Emerging and Fastidious Uropathogens Were Detected by M-PCR with Similar Prevalence and Cell Density in Catheter and Midstream Voided Urine Indicating the Importance of These Microbes in Causing UTIs

Abstract

Introduction

This study compared microbial compositions of midstream and catheter urine specimens from patients with suspected complicated urinary tract infections to determine if emerging and fastidious uropathogens are infecting the bladder or are contaminants.

Methods

Urine was collected by in-and-out catheter (n = 1000) or midstream voiding (n = 1000) from 2000 adult patients (≥60 years of age) at 17 DispatchHealth sites across 11 states. The two groups were matched by age (mean 81 years), sex (62.1% female, 37.9% male), and ICD-10-CM codes. Microbial detection was performed with multiplex polymerase chain reaction (M-PCR) with a threshold for “positive detection” ≥ 10,000 cells/mL for bacteria or any detection for yeast. Results were divided by sex.

Results

In females, 28 of 30 microorganisms/groups were found by both collection methods, while in males 26 of 30 were found by both. There were significant overlaps in the detection and densities of classical uropathogens including Escherichia coli, Enterococcus faecalis, and Klebsiella pneumoniae, as well as emerging uropathogens including Actinotignum schaalii and Aerococcus urinae. In females, detection rates were slightly higher in midstream voided compared to catheter-collected (p = 0.0005) urine samples, while males showed the opposite trend (p < 0.0001). More polymicrobial infections were detected in midstream voided compared to catheter-collected samples (64.4% vs 45.7%, p < 0.0001) in females but the opposite in males (35.6% vs 47.0%, p = 0.002).

Discussion

In-and-out catheter-collected and midstream voided urine specimens shared significant similarities in microbial detections by M-PCR, with some differences found for a small subset of organisms and between sexes.

Conclusion

Non-invasive midstream voided collection of urine specimens for microbial detection and identification in cases of presumed UTI does not result in significantly more contamination compared to in-and-out catheter-collected specimens. Additionally, organisms long regarded as contaminants should be reconsidered as potential uropathogens.

Keywords:

• urinary tract infection
• standard urine culture
• diagnostic testing
• multiplex polymerase chain reaction
• catheter
• midstream voided

Abbreviations

CFU, colony forming unit; CoNS, coagulase-negative Staphylococcus; P-AST, pooled-antibiotic susceptibility testing; M-PCR, multiplex-polymerase chain reaction; SUC, standard urine culture; UTI, urinary tract infection; VGS, Viridans group streptococcus.

Data Sharing Statement

All relevant data are within manuscript text, figures, and tables.

Ethics Approval and Informed Consent

Data from the study was collected via a database for which the the subject cannot be readily identified or contacted. The Western Institutional Review Board deemed the use of the data to be exempt under 45 CFR § 46.104(d)(4) as the information is used in a manner that the identity of the subject cannot be readily ascertained directly or through identifiers linked to the subjects, the subject is not contacted, and the investigator will not re-identify subjects.

Acknowledgment

The authors thank Laura Parnell from Precision Consulting and Michael Percaccio from Pathnostics for reviewing the manuscript.

Disclosure

D.B., N.L., E.H., R.A.F., and M.M. are employees of Pathnostics, and D.W. and X.Z. are paid consultants of Pathnostics. L.A.A. reports personal fees from Pathnostics, outside the submitted work. In addition, N.L. has patents (10,160,991, 11,053,532, 17/335,767, 63/493,416, AU2018254514 B2, BR112019021943-9 B1 and NZ 759292) issued to Pathnostics; pending patents (17/178,091 17/880,227 63/503,939) to Pathnostics. D.B. reports patents (US10160991, US11053532, US17178091, US17335767, AU2018254514B2, BR1120190219439B1, NZ759292) issued to PATHNOSTICS; pending patents (US17830227, US18351385, US18351286, US63493416, US63503393, US63514785, PCTUS2216816, PCTUS2277477, EP3612638, JP2022042545, CA3175879, CA3176586, CA3061015, HK620200143373, CN2018800399569, IL294577) to PATHNOSTICS. The authors report no other conflicts of interest in this work.

Additional information

Funding

Pathnostics funded the study.