To explore a comprehensive genomic analysis of Clostridium perfringens type A strains from diverse regions in China, investigating their virulence genes, antibiotic resistance genes, and mobile genetic elements (MGEs) to inform strategies for infection control and resistance gene surveillance.

We conducted whole-genome sequencing on 168 C. perfringens type A strains from nine provinces in China (2016–2021). Previously described alpha-toxin (PLC) sequence typing for C. perfringens was used for comparisons with core genome multilocus sequence typing. Virulence genes, antibiotic resistance genes, and MGEs, including CRISPR/Cas, prophages, and plasmids of C. perfringens type A were investigated by molecular and bioinformatic methods.

PLC type II contained the largest number of isolates (n = 44). The same type strains were largely clustered in the same branches. Tetracycline resistance genes tetA(P) and tetB(P) had high prevalence in type A isolates. 395 prophages were predicted including 265 “incomplete,” 55 “questionable,” and 75 “intact” prophages. CRISPR/Cas systems were more common in isolates from humans (63 %) than in those from animals and food (52 % and 46 %, respectively). Fifty-seven percent of strains likely had the tcp conjugation locus (tcpC to tcpH), and 12 isolates likely carried the conjugative pCW3 plasmid. Type A strains exhibited fewer plasmid-encoded toxins.

cgMLST analysis demonstrated some micro-evolution and regional transmission trends within type A, which exhibited partial correlated with PLC typing. This study highlights the need for enhanced surveillance of antimicrobial resistance and pathogenicity-associated MGEs in C. perfringens type A.