Serotypes and antimicrobial resistance profiles of recovered from clinical swine samples.

Background And Aim: is an important foodborne pathogen and is recognized as a major public health issue. The emergence of multidrug-resistant (MDR) represents a major challenge for national public health authorities. We investigated the distribution of serovars and antimicrobial resistance of isolates from clinical swine samples stored at the Veterinary Diagnostic Laboratory, Faculty of Veterinary Medicine, Kasetsart University from 2016 to 2017.

Materials And Methods: Clinical samples were collected and subjected to standard microbiological techniques outlined in the Manual of Clinical Microbiology to identify serovars. Susceptibility to antimicrobials was tested by the Kirby-Bauer disk diffusion method using a panel of 14 antimicrobials.

Results: A total of 144 isolates were identified and the dominant serovar was Choleraesuis (66.67%), followed by monophasic Typhimurium (18.75%), S. Typhimurium (9.03%), and Rissen (5.56%). The isolates displayed high resistance rates to ampicillin (AMP [100%]), amoxicillin (AX [100%]), tetracycline (TE [100%]), cefotaxime (CTX [89.58%]), ceftriaxone (CRO [87.50%]), chloramphenicol (C [82.64%]), gentamicin (CN [79.17%]), nalidixic acid (NA [72.92%]), and ceftazidime (CAZ [71.53%]). All isolates were MDR, with 29 distinct resistance patterns. The dominant MDR pattern among serovars Choleraesuis and Rissen exhibited resistance to 9 antimicrobials: (R7-14 AMP-AX-CAZ-CRO-CTX-NA-C-CN-TE). However, all tested isolates were susceptible to AX/clavulanic acid and fosfomycin.

Conclusion: High resistance levels to the third generation of cephalosporins such as CAZ, CRO, and CTX highlight the need for careful and reasonable usage of antimicrobials in animals and humans, especially for . Choleraesuis infections.