Pathogenicity and virulence of Clostridium perfringens

Genomic analysis of Clostridium perfringens type D isolates from goat farms

C. perfringens type D strains are the leading cause of enterotoxaemia in ruminants such as goats, sheep, and cattle. However, there has been no prior research on the genomic characteristics of C. perfringens type D strains from various regions in China. Here, we investigated the antibiotic resistance, genomic characteristics, and phylogenetic relationship of C. perfringens type D isolates recovered from goat farms in Shaanxi, Gansu, and Ningxia provinces. The antibiotic resistance test indicated that the isolates displayed high minimum inhibitory concentration (MIC) values to sulfafurazole, whereas the other antibiotics tested, such as penicillin, enrofloxacin, and florfenicol, worked well on them. Additionally, only tetracycline resistance genes [tetA(P) and tetB(P)] were identified from the isolates. A collective of 13 toxin genes, including etx and cpe were detected among the isolates. Sequence comparison revealed that the etx and cpe genes shared high sequence identities, and they could coexist on a pCW3-like plasmid, representing a potential risk to both animal breeding and public health. Phylogenetic analysis using core genome multi-locus sequence typing (cgMLST) and core genome single nucleotide polymorphisms (SNPs) revealed the close genetic relationship and potential regional/transregional transmission of the C. perfringens type D isolates in Shaanxi and Gansu provinces. Furthermore, pan-genomic analysis suggested the functional differences at the protein-coding gene level, although isolates from the same source shared a close genetic relationship. In conclusion, this study indicated the antibiotic resistance, virulence markers, potential transregional transmission, and genomic diversity of C. perfringens type D strains from various regions in China, which could provide references for the prevention of C. perfringens foodborne diseases and further research.

The biology and pathogenicity of Clostridium perfringens type F: a common human enteropathogen with a new(ish) name

SUMMARYIn the 2018-revised Clostridium perfringens typing classification system, isolates carrying the enterotoxin (cpe) and alpha toxin genes but no other typing toxin genes are now designated as type F. Type F isolates cause food poisoning and nonfoodborne human gastrointestinal (GI) diseases, which most commonly involve type F isolates carrying, respectivefooly, a chromosomal or plasmid-borne cpe gene. Compared to spores of other C. perfringens isolates, spores of type F chromosomal cpe isolates often exhibit greater resistance to food environment stresses, likely facilitating their survival in improperly prepared or stored foods. Multiple factors contribute to this spore resistance phenotype, including the production of a variant small acid-soluble protein-4. The pathogenicity of type F isolates involves sporulation-dependent C. perfringens enterotoxin (CPE) production. C. perfringens sporulation is initiated by orphan histidine kinases and sporulation-associated sigma factors that drive cpe transcription. CPE-induced cytotoxicity starts when CPE binds to claudin receptors to form a small complex (which also includes nonreceptor claudins). Approximately six small complexes oligomerize on the host cell plasma membrane surface to form a prepore. CPE molecules in that prepore apparently extend β-hairpin loops to form a β-barrel pore, allowing a Ca2+ influx that activates calpain. With low-dose CPE treatment, caspase-3-dependent apoptosis develops, while high-CPE dose treatment induces necroptosis. Those effects cause histologic damage along with fluid and electrolyte losses from the colon and small intestine. Sialidases likely contribute to type F disease by enhancing CPE action and, for NanI-producing nonfoodborne human GI disease isolates, increasing intestinal growth and colonization.

Mechanisms of intestinal epithelial cell damage by Clostridiumperfringens

Clostridium perfringens, a Gram-positive bacterium, causes intestinal diseases in humans and livestock through its toxins, related to alpha toxin (CPA), beta toxin (CPB), C. perfringens enterotoxin (CPE), epsilon toxin (ETX), Iota toxin (ITX), and necrotic enteritis B-like toxin (NetB). These toxins disrupt intestinal barrier, leading to various cell death mechanisms such as necrosis, apoptosis, and necroptosis. Additionally, non-toxin factors like adhesins and degradative enzymes contribute to virulence by enhancing colonization and survival of C. perfringens. A vicious cycle of intestinal barrier breach, misregulated cell death, and subsequent inflammation is at the heart of chronic inflammatory and infectious gastrointestinal diseases. Understanding these mechanisms is essential for developing targeted therapies against C. perfringens-associated intestinal diseases.

High intestinal carriage of Clostridium perfringens in healthy individuals and ICU patients in Hangzhou, China

Clostridium perfringens has emerged as a growing public health concern due to its ability to cause various infections and its increasing resistance to antibiotics. To assess its current epidemiology in clinical settings, we conducted a survey involving 426 healthy individuals and 273 ICU inpatients at a provincial hospital in China. Our findings revealed a high prevalence of C. perfringens in healthy individuals (45.77%, 95% CI: 41.0%-50.6%) and ICU patients (12.82%, 95% CI: 9.1%-17.4%). The identified 220 C. perfringens isolates displayed substantial resistance to erythromycin (57.9%), clindamycin (50.7%), and tetracycline (32.0%), primarily attributed to the presence of erm(Q) (54.4%), lnu(P) (13.8%), tetB(P) (83.6%), and tetA(P) (66.7%). Notably, C. perfringens isolates from this particular hospital demonstrated a high degree of sequence type diversity and phylogenic variation, suggesting that the potential risk of infection primarily arises from the bacteria's gut colonization rather than clonal transmissions within the clinical environment. This study provides an updated analysis of the current epidemiology of C. perfringens in healthy individuals and ICU patients in China and emphasizes the need to optimize intervention strategies against its public health threat.

IMPORTANCE

Clostridium perfringens is a bacterium of growing public health concern due to its ability to cause infections and its increasing resistance to antibiotics. Understanding its epidemiology in clinical settings is essential for intervention strategies. This study surveyed healthy individuals and ICU inpatients in a provincial hospital in China. It found a high prevalence of C. perfringens, indicating infection risk. The isolates also showed significant antibiotic resistance. Importantly, the study revealed diverse sequence types and phylogenetic variation, suggesting infection risk from intestinal colonization rather than clonal transmission in hospitals. This analysis emphasizes the need to optimize intervention strategies against this public health threat.

Safety and efficacy evaluation of halicin as an effective drug for inhibiting intestinal infections

Halicin, the first antibacterial agent discovered by artificial intelligence, exerts broad-spectrum antibacterial effects and has a unique structure. Our study found that halicin had a good inhibitory effect on clinical isolates of drug-resistant strains and Clostridium perfringens (C. perfringens). The safety of halicin was evaluated by acute oral toxicity, genotoxicity and subchronic toxicity studies. The results of acute toxicity test indicated that halicin, as a low-toxicity compound, had an LD50 of 2018.3 mg/kg. The results of sperm malformation, bone marrow chromosome aberration and cell micronucleus tests showed that halicin had no obvious genotoxicity. However, the results of the 90-day subchronic toxicity test indicated that the test rats exhibited weight loss and slight renal inflammation at a high dose of 201.8 mg/kg. Teratogenicity of zebrafish embryos showed that halicin had no significant teratogenicity. Analysis of intestinal microbiota showed that halicin had a significant effect on the intestinal microbial composition, but caused a faster recovery. Furthermore, drug metabolism experiments showed that halicin was poorly absorbed and quickly eliminated in vivo. Our study found that halicin had a good therapeutic effect on intestinal infection model of C. perfringens. These results show the feasibility of developing oral halicin as a clinical candidate drug for treating intestinal infections.

Cooperation of quorum sensing and central carbon metabolism in the pathogenesis of Gram-positive bacteria

Quorum sensing (QS), an integral component of bacterial communication, is essential in coordinating the collective response of diverse bacterial pathogens. Central carbon metabolism (CCM), serving as the primary metabolic hub for substances such as sugars, lipids, and amino acids, plays a crucial role in the life cycle of bacteria. Pathogenic bacteria often utilize CCM to regulate population metabolism and enhance the synthesis of specific cellular structures, thereby facilitating in adaptation to the host microecological environment and expediting infection. Research has demonstrated that QS can both directly or indirectly affect the CCM of numerous pathogenic bacteria, thus altering their virulence and pathogenicity. This article reviews the interplay between QS and CCM in Gram-positive pathogenic bacteria, details the molecular mechanisms by which QS modulates CCM, and lays the groundwork for investigating bacterial pathogenicity and developing innovative infection treatment drugs.

