Are positive urine cultures obtained using recollector bags reliable?

Abstract

Bacterial growth from a urine sample is the gold standard for diagnosis of UTI, its reliability critically depending on the method used to obtain the sample. 

Objective: To investigate the agreement between positive cultures of urine using a recollector and the presence of pathogens in the urinary tract. 

Materials and Methods: in infants with a suspected UTI samples of urine obtained with a recollector (CR) were cultured, and bacterial growth determined in the first 24 hrs, each infant had a second sample taken by supra-pubic puncture (SPP). 

Results: Of 109 CR samples, 10 were negative and 99 positive, of the SPP samples, there were 82 negatives and 27 positive cultures. Comparing methods, the 10 CR negative were also SPP negative, conversely of the 99 CR positive samples, only 27 were also SPP positive. 

Conclusions: Using a CR method the positive cultures are not reliable, being often false positives, and must not be used to confirm a diagnosis of UTI. In these cases of CR positivity, a repeat exam using SPP or a specimen obtained using a catheter must be used.