/chronic pelvic pain syndrome. CP is one of the most common prostate diseases in young men, accounting for 8% of all men visiting a urologic clinic. Although oral medication is the gold standard therapy for patients with BPH, approximately 13% of men present with clinical progression within 4 years after the initiation of treatment, with 5% requiring surgical intervention. The identification of proinflammatory cytokines and pathogens responsible for the clinical progression of BPH is still underway. Several topics regarding the association between PCa and the microbiome are discussed in this review as follows: i) intraprostatic microbiome and the risk of PCa, ii) gut microbiome and PCa, iii) gut microbiome and the risk of radiation-induced side effects, iv) isoflavone intake and equol-producing intestinal flora on PCa, and v) the inhibitory effect of daidzein and equol on tumor growth and progression of PCa. Further studies are required for a comprehensive understanding between the urogenital microbiome and prostate pathogenesis to facilitate the development of preventive and therapeutic approaches for prostate diseases.

Antibiotic therapy of chronic bacterial prostatitis is more effective considering antibiotic susceptibility of all pathogens isolated

Purpose

Because of the insufficient efficacy of the current treatment of chronic bacterial prostatitis (CBP), it is justified to search for a more effective antibiotic therapy (ABT).

Materials and Methods

This single-centre prospective observational comparative study was conducted in 2012 to 2019 (patients: 60 men with CBP; age: 20–45 y). The clinical examination was performed on admission and at 1, 3, 6, or 12 months. All patients underwent the Meares–Stamey test to obtain expressed prostatic secretion (EPS) and/or post-massage urine (PMU) samples for extended bacteriological examination. The patients were randomly divided into 2 treatment groups (30/30 patients): group I, fluoroquinolones (FQs); group II, a combination of FQs with cephalosporins/macrolides with a treatment duration of 1 month.

Results

Patients of both groups had severe symptomatic CBP with an average duration of 4 years. Twenty-three microorganisms (15 aerobes, 9 anaerobes) were identified in PMU. At 3 months follow-up, a positive clinical effect was noted in both groups, which was significant (p<0.05) only in group II concerning NIH-CPSI questionnaire, leukocyturia, prostate volume, maximum urine flow, and decreased pathospermia. At 6 months follow-up, in group II the frequency of Escherichia coli and Enterococcus spp. decreased significantly. In group I aerobes changed only insignificantly from the initial level, but anaerobes increased significantly. In group II the titers of both, aerobes and anaerobes, were significantly lower (p<0.05) at 6 months follow-up as compared to initial values.

Conclusions

ABT targeting all taxa in EPS/PMU is a more effective alternative to standard therapeutic regimens for CBP.

The Firmicutes/Bacteroidetes ratio of the human gut microbiota is associated with prostate enlargement

BACKGROUND

The pathophysiology of the prostate enlargement underlying lower urinary tract symptoms is unknown. Meanwhile, the gut microbiota can contribute to various host conditions. We hypothesized that the gut microbiota plays a role in prostate enlargement.

METHODS

We included 128 patients who underwent prostate biopsies at our hospitals between December 2018 and March 2020, excluding those who had used antibiotics within the past 6 months and those who were diagnosed with prostate cancer of cT3 or higher. Patients with prostate volumes ≥30 ml were defined as the prostate-enlargement (PE) group; those with prostate volumes <30 ml were defined as the non-PE group. Their gut microbiotas were analyzed via 16S rRNA metagenomic analyses of rectal swab samples and were compared between the groups.

RESULTS

The PE group included 66 patients; the non-PE group included 62 patients. Age, body mass index, and prostate-specific antigen levels did not significantly differ between the groups. Linear discriminant analysis effect size analysis indicated a higher proportion of Firmicutes and Actinobacteria in the PE group and a higher proportion of Bacteroidetes in the non-PE group. The Firmicutes/Bacteroidetes (F/B) ratio was significantly higher in the PE group than in the non-PE group (2.21 ± 0.39 vs. 1.61 ± 0.40, p = 0.015).

CONCLUSION

The F/B ratio of the gut microbiota was associated with prostate enlargement. Although the detailed mechanisms are unclear, the gut microbiota might affect prostate enlargement.

Does the microbiota spectrum of prostate secretion affect the clinical status of patients with chronic bacterial prostatitis?

OBJECTIVE

To explore the influence of the microbiota of prostate secretion on the clinical status of patients with chronic bacterial prostatitis.

METHODS

This was an observational, single-center, comparative study. We evaluated the survey cards of 230 outpatients aged 18-45 years with a history of prostatitis from 2012 to 2019. As a result, 170 outpatients were selected for the study. All patients underwent an assessment of symptoms using International Prostate Symptom Score-quality of life, National Institutes of Health-Chronic Prostatitis Symptom Index, International Index of Erectile Function, pain visual analog scale. A bacteriological study (after the Meares-Stamey test) of post-massage urine was carried out on an extended media set. The following parameters were determined in each patient: leukocyturia and bacteriuria, serum testosterone and total prostate-specific antigen levels. Uroflowmetry, transrectal prostate ultrasound with color duplex mapping and ejaculate analysis were also carried out.

