September 27, 2023
A new study covered by Healio suggests adopting a new standard cutoff for determining urinary tract infections in febrile children undergoing bladder catheterization. According to a study author, there were no existing studies that compared a urine culture with a culture-independent reference standard. Instead, guidelines defining UTI were “based on a good guess.” This study is the first to compare the guess with another standard to better diagnose the number of UTIs.
The study included 341 children under three (74% girls; 40% aged 2-11 months; 67% white) who underwent bladder catheterization. A documented temperature of at least 39°C was noted in 64% of study participants. Among these children, there were 46 confirmed UTIs. Researchers evaluated diagnostic properties of conventional urine culture at cutoffs of 10,000 CFU/mL, the standard 50,000 CFU/mL and 100,000 CFU/mL to identify UTI cases using 16S ribosomal RNA (rRNA) sequencing as the reference standard. Researchers considered a participant to have a UTI if at least 80% of sequences belonged to a single taxon and if they found evidence of a host inflammatory response in the urine.
The 10,000 cutoff identified 45 of 46 UTIs. Meanwhile the 50,000 cutoff identified 37 cases and 100,000 an even greater comparative drop. Study authors conclude their research supports the use of a 10,000 cutoff to diagnose UTI in febrile children undergoing bladder catheterization. The belief is the study revealed that UTIs have been underdiagnosed for a long time. An additional topic the research may address is inappropriate antibiotic use.
PIDS member Ellen Wald co-authored an accompanying editorial for the study’s publication. The editorial said, “One advantage of 16S sequencing over conventional culture is that it can indicate the presence of organisms difficult to culture conventionally. There is also the exciting future promise of rapid turnaround times for 16S sequencing and the potential for determining the presence of antibiotic-resistant organisms…The results of this study affirm the strength of current culture techniques, provide a step forward in helping to capture important symptomatic UTIs that may occur with low colony counts (a threshold of 10,000 CFU/mL is reasonable) but with evidence of urinary inflammation, and endorse continued exploration of 16S rRNA sequencing as a diagnostic aid in UTI.”