Prevalence, toxinotyping, antimicrobial susceptibility and biofilm-forming ability of Clostridium perfringens isolated from free-living rodents and shrews

Abstract

Background and objectives: Clostridium perfringens (C. perfringens), is a spore-forming and toxin-producing pathogenic Gram-positive rod-shaped bacterium with immense public health/zoonotic concern. Rodents are well-known reservoirs and vectors for a large number of zoonoses and strong links have been recognized between synanthropic rodents and foodborne disease outbreaks throughout the world. To date, no study has been conducted for studying the prevalence of C. perfringens in rodents and shrews. In this study, we investigated faecal samples from free-living rodents and shrews trapped in Meghalaya, a North-eastern hill state of India for the presence of virulent and antimicrobial-resistant C. perfringens.

Methods: A total of 122 animals comprising six species of rodents and one species of shrews were trapped: Mus musculus (n = 15), Mus booduga (n = 7), Rattus rattus (n = 9), Rattus norvegicus (n = 3), Bandicota indica (n = 30), Bandicota bengalensis (n = 32) and Suncus murinus (n = 26). The faecal swabs were collected and processed for the isolation of C. perfringens. Toxinotyping was done using PCR. Antimicrobial susceptibility testing and biofilm forming ability testing were done using Kirby Bauer disc diffusion method and crystal violet assay.

Results: C. perfringens was isolated from 27 of the 122 faecal swabs (22.1%), from six species of rodents and shrews. Five of the host species were rodents, Bandicota bengalensis (25%), Bandicota indica (16.7%), Rattus norvegicus (33.3%), Mus musculus (13.3%), Mus booduga (42.8%) and Suncus murinus (shrew) (29.6%). The common toxinotype was type A (59.2%) followed by Type A with beta2 toxin (33.3%), Type C (3.7%) and Type C with beta2 toxin (3.7%). None of the isolates harboured cpe, etx, iap, and NetB genes and therefore none was typed as either B, D, E, F, or G. Nine isolates (33.3%) turned out to be multi-drug resistant (MDR), displaying resistance to three or more categories of antibiotics tested. Twenty-three out of twenty-seven isolates (85.2%) were forming biofilms.

Conclusion: Globally, this is the first study to report the prevalence of C. perfringens and its virulence profile and antimicrobial resistance in free-living rodents and shrews. The rodents and shrews can potentially contaminate the food and environment and can infect humans and livestock with multi-drug resistant/virulent Type A and Type C C. perfringens.

Keywords: Antimicrobial resistance; Biofilm formation; C. perfringens; Rodents; Shrews; Toxinotype.