Increasing International Prostate Symptom Score predicts presence of bacteria within the bladder in the absence of urinary tract infection
Bacteria have been identified in urine deemed sterile by standard culture and have been shown to influence lower urinary tract symptoms (LUTS). We define the relationship between International Prostate Symptom Score (IPSS) and the bladder microbiome.
Catheterized urine specimens (CUS) were collected from 49 adult men: 29 with benign prostatic hyperplasia (BPH)/LUTS based on IPSS who were undergoing BPH surgery, and 20 asymptomatic males (ASM) undergoing non-BPH surgery. Men with preoperative urinary tract infection, history of urinary retention or instrumentation were excluded. CUS were obtained prior to administration of perioperative antibiotics and expanded quantitative urine culture (EQUC) and 16S rRNA sequencing were performed. EQUC utilizes 100x more urine, additional media and environmental conditions, with double the incubation period of standard culture. Colonies grown were identified using mass spectrometry. Relative proportions of bacterial species/genera identified by either method were compared to patient IPSS scores using chi-square tests.The odds ratios for IPSS category and BPH associated with presence of bacteria were reported from univariable logistic regression models.
We detected bacteria in 20/49 (40.8%) of patients: 3/18 (16.7%) men with mild LUTS, 4/10 (40.0%) men with moderate LUTS and 13/21 (61.9%) men with severe LUTS (p = 0.017). There was no difference between patients with and without bacteria with respect to age, race, ethnicity, BMI, tobacco use, hypertension diabetes and circumcised status. An increase in IPSS category was associated with significantly higher odds of detectable bacteria (OR: 2.81, 95% CI: 1.34-5.92). Compared to ASM, men with BPH were over eight times more likely to have bacteria detected (OR: 8.03, 95% CI: 1.92-33.62). Men with severe LUTS were found to have more Streptococcus species (p = 0.025).
Increasing IPSS predicts the presence of bacteria in the bladders of non-instrumented, non-infected men. Those with severe LUTS are likely to harbor Streptococcus species compared to mildly and moderately symptomatic men. Further characterization of the male urinary microbiome may elucidate a pathophysiological relationship to LUTS.
Funding: Internal Funding (Loyola University Stritch School of Medicine Research Funding Committee, LU-207906)