Fluorescence in situ hybridization rapidly detects three different pathogenic bacteria in urinary tract infection samples

The detection of pathogenic bacteria in urine is an important criterion for diagnosing urinary tract infections (UTIs). By using fluorescence in situ hybridization (FISH) with rRNA-targeted, fluorescently labeled oligonucleotide probes, bacterial pathogens present in urine samples were identified within 3–4 h. In this study, three probes that are specific for Escherichia coli, Enterococcus faecalis and Staphylococcus aureus were designed based on the conserved 16 S RNA sequences, whereas probe Eub338 broadly recognizes all bacteria. We collected a total of 1000 urine samples, and 325 of these samples tested positive for a UTI via traditional culturing techniques; additionally, all 325 of these samples tested positive with the Eub338 probe in FISH analysis. FISH analyses with species-specific probes were performed in parallel to the test the ability to differentiate among several pathogenic bacteria. The samples for these experiments included 76 E. coli infected samples, 32 E. faecalis infected samples and 9 S. aureus infected samples. Compared to conventional methods of bacterial identification, the FISH method produced positive results for > 90% of the samples tested. FISH has the potential to become an extremely useful diagnostic tool for UTIs because it has a quick turnaround time and high accuracy.