Higher Cefazolin Urine Breakpoint

by Matthew Songin Patient Caseson Posted on

Higher Cefazolin Urine Breakpoint

A 32-year-old patient is sent home from the ED on cephalexin for an uncomplicated UTI. A few days later the urine culture results with a “cefazolin, uncomplicated UTI susceptible” E. coli with an MIC of 8 µg/mL. Does a new prescription need to be called in?

How did others respond?

Reveal the answer

Best Answer

No

Explanation: For uncomplicated UTI due to E. coli, K. pneumoniae, and P. mirabilis, the CLSI recommends a cefazolin breakpoint of 16 µg/mL, which is 3- fold dilutions higher than the non-urine breakpoint of 2 µg/mL. Using higher urine breakpoints for cefazolin allows for more frequent use of narrow-spectrum antibiotics for uncomplicated UTIs, which reduces risk of resistance and C. difficile infections. Microbiology laboratories adopting the higher CLSI urine breakpoint should collaborate with their antimicrobial stewardship program and other clinical stakeholders on optimal ways to report susceptibility on urine cultures.

Click here for details/references