Molecular genotyping, biofilm formation and antibiotic resistance of enterotoxigenic Clostridium perfringens isolated from meat supplied to school cafeterias in South Korea

Isolation and characterization of bacteriophages against E.coli urinary tract infection and evaluating their anti-biofilm activity and antibiotic synergy

Urinary tract infections (UTIs) by Uropathogenic Escherichia coli (UPEC) are a significant health concern, especially due to the increasing prevalence of antibiotic resistance. This study focuses on isolating and characterizing bacteriophages specific to UPEC strains isolated from UTI samples. The isolated phages were assessed for their ability to target and lyse UPEC in vitro, focusing on their efficacy in disrupting biofilms, a key virulence factor contributing to UTI recurrence and antibiotic resistance. The morphological structure observed by TEM belongs to Myoviridae, the phage exhibited icosahedral symmetry with a long non-constricting tail, the approximate measurement of the phage head was 39 nm in diameter, and the phage tail was 105.317 nm in length. One-step growth experiments showed that the latent period was approximately 20 min, followed by a rise period of 40 min, and a growth plateau was reached within 20 min and the burst size observed was 26 phages/infected bacterial cells. These phages were capable of killing cells within the biofilms, leading to a reduction in living cell counts after a single treatment. This study highlights the potential of phages to play a significant role in disrupting, inactivating, and destroying Uropathogenic Escherichia coli (UPEC) biofilms. Such findings could be instrumental in developing treatment strategies that complement antibiotics and disinfectants. The phage-antibiotic synergistic activity was compared to have the possibility to facilitate the advancement of focused and enduring alternatives to traditional antibiotic therapies for UTIs.

Prevalence and Antibiotic Resistance Profile of Clostridium perfringens Isolated from Pork and Chicken Meat in Vietnam

Clostridium perfringens is one of the most important zoonotic pathogens as it can cause food poisoning in humans and necrotic enteritis in both animals and humans. Meat, especially pork and chicken meat, is considered the main vehicle for the transmission of C. perfringens from animals to humans. The purpose of this study was to determine the prevalence, toxinotype, and antimicrobial resistance profile of C. perfringens isolated from pork and chicken meat sold in Vietnam. The isolation results showed that 15/50 (30%) of pork samples and 8/50 (16%) of chicken meat samples were contaminated with C. perfringens. The isolates exhibited their highest resistance rate to tetracycline (21/23; 91.30%) and clindamycin (10/23; 43.48%). On the contrary, their lowest resistance rates were observed in response to imipenem (2/23; 8.70%) and cefoxitin (1/23; 4.35%). In particular, 34.78% (8/23) of C. perfringens isolates were identified to be multidrug-resistant strains. The results of toxin genotyping indicated that all isolates were positive for the cpa gene and belonged to type A.

Toxin gene detection and antibiotic resistance of Clostridium perfringens from aquatic sources

Clostridium perfringens is a zoonotic opportunistic pathogen that produces toxins that can cause necrotic enteritis and even "sudden death disease". This bacterium is widely distributed in the intestines of livestock and human, but there are few reports of distribution in aquatic animals (Hafeez et al., 2022). In order to explore the isolation rate of C. perfringens and the toxin genes they carry, 141 aquatic samples, including clams (Ruditapes philippinarum), oysters (Ostreidae), and mud snails (Bullacta exerata Philippi), were collected from the coastal areas of Shandong Province, China. C. perfringens strains were tested for cpa, cpb, etx, iap, cpb2, cpe, netB, and tpeL genes. 45 clam samples were boiled at 100 °C for 5 min before bacteria isolation. 80 strains were isolated from 141 samples with the positive rate being 57 %.And the positive rates of cooked clams was 87 % which was higher than the average. In detection of 8 toxin genes, all strains tested cpa positive, 3 strains netB positive, and 2 cpb and cpe, respectively. 64 strains were selected to analyze the antibiotic resistance phenotype of 10 antibiotics. The average antibiotic resistance rates of the strains to tetracycline, clindamycin, and ampicillin were 45 %, 20 %, and 16 % respectively, and the MIC of 4 strains to clindamycin was ≥128 μg/mL. A high isolation rate of C. perfringens from aquatic animals was shown, and it was isolated from boiled clams for the first time, in which cpe and netB toxin genes were detected for the first time too. The toxin encoded by cpe gene can cause food poisoning of human, thus the discoveries of this study have certain guiding significance for food safety. Antibiotics resistant C. perfringens of aquatic origin may arise from transmission in the terrestrial environment or from antibiotic contamination of the aquaculture environment and is of public health significance.

Addressing Current Challenges in Poultry Meat Safety: Development of a Cultivation and Colony Hybridization Approach to Recover Enterotoxigenic Clostridium perfringens from Broiler Chicken Carcasses

Enterotoxigenic Clostridium perfringens is one of the main causes of foodborne illness in Canada. The use of a conventional bacterial culture approach to isolate enterotoxigenic C. perfringens from poultry meat is common. This approach is based on the phenotype attributable to a double hemolysis phenomenon, whereas few enterotoxigenic strains of C. perfringens produce it, which further complicates the study of the reservoirs of this important pathogen. The objectives of the current study were to validate the ability of a digoxigenin-labeled probe to detect the C. perfringens cpe gene and to validate the use of either a filtration or a direct plating approach, combined with colony hybridization to detect enterotoxigenic C. perfringens. Pure DNA and pure colonies of enterotoxigenic C. perfringens and broiler chicken carcass rinsate samples were subjected to colony hybridization. The results showed that the synthesized DNA probe can detect the cpe gene from both DNA and pure colonies of enterotoxigenic C. perfringens, and from colonies grown from carcass rinsates artificially contaminated with enterotoxigenic C. perfringens. Our study suggests that this isolation method is a promising tool for a better understanding of the epidemiology of this zoonotic pathogen.