Bacillus subtilis HW2 enhances growth performance and alleviates gut injury via attenuation of endoplasmic reticulum stress and regulation of gut microbiota in broilers under necrotic enteritis challenge

This study investigated the effects of Bacillus subtilis HW2 on the growth performance, immune response, endoplasmic reticulum (ER) stress, and intestinal health in broilers with necrotic enteritis. Three hundred 1-day-old male Cobb 500 broilers (33.88 ± 2.34 g) were randomly allocated to 5 groups including non-infected control (NC group), basal diet + necrotic enteritis challenge (NE group), basal diet + 1 × 106 CFU/g B. subtilis HW2 + necrotic enteritis challenge (L-Pro group), basal diet + 5 × 106 CFU/g B. subtilis HW2 + necrotic enteritis challenge (M-Pro group), and basal diet + 1 × 107 CFU/g B. subtilis HW2 + necrotic enteritis challenge (H-Pro group), with 6 replicates per group. All broilers except NC group were orally given with sporulated coccidian oocysts at day 14 and Clostridium perfringens from days 19 to 21. Results showed that L-Pro and M-Pro groups improved growth performance and intestinal morphology in necrotic enteritis-challenged broilers, and L-Pro, M-Pro, and H-Pro groups improved intestinal barrier function and immune response and decreased ER stress in necrotic enteritis-challenged broilers. Analysis of the gut microbiota revealed that L-Pro group increased the abundances of Alistipes, Coprobacter, Barnesiella, and Limosilactobacillus, decreased Erysipelatoclostridium abundance on day 42 in necrotic enteritis-challenged broilers. M-Pro group increased Turicibacter abundance on day 28 and the abundances of Alistipes, Barnesiella, and Limosilactobacillus on day 42 in necrotic enteritis-challenged broilers. H-Pro group decreased Romboutsia abundance on day 28 and unidentified_Clostridia abundance on day 42 in necrotic enteritis-challenged broilers. Analysis of short-chain fatty acids (SCFAs) revealed higher isobutyric acid and isovaleric acid levels in L-Pro and M-Pro groups than NE group. Correlation analysis revealed the correlations between the biochemical parameters and gut microbiota as well as SCFAs, especially Romboutsia, Barnesiella, Coprobacter, isobutyric acid, and isovaleric acid. Overall, our results indicated that B. subtilis HW2 supplementation could ameliorate necrotic enteritis infection-induced gut injury. The optimal dietary supplementation dosage of Bacillus subtilis HW2 was 5 × 106 CFU/g.

Occurrence of Clostridium perfringens in Wild Mammals in the Amazon Biome

The objective of this study was to evaluate the occurrence of Clostridium perfringens in stool samples and swabs collected from wild mammals in the Amazon biome. Sixty-five faecal and swab samples were collected in situ and ex situ from 16 species and three genera of wild mammals, some of which were in good health and some of which had diarrhoea. After pre-enrichment, the samples were plated on selective agar for C. perfringens. Characteristic colonies were subjected to multiplex PCR for the detection of genes encoding the main C. perfringens toxins (alpha, beta, epsilon, and iota toxin and enterotoxin). Among the 65 samples, 40 (61.5%) were positive for the gene encoding the alpha toxin and were classified as type A, 36 of which were asymptomatic animals and four were diarrheal. No other toxinotypes were found. The findings of this study suggest that C. perfringens type A is commonly found in mammal species of the Amazon biome. This seems to be the first study to identify C. perfringens type A in species such as B. variegatus (common ground sloth), C. didactylus (two-toed sloth), P. flavus (Jupará), T. tetradactyla (anteater), S. collinsi (squirrel monkey), S. niger (black marmoset), and S. apella (Guyana capuchin) and in the genus Didelphis sp. (opossum).

Overexpressing the cpr1953 Orphan Histidine Kinase Gene in the Absence of cpr1954 Orphan Histidine Kinase Gene Expression, or Vice Versa, Is Sufficient to Obtain Significant Sporulation and Strong Production of Clostridium perfringens Enterotoxin or Spo0A by Clostridium perfringens Type F Strain SM101

The CPR1953 and CPR1954 orphan histidine kinases profoundly affect sporulation initiation and Clostridium perfringens enterotoxin (CPE) production by C. perfringens type F strain SM101, whether cultured in vitro (modified Duncan-Strong sporulation medium (MDS)) or ex vivo (mouse small intestinal contents (MIC)). To help distinguish whether CPR1953 and CPR1954 act independently or in a stepwise manner to initiate sporulation and CPE production, cpr1953 and cpr1954 null mutants of SM101 were transformed with plasmids carrying the cpr1954 or cpr1953 genes, respectively, causing overexpression of cpr1954 in the absence of cpr1953 expression and vice versa. RT-PCR confirmed that, compared to SM101, the cpr1953 mutant transformed with a plasmid encoding cpr1954 expressed cpr1954 at higher levels while the cpr1954 mutant transformed with a plasmid encoding cpr1953 expressed higher levels of cpr1953. Both overexpressing strains showed near wild-type levels of sporulation, CPE toxin production, and Spo0A production in MDS or MIC. These findings suggest that CPR1953 and CPR1954 do not function together in a step-wise manner, e.g., as a novel phosphorelay. Instead, it appears that, at natural expression levels, the independent kinase activities of both CPR1953 and CPR1954 are necessary for obtaining sufficient Spo0A production and phosphorylation to initiate sporulation and CPE production.

The impact of orphan histidine kinases and phosphotransfer proteins on the regulation of clostridial sporulation initiation

Sporulation is an important feature of the clostridial life cycle, facilitating survival of these bacteria in harsh environments, contributing to disease transmission for pathogenic species, and sharing common early steps that are also involved in regulating industrially important solvent production by some non-pathogenic species. Initial genomics studies suggested that Clostridia lack the classical phosphorelay that phosphorylates Spo0A and initiates sporulation in Bacillus, leading to the hypothesis that sporulation in Clostridia universally begins when Spo0A is phosphorylated by orphan histidine kinases (OHKs). However, components of the classical Bacillus phosphorelay were recently identified in some Clostridia. Similar Bacillus phosphorelay components have not yet been found in the pathogenic Clostridia or the solventogenic Clostridia of industrial importance. For some of those Clostridia lacking a classical phosphorelay, the involvement of OHKs in sporulation initiation has received support from genetic studies demonstrating the involvement of several apparent OHKs in their sporulation. In addition, several clostridial OHKs directly phosphorylate Spo0A in vitro. Interestingly, there is considerable protein domain diversity among the sporulation-associated OHKs in Clostridia. Further adding to the emergent complexity of sporulation initiation in Clostridia, several candidate OHK phosphotransfer proteins that were OHK candidates were shown to function as phosphatases that reduce sporulation in some Clostridia. The mounting evidence indicates that no single pathway explains sporulation initiation in all Clostridia and supports the need for further study to fully understand the unexpected and biologically fascinating mechanistic diversity of this important process among these medically and industrially important bacteria.

An Upper-Arm Clostridium perfringens Fracture-Related Infection: A Case Report

CONCLUSION

Fracture-related infections (FRI) pose serious complications, requiring swift surgical intervention. Although C. perfringens infections in FRIs are rare and literature is scarce, this case highlights the successful management and good functional outcome, offering valuable insights for clinicians dealing with such infections.

Gut Microbiota and Polycystic Ovary Syndrome (PCOS): Understanding the Pathogenesis and the Role of Probiotics as a Therapeutic Strategy

Polycystic ovary syndrome (PCOS) is one of the most common disorders among women in modern societies. A variety of factors can contribute to the development of PCOS. These women often exhibit high insulin resistance (IR), hyperandrogenism, irregular periods, and infertility. Dysbiosis of the gut microbiota (GMB) in women with PCOS has attracted the attention of many researchers. Porphyromonas spp., B. coprophilus, and F. prausnitzii are found in higher numbers in the gut of women with PCOS. Short-chain fatty acids (SCFAs), produced by the intestinal microbiota through fermentation, play an essential role in regulating metabolic activities and are helpful in reducing insulin resistance and improving PCOS symptoms. According to studies, the bacteria producing SCFAs in the gut of these women are less abundant than in healthy women. The effectiveness of using probiotic supplements has been proven to improve the condition of women with PCOS. Daily consumption of probiotics improves dysbiosis of the intestinal microbiome and increases the production of SCFAs.

Clostridium perfringens α toxin damages the immune function, antioxidant capacity and intestinal health and induces PLCγ1/AMPK/mTOR pathway-mediated autophagy in broiler chickens

Clostridium perfringens α toxin is generated by all types of C. perfringens and is closely related to necrotic enteritis in poultry. This study was conducted to investigate the effects of α toxin on immune function, antioxidant capacity, intestinal health and the underlying mechanisms in broiler chickens. A total of 144 twenty-day-old broiler chickens were randomly assigned to four treatments. On d 21, the birds were intraperitoneally injected with PBS (control group) or α toxin at 0.025, 0.1 or 0.4 U/kg of body weight. Samples were collected at 3 h and 24 h post injection (p.i.). Results showed that α toxin challenge linearly decreased the average daily gain during the 3 days after infection and decreased plasma IgA and IgM levels 3 h p.i. Plasma diamine oxidase and d-lactate levels were linearly elevated by α toxin challenge at 3 h p.i. and 24 h p.i. Alpha toxin challenge linearly decreased plasma and jejunal mucosal catalase, glutathione peroxidase and total superoxide dismutase activities at 3 h p.i. and linearly decreased glutathione peroxidase and total superoxide dismutase activities at 24 h p.i. The ileal villus height to crypt depth ratio decreased linearly with increasing α toxin levels at 3 h p.i. and 24 h p.i. Alpha toxin challenge linearly elevated jejunal IL-1β, IL-6, IL-8 and tumor necrosis factor α mRNA expression at 3 h p.i. Additionally, α toxin challenge linearly reduced the jejunal claudin-1, claudin-3 and zonula occludens 1 mRNA expression at 3 h p.i. and the claudin-3, occludin and zonula occludens 1 mRNA expression at 24 h p.i. What's more, α toxin linearly increased the jejunal PLCγ1, AMPKα1 and ATG5 mRNA expression and linearly decreased the mTOR mRNA expression. In conclusion, C. perfringens α toxin challenge decreased body weight gain, impaired immune function, antioxidant capacity and intestinal health, and induced PLCγ1/AMPK/mTOR pathway-mediated autophagy. The recommended intraperitoneal injection dose for moderate injury was 0.1 U/kg of body weight and the recommended sampling time was 3 h p.i. in broiler chickens.

