Toxigenic Profile of Clostridium perfringens Strains Isolated from Natural Ingredient Laboratory Animal Diets

Abstract

Clostridium perfringens is an anaerobic, gram-positive, spore-forming bacterium that ubiquitously inhabits a wide varietyof natural environments including the gastrointestinal tract of humans and animals. C. perfringens is an opportunistic enteropathogen capable of producing at least 20 different toxins in various combinations. Strains of C. perfringens are currentlycategorized into 7 toxinotypes (A, B, C, D, E, F, and G) based on the presence or absence of 6 typing-toxins (α, β, epsilon, iota, enterotoxin, and netB). Each toxinotype is associated with specific histotoxic and enteric diseases. Spontaneous enteritis due to C. perfringens has been reported in laboratory animals; however, the source of the bacteria was unknown. The Quality Assurance Laboratory (QAL) at the National Institute of Environmental Health Sciences (NIEHS) routinely screens incoming animal feeds for aerobic, enteric pathogens, such as Salmonella spp. and E. coli. Recently, QAL incorporated anaerobic screening of incoming animal feeds. To date, the lab has isolated numerous Clostridium species, including C. perfringens, from 23 lots ofnatural ingredient laboratory animal diets. Published reports of C. perfringens isolation from laboratory animal feeds couldnot be found in the literature. Therefore, we performed a toxin profile screen of our isolated strains of C. perfringens usingPCR to determine which toxinotypes were present in the laboratory animal diets. Our results showed that most C. perfringens strains we isolated from the laboratory animal feed were toxinotype A with most strains also possessing the theta toxin. Two of the C. perfringens strains also possessed the β toxin. Our results demonstrated the presence of C. perfringens in nonsterile, natural ingredient feeds for laboratory animals which could serve as a source of this opportunistic pathogen.

Phenotypical Identification and Toxinotyping of Clostridium perfringens Isolates from Healthy and Enteric Disease‐Affected Chickens

“…Although C. perfringens is a signifcant food-borne zoonotic pathogen, very limited microbiological and epidemiological studies have been reported in Bangladesh. In our study, 4 (10.5%) of the type F isolates harbored the enterotoxigenic gene (cpe), which is a potential virulence determinant of C. perfringens for food poisoning in humans [4,5,19,30]. Te low incidence of enterotoxin in chicken may be due to sample source variation as well as the genetic absence of an encoded gene.…”

“…However, in addition to foodborne intoxication, the enterotoxin producing C. perfringens strains also frequently cause neonatal diarrhea [31]. Furthermore, the enterotoxin gene (cpe) encoded by C. perfringens type F isolates clearly poses the risk of human food-borne intoxication as well as food-borne zoonosis [4,5,32]. Finally, it is recognized that any C. perfringens isolates with alpha toxin and enterotoxin have a signifcant impact on the production of necrotic enteritis in chickens and also cause fatal food-borne enteric disease in humans.…”

“…Te principal mechanism of disease manifestation by C. perfringens is associated with the release of six major extracellular toxins, which are described as alpha (α), beta (β), epsilon (ε), iota (ι), enterotoxin (cpe), and NetB. Based on the production of the abovementioned toxins, C. perfringens is classifed into seven toxinogenic types, A to G [4,5]. In the toxinogenic typing scheme, type A and all other types of C. perfringens produce alpha (a) toxin.…”

“…In the toxinogenic typing scheme, type A and all other types of C. perfringens produce alpha (a) toxin. In addition to alpha (α) toxin, type B produces beta (β) and epsilon (ε) toxins, type C produces beta (β) toxin, type D produces epsilon (ε) toxin, type E produces iota (ι) toxin, type F produces enterotoxin (cpe), and type G produces NetB toxin [4,5]. Among all the C. perfringens types, type F is most frequently associated with food poisoning in humans and causes food-borne illness by producing an enterotoxin (cpe) [4][5][6][7].…”

“…In addition to alpha (α) toxin, type B produces beta (β) and epsilon (ε) toxins, type C produces beta (β) toxin, type D produces epsilon (ε) toxin, type E produces iota (ι) toxin, type F produces enterotoxin (cpe), and type G produces NetB toxin [4,5]. Among all the C. perfringens types, type F is most frequently associated with food poisoning in humans and causes food-borne illness by producing an enterotoxin (cpe) [4][5][6][7]. Still, to date, it is positioned as the third most common food poisoning agent in the industrialized world [2].…”