High Prevalence of Asymptomatic Bacteriuria in Adult Females Detected by M-PCR

Objectives: The prevalence of asymptomatic bacteriuria (ASB) in non-catheterized females has been reported to range from 1 - 50% depending on age (Table 1).1 With recent evidence of the low sensitivity of standard urine culture (SUC),2–11 we aimed to determine the prevalence of ASB in adult females using multiplex polymerase chain reaction (M-PCR).

Methods: Adult (> 18) self-reported “healthy” female volunteers gave written informed consent (Western IRB 20230847) and a provided midstream urine specimen. A total of 349 female subjects from 2 states were recruited from the community (at theaters, sporting events, social gatherings, etc.) between 2/28/2023 and 3/22/2023. All specimens underwent SUC and M-PCR testing (Guidance® UTI, Pathnostics in Irvine, CA) for microbial detection, as previously described.
Symptom status was determined by the US Food and Drug Administration (FDA) symptom scores on the validated American English Acute Cystitis Symptom Score (ACSS) Questionnaire, asking patients to evaluate four typical UTI symptoms: urinary frequency, urinary urgency, dysuria, and suprapubic pain, as well as visible blood in the urine, according to each one’s severity (scoring 0–3): no (0), mild (1), moderate (2), severe (3). Asymptomatic cases were defined as having four FDA symptom scores adding up to < 4, none of the four symptom scores being > 1, and the absence of visible blood in the urine. Bacteriuria was defined as >1 microorganism detected at a density >10,000 cells/mL by M-PCR.

Results: Only 6 subjects (2%) had bacteriuria detected by SUC but not M-PCR and 101 (29%) had bacteriuria detected by M-PCR but not SUC. We found a high (79 - 85%) prevalence of ASB in adult females and this prevalence did not change significantly with age.
The number of participants with the given result is labeled above each bar (n = x). “Asymptomatic” and “Symptomatic” refer to the results of the validated American English Acute Cystitis Symptom Score (ACSS) Questionnaire.
Prevalence (%) of Bacteriuri and Symptoms by age group legend: Figure 2. Prevalence of Bacteriuria and Symptoms by age group. Bar height represents the percentage of all participants in a particular age group with the bacteriuria. The percentage and number of participants with the given result is labeled above each bar (n = x). Differences across age groups were not significant by the Chi-square test.

Conclusions: We found the prevalence of ASB in healthy adults in the community is considerably higher than has been reported in previous literature and does not vary significantly across age groups. This finding is consistent with the emerging understanding of the urine microbiome and has implications for the interpretation of bacteriuria in screening programs and clinical testing.