Baicalin-aluminum alleviates necrotic enteritis in broiler chickens by inhibiting virulence factors expression of Clostridium perfringens

Clostridium perfringens type A is the main cause of necrotic enteritis (NE) in chickens. Since the use of antibiotics in feed is withdrawn, it is imperative to find out suitable alternatives to control NE. Baicalin-aluminum complex is synthesized from baicalin, a flavonoid isolated from Scutellaria baicalensis Georgi. The present study investigated the effects of baicalin-aluminum on the virulence-associated traits and virulence genes expression of C. perfringens CVCC2030, it also evaluated the in vivo therapeutic effect on NE. The results showed that baicalin-aluminum inhibited bacterial hemolytic activity, diminished biofilm formation, attenuated cytotoxicity to Caco-2 cells, downregulated the expression of genes encoding for clostridial toxins and extracellular enzymes such as alpha toxin (CPA), perfringolysin O (PFO), collagenase (ColA), and sialidases (NanI, NanJ). Additionally, baicalin-aluminum was found to negatively regulate the expression of genes involved in quorum sensing (QS) communication, including genes of Agr QS system (agrB, agrD) and genes of VirS/R two-component regulatory system (virS, virR). In vivo experiments, baicalin-aluminum lightened the intestinal lesions and histological damage, it inhibited pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) expression in the jejunal and ileal tissues. Besides, baicalin-aluminum alleviated the upregulation of C. perfringens and Escherichia coli and raised the relative abundance of Lactobacillus in the ileal digesta. This study suggests that baicalin-aluminum may be a potential candidate against C. perfringens infection by inhibiting the virulence-associated traits and virulence genes expression.

Molecular characteristics and phylogenetic analysis of Clostridium perfringens from different regions in China, from 2013 to 2021

Clostridium perfringens (C. perfringens) is a significant foodborne pathogen and a common cause of intestinal diseases in both animals and humans. Our study investigated MLST, phenotypic antimicrobial resistance profiles, and resistance genes among isolates from human, animal and food. 186 C. perfringens isolates were obtained from nine provinces in China between 2013 and 2021. Additionally, some specific ST complexes were analyzed by cgMLST and cgSNP to investigate genetic relatedness. MLST indicated the most prevalent STs of C. perfringens of human and animal origin were as follows: ST221 (5/147), ST62 (4/147), ST408 (4/147), and ST493 (4/147) were predominant in humans, while ST479 (5/25) was the major type in animals. Within the same ST complex, genetically unrelated relationships or potential clustering/transmission events were further recognized by cgMLST and cgSNP, illustrating that these two methods are valuable in defining outbreaks and transmission events. All tested isolates were susceptible to vancomycin and meropenem. The rates of resistance to metronidazole, penicillin, cefoxitin, moxifloxacin, and chloramphenicol were low (metronidazole: 1.08%; penicillin: 9.68%; cefoxitin: 0.54%; moxifloxacin: 6.45%; and chloramphenicol: 3.76%). Interestingly, 49.66% of human origin were clindamycin-resistant, and 18.2% were penicillin-insensitive. Importantly, the portion of MDR isolates was significantly lower than in previous reports. The study provides an overview of the epidemiological characteristics of C. perfringens with different origins and hosts in China. C. perfringens demonstrated remarkable genetic diversity and distinct molecular features compared to antibiotic-resistance profiles from other studies.

Prevalence and Characterisation of Clostridium perfringens Isolates in Food-Producing Animals in Romania

The aim of the current study was to investigate the prevalence of Clostridium perfringens (C. perfringens) recovered from animal faeces, as well as to determine the antimicrobial susceptibility of such isolates. A total of 14 (14/100; 14%) C. perfringens isolates were isolated from the 100 analysed samples (twelve recovered from faecal samples collected from pigs and two from veal calves' faecal samples). The preponderant genotype was type A, with all isolates being cpa-positive. The most potent antimicrobial agents against C. perfringens proved to be vancomycin, rifampicin and lincomycin. A strong resistance to tetracycline (71.4%), penicillin (64.2%), erythromycin (42.8%) and enrofloxacin (35.7%) was also observed. To the best of our knowledge, this is the first analysis regarding the prevalence, characterization and antimicrobial susceptibility of C. perfringens in food-producing animals in Romania, adding further evidence for the probable role of animals as a source of resistant C. perfringens strains.

Untargeted metabolomics description of propolis's in vitro antibacterial mechanisms against Clostridium perfringens

Propolis is a natural resinous substance that is collected by honeybees (Apis mellifera) with promising antibacterial effects. Here, we examined the antibacterial activity of Chinese propolis against Clostridium perfringens, a bacterial pathogen that threatens food safety and causes intestinal erosion. The inhibitory effects of the ethanolic extract of Chinese propolis (CPE) on human-associated C. perfringens strains were determined by using the circle of inhibition, the minimum inhibitory concentrations, and bactericidal concentrations. CPE also induced morphological elongation, bacterial cell wall damage, and intracellular material leakage in C. perfringens. Untargeted HPLC-qTOF-MS-based metabolomics analysis of the bacterial metabolic compounds revealed that propolis triggered glycerophospholipid metabolism, one carbon pool by folate, and d-glutamine and d-glutamate metabolism alterations in C. perfringens. Finally, caffeic acid phenethyl ester was identified as the key active ingredient in CPE. This study suggested the usage of propolis as an alternative to antibiotics in controlling C. perfringens.

Antimicrobial potential of myricetin-coated zinc oxide nanocomposite against drug-resistant Clostridium perfringens

BACKGROUND

Clostridium perfringens (C. perfringens) is an important pathogen in livestock animals and humans causing a wide array of systemic and enteric diseases. The current study was performed to investigate the inhibitory activity of myricetin (MYR), polyvinyl alcohol (PVA), and zinc oxide (ZnO) nanocomposite against growth and α-hemolysin of C. perfringens isolated from beef meat and chicken sources.

RESULTS

The overall occurrence of C. perfringens was 29.8%. The prevalence of C. perfringens was higher in chicken (38.3%) than in beef meat products (10%). The antimicrobial susceptibility testing revealed that C. perfringens isolates exhibited high resistance levels for metronidazole (93%), bacitracin (89%), penicillin G (84%), and lincomycin (76%). Of note, 1% of C. perfringens isolates were pandrug-resistant (PDR), 4% were extensive drug-resistant (XDR), while 91% were multidrug-resistant. The results of broth microdilution technique revealed that all tested C. perfringens isolates were susceptible to MYR-loaded ZnO/PVA with minimum inhibitory concentrations (MICs) ranged from 0.125 to 2 µg/mL. Moreover, the MYR either alone or combined with the nanocomposite had no cytotoxic activities on chicken red blood cells (cRBCs). Transcriptional modifications of MYR, ZnO, ZnO/PVA, and ZnO/PVA/MYR nanocomposite were determined, and the results showed significant down-regulation of α-hemolysin fold change to 0.5, 0.7, 0.6, and 0.28, respectively compared to the untreated bacteria.

