A biosensor-based antimicrobial susceptibility test (b-AST) may enable the rapid determination of antibiotic susceptibility of urinary tract pathogens, according to a study published in the January issue of The Journal of Urology.
Kathleen E. Mach, from the Stanford University School of Medicine in California, and colleagues cultured bacteria from 252 urine samples from patients at the Veterans Affairs Palo Alto Health Care System. Bacterial growth with and without antibiotics was monitored by measuring viable counts, and by using a direct biosensor quantitation of bacterial 16S rRNA. Pathogen identification and antibiotic susceptibility were determined directly from patient samples and compared between the b-AST and standard microbiological analysis.
The researchers established that the quantitation of 16S rRNA can be used to measure bacterial growth directly from patient urine samples. In 368 pathogen-antibiotic tests, the b-AST was 94 percent accurate compared to standard microbiological analysis, and provided culture and susceptibility information within 3.5 hours. "b-AST uses an electrochemical biosensor to detect differential 16S rRNA levels after short-term pathogen culture in the presence and absence of antibiotics. In a pilot clinical validation study using infected urine samples the overall agreement of b-AST with the standard clinical microbiology AST was 94 percent," the authors write.