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

BACKGROUND AND OBJECTIVES

Clostridium perfringens (C. perfringens), is a spore-forming and toxin-producing pathogenic anaerobic 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 (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.

A novel in situ methodology for visual detection of Clostridium perfringens in pork harnessing saltatory rolling circle amplification

Clostridium perfringens (C. perfringens), a prolific toxin-producing anaerobe is an important foodborne pathogen with a huge public health concern. Rapid and on-site detection of C. perfringens is of specific importance in developing countries. In the present study, saltatory rolling circle amplification (SRCA) assay was developed for culture-independent, rapid and visual detection of C. perfringens and evaluated in meat with pork as a model. The specificity of the SRCA assay was ascertained by using 62 C. perfringens and 18 non- C. perfringens strains. The analytical sensitivity of the developed SRCA, conventional and real-time PCR assays were 80 fg, 800 fg and 800 fg DNA per tube, respectively. The limit of detection of the SRCA assay was 80 CFU/g of pork in the absence of enrichment and 8 CFU/g after short enrichment of 6 h. The detection limits of 80 CFU/g and 8 CFU/g of pork were attained within 120 min and 8 h, respectively. Real-world or field relevancy of the developed assay was evaluated by screening 82 raw and processed pork samples. As the developed assay is simple, user-friendly, cost-effective and sophisticated-equipment free, it would be more suitable for on-site testing of C. perfringens in foods. To our information, this is the first report to apply SRCA for the detection of C. perfringens.

Development of a novel polymerase spiral reaction (PSR) assay for rapid and visual detection of Clostridium perfringens in meat

C. perfringens is a widespread foodborne pathogen and one of the major concerns in the meat industry. There is a need for a simple, rapid and equipment free detection system for C. perfringens as conventional anaerobic culture method is labour and resource intensive. Here, we applied a novel polymerase spiral reaction phenomenon to develop and evaluate an assay for effortless and visual detection of C. perfringens in meat foods employing pork as a representative model. Specificity of the assay was determined using 51 C perfringens and 20 non- C. perfringens strains. Analytical sensitivity of the developed test was 80 fg DNA per tube indicating 100 times more sensitivity than end-point PCR assay. The detection limits were 980 CFU/g and 9.8 × 10⁴ CFU/g of pork for PSR and PCR assays, respectively. The operation time of the PSR assay including DNA extraction was 120 min. The developed PSR assay was accurate and effective in comparison to culture method, in detecting C. perfringens in 38 of 74 pork samples. Therefore the specificity, sensitivity, negative predictive value, positive predictive value and accuracy rate of the developed PSR assay were 100%. The developed PSR assay is easy to perform, rapid, affordable, permitting sophisticated-equipment free amplification and naked eye interpretation. This is the initial report in which the PSR assay was optimized for the detection of C. perfringens.

Outbreak of foodborne gastroenteritis in a senior high school in South-eastern Ghana: a retrospective cohort study

BACKGROUND

On 4th February 2015, a group of Senior High School students from Fanteakwa district presented to the emergency unit of the district hospital with complaints of abdominal pain, vomiting and diarrhoea. All the students had eaten from a specific food vendor and had neither eaten any other common meal that day nor the previous day. A foodborne disease outbreak was suspected. We investigated to verify the outbreak, determine its magnitude, identify the source and implement control measures.

METHODS

A retrospective cohort study was conducted. We reviewed medical records and interviewed patrons of the food vendor. We collected data on age, sex, signs and symptoms, date of illness onset, date of admission, date of discharge, treatments given and outcome. A case of foodborne disease was any person in the school with abdominal pain, vomiting and or diarrhoea from 4th to 11th February 2015 and had eaten from the food vendor. We conducted active case search to identify more cases. We conducted environmental assessment and collected clinical and food samples for laboratory testing. Descriptive and inferential statistical analyses were performed using Stata 12.0.

RESULTS

A total of 68 cases were recorded giving overall attack rate of 35.79 % (68/190) with no death. Of these, 51.47 % (35/68) were males. Mean age of case-patients was 17.8 (standard deviation +/-1.62). The index case, a 17-year-old female student ate from the food vendor on 4th February at 9:00 am and fell ill at 3:40 pm later that day. Compared to those who ate other food items, students who drank water from container at the canteen were more likely to develop foodborne disease at statistically significant levels [RR = 2.6, 95 % CI = (2.11-3.15)]. Clostridium perfringens (C. perfringens) and Salmonella species (Salmonella spp) were isolated from water and stew respectively. Clinical features of case-patients were compatible with both organisms.

CONCLUSION

A foodborne gastroenteritis outbreak occurred in a Senior High School in Fanteakwa District from 4th to 7th February 2015. The most probable aetiologic agent was C. perfringens with contaminated water at canteen as the vehicle of transmission. Concurrent Salmonella spp infection could not be ruled out. Rapid outbreak response helped in controlling the outbreak.

An unusual etiology of post-traumatic meningitis

Clostridium perfringens and related species are well-known culprits of post-traumatic soft tissue and bone infection. However, central nervous system involvement with these organisms spontaneously or subsequent to trauma is unusual. The authors reported a case of post-traumatic meningitis in which both C perfringens and Enterococcus faecium were isolated.