Rapid susceptibility testing on urine for antimicrobial stewardship in general practice

Rapid antimicrobial susceptibility testing (AST) can improve antimicrobial management and patient outcome. Urinary tract infection (UTI) is one of the most common reasons for antimicrobial prescription in general practice. The performance of direct susceptibility testing on urine using disc diffusion (DST) was determined. The influence of routine AST on antimicrobial management of patients with UTIs in general practice and the potential for improvement by rapid DST on urine as an antimicrobial stewardship intervention was investigated.

Consecutive patients with a urine submitted for culture by a general practitioner were included. Routine urine culture and AST by VITEK, and additional DST were performed. The categorical agreement (CA) between the two susceptibility tests was established. Dates of antimicrobial prescriptions were collected and related to the availability of the AST results to determine whether treatment was AST guided. The potential impact of DST on antimicrobial management was determined by the reduction of no or inappropriate treatment days, i.e. the reduction of days between the start of AST guided treatment and urine specimen receipt at the laboratory.

373 patients were included. The CA between AST and DST was >98%. In 36% (135/373) antimicrobial prescription was guided by routine AST. Of the 517 days of no or inappropriate treatment in these patients, 33% (173/517) could have been saved by DST.

DST on urine is a reliable method. AST results substantially contribute to antimicrobial management of patients with UTI in general practice and DST can further improve antimicrobial prescription in these patients.