Background: The weighted-incidence syndromic combination antibiogram (WISCA) displays antimicrobial susceptibility (S) per drug for a given syndrome, rather than per organism as in traditional antibiograms. We sought to construct a WISCA resistance (R) profile (WISCA-R) per oral agent among drugs commonly used in treatment of urinary tract infections (UTIs), to identify agents with low R, and to monitor WISCA-R profiles over a 4-year period.
Methods: Isolates were identified by conventional methods from urine cultures over a 4-year period ending in December 2021 and were tested by disk diffusion or Vitek-2 (bioMérieux), according to CLSI guidelines, against amoxicillin-clavulanate (AMC), ampicillin (AM), cefazolin (KZ), ciprofloxacin (CIP), fosfomycin (FOS), nitrofurantoin (FM), and trimethoprim/sulfamethoxazole (SXT). For FOS, CLSI Escherichia coli and Enterococcus faecalis breakpoints were applied to Gram-negative and -positive organisms, respectively, similar to recently published investigations.
WISCA-R was constructed by multiplying the weighted incidence by the corresponding probability of R to the studied drug, including intrinsic R/imputed S, followed by the sum of obtained probabilities, to obtain the WIS