Variation in antimicrobial susceptibility profiles of canine urinary pathogens between a US national surveillance program and a commercial diagnostic laboratory

Antimicrobial resistance (AMR) in companion animals is an important animal and public health concern. Antimicrobial susceptibility testing (AST) data are used to guide antimicrobial stewardship and monitor resistance trends, but susceptibility estimates may differ among data sources. This study compared AST results for Escherichia coli and Staphylococcus pseudintermedius isolated from canine urinary tract infections in Texas using data from a national surveillance program (NSP) and a commercial diagnostic laboratory (CDL) from 2019 to 2021. A total of 10,455 AST results were analyzed. Overall susceptibility estimates varied by bacteria–antimicrobial combination, data source, and year. For E. coli , chloramphenicol susceptibility was higher in CDL than NSP isolates across all three years (all P < 0.001). In contrast, susceptibility to cefovecin and cephalexin was lower in CDL isolates in 2019 ( P = 0.041 and P = 0.035, respectively). For S. pseudintermedius , CDL isolates had lower odds of penicillin susceptibility than NSP isolates in 2021 (OR, 0.22; 95% CI, 0.09–0.54; P = 0.001). These findings show that AST estimates from NSP and CDL sources are complementary but not directly interchangeable. Data-source effects should therefore be considered when interpreting laboratory-based AMR data for stewardship and surveillance. Integrating both sources may improve companion animal AMR monitoring within a One Health framework.