CONCLUSION

This is an in vitro study reporting the antimicrobial potential of MYR-coated ZnO nanocomposite as an effective therapeutic candidate against C. perfringens. An in vivo approach is the next step to provide evidence for applying these alternatives in the treatment and prevention of C. perfringens-associated diseases.

Effect of Thymus vulgaris L. essential oil and thymol on the microbiological properties of meat and meat products: A review

Since foodborne diseases are often considered as one of the biggest public health threats worldwide, effective preservation strategies are needed to inhibit the growth of undesirable microorganisms in food commodities. Up to now, several techniques have been adopted for the production of safe and high-quality products. Although the traditional methods can improve the reliability, safety, and shelf-life of food, some of them cannot be applied without rising health concerns. Thereby, the addition of various phytochemicals has gained much attention during the last decades, especially for meat products that may be contaminated with pathogenic and spoilage organisms.

Thyme (Thymus vulgaris L.), as an important medicinal and culinary herb, is a promising source of bioactive compounds that have a great impact on the microbiological stability of meat by suppressing the undesirable microflora. However, the use of these antimicrobials is still facing difficulties due to their aromatic properties and variable efficacy against targeted species.

In this paper, we provide an overview on the potential effects of thyme essential oil (EO) and thymol as bio-preservative agents in meat products. Furthermore, this paper provides insights into the limitations and current challenges of the addition of EOs and their constituents to meat commodities and suggests viable solutions that can improve the applicability of these phytochemicals.

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.

Fate of Clostridia and other spore-forming Firmicute bacteria during feedstock anaerobic digestion and aerobic composting

Pathogenic spore-forming Firmicutes are commonly present in animal and human wastes that are used as fertilizers in crop production. Pre-treatments of organic waste prior to land application offer the potential to abate enteric microorganisms, and therefore reduce the risk of contamination of crops or adjacent water resources with pathogens carried in these materials. The inactivation and reduction of gram-positive spore formers such as Clostridium spp., Clostridioides spp. and Bacillus spp. from animal and human waste can be challenging given the recalcitrance of the spores these bacteria produce. Given the significance of these organisms to human and animal health, information concerning spore-forming bacteria inactivation during anaerobic digestion (AD) and aerobic composting (AC) is required as the basis for recommending safe organic waste management practices. In this review, an assessment of the inactivation of spore-forming Firmicutes during AD and AC was conducted to provide guidance for practical management of organic matrices of animal or human origin. Temperature and pH may be the main factors contributing to the inactivation of spore-forming Firmicutes during batch lab-scale AD (log reduction <0.5-5 log). In continuous digesters, wet AD systems do not effectively inactivate spore-forming Firmicutes even under thermopholic conditions (log reduction -1.09 - 0.98), but dry AD systems could be a feasible management practice to inactivate spore-forming Firmicutes from organic materials with high solid content (log reduction 1.77-3.1). In contrast, composting is an effective treatment to abate spore-forming Firmicutes (log reduction 1.7-6.5) when thermophilic conditions last at least six consecutive days. Temperature, moisture content and composting scale are the key operating conditions influencing the inactivation of spore-forming Firmicutes during composting. Where possible, undertaking AD with subsequent composting to ensure the biosafety of digestate before its downstream processing and recycling is recommended to abate recalcitrant bacteria in digestate.

Prevalence, Antibiotic Resistance, Toxin-Typing and Genotyping of Clostridium perfringens in Raw Beef Meats Obtained from Qazvin City, Iran

Background: Clostridium perfringens is one of the highest prevailing spore-forming foodborne pathogens, which is widely distributed and causes severe disease and outbreaks in humans and animals. Raw meat and poultry are the main vehicles of this pathogen. In this study, we investigated the prevalence, antibiotic resistance pattern, toxin-encoding genes and genetic diversity of C. perfringens isolates from raw whole and minced meat samples purchased from local markets in Qazvin city, Iran (the source of beef cattle production was also located in Qazvin city, Iran). Methods: We used conventional culture-based and Kirby–Bauer disk diffusion and conventional and arbitrary primer PCR methods. Results: A total of 18 C. perfringens strains were isolated from 133 raw meat samples (13.53%). Up to 44.4 and 55.5% of these isolates were detected in raw minced and whole meat samples, respectively. We found that 72.2, 66.6, 61.1, 37.8 and 33.3% of the C. perfringens isolates were resistant to ampicillin, tetracycline, amoxicillin, ciprofloxacin and chloramphenicol antibiotics, respectively. Multidrug resistance was found in 38% of the isolates. Among the four main toxin genes evaluated, the Cpa gene was detected in all isolates, and 61.1% of the isolates were mostly recognized as type A C. perfringens. High levels of genetic diversity were observed among the isolates, and they were classified into five distinct groups. Conclusions: The isolates from whole meat samples were more resistant to antibiotics. However, toxin genes were more detected in the isolates from minced meat samples. Our findings suggest that contamination of raw meat products with multidrug resistant C. perfringens could be regarded as one of the concerning pathogens in these products. Comprehensive monitoring of C. perfringens isolates is strongly recommended.

Genetic Relatedness, Antibiotic Resistance, and Effect of Silver Nanoparticle on Biofilm Formation by Clostridium perfringens Isolated from Chickens, Pigeons, Camels, and Human Consumers

In this study, we determined the prevalence and toxin types of antibiotic-resistant Clostridium perfringens in chicken, pigeons, camels, and humans. We investigated the inhibitory effects of AgNPs on biofilm formation ability of the isolates and the genetic relatedness of the isolates from various sources determined using RAPD-PCR. Fifty isolates were identified using PCR, and all the isolates were of type A. The cpe and cpb2 genes were detected in 12% and 56% of the isolates, respectively. The effect of AgNPs on biofilm production of six representative isolates indicated that at the highest concentration of AgNPs (100 µg/mL), the inhibition percentages were 80.8–82.8%. The RAPD-PCR patterns of the 50 C. perfringens isolates from various sources revealed 33 profiles and four clusters, and the discriminatory power of RAPD-PCR was high. Multidrug-resistant C. perfringens isolates are predominant in the study area. The inhibition of biofilm formation by C. perfringens isolates was dose-dependent, and RAPD-PCR is a promising method for studying the genetic relatedness between the isolates from various sources. This is the first report of AgNPs’ anti-biofilm activity against C. perfringens from chickens, pigeons, camels, and humans, to the best of our knowledge.

