Antimicrobial resistance profiling and molecular typing of beta-2 toxin-producing Clostridium perfringens from pig-derived isolates in Xinjiang, China.

In this study, a total of 322 pig fecal samples were collected from various regions of Xinjiang, from which 62 Clostridium perfringens isolates were identified using both morphological and molecular methods, yielding an isolation rate of 19.3 % (62/322). All isolates were classified as type A, with 38.7 % (24/62) carrying the cpb2 gene encoding the β2-toxin. The antimicrobial susceptibility testing showed that the isolates exhibited the highest resistance rate to chloramphenicol (a phenicol), at 77.4 % (48/62). 82.3 %(51/62) displayed multidrug resistance. Molecular analysis of resistance genes revealed that lnu(P) had the highest detection rate (51.6 %, 32/62), followed by tetB(P) (50.0 %, 31/62), tetA(P) (45.2 %, 28/62), and aac(6')-aph(2'') (45.2 %, 28/62). Among the 24 cpb2-positive C. perfringens isolates, multi-locus sequence typing (MLST) identified eight distinct sequence types (STs), including four novel STs: ST892, ST893, ST895, and ST896. ST893 was the most prevalent, accounting for 37.5 % (9/24) of cpb2-positive strains. This study provides the first comprehensive characterization of antimicrobial resistance profiles and molecular types of porcine-origin C. perfringens in Xinjiang. The identification of novel STs and resistance gene distributions offers important information for guiding regional surveillance and control strategies.