RESULTS

Aerobic-anaerobic bacterial associations were identified in all patients. Three comparison groups were identified depending on the microbiota's spectrum (in post-massage urine): aerobes prevailed in group 1 (n = 67), anaerobes prevailed in group 2 (n = 33), and the levels of aerobic and anaerobic bacteriuria were higher than ≥10³  colony-forming units per mL in group 3 (n = 70). It was found that the severity of clinical symptoms (urination disorders, sexual dysfunction etc.) of chronic bacterial prostatitis, laboratory and instrumental changes (testosterone, prostate-specific antigen, prostate volume etc.) in groups 2 and 3 were significantly higher than in group 1.

CONCLUSION

In patients with chronic bacterial prostatitis, a predominance of anaerobes or a combination of aerobes and anaerobes in a titer of ≥10³  colony-forming units per mL in post-massage urine is associated with worse clinical status.

Culture-independent Next Generation Sequencing of Urine and Expressed Prostatic Secretions in Men With Chronic Pelvic Pain Syndrome

OBJECTIVE

To compare standard cultures and next-generation sequencing (NGS) in men with chronic prostatitis/chronic pelvic pain syndrome (CPPS). CPPS shares clinical features with urinary tract infections, but bacteria are seldom found. NGS is more sensitive than standard cultures.

MATERIALS AND METHODS

Men diagnosed with CPPS (National Institute of Health Category III) underwent traditional cultures and NGS of their urine and expressed prostatic secretions (EPS). Characteristics between groups were compared statistically.

RESULTS

Thirty-one men with CPPS were included (mean age 44.5). All standard urine cultures were negative, and 3 EPS cultures were positive. Seventy-eight unique microbes were detected with NGS, including uropathogens in 10 of the men. There were no bacteria identified by NGS in EPS that were not also found in the urine. Men with positive NGS did not differ from those without in age, symptom severity or phenotype. Men with typical urinary tract infection symptoms (eg, dysuria, chills) were more likely to have uropathogens detected on NGS relative to men without such symptoms. Nine patients were prescribed antibiotics based on their NGS findings, but only 1 exhibited symptom improvement (11%).

CONCLUSION

NGS commonly identified bacteria in CPPS patients, but these did not localize to the prostate. NGS positivity did not correlate with symptom severity and antibiotic therapy was seldom effective. NGS detected uropathogens more frequently in those with clinical symptoms suggestive of urinary tract infection. Clinical trials are needed to examine the utility of NGS-guided antibiotics in this subpopulation.

Urinary Microbiota-Are We Ready for Prime Time? A Literature Review of Study Methods' Critical Steps in Avoiding Contamination and Minimizing Biased Results

Within the last few years, there have been an increased number of clinical studies involving urinary microbiota. Low-biomass microbiome sequencing (e.g., urine, lung, placenta, blood) is easily biased by contamination or cross-contamination. So far, a few critical steps, from sampling urine to processing and analyzing, have been described (e.g., urine collection modality, sample volume size, snap freezing, negative controls usage, laboratory risks for contamination assessment, contamination of negative results reporting, exploration and discussion of the impact of contamination for the final results, etc.) We performed a literature search (Pubmed, Scopus and Embase) and reviewed the published articles related to urinary microbiome, evaluating how the aforementioned critical steps to obtain unbiased, reliable results have been taken or have been reported. We identified different urinary microbiome evaluation protocols, with non-homogenous reporting systems, which can make gathering results into consistent data for similar topics difficult and further burden the already so complex emerging field of urinary microbiome. We concluded that to ease the progress in this field, a joint approach from researchers, authors and publishers would be necessary in order to create mandatory reporting systems which would allow to recognize pitfalls and avoid compromising a promising field of research.

Screening for chronic prostatitis pathogens using high-throughput next-generation sequencing

BACKGROUND

The pathogens responsible for chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS; NIH category III) are not currently known. the present study utilized high-throughput next-generation sequencing to screen for potential pathogens associated with NIH category III CP (CP III).

METHODS

This study included 33 patients with CP III and 30 healthy men, from which one sample each of urethral secretions and expressed prostatic secretion (EPS) was collected. High-throughput next-generation sequencing was performed to detect the sequence variations and the relative abundance of the bacterial 16S ribosomal variable region and fungal internal transcribed spacer region in all samples. Bioinformatics software and databases were used for data analysis, and differences with P < .05 were considered statistically significant.

RESULTS

Unweighted pair group method with arithmetic mean (UPGMA) cluster analysis, principal component analysis (PCA), and Spearman's rank correlation showed that the microbial compositions of the urethral secretions and EPS collected from the same subject were essentially the same.

CONCLUSIONS

No potential pathogens were identified in diagnosed patients with CP III. The EPS may be free from bacteria before and after infection. Changes in the urinary tract microbiome may disrupt the microecological balance of the urinary system, thereby leading to CP III. Conversely, the true pathogens of CP III may not be prokaryotic or eukaryotic microorganisms, Future research may involve the evaluation of noncellular microbes.