Dual-mode sensor based on the synergy of magnetic separation and functionalized probes for the ultrasensitive detection of Clostridium perfringens

Clostridium perfringens is an important foodborne pathogen, which has caused serious public health problems worldwide. So, there is an urgent need for rapid and ultrasensitive detection of C. perfringens. In this paper, a dual-mode sensing platform using the synergy between fluorescent and electrochemical signals for Clostridium perfringens detection was proposed. An electrochemical aptasensor was constructed by a dual-amplification technology based on a DNA walker and hybridization chain reaction (HCR). When the C. perfringens genomic DNA was present, it specifically bonded with FAM-labeled aptamer which triggered the DNA walker on hairpin DNA (hDNA) tracks to start the synthesis of double-stranded DNA. HCR occurred subsequently and produced long-chain DNA to absorb more methylene blue (MB). In this cycle, the fluorescent signals of released FAM-labeled aptamer could also be detected. The synergistic effects of MB and FAM significantly improved the sensitivity and accuracy of the dual-mode sensor. As a result, the biosensor displayed an excellent analytical performance for C. perfringens at a concentration of 1 to 10⁸ CFU g⁻¹. A minimum concentration of 1 CFU g⁻¹ and good accuracy were detected in real samples. The proposed ultrasensitive detection method for detecting C. perfringens in food showed great potential in controlling foodborne diseases.

Clostridium perfringens is an important foodborne pathogen, which has caused serious public health problems worldwide.

Role of Clostridium perfringens Necrotic Enteritis B-like Toxin in Disease Pathogenesis

Necrotic enteritis (NE) is a devastating enteric disease caused by Clostridium perfringens type A/G that impacts the global poultry industry by compromising the performance, health, and welfare of chickens. Coccidiosis is a major contributing factor to NE. Although NE pathogenesis was believed to be facilitated by α-toxin, a chromosome-encoded phospholipase C enzyme, recent studies have indicated that NE B-like (NetB) toxin, a plasmid-encoded pore-forming heptameric protein, is the primary virulence factor. Since the discovery of NetB toxin, the occurrence of NetB⁺ C. perfringens strains has been increasingly reported in NE-afflicted poultry flocks globally. It is generally accepted that NetB toxin is the primary virulent factor in NE pathogenesis although scientific evidence is emerging that suggests other toxins contribute to NE. Because of the complex nature of the host-pathogen interaction in NE pathogenesis, the interaction of NetB with other potential virulent factors of C. perfringens needs better characterization. This short review will summarize the primary virulence factors involved in NE pathogenesis with an emphasis on NetB toxin, and a new detection method for large-scale field screening of NetB toxin in biological samples from NE-afflicted commercial broiler flocks.

Evaluating the Prevalence of Foodborne Pathogens in Livestock Using Metagenomics Approach

Food safety is the most important global health issue due to foodborne pathogens after consumption of contaminated food. Foodborne bacteria such as Escherichia coli, Salmonella enterica, Staphylococcus aureus, Campylobacter spp., Bacillus cereus, Vibrio spp., Yersinia enterocolitica and Clostridium perfringens are leading causes of the majority of foodborne illnesses and deaths. These foodborne pathogens often come from the livestock feces, thus, we analyzed fecal microbial communities of three different livestock species to investigate the prevalence of foodborne pathogens in livestock feces using metagenomics analysis. Our data showed that alpha diversities of microbial communities were different according to livestock species. The microbial diversity of cattle feces was higher than that of chicken or pig feces. Moreover, microbial communities were significantly different among these three livestock species (cattle, chicken, and pig). At the genus level, Staphylococcus and Clostridium were found in all livestock feces, with chicken feces having higher relative abundances of Staphylococcus and Clostridium than cattle and pig feces. Genera Bacillus, Campylobacter, and Vibrio were detected in cattle feces. Chicken samples contained Bacillus, Listeria, and Salmonella with low relative abundance. Other genera such as Corynebacterium, Streptococcus, Neisseria, Helicobacter, Enterobacter, Klebsiella, and Pseudomonas known to be opportunistic pathogens were also detected in cattle, chicken, and pig feces. Results of this study might be useful for controlling the spread of foodborne pathogens in farm environments known to provide natural sources of these microorganisms.

Genotyping and Antimicrobial Susceptibility of Clostridium perfringens and Clostridioides difficile in Camel Minced Meat

The present study aimed to determine the occurrence, genotypes, and antimicrobial resistance of Clostridium perfringens (C. perfringens) and Clostridioides difficile (C. difficile) in camel minced meat samples collected from small butcher shops and supermarkets in Al-Ahsa Governorate, Saudi Arabia. A total of 100 camel minced meat samples were randomly collected from small butcher’s shops (n = 50) and supermarkets (n = 50) in Al-Ahsa Governorate, Saudi Arabia. C. perfringens and C. difficile were isolated and identified using the VITEK-2 compact system and 16S rRNA gene amplification. Genotypes, toxin genes, and antimicrobial susceptibility of the isolates were determined. Moreover, ELISA was used to detect C. perfringens and C. difficile toxins. C. perfringens and C. difficile were isolated from 14% and 4% of the tested minced meat samples, respectively. Out of the 14 C. perfringens isolates, type A (64.3%), type B (7.1%), type C (21.5%), and type D (7.1%) were detected. However, out of the four C. difficile isolates, three (75%) were type A⁺B⁺ and one (25%) was type A⁻B⁺. None of the C. perfringens or C. difficile toxins were identified using ELISA. C. perfringens and C. difficile isolates exhibited a high rate of resistance to tetracycline (56% and 75%, respectively). However, all isolates were susceptible to amoxicillin-clavulanate. Multidrug resistance was observed in three (21.4%) C. perfringens and one (25%) C. difficile isolates. In conclusion, camel minced meat was contaminated with C. perfringens and C. difficile, which present a potential risk of food poisoning. The majority of the isolates were resistant to at least one antimicrobial, and some isolates were multidrug-resistant. Therefore, food safety standards and frequent inspections of abattoirs, small butcher shops, and supermarkets should be enforced.