Habitat shapes the gut microbiome diversity of Malayan tigers (Panthera tigris jacksoni) as revealed through metabarcoding 16S rRNA profiling

The gut microbiome refers to the microorganism community living within the digestive tract. The environment plays a crucial role in shaping the gut microbiome composition of animals. The gut microbiome influences the health and behavior of animals, including the critically endangered Malayan tiger (Panthera tigris jacksoni). However, the gut microbiome composition of Malayan tigers, especially those living in their natural habitats, remains poorly understood. To address this knowledge gap, we used next-generation sequencing DNA metabarcoding techniques to analyze the gut microbiome of wild Malayan tigers using fecal samples collected from their natural habitats and in captivity. Our aim was to determine the gut microbiota composition of the Malayan tiger, considering the different types of habitat environments. The results revealed a diverse microbial community within the gut microbiome of Malayan tigers. The prominent phyla that were observed included Firmicutes, Proteobacteria, Actinobacteriota, Fusobacteriota and Bacteroidota. Beta diversity analysis revealed significant differences in gut microbiome composition of Malayan tigers that inhabited oil palm plantations, in villages and protected areas. Diversity analysis also revealed significant difference in the gut microbiome between wild and captive Malayan tigers. However, the distinctions of gut microbiome between wild and captive alpha diversity did not yield significant differences. The differences in microbiome diversity resulted from the interplay of dietary intake and environmental factors. This information will facilitate the establishment of focused conservation approaches and enhance our understanding of the effect of microbiome composition on Malayan tiger health.

Microfluidic systems for infectious disease diagnostics

Microorganisms, encompassing both uni- and multicellular entities, exhibit remarkable diversity as omnipresent life forms in nature. They play a pivotal role by supplying essential components for sustaining biological processes across diverse ecosystems, including higher host organisms. The complex interactions within the human gut microbiota are crucial for metabolic functions, immune responses, and biochemical signalling, particularly through the gut-brain axis. Viruses also play important roles in biological processes, for example by increasing genetic diversity through horizontal gene transfer when replicating inside living cells. On the other hand, infection of the human body by microbiological agents may lead to severe physiological disorders and diseases. Infectious diseases pose a significant burden on global healthcare systems, characterized by substantial variations in the epidemiological landscape. Fast spreading antibiotic resistance or uncontrolled outbreaks of communicable diseases are major challenges at present. Furthermore, delivering field-proven point-of-care diagnostic tools to the most severely affected populations in low-resource settings is particularly important and challenging. New paradigms and technological approaches enabling rapid and informed disease management need to be implemented. In this respect, infectious disease diagnostics taking advantage of microfluidic systems combined with integrated biosensor-based pathogen detection offers a host of innovative and promising solutions. In this review, we aim to outline recent activities and progress in the development of microfluidic diagnostic tools. Our literature research mainly covers the last 5 years. We will follow a classification scheme based on the human body systems primarily involved at the clinical level or on specific pathogen transmission modes. Important diseases, such as tuberculosis and malaria, will be addressed more extensively.

Elucidating the Varying Impact of Necrotic Enteritis Using Performance and Health Indicators in Broiler Infection Models

Necrotic enteritis (NE) continues to be a significant burden to the poultry industry, compounded by pressure to reduce antibiotic use. Researchers use NE-challenge models to study the infection biology of NE and as screening tools to develop potential novel interventions. Currently, data are limited comparing such models between research establishments, and few indicate which quantitative metrics provide the most accurate measure for determining the efficacy of interventions. We compared data from 10 independent NE-challenge trials incorporating six challenge models employed in four geographical regions to determine the extent of variability in bird responses and to determine, using principal component analysis (PCA), which variables discriminated most effectively between nonchallenged control (NC) and challenged control (CC) groups. Response variables related to growth performance (weight gain, feed intake, feed conversion), health (mortality, lesion scores, NE induction rate), and, in three trials only, gut integrity (tight junction protein claudin-1, claudin-2, and zonula occludens-1 expression, coccidia counts, and intestinal permeability [assessed by FITC-dextran assay]). Treatments included a CC, which varied between trials (for example, in Eimeria predisposition, Clostridium perfringens strain, and days of inoculation), and a NC. The degree of response to challenge in CC birds varied significantly among models and trials. In all trials, lesion scores 1 to 4 days postchallenge were increased in CC vs. NC birds and varied both within and among models (by 0.29-1.17 points and 0.05-2.50 points, respectively). In addition, NE-related mortality at day 28 was increased in CC vs. NC, both within and among models (by 1.79%-4.72% and 0.02%-16.70%, respectively), and final (day 35 or 42) body weight was reduced by 3.9%-14.4% and overall FCR increased by up to 27% across trials (P , 0.05). A PCA on the combined dataset including only performance indicators failed to adequately differentiate NC and CC groups. However, the combination of performance and gut integrity variables and standardization of data by trial and phase achieved greater resolution between groups. This indicated that the inclusion of both types of variables in future NE-challenge studies would enable the generation of more robust predictions about intervention efficacy from different types of infection models. A final PCA based on a subset of key indicator variables, including body weight, feed intake, feed conversion ratio, mortality, and lesion score, achieved a good level of separation between NC and CC status of birds and could, with further research, be a useful supplement to existing approaches for assessing and predicting the NE status of birds in the field.

Metagenomic analysis for exploring the potential of Lactobacillus yoelii FYL1 to mitigate bacterial diarrhea and changes in the gut microbiota of juvenile yaks

Diarrhea in calves is a common disease that results in poor nutrient absorption, poor growth and early death which leads to productivity and economic losses. Therefore, it is important to explore the methods to reduce diarrhea in yak's calves. Efficacy of lactic acid bacteria (LAB) for improvement of bacterial diarrhea is well recognized. For this purpose, two different doses (107 CFU, 1011 CFU) of Lactobacillus yoelii FYL1 isolated from yaks were fed to juvenile yaks exposed to E. coli O78. After a trial period of ten days fresh feces and intestinal contents of the experimental yaks were collected and metagenomics sequencing was performed. It was found that feeding a high dose of Lactobacillus yoelii FYL1 decreased abundance of phylum Firmicutes in the E. coli O78 infected group whereas, it was high in animals fed low dose of Lactobacillu yoelii FYL1. Results also revealed that counts of bacteria from the family Oscillospiraceae, genus Synergistes and Megasphaera were higher in control group whereas, order Bifidobacteriales and family Bifidobacteriaceae were higher in infected group. It was observed that bacterial counts for Pseudoruminococcus were significantly (P < 0.05) higher in animals of group that were given high dose of Lactobacillus yoelii FYL1 (HLAB). Compared to infected group multiple beneficial bacterial genera such as Deinococus and Clostridium were found higher in the animals that were given a low dose of Lactobacillus yoelii FYL1 (LLAB). The abundance of pathogenic bacterial genera that included Parascardovia, Bacteroides and Methanobrevibacter was decreased (P < 0.05) in the lower dose treated group. The results of functional analysis revealed that animals of LLAB had a higher metabolism of terpenoids and polyketides compared to animals of infected group. Virus annotation also presented a significant inhibitory effect of LLAB on some viruses (P < 0.05). It was concluded that L. yoelii FYL1 had an improved effect on gut microbiota of young yaks infected with E. coli O78. This experiment contributes to establish the positive effects of LAB supplementation while treating diarrhea.

From bytes to bites: Advancing the food industry with three-dimensional food printing

The rapid advancement of three-dimensional (3D) printing (i.e., a type of additive manufacturing) technology has brought about significant advances in various industries, including the food industry. Among its many potential benefits, 3D food printing offers a promising solution to deliver products meeting the unique nutritional needs of diverse populations while also promoting sustainability within the food system. However, this is an emerging field, and there are several aspects to consider when planning for use of 3D food printing for large-scale food production. This comprehensive review explores the importance of food safety when using 3D printing to produce food products, including pathogens of concern, machine hygiene, and cleanability, as well as the role of macronutrients and storage conditions in microbial risks. Furthermore, postprocessing factors such as packaging, transportation, and dispensing of 3D-printed foods are discussed. Finally, this review delves into barriers of implementation of 3D food printers and presents both the limitations and opportunities of 3D food printing technology.

Types A and F Clostridium perfringens in healthcare wastewater from Ghana

IMPORTANCE

Clostridium perfringens causes gas gangrene and food poisoning in humans, and monitoring this bacterium is important for public health. Although whole-genome sequencing is useful to comprehensively understand the virulence, resistome, and global genetic relatedness of bacteria, limited genomic data from environmental sources and developing countries hamper our understanding of the richness of the intrinsic genomic diversity of this pathogen. Here, we successfully accumulated the genetic data on C. perfringens strains isolated from hospital effluent and provided the first evidence that predicted pathogenic C. perfringens may be disseminated in the clinical environment in Ghana. Our findings suggest the importance of risk assessment in the environment as well as the clinical setting to mitigate the potential outbreak of C. perfringens food poisoning in Ghana.

