Occurrence and multilocus sequence typing of Clostridium perfringens isolated from retail duck products in Tai'an region, China

Abstract

Clostridium perfringens is an important zoonotic microorganism, which can cause diseases in animal and human under certain conditions. Contamination of C. perfringens in chicken and pork meat has been reported worldwide, but it is rarely reported in duck products. The current study was undertaken to investigate C. perfringens contamination in duck products from a large retail market in Tai'an region, China and the serotype distribution, antimicrobial resistance and genetic relatedness of the isolates. In total, 173 samples of duck products, 10 samples of environmental origins and 7 samples of fresh faeces from healthy shopkeepers were collected between March and November 2018, of which, 58 (31.69%), 10 (100%) and 7 (100%) samples were determined to be positive for C. perfringens, respectively. Ninety-nine isolates of C. perfringens were recovered, all of which were identified as type A. Beta2 (cpb2) toxin gene was found in 54.30% and 33.30% of the isolates from duck products and healthy shopkeepers, respectively. Antimicrobial susceptibility testing revealed that 90.10% of the isolates from duck products and environment showed multiple antibiotic resistance, among which, 49.40% were resistant to at least 6 classes of commonly used antibiotics. Multilocus sequence typing (MLST) showed that 58 representative isolates were divided into 41 sequences types (STs), among which, ST11 (8.60%) was the most common; 37.90% of all isolates were classified into four clonal complexes (CC1-CC4). The most prolific clonal complex (CC1), accounting for 24.13% of all isolates, contained isolates mainly from carcass, animal intestinal contents and environment of four retail stores. A portion of human isolates and duck isolates was distributed in the same CC or ST. In conclusion, C. perfringens contamination in some duck products in Tai'an retail market was relatively high, and most of the isolates exhibited broad-spectrum antimicrobial resistance. Although all the isolates belong to type A, considerable genetic diversity was observed, and a portion of the strains from human and duck was found to be phylogenetically close. The results indicated that antimicrobial-resistance strains of duck origin pose a potential threat to humans by spreading through the food chain.