Isolation, toxinotyping and antimicrobial susceptibility testing of Clostridium perfringens isolated from Pakistan poultry

BACKGROUND AND OBJECTIVES

Clostridium perfringens is a causative agent of enteric infections in animals including poultry by producing twenty different types of toxins. A single strain produces only a subset of these toxins, which form the basis of its classification into seven toxinotypes (A-G). C. perfringens toxinotype A is a widespread cause of necrotic enteritis (NE) in poultry. The current study was conducted to determine the prevalence of different toxins and antimicrobial susceptibility of C. perfringens isolated from Pakistan NE affected poultry.

METHODS

A total of 134 intestinal samples of the diseased birds were collected postmortem and processed for isolation of C. perfringens using tryptose sulphite cycloserine (TSC) agar supplemented with d-cycloserine. Isolates were confirmed by Gram's staining, biochemical and molecular analyses. Toxinotyping was performed by multiplex PCR. Antimicrobial susceptibility profile of isolates was performed by Kirby Bauer disc diffusion method.

RESULTS

A total of 34 strains of C. perfringens were isolated from 134 samples with prevalence rate of 25.37%. All the isolated strains were toxinotype A, as they were positive for alpha toxin (CPA) and negative for other tested toxins such as beta (CPB), epsilon (ETX), iota (ITX), enterotoxin (CPE), toxin perfringens large (TpeL) and necrotic B-like toxin (NetB). Interestingly, all the isolated strains of C. perfringens were multidrug resistant. The highest resistance was observed against Neomycin, Trimethoprim, Tetracycline and Lincomycin which are routinely used at Pakistan poultry production.

CONCLUSION

C. perfringens toxinotype A is prevalent in Pakistan poultry. Incidence of C. perfringens with prevalence rate of 25.37% can pose serious threat to Pakistan's poultry industry given that all the isolated strains were multidrug resistant. Our findings highlight the need for new antibiotics and antibiotic alternatives to overcome multidrug resistance.

Microbial biofilm: formation, architecture, antibiotic resistance, and control strategies

The assembly of microorganisms over a surface and their ability to develop resistance against available antibiotics are major concerns of interest. To survive against harsh environmental conditions including known antibiotics, the microorganisms form a unique structure, referred to as biofilm. The mechanism of biofilm formation is triggered and regulated by quorum sensing, hostile environmental conditions, nutrient availability, hydrodynamic conditions, cell-to-cell communication, signaling cascades, and secondary messengers. Antibiotic resistance, escape of microbes from the body's immune system, recalcitrant infections, biofilm-associated deaths, and food spoilage are some of the problems associated with microbial biofilms which pose a threat to humans, veterinary, and food processing sectors. In this review, we focus in detail on biofilm formation, its architecture, composition, genes and signaling cascades involved, and multifold antibiotic resistance exhibited by microorganisms dwelling within biofilms. We also highlight different physical, chemical, and biological biofilm control strategies including those based on plant products. So, this review aims at providing researchers the knowledge regarding recent advances on the mechanisms involved in biofilm formation at the molecular level as well as the emergent method used to get rid of antibiotic-resistant and life-threatening biofilms.

Comparative Genome Analysis and Spore Heat Resistance Assay Reveal a New Component to Population Structure and Genome Epidemiology Within Clostridium perfringens Enterotoxin-Carrying Isolates

Clostridium perfringens causes a variety of human and animal enteric diseases including food poisoning, antibiotic-associated diarrhea, and necrotic enteritis. Yet, the reservoirs of enteropathogenic enterotoxin-producing strains remain unknown. We conducted a genomic comparison of 290 strains and a heat resistance phenotyping of 30 C. perfringens strains to elucidate the population structure and ecology of this pathogen. C. perfringens genomes shared a conserved genetic backbone with more than half of the genes of an average genome conserved in >95% of strains. The cpe-carrying isolates were found to share genetic context: the cpe-carrying plasmids had different distribution patterns within the genetic lineages and the estimated pan genome of cpe-carrying isolates had a larger core genome and a smaller accessory genome compared to that of 290 strains. We characterize cpe-negative strains related to chromosomal cpe-carrying strains elucidating the origin of these strains and disclose two distinct groups of chromosomal cpe-carrying strains with different virulence characteristics, spore heat resistance properties, and, presumably, ecological niche. Finally, an antibiotic-associated diarrhea isolate carrying two copies of the enterotoxin cpe gene and the associated genetic lineage with the potential for the emergence of similar strains are outlined. With C. perfringens as an example, implications of input genome quality for pan genome analysis are discussed. Our study furthers the understanding of genome epidemiology and population structure of enteropathogenic C. perfringens and brings new insight into this important pathogen and its reservoirs.

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.

Antimicrobial resistance profiling and molecular typing of ruminant-borne isolates of Clostridium perfringens from Xinjiang, China

OBJECTIVES

Clostridium perfringens (C. perfringens) can cause intestinal diseases in livestock and humans, which seriously threatens the healthy development of animal husbandry and human food safety. Here, the characteristics of antimicrobial resistance and molecular typing of ruminant-borne strains of C. perfringens in Xinjiang, China were explored and profiled.

METHODS

A total of 307 clinical feces collected from ruminants (cattle and sheep) with diarrheal symptoms were screened for C. perfringens. The recovered isolates were characterized in respect to their antimicrobial resistance pattern and molecular typing.

RESULTS

A total of 109 isolates of C. perfringens were isolated from 307 clinical feces of ruminants, most of which displayed the multidrug resistance (MDR) phenotype. Demonstration of the quinolone-resistance gene was the highest among the isolates (70.6%). The multiplex PCR typing based on toxin genes showed that type A and type D strains made up 82.6% (90/109) and 17.4% (19/109), among which, the isolates carrying β2 gene occupied 43.3% (39/90) of type A strains and 31.6% (6/19) of type D strains. These isolates were divided into 6 genotypes (I-VI) by enterobacterial repetitive intergenic consensus sequence-based PCR (ERIC-PCR) method. A total of 33 ST types (ST1-ST33) were identified by multilocus sequence typing (MLST) method.

CONCLUSION

C. perfringens isolates with multidrug resistance (MDR) were frequent and circulating in ruminants. Among them, type A-Ⅰ-ST19 was the dominant genotype of C. perfringens, displaying obvious genetic diversity. This study provided important epidemiological data for the risk assessment of food safety associated with ruminant-borne C. perfringens in Xinjiang, China.

