Prevalence and multilocus sequence typing of Clostridium perfringens isolated from retail chicken products and diseased chickens in Tai'an region, China.

Background: Clostridium perfringens is an important zoonotic microorganism, which can cause diseases in animals and humans under suitable conditions. Contamination of C. perfringens in chicken products has been reported worldwide, but the genetic diversity and relationship of isolates were seldom analyzed.

Objectives: The current study was undertaken to investigate the prevalence of C. perfringens from retail chicken products and sick chickens with suspected necrotic enteritis (NE) in Tai'an area, China.

Methods: In total, 295 samples were collected from Tai'an large poultry retail market and veterinary hospital in 2018, then the isolates were tested for toxin genes, drug resistance and multilocus sequence typing (MLST).

Results: Overall, 138 (46.78%) samples were determined to be positive for C. perfringens, and 99.37% of the isolates were identified as C. perfringens type A, with the remaining isolates being type F; 18.99% of the isolates were positive for cpb2 gene. Antimicrobial susceptibility testing revealed that 52.27% of the isolates from poultry retail market and diseased chickens showed multiple antibiotic resistance. MLST results showed that 50 analyzed isolates can be divided into 39 sequences types (STs), clustered in three clonal complexes (CCs) and 23 singletons. Although most of the isolates belong to type A, considerable genetic diversity can be observed, with the Simpson's diversity index up to 0.9181. MLST results and phylogenetic analysis showed that a portion of the isolates from humans and chickens were assigned to the same clusters in the phylogenetic tree or found to be in the same CCs, indicating the chicken isolates and the human isolates are related in certain stratification.

Conclusions: This study showed that the contamination rate of C. perfringens in the local retail chicken products was relatively high. Most of the isolates exhibit broad-spectrum antimicrobial resistance. The high antibiotic resistance of C. perfringens isolates and the relationship between isolates from human and chicken indicated potential public health risks.