Performance of an innovative culture-based digital dipstick for detection of bacteriuria

Abstract

ABSTRACT UTI-lizer is a recent digital format for easy-to-use culture-based detection, preliminary identification, and quantification of bacteria in urine at the point of care (PoC). This study aimed to evaluate the diagnostic accuracy of UTI-lizer tests for detection of bacteriuria caused by five common bacterial species: Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Proteus mirabilis, and Staphylococcus saprophyticus. We evaluated the accuracy of UTI-lizer tests by comparing test results of UTI-lizer with those of current standard bacterial culture-based diagnostics in clinical microbiology laboratories in a retrospective and a prospective study. Comparator methods were classical bacterial culture in combination with matrix-assisted laser desorption/ionization-time of flight mass spectrometry mediated bacterial identification. In the retrospective study, we tested 104 urine samples with in-panel microorganisms, plain urethral microbiota, and culture-negative samples. In the prospective study, we used 137 urine samples within 10 hours of their collection at general practitioner clinics. The retrospective study demonstrated 100% sensitivity and specificity in the detection of bacteriuria, and 98.6% sensitivity and 96.8% specificity in identifying primary pathogens with UTI-lizer when compared to clinical standards. S. saprophyticus and E. coli could not be distinguished. The combined nitrite and esterase test predicted the presence of bacteriuria in only 36.5% of cases. The prospective study demonstrated 100% sensitivity and 89.6% specificity in the detection of significant bacteriuria for in-panel microorganisms with a coverage rate of 88.3% (121/137). This study indicates that digital dipsticks are a promising alternative for the detection of the five main pathogens that cause the vast majority of urinary tract infections (UTIs). The results demonstrate that digital dipsticks have the potential to uniquely provide—in primary care or at the point of care—a UTI diagnostic quality on par with that of current gold-standard testing. The ease of testing, rapid test handling time, and time to result as well as simple test equipment make digital dipsticks an attractive solution for decentralized testing for bacteriuria and with that improvement in UTI diagnostics. These results motivate future studies to validate the use of UTI-lizer at the PoC setting. IMPORTANCE In this study, we explore the transformative potential of UTI-lizer, an emerging technology not yet commercially available. Our manuscript shows that UTI-lizer is a promising alternative for detecting the five main pathogens that cause urinary tract infections (UTIs). The results also indicate that digital dipsticks have the potential to uniquely provide UTI diagnostic quality on par with that of gold-standard testing, with the added benefits of ease of testing, rapid test handling time, and simple test equipment. This technology can be helpful in quickly ruling out bacterial infections and reducing the unnecessary use of antibiotics, especially in primary care settings or at the point of care. Moreover, the UTI-lizer test can reduce the number of negative urine samples sent to central laboratories, thus easing the burden of UTI diagnostics on the healthcare system. We believe our study, as well as current and upcoming research based on this technology, is highly relevant for clinical microbiologists, microbiology scientists, general practitioners, and urologists.

Keywords

• point of care
• in vitro diagnostics
• urinary tract infection
• microbiological culture
• bacteriuria
• dipstick