Comparison of the Pathogenicity of Five Clostridium perfringens Isolates Using an Eimeria maxima Coinfection Necrotic Enteritis Disease Model in Commercial Broiler Chickens

Clostridium perfringens (CP) is the etiologic agent of necrotic enteritis (NE) in broiler chickens that is responsible for massive economic losses in the poultry industry in response to voluntary reduction and withdrawal of antibiotic growth promoters. Large variations exist in the CP isolates in inducing intestinal NE lesions. However, limited information is available on CP isolate genetics in inducing NE with other predisposing factors. This study investigated the ability of five CP isolates from different sources to influence NE pathogenesis by using an Eimeria maxima (EM) coinfection NE model: Str.13 (from soil), LLY_N11 (healthy chicken intestine), SM101 (food poisoning), Del1 (netB+tpeL-) and LLY_Tpel17 (netB+tpeL+) for NE-afflicted chickens. The 2-wk-old broiler chickens were preinfected with EM (5 × 103 oocysts) followed by CP infection (around 1 × 109 colony-forming units per chicken). The group of the LLY_Tpel17 isolate with EM coinfection had 25% mortality. No mortality was observed in the groups infected with EM alone, all CP alone, or dual infections of EM/other CP isolates. In this model of EM/CP coinfections, the relative percentages of body weight gain showed statistically significant decreases in all EM/CP groups except the EM/SM101 group when compared with the sham control group. Evident gut lesions were only observed in the three groups of EM/LLY_N11, EM/Del1, and EM/LLY_Tpel17, all of which possessed an essential NE pathogenesis locus in their genomes. Our studies indicate that LLY_Tpel17 is highly pathogenic to induce severe gut lesions and would be a good CP challenge strain for studies investigating pathogenesis and evaluating the protection efficacy for antibiotic alternative approaches.

Tracing Clostridium perfringens strains along the chicken production chain from farm to slaughter by multilocus sequence typing

The current study is undertaken to characterize the prevalence, genotypes distribution, antibiotic resistance and genetic diversity of Clostridium perfringens (C. perfringens) collected from different stages of a chicken production chain. In total, 579 samples from a broiler farm and 378 samples from the slaughterhouse were collected from a large-scale rearing and slaughter one-stop enterprise in Weifang, China, between June and July 2019, of which 30.40% of the samples from farm and 54.50% of samples from slaughterhouse were determined to be positive for C. perfringens, respectively. The contamination of chicken products was relatively serious, with the total positive rate of carcasses at 59.73%; the positive rate of carcass samples was the highest in the evisceration process, which might be the critical point of C. perfringens contamination. A total of 476 isolates of C. perfringens were recovered; and 99.58% of recovered isolates were identified as type A, with the remaining isolates being type G. Antimicrobial susceptibility testing revealed that 97.15% of the isolates showed multiple antibiotic resistance and 67.89% of them were resistant to at least five classes of commonly used antibiotics. Multilocus sequence typing results of 91 representative isolates showed that the isolates can be divided into 74 sequences types (STs); 40.66% of the isolates can be included into seven clonal complexes (CCs). Although most of the isolates were classified as type A, considerable genetic diversity was observed, with the Simpson's diversity index of ST up to 0.9902. Some isolates from farm stage and slaughter stage were distributed in the same ST or CC, indicating that chicken products may be contaminated by the same ST or CC of C. perfringens originated from the farm stage. The high contamination rates of chicken products and the widespread multiple antibiotic resistance of isolates indicated potential public health risks, control measures at rearing and slaughtering stage should be considered to reduce this risk.

Biofilm and Spore Formation of Clostridium perfringens and Its Resistance to Disinfectant and Oxidative Stress

Clostridium perfringens is a major human pathogen that causes gastroenteritis via enterotoxin production and has the ability to form spores and biofilms for environmental persistence and disease transmission. This study aimed to compare the disinfectant and environmental resistance properties of C. perfringens vegetative cells and spores in planktonic and sessile conditions, and to examine the nucleotide polymorphisms and transcription under sessile conditions in C. perfringens strains isolated from meat. The sporulation rate of sessile C. perfringens TYJAM-D-66 (cpe+) was approximately 19% at day 5, while those of CMM-C-80 (cpe−) and SDE-B-202 (cpe+) were only 0.26% and 0.67%, respectively, at day 7. When exposed to aerobic conditions for 36 h, TYJAM-D-66, CMM-C-80, and SDE-B-202 vegetative cells showed 1.70 log, 5.36 log, and 5.67 log reductions, respectively. After treatment with sodium hypochlorite, the survival rates of TYJAM-D-66 vegetative cells (53.6%) and spores (82.3%) in biofilms were higher than those of planktonic cells (9.23%). Biofilm- and spore-related genes showed different expression within TYJAM-D-66 (–4.66~113.5), CMM-C-80 (–3.02~2.49), and SDE-B-202 (–5.07~2.73). Our results indicate the resistance of sessile cells and spores of C. perfringens upon exposure to stress conditions after biofilm formation.

Contamination and Biofilm Formation of Foodborne and Opportunistic Pathogens in Yellow-Feathered Chicken Carcass

This study aims to analyze the contamination and biofilm formation of foodborne and opportunistic pathogens in yellow-feathered chicken carcasses sampled in different seasons and to prove the relationship between biofilm-forming ability and bacterial extracellular polysaccharide (EPS) production. A total of 78 strains were isolated from chicken samples. The strains consisted of 30.8% Escherichia coli, 14.1% Pseudomonas aeruginosa, 12.8% Salmonella enteritidis, 12.8% Klebsiella pnenmoniae, 10.2% Enterobacter cloacae, 8.9% Proteus mirabilis, 5.1% Klebsiella oxytoca, 1.3% Staphylococcus aureus, and 1.3% Citrobacter braakii. Crystal violet staining assay revealed six strains with strong biofilm-forming ability, namely, E. coli S7, K. oxytoca B12, K. pnenmoniae B6, S. enteritidis H4, P. aeruginosa M5, and S. aureus G1, which showed had high abilities of cell motility and EPS production. Confocal laser scanning microscopy and scanning electron microscopy showed that all six strains can form mature biofilm architectures after 5 d of cultivation. This study may serve as a reference to control the contamination of foodborne pathogens in yellow-feathered chicken and enhance the quality and shelf life of these chicken products.

