Recurrent E. coli Urinary Tract Infections in Nursing Homes: Insight in Sequence Types and Antibiotic Resistance Patterns.

INTRODUCTION: Recurrent urinary tract infections (rUTI) largely contribute to antibiotic use in older adults. Understanding the genetic characteristics of Escherichia coli (E.coli) is needed to identify patients at risk for recurrence. The aim of this study was to obtain a greater understanding of the genetics of E. coli rUTI in nursing home residents. METHODS: This is a secondary analysis of a multicenter Dutch nursing home study (PROGRESS). E. coli strains from residents with a suspected UTI and positive urine culture were analyzed using antimicrobial susceptibility testing and whole-genome sequencing (WGS). Same-strain recurrences were identified by single-nucleotide polymorphism (SNP) analysis. RESULT: In total, 121 E. coli strains were analyzed using WGS, of which 54 belonged to a rUTI episode. One third of E. coli rUTI episodes were caused by the same strain (n = 18, 33.3%). Same-strain recurrence occurred anywhere between 30 and 434 days after the index UTI, caused by sequence types (ST): ST12, ST23, ST73, ST131, ST453, ST538 and ST2522, in seven nursing home residents. In both single UTI and rUTI, antimicrobial resistance rates were low. CONCLUSION: Recurrent UTI in nursing home residents are caused by same-strain E. coli as well as due to different E. coli strains or other uropathogens. Same-strain recurrence can occur over 400 days after the index UTI, suggesting that some strains have the ability to colonize the bladder or gut for longer periods.

Susceptibility Testing by Volatile Organic Compound Detection Direct from Positive Blood Cultures: A Proof-of-Principle Laboratory Study.

BACKGROUND: Bacteria produce volatile organic compounds (VOCs) during growth, which can be detected by colorimetric sensor arrays (CSAs). The SpecifAST® system (Specific Diagnostics) employs this technique to enable antibiotic susceptibility testing (AST) directly from blood cultures without prior subculture of isolates. The aim of this study was to compare the SpecifAST® AST results and analysis time to the VITEK®2 (bioMérieux) system. METHODS: In a 12-month single site prospective study, remnants of clinical positive monomicrobial blood cultures were combined with a series of antibiotic concentrations. Volatile emission was monitored at 37 °C via CSAs. Minimal Inhibitory Concentrations (MICs) of seven antimicrobial agents for Enterobacterales, Staphylococcus, and Enterococcus spp. were compared to VITEK®2 AST results. MICs were interpreted according to EUCAST clinical breakpoints. Performance was assessed by calculating agreement and discrepancy rates. RESULTS: In total, 96 positive blood cultures containing Enterobacterales, Staphylococcus, and Enterococcus spp. were tested (269 bug-drug combinations). The categorical agreement of the SpecifAST® system compared to the VITEK®2 system was 100% and 91% for Gram-negatives and Gram-positives, respectively. Errors among Gram-positives were from coagulase-negative staphylococci. Overall results were available in 3.1 h (±0.9 h) after growth detection without the need for subculture steps. CONCLUSION: The AST results based on VOC detection are promising and warrant further evaluation in studies with a larger sample of bacterial species and antimicrobials.

Diapers as Promising Alternative Collection Method for Urine Specimens in Nursing Home Residents: A Noninferiority Study.

OBJECTIVE: There is unmet need for an easy, noninvasive urine collection method to diagnose urinary tract infections (UTIs) in nursing home residents suffering from urinary incontinence or cognitive impairments. UTIs are highly prevalent in nursing home residents, and urine specimen collection can be difficult. The objective of this study was to assess if urine specimens collected from super-absorbing incontinence pads (adult diapers) are a reliable collection method for UTI diagnosis. DESIGN: This was a paired noninferiority laboratory study, in which pairing refers to UTI diagnostics performed directly using clinical urine specimens (reference specimen) and indirectly using urine extracted from diapers (diaper specimen). SETTING AND PARTICIPANTS: In this study, remnants of 250 clinical urine specimens were used to assess noninferiority in diagnosing UTIs, based on a 1-sided type I error of 2.5%, a power of 90%, and a noninferiority margin of 15%. METHODS: Urine specimens were poured on super-absorbing disposable adult diapers and extracted after 3 hours, to use for dipstick urinalysis and bacterial culture. UTIs were defined as presence of leukocytes and a positive bacterial culture. Noninferiority was assessed by calculating a Wald-type test statistic. RESULTS: Noninferiority was established for diagnosing UTIs in diaper specimens, and for each of its components (dipstick leukocyte detection and bacterial culture positivity). Positive bacterial cultures were found in 72 (29.0%) diaper specimens compared with 65 (26.2%) reference specimens (difference -2.8%, 97.5% CI -7.1% to 1.5%). Leukocytes were present in 162 (64.8%) diaper specimens, compared with 175 (70.0%) reference specimens (difference -5.7%, 97.5% CI: -10.6% to -0.7%). CONCLUSION AND IMPLICATIONS: Our results on diagnosing UTIs, by dipstick analysis and bacterial cultures, using super-absorbing adult diapers are promising. Before translation into clinical practice, further studies are needed to evaluate the risk of bacterial contamination by wearing adult diapers, possibly resulting in overdiagnosis of UTI.

Sensitivity of point-of-care testing C reactive protein and procalcitonin to diagnose urinary tract infections in Dutch nursing homes: PROGRESS study protocol.

INTRODUCTION: Suspected urinary tract infection (UTI) ranks among the most common reasons for antibiotic use in nursing homes. However, diagnosing UTI in this setting is challenging because UTI often presents with non-specific symptomatology. Moreover asymptomatic bacteriuria is common in elderly, which complicates attribution of causality to detection of bacteria in urine. These diagnostic challenges contribute to overuse of antibiotics and emergence of antimicrobial resistance in nursing homes. Given the diagnostic challenges, there is a need for point-of-care (POC) diagnostic tests to support clinical rules for diagnosing UTI. Procalcitonin (PCT) and C reactive protein (CRP) are inflammatory blood markers that have been proven useful to support diagnosis and monitoring of (bacterial) respiratory tract infections and sepsis. While limited studies suggest their usefulness in supporting UTI diagnosis, their utility has not been studied in elderly populations for this purpose. METHODS AND ANALYSIS: In a 24-month matched prospective study, 'PROGRESS' will assess and compare the sensitivity of rapid POC measurements of blood CRP and PCT levels to support clinical rules for diagnosing UTI in nursing home residents. The primary outcome measure is sensitivity of the POC tests to identify patients with true UTI based on the predefined definition, as derived from receiver operating curves. ETHICS AND DISSEMINATION: This study will be conducted in accordance with Good Clinical Practice guidelines and the principles of the Declaration of Helsinki. The study protocol is approved by the Medical Ethical Committee of Amsterdam UMC location VUmc with reference number 2017.350 and National Central Committee on Research involving Human Subjects with reference number NL62067.029.17. TRIAL REGISTRATION NUMBER: NTR6467.