Impact of CRAMP-34 on Pseudomonas aeruginosa biofilms and extracellular metabolites

Biofilm is a structured community of bacteria encased within a self-produced extracellular matrix. When bacteria form biofilms, they undergo a phenotypic shift that enhances their resistance to antimicrobial agents. Consequently, inducing the transition of biofilm bacteria to the planktonic state may offer a viable approach for addressing infections associated with biofilms. Our previous study has shown that the mouse antimicrobial peptide CRAMP-34 can disperse Pseudomonas aeruginosa (P. aeruginosa) biofilm, and the potential mechanism of CRAMP-34 eradicate P. aeruginosa biofilms was also investigated by combined omics. However, changes in bacterial extracellular metabolism have not been identified. To further explore the mechanism by which CRAMP-34 disperses biofilm, this study analyzed its effects on the extracellular metabolites of biofilm cells via metabolomics. The results demonstrated that a total of 258 significantly different metabolites were detected in the untargeted metabolomics, of which 73 were downregulated and 185 were upregulated. Pathway enrichment analysis of differential metabolites revealed that metabolic pathways are mainly related to the biosynthesis and metabolism of amino acids, and it also suggested that CRAMP-34 may alter the sensitivity of biofilm bacteria to antibiotics. Subsequently, it was confirmed that the combination of CRAMP-34 with vancomycin and colistin had a synergistic effect on dispersed cells. These results, along with our previous findings, suggest that CRAMP-34 may promote the transition of PAO1 bacteria from the biofilm state to the planktonic state by upregulating the extracellular glutamate and succinate metabolism and eventually leading to the dispersal of biofilm. In addition, increased extracellular metabolites of myoinositol, palmitic acid and oleic acid may enhance the susceptibility of the dispersed bacteria to the antibiotics colistin and vancomycin. CRAMP-34 also delayed the development of bacterial resistance to colistin and ciprofloxacin. These results suggest the promising development of CRAMP-34 in combination with antibiotics as a potential candidate to provide a novel therapeutic approach for the prevention and treatment of biofilm-associated infections.

Effects of Lactobacillus plantarum HW1 on Growth Performance, Intestinal Immune Response, Barrier Function, and Cecal Microflora of Broilers with Necrotic Enteritis

The purpose of the study was to investigate the effects of Lactobacillus plantarum HW1 on growth performance, intestinal immune response, barrier function, and cecal microflora of broilers with necrotic enteritis. In total, 180 one-day-old male Cobb 500 broilers were randomly allocated into three groups comprising a non-infected control (NC) group, basal diet + necrotic enteritis challenge (NE) group, and basal diet + 4 × 106 CFU/g Lactobacillus plantarum HW1 + necrotic enteritis challenge (HW1) group. Broilers in the NE and HW1 groups were orally given sporulated coccidian oocysts at day 14 and Clostridium perfringens from days 19 to 21. The results showed that the HW1 treatment increased (p < 0.05) the average daily gain of broilers from days 15 to 28 and from days 0 to 28 compared with the NE group. Moreover, the HW1 treatment decreased (p < 0.05) the oocysts per gram of excreta, intestinal lesion scores, ileal interleukin (IL) 1β and tumor necrosis factor α levels, and serum D-lactic acid and diamine oxidase levels, while increasing (p < 0.05) the ileal IL-10 level, thymus index, and protein expressions of ileal occludin and ZO-1. Additionally, the HW1 treatment decreased (p < 0.05) the jejunal and ileal villus height, jejunal villus height/crypt depth value, and cecal harmful bacterial counts (Clostridium perfringens, Salmonella, Escherichia coli, and Staphylococcus aureus), and increased (p < 0.05) the cecal Lactobacillus count. In conclusion, dietary supplementation with 4 × 106 CFU/g Lactobacillus plantarum HW1 could relieve necrotic enteritis infection-induced intestinal injury and improve growth performance in broilers by improving intestinal barrier function and regulating intestinal microbiology.

Surrogates of foodborne and waterborne protozoan parasites: A review

The protozoan parasites Cryptosporidium parvum, Cyclospora cayetanensis, and Toxoplasma gondii are major causes of waterborne and foodborne diseases worldwide. The assessment of their removal or inactivation during water treatment and food processing remains challenging, partly because research on these parasites is hindered by various economical, ethical, methodological, and biological constraints. To address public health concerns and gain new knowledge, researchers are increasingly seeking alternatives to the use of such pathogenic parasites. Over the past few decades, several non-pathogenic microorganisms and manufactured microparticles have been evaluated as potential surrogates of waterborne and foodborne protozoan parasites. Here, we review the surrogates that have been reported for C. parvum, C. cayetanensis, and T. gondii oocysts, and discuss their use and relevance to assess the transport, removal, and inactivation of these parasites in food and water matrices. Biological surrogates including non-human pathogenic Eimeria parasites, microorganisms found in water sources (anaerobic and aerobic spore-forming bacteria, algae), and non-biological surrogates (i.e. manufactured microparticles) have been identified. We emphasize that such surrogates have to be carefully selected and implemented depending on the parasite and the targeted application. Eimeria oocysts appear as promising surrogates to investigate in the future the pathogenic coccidian parasites C. cayetanensis and T. gondii that are the most challenging to work with.

Unbridled Threat of Gas Gangrene in a Patient With Uncontrolled Diabetes Mellitus: A Compelling Case Report of Clostridium perfringens Infection

Clostridium perfringens, a Gram-positive anaerobic bacterium, is well-known for its association with gas gangrene, a severe and rapidly progressing infection characterized by tissue gas production and necrosis. In this case report, we present the instance of a 64-year-old male with poorly controlled diabetes mellitus who developed a C. perfringens-related infection following a traumatic foot wound. The report emphasizes the critical significance of early diagnosis and aggressive treatment in C. perfringens infections, particularly in patients with underlying risk factors. Detailed accounts of clinical findings, laboratory results, computed tomography, and surgical interventions are provided. A multidisciplinary approach proved essential for successful management. The inherent scholarly value of this case is substantiated by its meticulous documentation of the clinical trajectory, diagnostic modalities, and treatment modalities employed. The intricate collaboration across diverse medical disciplines, the uncommon manifestation of the infection following a traumatic foot wound, and the favorable outcome achieved through prompt and multidisciplinary intervention collectively contribute to the exceptional nature and didactic significance of this case. The dissemination of such clinical experiences assumes paramount importance in advancing medical scholarship, cultivating awareness, and engendering a profound comprehension of the complexities associated with C. perfringens infections, thereby enriching the wider scientific and medical community.

Characterization of thermostable bacteriophage CPD2 and its endolysin LysCPD2 as biocontrol agents against Clostridium perfringens

Clostridium perfringens is one of the major foodborne pathogens in humans and animals. With the prevalence of antibiotic-resistant C. perfringens strains, bacteriophages and their endolysins have received considerable attention as promising alternatives to antibiotics. In this study, C. perfringens phage CPD2 was isolated from retail chicken samples. CPD2 belongs to the Podoviridae family and exhibits remarkable thermostability. While CPD2 has narrow host specificity, its endolysin LysCPD2 showed a broader lytic range, killing not only C. perfringens strains but other Gram-positive bacteria, such as B. cereus and B. subtilis. In addition, due to its exceptional thermal stability, LysCPD2 showed significant antibacterial ability against germinating C. perfringens spores during the heat activation process (75 °C for 20 min). Taken together, these results indicate that both thermostable phage CPD2 and its endolysin LysCPD2 can be used as efficient antimicrobial agents to control C. perfringens during thermal processing of foods.

Detection of Clostridium perfringens in donor milk at a human breast milk bank: a case report

BACKGROUND

The breast milk bank is a professional organization that collects donor human milk (DHM) for special medical needs by recruiting qualified breast milk donors. Such organizations are also responsible for the disinfection, processing, testing, storage, distribution, and use of breast milk. As DHM is a biological product, it may get contaminated. Microbiological testing is the final step to determine microbial contamination of DHM. However, a universal method for the microbiological analysis of DHM in breast milk banks globally is lacking.DHM without strict screening may become a potential carrier of pathogens and seriously threaten the health of infants. Clostridium perfringens, a gram-positive anaerobic bacterium, is capable of causing wound infections, including gas gangrene, enteritis/enterocolitis, and enterotoxemia. Here, the first case of C. perfringens detected in DHM has been reported to facilitate the identification of such contamination in breast milk banks.

CASE PRESENTATION

A breastfeeding mother donated 3000 mL of milk to the breast milk bank of the First Affiliated Hospital of the Army Medical University(over 2900 beds and patient receiving capacity of over 132,000), Chongqing, China. The milk sample was subjected to microbiological screening using liquid enrichment, followed by anaerobic and aerobic culturing. The results revealed the growth of C. perfringens in the anaerobic culture medium, but no bacteria or yeast-like fungi were observed in the aerobic culture medium. The donor did not exhibit any clinical symptoms, and her routine blood results and body temperature were normal. However, the infant fed with her milk had recurrent bloody stools. Breast milk bank infection control emergency handling as well as environmental sampling and investigation revealed that the cause was contamination of the donor's home-use breast pump with C. perfringens. The infant no longer experienced bloody stool once the donor changed the breast pump.