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.

Evaluation and Optimization of Antibiotics Resistance Profile against Clostridium perfringens from Buffalo and Cattle in Pakistan

Clostridium perfringens is a serious threat to successful bovine farming. It causes severe damage to the buffalo and cattle health causing a drastic reduction in milk and meat production. In Pakistan, C. perfringens is a constant threat, and for its management, antibiotics are mostly used. Most bovine farmers use a single antibiotic to suppress the bacterial infection which in turn, increases the antimicrobial resistance (AMR) against the particular antibiotic. To reduce the resistance, the administration of multiple antibiotics in their standard doses at different times can be a possible remedy to manage the AMR and reduce their viability. This study aims to evaluate the effect of 11 commonly used antibiotics at their standard concentrations for inhibiting 33 strains of C. perfringens from five districts of Punjab province in Pakistan. Based on the zone of inhibition, ciprofloxacin, ampicillin, and cefotaxime (CAC) at their standard concentrations effectively inhibited the bacterium. These antibiotics showed appropriate significance statistically, i.e., correlation, Chi-square test, and cluster analysis. Optimization of these antibiotics using response surface methodology (RSM) revealed that the selected antibiotics from medium to high range not only reduce the bacterial propagation but also their population up to a considerable extent. Hence, the health of milk- and meat-producing large animals could be improved, which will be cost-effective and less harmful to the animal, human health, and the environment. Moreover, optimized administration of the selected antibiotics would reduce the impact of drug-resistant superbugs.

Insights on toxin genotyping, virulence, antibiogram profiling, biofilm formation and efficacy of disinfectants on biofilms of Clostridium perfringens isolated from poultry, animals and humans

AIMS

This study aimed to determine the toxin genotypes, virulence determinants and antibiogram of Clostridium perfringens isolated from poultry, animals and humans. Biofilm formation and the efficacy of disinfectants on C. perfringens biofilms were studied.

METHODS AND RESULTS

Thirty C. perfringens isolates (20 clinical and 10 from chicken carcasses) were genotyped by PCR and all isolates were genotype A (cpa+). The overall prevalence of cpe, cpb2, netB and tpeL virulence genes was 6·7, 56·7, 56·7 and 36·7% respectively. Twenty-one isolates (70%) were multidrug-resistant, 8 (26·7%) were extensive drug-resistant and one isolate (3·3%) was pan drug-resistant. The average multiple antibiotic resistance index was 0·7. Biofilms were produced by 63·3% of C. perfringens isolates and categorized as weak (36·7%), moderate (16·7%) and strong (10%). Sodium hypochlorite caused significant reduction in C. perfringens biofilms (P < 0·0001).

CONCLUSIONS

All C. perfringens strains in this study were type A, resistant to multiple antibiotics and most of them were biofilm producers. Sodium hypochlorite showed higher efficacy in reducing C. perfringens biofilms.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study reported the efficacy of disinfectants in reducing C. perfringens biofilms of economic and public health concern and recommends application on surfaces in farms, food processing plants and slaughterhouses.

Prevalence, molecular typing and antibiotic resistance of Clostridium perfringens in free range ducks in Northeast India

This study reports faecal prevalence of Clostridium perfringens in free range ducks in North East India for the first time. We also report C. perfringens type A carrying cpb2 and cpe and type C carrying cpb2 and cpe strains in these ducks. Notably, a high prevalence (17.5%) of enterotoxin carrying C. perfringens strains and low antimicrobial resistance were observed.

Prevalence and multilocus sequence typing of Clostridium perfringens isolated from 4 duck farms in Shandong province, China

Clostridium perfringens is an important zoonotic microorganism. The present study was undertaken to investigate prevalence, serotype distribution, antibiotic resistance, and genetic diversity of C. perfringens isolates from 4 duck farms in Shandong, China. In total, 424 samples of cloacal swabs and environment were collected from 3 commercial meat-type duck farms in Tai'an, Liaocheng, and Weifang and one breeder duck farm in Liaocheng between December 2018 and June 2019, of which, 207 (48.82%) samples were determined to be positive for C. perfringens; a total of 402 isolates of C. perfringens were recovered, all of which were identified as type A; 30.85% of the isolates were positive for cpb2 gene; and cpe gene was found in 0.5% of the isolates. Antimicrobial susceptibility testing revealed that some of the isolates exhibited high antibiotic resistance, and 39.14% of the isolates were resistant to at least 5 classes of commonly used antibiotics. Multilocus sequence typing analysis showed that 85 representative isolates encompassed 54 different sequences types (STs), clustered in 5 clonal complexes (CCs) and 40 singletons. ST3, the most common ST in 54 STs, constituting 15.29% of all isolates, was also the most prevalent ST of isolates from the Liaocheng breeder duck farm (farm 3). CC1, the most prolific CC, containing 15.29% of the analyzed isolates, was the popular subtype of isolates from Liaocheng meat duck farm (farm 2). Although all the isolates belong to type A, the genetic diversity varied greatly in different regions; the Simpson's Diversity Index of STs for Liaocheng, Tai'an, and Weifang were 0.5941, 0.9198, and 0.9627, respectively. Some of cloacal isolates and environmental isolates were distributed in the same ST or CC, indicating close genetic relationship between cloacal isolates and environmental isolates. A portion of the strains from humans and ducks was found to be phylogenetically close. The close relationship between strains from humans and ducks, the high antibiotic resistance of C. perfringens, and the cpe-positive isolates indicated potential public health risks.

Prevalence and characterization of Clostridium perfringens isolated from feces of captive cynomolgus monkeys (Macaca fascicularis)

Clostridium perfringens is ubiquitous in the environment and the gastrointestinal tract of warm-blooded animals. While part of the gut microbiome, abnormal growth of C. perfringens causes histotoxic, neurologic, and enteric diseases in a variety of animal species, including humans, due to the production of toxins. There is extremely limited information on C. perfringens infection in non-human primates. Presently, 10 strains were successfully isolated from 126 monkeys and confirmed by molecular and biochemical analyses. All isolates were genotype A based on molecular analysis. Alpha toxin was identified in all isolates. Beta 2 toxin was detected in only three isolates. No other toxins, including enterotoxin, beta, iota, epsilon, and net B toxin, were identified in any isolate. All isolates were highly susceptible to β-lactam antibiotics. Double hemolysis and lecithinase activity were commonly observed in all strains. Biofilm formation, which can increase antibiotic resistance, was identified in 90% of the isolates. The data are the first report the prevalence and characteristics of C. perfringens isolated from captive cynomolgus monkeys.