CONCLUSIONS

C. perfringens can enter breast milk from contaminated pumping environments or devices, thus causing illness in infants. The microbiological testing of DHM in breast milk banks can be accomplished using liquid enrichment, along with anaerobic and aerobic culture, which is of immense significance in improving the standards for microbiological screening, DHM safety, and infant health.

Acquisition site-based remodelling of Clostridium perfringens- and Clostridioides difficile-related gut microbiota

INTRODUCTION

Clostridium perfringens is a gram-positive, anaerobic sporulating bacillus which can infect several hosts, thereby being considered the causative agent of many gut illnesses. Some studies have suggested that C. perfringens's virulence factors may negatively affect gut microbiota homeostasis by decreasing beneficial bacteria; however, studies have failed to evaluate the simultaneous presence of other pathogenic bacteria, such as C. difficile (another sporulating bacillus known to play a role in gut microbiota imbalance). Conscious of the lack of compelling data, this work has ascertained how such microorganisms' coexistence can be associated with a variation in gut microbiota composition, compared to that of C. perfringens colonisation.

METHODS

PCR was thus used for identifying C. perfringens and C. difficile in 98 samples. Amplicon-based sequencing of 16S- and 18S-rRNA genes' V4 hypervariable region from such samples was used for determining the microbiota's taxonomical composition and diversity.

RESULTS

Small differences were observed in bacterial communities' taxonomic composition and diversity; such imbalance was mainly associated with groups having hospital-acquired diarrhoea.

CONCLUSION

The alterations reported herein may have been influenced by C. difficile and diarrhoea acquisition site, despite C. perfringens' ability to cause alterations in microbiota due to its virulence factors. Our findings highlight the need for a holistic view of gut microbiota.

Clostridium perfringens phospholipase C, an archetypal bacterial virulence factor, induces the formation of extracellular traps by human neutrophils

Neutrophil extracellular traps (NETs) are networks of DNA and various microbicidal proteins released to kill invading microorganisms and prevent their dissemination. However, a NETs excess is detrimental to the host and involved in the pathogenesis of various inflammatory and immunothrombotic diseases. Clostridium perfringens is a widely distributed pathogen associated with several animal and human diseases, that produces many exotoxins, including the phospholipase C (CpPLC), the main virulence factor in gas gangrene. During this disease, CpPLC generates the formation of neutrophil/platelet aggregates within the vasculature, favoring an anaerobic environment for C. perfringens growth. This work demonstrates that CpPLC induces NETosis in human neutrophils. Antibodies against CpPLC completely abrogate the NETosis-inducing activity of recombinant CpPLC and C. perfringens secretome. CpPLC induces suicidal NETosis through a mechanism that requires calcium release from inositol trisphosphate receptor (IP3) sensitive stores, activation of protein kinase C (PKC), and the mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK/ERK) pathways, as well as the production of reactive oxygen species (ROS) by the metabolism of arachidonic acid. Proteomic analysis of the C. perfringens secretome identified 40 proteins, including a DNAse and two 5´-nucleotidases homologous to virulence factors that could be relevant in evading NETs. We suggested that in gas gangrene this pathogen benefits from having access to the metabolic resources of the tissue injured by a dysregulated intravascular NETosis and then escapes and spreads to deeper tissues. Understanding the role of NETs in gas gangrene could help develop novel therapeutic strategies to reduce mortality, improve muscle regeneration, and prevent deleterious patient outcomes.

Bacterial Infection of an Alveolar Echinococcus Cyst from C. perfringens Septicemia: A Case Report and Review of the Literature

Background and Objectives: Alveolar echinococcosis (AE) is a highly variable disease able to present as structurally diverse cysts in different organs based on the host's immunological state as well as the time between diagnosis and the primary infection. Bacterial superinfections, especially with anaerobic pathogens from the Clostridiaceae genus, can further alter the radiological findings due to pneumobilia, newly formed abscess formations, and inflammatory changes. Materials and Methods: We present a case of a 71-year-old Caucasian male admitted to our intensive care unit with septic shock, pneumobilia, and a complex cyst of the liver with calcification, as shown by an initial CT. Because of the septic shock, the patient was started on broad-band antibiotics. Clostridiaceae infection was considered an important differential diagnosis due to the presence of pneumobilia observed in the initial CT, without a history of previous endoscopy. Furthermore, serology for echinococcus was positive, and blood cultures showed growth of C. perfringens. Therefore, the patient was additionally treated with albendazole. After recovery, further staging was conducted, showing complete remission of the cyst and a left-over lesion classified as Alveolar Echinococcosis Ulm Classification (AEUC) V. In summary, the patient had a pre-existing, controlled AE infection that became superinfected with C. perfringens, likely attributable to the anaerobic necrotic tissue, leading to septicemia. Results: The anaerobic tissue within the AE cyst provided an ideal medium for C. perfringens to replicate, leading to cyst infection, which subsequently caused septic shock and pneumobilia. The initial findings from CT and MRI were confounded by the superinfection, demonstrating the diagnostic challenges of AE, especially when presenting with complications. Conclusions: Diagnosing AE remains a demanding task, even with the excellent tools available through serology, coupled with CT, FDG-PET-CT, and MRI. Notably, older superinfected cysts can pose difficulties when integrated into the appropriate diagnostic context. Prompt diagnosis is critical for the accurate treatment of echinococcosis and its complications, such as bacterial superinfections. From a clinical perspective, septicemia from Clostridiaceae and infections with C. perfringens-pathogens capable of inducing pneumobilia-should be regarded as significant differential diagnoses for pneumobilia in the absence of a recent history of endoscopy.

Genome-based metabolic and phylogenomic analysis of three Terrisporobacter species

Acetogenic bacteria are of high interest for biotechnological applications as industrial platform organisms, however, acetogenic strains from the genus Terrisporobacter have hitherto been neglected. To date, three published type strains of the genus Terrisporobacter are only covered by draft genome sequences, and the genes and pathway responsible for acetogenesis have not been analyzed. Here, we report complete genome sequences of the bacterial type strains Terrisporobacter petrolearius JCM 19845T, Terrisporobacter mayombei DSM 6539T and Terrisporobacter glycolicus DSM 1288T. Functional annotation, KEGG pathway module reconstructions and screening for virulence factors were performed. Various species-specific vitamin, cofactor and amino acid auxotrophies were identified and a model for acetogenesis of Terrisporobacter was constructed. The complete genomes harbored a gene cluster for the reductive proline-dependent branch of the Stickland reaction located on an approximately 21 kb plasmid, which is exclusively found in the Terrisporobacter genus. Phylogenomic analysis of available Terrisporobacter genomes suggested a reclassification of most isolates as T. glycolicus into T. petrolearius.

Molecular characterization of Clostridium perfringens isolates from a tertiary children's hospital in Guangzhou, China, establishing an association between bacterial colonization and food allergies in infants

BACKGROUND

Cow's milk protein allergy (CMPA) is one of the most common types of food allergy in infants. Faecal pathogen cultures showed that the positive rate of Clostridium perfringens was more than 30%, which was significantly higher than that for other bacteria. Therefore, it is speculated that Clostridium perfringens colonization may be one of the pathogenetic factors for CMPA in infants. We conducted a real-world evidence study. Infants aged 0-6 months with diarrhoea and mucoid and/or bloody stools were recruited from a large tertiary hospital in China. Faecal pathogen cultures for the detection of Clostridium perfringens were confirmed by flight mass spectrometry, and potential toxin genes were identified using PCR. After 12 months of follow-up, the diagnoses of CMPA and food allergy were recorded. The correlation was assessed by Pearson correlation analysis.

RESULTS

In this study, 358 infants aged 0-6 months with gastrointestinal symptoms and faecal pathogen cultures were recruited. A total of 270 (44.07% girls; mean age, 2.78 ± 2.84 months) infants were followed up for 12 months. Overall, the rate of positivity for Clostridium perfringens in faecal pathogen cultures was 35.75% (128/358) in infants aged ≤ 6 months. The earliest Clostridium perfringens colonization was detected within 2 days after birth. The majority of Clostridium perfringens isolates were classified as type C in 85 stool samples. In the Clostridium perfringens-positive group, 48.21% (54/112) of infants were clinically diagnosed with food allergies after 12 months, including 37.5% (42/112) with CMPA, which was significantly higher than that of the negative group, with 7.59% (12/158) exhibiting food allergies and 5.06% (8/158) presenting CMPA (P < 0.0001). Faecal Clostridium perfringens positivity was significantly correlated with CMPA, food allergy, faecal occult blood, faecal white blood cells, antibiotic use, increased peripheral blood platelet counts, and decreased haemoglobin levels (P < 0.0001).

CONCLUSIONS

This study demonstrates that intestinal colonization by Clostridium perfringens is common in infants. The majority of Clostridium perfringens isolates are classified as type C. Colonization of the intestine by Clostridium perfringens is associated with the development of CMPA and food allergy in infants.