Prevalence, toxin-typing, and antimicrobial susceptibility of Clostridium perfringens from retail meats in Seoul, Korea

Clostridium perfringens is a ubiquitous, Gram-positive, spore-forming bacterium. It can contaminate many types of retail meat products and cause food poisoning by producing enterotoxins in the small intestines of humans and domestic animals. We investigated the prevalence, toxin-encoding gene profile, and antimicrobial resistance of C. perfringens in beef, chicken, and pork meat purchased from retail markets in Seoul, Korea. C. perfringens was detected according to the International Organization for Standardization 7937, with some modifications, and confirmed using the Vitek 2 system. In total, 38 C. perfringens strains were isolated from 200 meat samples (38/200, 19%; thirty-three from chicken, and five from beef). Among the six toxins evaluated, including alpha, beta, epsilon, iota, enterotoxin (encoded in the cpe gene), and netB, only the cpa gene was detected in all isolates by polymerase chain reaction (PCR) amplification. The antimicrobial resistance of the isolates was evaluated using the agar dilution method and resistance to ampicillin (12/38, 31.6%), tetracycline (38/38, 100%), chloramphenicol (26/38, 68.4%), metronidazole (13/38, 34.2%), and imipenem (27/38, 71%) was observed. Interestingly, 30 of the 38 isolates (78.9%) were multiple-drug resistant, showing resistance to more than three different antimicrobial classes.

Quantitative microbial risk assessment for Clostridium perfringens foodborne illness following consumption of kimchi in South Korea

The purpose of this study was to conduct a risk assessment for Clostridium perfringens foodborne illness via kimchi consumption in South Korea. Prevalence of C. perfringens in kimchi, kimchi consumption amount and frequency, and distribution conditions (time and temperature) from manufacture to the home were determined. C. perfringens initial contamination level was estimated using Beta distribution [Beta (6, 79)]. Potential C. perfringens cell counts during distribution were predicted using the Weibull model (primary models, R ² = 0.923-0.953) and a polynomial model [(δ = 1/(0.2385 + (- 0.0307 × Temp) + (0.0011 × Temp²)), R ² = 0.719]. Average daily consumption data was assessed using Gamma distribution [1.0444, 91.767, RiskShift (0.16895), RiskTruncate (0, 1078)]. The mean risk of C. perfringens-associated foodborne illness following kimchi consumption was found to be 1.21 × 10^-17. These results suggest that the risk of C. perfringens foodborne illness from kimchi consumption, under current conditions, can be considered to be very low in S. Korea.

Genotyping and antimicrobial susceptibility of Clostridium perfringens isolated from dromedary camels, pastures and herders

The present study aimed to isolate and genotype C. perfringens from healthy and diarrheic dromedary camels, pastures and herders; and to evaluate and compare antimicrobial susceptibility of the isolates. A total of 262 (56.3%) C. perfringens isolates were recovered from 465 samples of healthy and diarrheic dromedary camels, pastures and herders. C. perfringens type A (75.2%), type B (4.2%), type C (13.7%) and type D (6.9%) were detected. C. perfringens type A with only cpa⁺ gene was found in 191 (72.9%) isolates and with cpa⁺ associated cpb2⁺ was found only in 6 (2.3%) isolates. None of the isolates were positive for cpe and iap genes. The highest antimicrobial resistance (82.8%) was observed to ceftiofur with MIC₅₀ and MIC₉₀ values of <64 and ≥256 μg/mL, respectively, followed by penicillin G (72.9%) and erythromycin (61.5%). The lowest resistance (1.9%) was observed for doxycycline with MIC₅₀ and MIC₉₀ values of <1 and 4 μg/mL, respectively, followed by florfenicol (5.3%) and clindamycin (12.2%). In conclusion, C. perfringens type A with cpa⁺ gene was the most prevalent toxin type isolated in this study. The majority of the isolates were resistant to at least one of the ten antimicrobials tested. Antimicrobial resistance patterns of C. perfringens isolates provide further evidence on the emergence of multiple-drug resistant C. perfringens. Therefore, the dissemination of surveillance programs to monitor and control C. perfringens in dromedary camels is required.

Phylogenomic analysis of gastroenteritis-associated Clostridium perfringens in England and Wales over a 7-year period indicates distribution of clonal toxigenic strains in multiple outbreaks and extensive involvement of enterotoxin-encoding (CPE) plasmids

Clostridium perfringens is a major enteric pathogen known to cause gastroenteritis in human adults. Although major outbreak cases are frequently reported, only limited whole-genome sequencing (WGS) based studies have been performed to understand the genomic epidemiology and virulence gene content of outbreak-associated C. perfringens strains. We performed phylogenomic analysis on 109 C. perfringens isolates (human and food) obtained from disease cases in England and Wales between 2011 and 2017. Initial findings highlighted the enhanced discriminatory power of WGS in profiling outbreak C. perfringens strains, when compared to the current Public Health England referencing laboratory technique of fluorescent amplified fragment length polymorphism analysis. Further analysis identified that isogenic C. perfringens strains were associated with nine distinct care-home-associated outbreaks over the course of a 5-year interval, indicating a potential common source linked to these outbreaks or transmission over time and space. As expected, the enterotoxin cpe gene was encoded in all but 4 isolates (96.3 %; 105/109), with virulence plasmids encoding cpe (particularly pCPF5603 and pCPF4969 plasmids) extensively distributed (82.6 %; 90/109). Genes encoding accessory virulence factors, such as beta-2 toxin, were commonly detected (46.7 %; 51/109), and genes encoding phage proteins were also frequently identified. Overall, this large-scale genomic study of gastroenteritis-associated C. perfringens suggested that three major cpe-encoding (toxinotype F) genotypes underlie these outbreaks: strains carrying (1) pCPF5603 plasmid, (2) pCPF4969 plasmid and (3) chromosomal-cpe strains. Our findings substantially expanded our knowledge on type F C. perfringens involved in human-associated gastroenteritis, with further studies required to fully probe the dissemination and regional reservoirs of this enteric pathogen, which may help devise effective prevention strategies to reduce the food-poisoning disease burden in vulnerable patients, such as the elderly.