Foodborne Clostridioides Species: Pathogenicity, Virulence and Biocontrol Options

Clostridioides species possess many virulence factors and alarming levels of muti-drug resistance which make them a significant risk to public health safety and a causative agent of livestock disease. Clostridioides result in serious systemic and gastrointestinal diseases such as myonecrosis, colitis, food poisoning and gastroenteritis. As foodborne pathogens, Clostridioides species are associated with significant incidences of morbidity and mortality where the application of broad-spectrum antibiotics predisposes patients to virulent Clostridioides colonisation. As part of the One Health approach, there is an urgent need to eliminate the use of antibiotics in food production to safeguard animals, humans and the environment. Alternative options are warranted to control foodborne pathogens at all stages of food production. Antimicrobial peptides and bacteriophages have demonstrated efficacy against Clostridioides species and may offer antimicrobial biocontrol options. The bacteriocin nisin, for example, has been implemented as a biopreservative for the control of Listeria, Staphylococcus and Clostridia species in food. Bacteriophage preparations have also gained recognition for the antibacterial action against highly virulent bacterial species including foodborne pathogens. Studies are warranted to mitigate the formulation and administration limitations associated with the application of such antimicrobials as biocontrol strategies. This review outlines foodborne Clostridioides species, their virulence factors, and potential biocontrol options for application in food production.

Autolysin as a fibronectin receptor on the cell surface of Clostridium perfringens

OBJECTIVE

Clostridium perfringens causes food poisoning and gas gangrene, a serious wound-associated infection. C. perfringens cells adhere to collagen via fibronectin (Fn). We investigated whether the peptidoglycan hydrolase of C. perfringens, i.e., autolysin (Acp), is implicated in Fn binding to C. perfringens cells.

METHODS

This study used recombinant Acp fragments, human Fn and knockout mutants (C. perfringens 13 acp::erm and HN13 ΔfbpC ΔfbpD). Ligand blotting, Western blotting analysis, and complementation tests were performed. The Fn-binding activity of each mutant was evaluated by ELISA.

RESULTS

From an Fn-binding assay using recombinant Acp fragments, Fn was found to bind to the catalytic domain of Acp. In mutant cells lacking Acp, Fn binding was significantly decreased, but was restored by the complementation of the acp gene. There are three known kinds of Fn-binding proteins in C. perfringens: FbpC, FbpD, and glyceraldehyde-3-phosphate dehydrogenase. We found no difference in Fn-binding activity between the mutant cells lacking both FbpC and FbpD (SAK3 cells) and the wild-type cells, indicating that these Fn-binding proteins are not involved in Fn binding to C. perfringens cells.

CONCLUSIONS

We found that the Acp is an Fn-binding protein that acts as an Fn receptor on the surface of C. perfringens cells.

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.

Genome characteristics of the optrA-positive Clostridium perfringens strain QHY-2 carrying a novel plasmid type

Clostridium perfringens is a bacterial species of importance to both public and animal health. The gene optrA is the first gene that confers resistance to the tedizolid, a last-resort antimicrobial agent in human medicine. Herein, we whole-genome sequenced and analyzed one optrA-positive C. perfringens strain QHY-2 from Tibetan sheep in Qinghai province and identified one optrA plasmid pQHY-2. The plasmid shared similar structure with the optrA-positive plasmids p2C45 and p21-D-5b previously identified in C. perfringens, demonstrating the potential horizontal transmission of the optrA plasmids among C. perfringens strains. Annotation of the optrA-positive plasmids showed optrA and erm(A) located on a segment flanked by IS element IS1216E, and fexA, optrA, and erm(A) located on a segment flanked by IS element ISVlu1, which revealed the possible dissemination mechanism. Additionally, a Tn6218-like transposon carrying aac(6')-aph(2″) and erm(B) was also detected on pQHY-2, demonstrating the transposition of Tn6218 and spread of antibiotic resistance among Clostridium bacteria. Molecular analysis indicated the optrA-positive plasmids belonged to a plasmid type distinct from the pCW3-like plasmids, pCP13-like plasmids, or pIP404-like plasmids. Further structure analysis showed they might be formed by inserting segments into plasmid pCPCPI53k-r1_1, which coexist with two pCW3-like plasmids and one pCP13-like plasmid in C. perfringens strain CPI 53k-r1 isolated from a healthy human in Finland. IMPORTANCE Antimicrobial resistance is now a global concern posing threats to food safety and public health. The pCW3-like plasmids can encode several main toxin genes and three antibiotic resistance genes (ARGs), including tetA(P), tetB(P), and erm(B), which used to be considered as the main carrier of ARGs in Clostridium perfringens. In this study, we found the optrA plasmids, which belonged to a novel plasmid type, could also harbor many other ARGs, indicating this type of plasmid might be the potential repository of ARGs in C. perfringens. Additionally, this type of plasmid could coexist with the pCW3-like plasmids and pCP13-like plasmids that encoded toxin genes associated with gastrointestinal diseases, which showed the potential threat to public health.

Microbiology of street food: understanding risks to improve safety

Street foods play important socioeconomic and cultural roles and are popular worldwide. In addition to providing convenient and low-cost meals for urban populations, street food offers an essential source of income for vendors, especially women, and it can reflect traditional local culture, which is an important attraction for tourists. Despite these benefits, the microbiological safety of street food has become a worldwide concern because it is often prepared and sold under inadequate safety conditions, without legal control and sanitary surveillance. Consequently, high counts of fecal indicator bacteria and several foodborne pathogens have been detected in street foods. This review provides insight into the microbiology of street food, focus on the associated microbiological safety aspects and main pathogens, and the global status of this important economic activity. Furthermore, the need to apply molecular detection rather than traditional culture-based methods is discussed to better understand the actual risks of microbial infection associated with street foods. Recognition is always the first step toward addressing a problem.

Antimicrobial, antiproliferative activities and molecular docking of metabolites from Alternaria alternata

Endophytic fungi allied to plants have sparked substantial promise in discovering new bioactive compounds. In this study, propagation of the endophytic fungus Alternaria alternata HE11 obtained from Colocasia esculanta leaves led to the isolation of Ergosterol (1), β-Sitosterol (2), Ergosterol peroxide (3), in addition to three dimeric naphtho-γ-pyrones, namely Fonsecinone A (4), Asperpyrone C (5), and Asperpyrone B (6), which were isolated from genus Alternaria for the first time. Structures of the isolated compounds were established on the basis of extensive 1D and 2D NMR and, MS measurements. The ethyl acetate extract, as well as compounds 1, 3, 4 and 6 were evaluated for their antimicrobial activity using agar well-diffusion and broth microdilution assays. Molecular docking study was carried out to explore the pharmacophoric moieties that governed the binding orientation of antibacterial active compounds to multidrug efflux transporter AcrB and the ATP binding site to E. coli DNA gyrase using MOE software. Results revealed that the most active antibacterial compounds 4 and 6 bind with high affinity in the phenylalanine-rich cage and are surrounded with other hydrophobic residues. The antiproliferative activity of all isolated compounds was in vitro evaluated using the human prostatic adenocarcinoma cell lines DU-145, PC-3, PC-3 M, 22Rv1 and CWR-R1ca adopting MTT assay. Compound 4 was the most active against almost all tested cell lines, with IC₅₀ values 28.6, 21.6, 17.1 and 13.3 against PC-3, PC-3 M, 22Rv1 and CWR-R1ca cell lines, respectively.

Pathogenicity and Antibiotic Resistance Diversity in Clostridium perfringens Isolates from Poultry Affected by Necrotic Enteritis in Canada

Necrotic enteritis (NE) caused by C. perfringens is one of the most common diseases of poultry and results in a huge economic loss to the poultry industry, with resistant clostridial strains being a serious concern and making the treatment difficult. Whole-genome sequencing approaches represent a good tool to determine resistance profiles and also shed light for a better understanding of the pathogen. The aim of this study was to characterize, at the genomic level, a collection of 20 C. perfringens isolates from poultry affected by NE, giving special emphasis to resistance mechanisms and production of bacteriocins. Antimicrobial resistance genes were found, with the tet genes (associated with tetracycline resistance) being the most prevalent. Interestingly, two isolates carried the erm(T) gene associated with erythromycin resistance, which has only been reported in other Gram-positive bacteria. Twelve of the isolates were toxinotyped as type A and seven as type G. Other virulence factors encoding hyaluronases and sialidases were frequently detected, as well as different plasmids. Sequence types (ST) revealed a high variability of the isolates, finding new allelic combinations. Among the isolates, C. perfringens MLG7307 showed unique characteristics; it presented a toxin combination that made it impossible to toxinotype, and, despite being identified as C. perfringens, it lacked the housekeeping gene colA. Genes encoding bacteriocin BCN5 were found in five isolates even though no antimicrobial activity could be detected in those isolates. The bcn5 gene of three of our isolates was similar to one previously reported, showing two polymorphisms. Concluding, this study provides insights into the genomic characteristics of C. perfringens and a better understanding of this avian pathogen.

NanJ Is the Major Sialidase for Clostridium perfringens Type F Food Poisoning Strain 01E809

Clostridium perfringens type F strains cause food poisoning (FP) when they sporulate and produce C. perfringens enterotoxin (CPE) in the intestines. Most type F FP strains carry a chromosomal cpe gene (c-cpe strains). C. perfringens produces up to three different sialidases, named NanH, NanI, and NanJ, but some c-cpe FP strains carry only nanJ and nanH genes. This study surveyed a collection of such strains and showed that they produce sialidase activity when cultured in Todd-Hewitt broth (TH) (vegetative cultures) or modified Duncan-Strong (MDS) medium (sporulating cultures). Sialidase null mutants were constructed in 01E809, a type F c-cpe FP strain carrying the nanJ and nanH genes. Characterization of those mutants identified NanJ as the major sialidase of 01E809 and showed that, in vegetative and sporulating cultures, nanH expression affects nanJ expression and vice versa; those regulatory effects may involve media-dependent changes in transcription of the codY or ccpA genes but not nanR. Additional characterization of these mutants demonstrated the following: (i) NanJ contributions to growth and vegetative cell survival are media dependent, with this sialidase increasing 01E809 growth in MDS but not TH; (ii) NanJ enhances 24-h vegetative cell viability in both TH and MDS cultures; and (iii) NanJ is important for 01E809 sporulation and, together with NanH, CPE production in MDS cultures. Lastly, NanJ was shown to increase CPE-induced cytotoxicity and CH-1 pore formation in Caco-2 cells. Collectively, these results suggest that NanJ may have a contributory role in FP caused by type F c-cpe strains that carry the nanH and nanJ genes.

Identification of orphan histidine kinases that impact sporulation and enterotoxin production by Clostridium perfringens type F strain SM101 in a pathophysiologically-relevant ex vivo mouse intestinal contents model

When causing food poisoning or antibiotic-associated diarrhea, Clostridium perfringens type F strains must sporulate to produce C. perfringens enterotoxin (CPE) in the intestines. C. perfringens is thought to use some of its seven annotated orphan histidine kinases to phosphorylate Spo0A and initiate sporulation and CPE production. We previously demonstrated the CPR0195 orphan kinase, but not the putative CPR1055 orphan kinase, is important when type F strain SM101 initiates sporulation and CPE production in modified Duncan-Strong (MDS) sporulation medium. Since there is no small animal model for C. perfringens sporulation, the current study used diluted mouse intestinal contents (MIC) to develop an ex vivo sporulation model and employed this model to test sporulation and CPE production by SM101 CPR0195 and CPR1055 null mutants in a pathophysiologically-relevant context. Surprisingly, both mutants still sporulated and produced CPE at wild-type levels in MIC. Therefore, five single null mutants were constructed that cannot produce one of the previously-unstudied putative orphan kinases of SM101. Those mutants implicated CPR1316, CPR1493, CPR1953 and CPR1954 in sporulation and CPE production by SM101 MDS cultures. Phosphorylation activity was necessary for CPR1316, CPR1493, CPR1953 and CPR1954 to affect sporulation in those MDS cultures, supporting their identity as kinases. Importantly, only the CPR1953 or CPR1954 null mutants exhibited significantly reduced levels of sporulation and CPE production in MIC cultures. These phenotypes were reversible by complementation. Characterization studies suggested that, in MDS or MIC, the CPR1953 and CPR1954 mutants produce less Spo0A than wild-type SM101. In addition, the CPR1954 mutant exhibited little or no Spo0A phosphorylation in MDS cultures. These studies, i) highlight the importance of using pathophysiologically-relevant models to investigate C. perfringens sporulation and CPE production in a disease context and ii) link the CPR1953 and CPR1954 kinases to C. perfringens sporulation and CPE production in disease-relevant conditions.

Characterization of Collagen Binding Activity of Clostridium perfringens Strains Isolated from Broiler Chickens

Clostridium perfringens is the etiological agent for necrotic enteritis (NE) in broiler chickens, which causes a substantial economic loss of an estimated USD 6 billion annually in the global poultry industry. Collagen adhesion is involved in the NE pathogenesis in poultry. In this study, the binding capabilities of chicken C. perfringens isolates of various genetic backgrounds (netB^-tpeL^-, netB⁺tpeL^-, netB⁺tpeL⁺) to collagen types I-V and gelatin were examined, and the putative adhesin protein cnaA gene was investigated at the genomic level. In total, 28 C. perfringens strains from healthy and NE-inflicted sick chickens were examined. The results on collagen adhesin-encoding gene cnaA by the quantitative-PCR results indicated that netB^-tpeL^- isolates had much lower copies of the detectable cnaA gene than netB⁺ isolates (10 netB⁺tpeL^- isolates, 5 netB⁺tpeL⁺ isolates). Most of the virulent C. perfringens isolates demonstrated collagen-binding abilities to types I-II and IV-V, while some strains showed weak or no binding to collagen type III and gelatin. However, the netB⁺tpeL⁺ isolates showed significantly higher binding capabilities to collagen III than netB^-tpeL^- and netB⁺tpeL^- isolates. The data in this study suggest that the collagen-binding capability of clinical C. perfringens isolates correlates well with their NE pathogenicity levels, especially for C. perfringens isolates carrying genes encoding crucial virulence factors and virulence-associated factors such as netB, cnaA, and tpeL. These results indicate that the presence of the cnaA gene may be correlated with C. perfringens virulence (particularly for netB⁺ isolates).

Clostridium perfringens-Opportunistic Foodborne Pathogen, Its Diversity and Epidemiological Significance

The C. perfringens species is associated with various environments, such as soils, sewage, and food. However, it is also a component of the gastrointestinal (GI) microflora (i.e., microbiota) of sick and healthy humans and animals. C. perfringens is linked with different systemic and enteric diseases in livestock and humans, such as gas gangrene, food poisoning, non-foodborne diarrhoea, and enterocolitis. The strains of this opportunistic pathogen are known to secrete over 20 identified toxins that are considered its principal virulence factors. C. perfringens belongs to the anaerobic bacteria community but can also survive in the presence of oxygen. The short time between generations, the multi-production capability of toxins and heat-resistant spores, the location of many virulence genes on mobile genetic elements, and the inhabitance of this opportunistic pathogen in different ecological niches make C. perfringens a very important microorganism for public health protection. The epidemiological evidence for the association of these strains with C. perfringens-meditated food poisoning and some cases of non-foodborne diseases is very clear and well-documented. However, the genetic diversity and physiology of C. perfringens should still be studied in order to confirm the importance of suspected novel virulence traits. A very significant problem is the growing antibiotic resistance of C. perfringens strains. The aim of this review is to show the current basic information about the toxins, epidemiology, and genetic and molecular diversity of this opportunistic pathogen.

Characterization of G-type Clostridium perfringens bacteriophages and their disinfection effect on chicken meat

OBJECTIVE

Clostridium perfringens is one of most important bacterial pathogens in the poultry industry and mainly causes necrotizing enteritis (NE). This pathogen and its toxins can cause foodborne diseases in humans through the food chain. In China, with the rise of antibiotic resistance and the banning of antibiotic growth promoters (AGPs) in poultry farming, food contamination and NE are becoming more prevalent. Bacteriophages are a viable technique to control C. perfringens as an alternative to antibiotics. We isolated Clostridium phage from the environment, providing a new method for the prevention of NE and C. perfringens contamination in meat.

METHODS

In this study, we selected C. perfringens strains from various regions and animal sources in China for phage isolation. The biological characteristics of Clostridium phage were studied in terms of host range, MOI, one-step curve, temperature and pH stability. We sequenced and annotated the genome of the Clostridium phage and performed phylogenetic and pangenomic analyses. Finally, we studied its antibacterial activity against bacterial culture and its disinfection effect against C. perfringens in meat.

RESULTS

A Clostridium phage, named ZWPH-P21 (P21), was isolated from chicken farm sewage in Jiangsu, China. P21 has been shown to specifically lyse C. perfringens type G. Further analysis of basic biological characteristics showed that P21 was stable under the conditions of pH 4-11 and temperature 4-60 °C, and the optimal multiple severity of infection (MOI) was 0.1. In addition, P21 could form a "halo" on agar plates, suggesting that the phage may encode depolymerase. Genome sequence analysis showed that P21 was the most closely related to Clostridium phage CPAS-15 belonging to the Myoviridae family, with a recognition rate of 97.24% and a query coverage rate of 98%. No virulence factors or drug resistance genes were found in P21. P21 showed promising antibacterial activity in vitro and in chicken disinfection experiments. In conclusion, P21 has the potential to be used for preventing and controlling C. perfringens in chicken food production.

Functional Characterization of the Putative POT from Clostridium perfringens

Proton-coupled oligopeptide transporters (POTs) are a fundamental part of the cellular transport machinery that provides plants, bacteria, and mammals with nutrition in the form of short peptides. However, POTs are not restricted to peptide transport; mammalian POTs have especially been in focus due to their ability to transport several peptidomimetics in the small intestine. Herein, we studied a POT from Clostridium perfringens (CPEPOT), which unexpectedly exhibited atypical characteristics. First, very little uptake of a fluorescently labelled peptide β-Ala-Lys-AMCA, an otherwise good substrate of several other bacterial POTs, was observed. Secondly, in the presence of a competitor peptide, enhanced uptake of β-Ala-Lys-AMCA was observed due to trans-stimulation. This effect was also observed even in the absence of a proton electrochemical gradient, suggesting that β-Ala-Lys-AMCA uptake mediated by CPEPOT is likely through the substrate-concentration-driving exchange mechanism, unlike any other functionally characterized bacterial POTs.

Divalent Cation Signaling in Clostridium perfringens Spore Germination

Spore germination plays an essential role in the pathogenesis of Clostridium perfringens-associated food poisoning. Germination is initiated when bacterial spores sense various stimuli, including chemicals and enzymes. A previous study showed that dipicolinic acid (DPA) chelated with calcium (Ca-DPA) significantly stimulated spore germination in C. perfringens. However, whether Ca2+ or DPA alone can induce germination is unknown. Therefore, we aimed to evaluate the possible roles of Ca2+ and other divalent cations present in the spore core, such as Mn2+ and Mg2+, in C. perfringens spore germination. Our study demonstrated that (i) Ca-DPA, but not DPA alone, induced C. perfringens spore germination, suggesting that Ca2+ might play a signaling role; (ii) all tested calcium salts induced spore germination, indicating that Ca2+ is critical for germination; (iii) the spore-specific divalent cations Mn2+ and Mg2+, but not Zn2+, induced spore germination, suggesting that spore core-specific divalent cations are involved in C. perfringens spore germination; and (iv) endogenous Ca2+ and Mg2+ are not required for induction of C. perfringens spore germination, whereas exogenous and partly endogenous Mn2+ are required. Collectively, our results suggest that exogenous spore core-specific divalent cation signals are more important than endogenous signals for the induction of spore germination.

Infections caused by Clostridium perfringens and Paeniclostridium sordellii after unsafe abortion

After the legalisation of abortion in the USA in 1973, the risk of infectious morbidity and mortality from this procedure notably decreased. With increasingly restrictive legislation targeting access to safe abortion services, reviewing infectious complications of unsafe pregnancy termination is crucial, particularly the diagnosis and management of life-threatening clostridial (and related anaerobic bacterial) infections that can complicate unsafe abortion. This Review deals with two especially devastating infections that are well-documented causes of septic abortion: the anaerobic, spore-forming pathogens Clostridium perfringens and Paeniclostridium sordellii. We seek to familiarise the reader with these bacteria, the clinical syndromes they can cause (with a focus on toxic shock syndrome), and provide a review of diagnosis and treatment options.

Characterization of NanR Regulation of Sialidase Production, Sporulation and Enterotoxin Production by Clostridium perfringens Type F Strains Carrying a Chromosomal Enterotoxin Gene

Clostridium perfringens type F food poisoning (FP) strains produce C. perfringens enterotoxin (CPE) to cause a common bacterial food-borne illness in the United States. During FP, CPE is synthesized in the intestines when C. perfringens sporulates. Besides CPE, FP strains also produce sialidases. Most FP strains carry their cpe gene on the chromosome and all surveyed chromosomal cpe (c-cpe) FP strains produce NanH sialidase or both NanJ and NanH sialidases. NanR has been shown previously to regulate sialidase activity in non-FP strains. The current study investigated whether NanR also regulates sialidase activity or influences sporulation and CPE production for c-cpe FP strains SM101 and 01E809. In sporulation medium, the SM101 nanR null mutant showed lower sialidase activity, sporulation, and CPE production than its wild-type parent, while the 01E809 nanR null mutant showed roughly similar sialidase activity, sporulation, and CPE production as its parent. In vegetative medium, the nanR null mutants of both strains produced more spores than their parents while NanR repressed sialidase activity in SM101 but positively regulated sialidase activity in 01E809. These results demonstrate that NanR regulates important virulence functions of c-cpe strains, with this control varying depending on strain and culture conditions.

Seasonal dynamics in bacterial communities of closed-cage broiler houses

The bacteria contained in air aerosols from poultry houses are closely connected to animal health and production. This study aimed to investigate the seasonal factors on microbial aerosol concentration, particle size and bacterial spectrum composition inside a closed-cage broiler house. Then, 16S rDNA sequencing technology was applied to analyze the characteristics of bacterial abundance and diversity. The results indicated that the concentration of bacterial aerosol in the broiler house varied significantly in different seasons, with a concentration range of 5.87–15.77 × 10³ CFU/m³, and the highest and lowest concentrations in the summer and winter, respectively. Microbiological analysis showed that the proportion of Gram-negative bacteria in autumn was significantly higher than that in summer (P < 0.05). In addition, the floral structure of potential pathogenic bacterial genera also differed by season. Escherichia-Shigella, Streptococcus, Acinetobacter, Pseudomonas were identified in the bacterial aerosols. Importantly, the relative abundance of Firmicutes in spring and autumn was much higher. In contrast, the relative abundance of Proteobacteria in spring and autumn was lower than that in summer and winter. Altogether, results revealed the effects of seasonal factors on the diversity and abundance of bacteria and the distribution characteristics of major opportunistic pathogens in the air of closed-cage broiler houses. These results will provide important information for exploring the potential risk of aerosols from poultry houses all four seasons.

Characterizing the Contributions of Various Clostridium perfringens Enterotoxin Properties to In Vivo and In Vitro Permeability Effects

Clostridium perfringens enterotoxin (CPE) is thought to cause lethal enterotoxemia when absorbed from the intestinal lumen into the circulation. CPE action sequentially involves receptor-binding, oligomerization into a prepore, and pore formation. To explore the mechanistic basis by which CPE alters permeability, this study tested the permeability effects of several recombinant CPE (rCPE) species: rCPE and rCPE_C186A (which form pores), rC-CPE and rCPE_D48A (which bind to receptors but cannot oligomerize), rCPE_C186A/F91C (which binds and oligomerizes without pore formation), and rCPE_Y306A/L315A (which has poor receptor-binding ability). On Caco-2 cells, i) only rCPE and rCPE_C186A were cytotoxic; ii) rCPE and rCPE_C186A affected transepithelial resistance (TEER) and 4 kDa fluorescent dextran (FD4) transit more quickly than binding-capable, but noncytotoxic, rCPE variants; whereas iii) rCPE_Y306A/L315A did not affect TEER or FD4 transit. Using mouse intestinal loops, rCPE (but not noncytotoxic rC-CPE, rCPE_D48A or rCPE_Y306A/L315A) was lethal and caused intestinal histologic damage within 4 h. After 2 h of treatment, rCPE was more strongly absorbed into the serum than those noncytotoxic rCPE species but by 4 h rC-CPE and rCPE_D48A became absorbed similarly as rCPE, while rCPE_Y306A/L315A absorption remained low. This increased rC-CPE and rCPE_D48A absorption from 2 to 4 h did not involve a general intestinal permeability increase because Evans Blue absorption from the intestines did not increase between 2 and 4 h of treatment with rC-CPE or rCPE_D48A. Collectively, these results indicate that CPE receptor binding is sufficient to slowly affect permeability, but CPE-induced cytotoxicity is necessary for rapid permeability changes and lethality. IMPORTANCE Clostridium perfringens enterotoxin (CPE) causes lethal enterotoxemia when absorbed from the intestines into the bloodstream. Testing recombinant CPE (rCPE) or rCPE variants impaired for various specific steps in CPE action showed that full CPE-induced cytotoxicity causes rapid Caco-2 monolayer permeability alterations, as well as enterotoxemic lethality and rapid CPE absorption in mouse small intestinal loops. However, receptor binding-capable, but noncytotoxic, rCPE variants did cause slow-developing in vitro and in vivo permeability effects. Absorption of binding-capable, noncytotoxic rCPE variants from the intestines did not correlate with general intestinal permeability alterations, suggesting that CPE binding can induce its own uptake. These findings highlight the importance of binding and, especially, cytotoxicity for CPE absorption during enterotoxemia and may assist development of permeability-altering rCPE variants for translational purposes.

Maternal amoxicillin affects piglets colon microbiota: microbial ecology and metabolomics in a gut model

Abstract

The first weeks of life represent a crucial stage for microbial colonization of the piglets’ gastrointestinal tract. Newborns’ microbiota is unstable and easily subject to changes under stimuli or insults. Nonetheless, the administration of antibiotics to the sow is still considered as common practice in intensive farming for pathological conditions in the postpartum. Therefore, transfer of antibiotic residues through milk may occurs, affecting the piglets’ colon microbiota. In this study, we aimed to extend the knowledge on antibiotic transfer through milk, employing an in vitro dedicated piglet colon model (MICODE—Multi Unit In vitro Colon Model). The authors’ focus was set on the shifts of the piglets’ microbiota composition microbiomics (16S r-DNA MiSeq and qPCR—quantitative polymerase chain reaction) and on the production of microbial metabolites (SPME GC/MS—solid phase micro-extraction gas chromatography/mass spectrometry) in response to milk with different concentrations of amoxicillin. The results showed an effective influence of amoxicillin in piglets’ microbiota and metabolites production; however, without altering the overall biodiversity. The scenario is that of a limitation of pathogens and opportunistic taxa, e.g., Staphylococcaceae and Enterobacteriaceae, but also a limitation of commensal dominant Lactobacillaceae, a reduction in commensal Ruminococcaceae and a depletion in beneficial Bifidobactericeae. Lastly, an incremental growth of resistant species, such as Enterococcaceae or Clostridiaceae, was observed. To the authors’ knowledge, this study is the first evaluating the impact of antibiotic residues towards the piglets’ colon microbiota in an in vitro model, opening the way to include such approach in a pipeline of experiments where a reduced number of animals for testing is employed.

Key points

• Piglet colon model to study antibiotic transfer through milk.

• MICODE resulted a robust and versatile in vitro gut model.

• Towards the “3Rs” Principles to replace, reduce and refine the use of animals used for scientific purposes (Directive 2010/63/UE).

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00253-022-12223-3.