Fatal necrotizing colitis following a foodborne outbreak of enterotoxigenic Clostridium perfringens type A infection

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.

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).

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.

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.

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.

NanI Sialidase Enhances the Action of Clostridium perfringens Enterotoxin in the Presence of Mucus

Clostridium perfringens enterotoxin (CPE) is the main virulence factor for C. perfringens type F strains to cause human gastrointestinal diseases, which can involve lethal enterotoxemia. During type F disease, CPE encounters an adherent mucus layer overlying the intestines, so the current study evaluated if NanI potentiates CPE activity in the presence of adherent mucus. CPE alone caused more cytotoxicity transepithelial electrical resistance (TEER) and permeability to fluorescent dextran (FD) for minimal mucus-producing HT29 cells versus that in their derivative HT29-MTX-E12 cells, which produce abundant adherent mucus. However, for HT29-MTX-E12 cells, the presence of NanI significantly increased CPE binding and pore formation, which enhanced their sensitivity to CPE effects on cytotoxicity, TEER, and FD permeability. When the ability of NanI to potentiate CPE-induced enterotoxemia was then tested in a mouse small intestinal loop enterotoxemia model, a pathophysiologically relevant 50 μg/mL dose of CPE did not kill mice. However, the copresence of purified NanI resulted in significant CPE-induced lethality. More CPE was detected in the sera of mice challenged with 50 μg/mL of CPE when NanI was copresent during challenge. The copresence of NanI and CPE during challenge also significantly increased intestinal histologic damage compared to that after challenge with CPE alone, suggesting that NanI enhancement of CPE-induced intestinal damage may increase CPE absorption into blood. Overall, these results indicate that (i) mucus inhibits CPE action and (ii) NanI can potentiate CPE action in the presence of mucus, which may help explain why type F strains that produce relatively low levels of CPE are still pathogenic.

IMPORTANCE NanI is a sialidase produced by some Clostridium perfringens type F strains. Here, we found that NanI can significantly increase the action of C. perfringens enterotoxin (CPE), which is the main toxin responsible for severe human enteric disease caused by type F strains. This effect likely helps to explain why even some type F strains that produce small amounts of CPE are pathogenic.

Navarro M, Li J, Shrestha A, Uzal F, A. McClane B. Pathogenicity and virulence of Clostridium perfringens

Clostridium perfringens is an extremely versatile pathogen of humans and livestock, causing wound infections like gas gangrene (clostridial myonecrosis), enteritis/enterocolitis (including one of the most common human food-borne illnesses), and enterotoxemia (where toxins produced in the intestine are absorbed and damage distant organs such as the brain). The virulence of this Gram-positive, spore-forming, anaerobe is largely attributable to its copious toxin production; the diverse actions and roles in infection of these toxins are now becoming established. Most C. perfringens toxin genes are encoded on conjugative plasmids, including the pCW3-like and the recently discovered pCP13-like plasmid families. Production of C. perfringens toxins is highly regulated via processes involving two-component regulatory systems, quorum sensing and/or sporulation-related alternative sigma factors. Non-toxin factors, such as degradative enzymes like sialidases, are also now being implicated in the pathogenicity of this bacterium. These factors can promote toxin action in vitro and, perhaps in vivo, and also enhance C. perfringens intestinal colonization, e.g. NanI sialidase increases C. perfringens adherence to intestinal tissue and generates nutrients for its growth, at least in vitro. The possible virulence contributions of many other factors, such as adhesins, the capsule and biofilms, largely await future study.

Healthcare-associated foodborne outbreaks in high-income countries: a literature review and surveillance study, 16 OECD countries, 2001 to 2019

BackgroundHealthcare-associated foodborne outbreaks (HA-FBO) may have severe consequences, especially in vulnerable groups.AimThe aim was to describe the current state of HA-FBO and propose public health recommendations for prevention.MethodsWe searched PubMed, the Outbreak Database (Charité, University Medicine Berlin), and hand-searched reference lists for HA-FBO with outbreak onset between 2001 and 2018 from Organisation for Economic Co-operation and Development (OECD) countries and HA-FBO (2012-2018) from the German surveillance system. Additionally, data from the European Food Safety Authority were analysed.ResultsThe literature search retrieved 57 HA-FBO from 16 OECD countries, primarily in the US (n = 11), Germany (n = 11) and the United Kingdom (n = 9). In addition, 28 HA-FBO were retrieved from the German surveillance system. Based on the number of outbreaks, the top three pathogens associated with the overall 85 HA-FBO were Salmonella (n = 24), norovirus (n = 22) and Listeria monocytogenes (n = 19). Based on the number of deaths, L. monocytogenes was the main pathogen causing HA-FBO. Frequently reported implicated foods were 'mixed foods' (n = 16), 'vegetables and fruits' (n = 15) and 'meat and meat products' (n = 10). Consumption of high-risk food by vulnerable patients, inadequate time-temperature control, insufficient kitchen hygiene and food hygiene and carriers of pathogens among food handlers were reported as reasons for HA-FBO.ConclusionTo prevent HA-FBO, the supply of high-risk food to vulnerable people should be avoided. Well working outbreak surveillance facilitates early detection and requires close interdisciplinary collaboration and exchange of information between hospitals, food safety and public health authorities.

NanI Sialidase Contributes to the Growth and Adherence of Clostridium perfringens Type F Strain F4969 in the Presence of Adherent Mucus

Clostridium perfringens type F strains causing nonfoodborne human gastrointestinal diseases (NFD) typically produce NanI sialidase as their major secreted sialidase. Type F NFDs can persist for several weeks, indicating their pathogenesis involves intestinal colonization, including vegetative cell growth and adherence, with subsequent sporulation that fosters enterotoxin production and release. We previously reported that NanI contributes to type F NFD strain adherence and growth using Caco-2 cells. However, Caco-2 cells make minimal amounts of mucus, which is significant because the intestines are coated with adherent mucus. Therefore, it was important to assess if NanI contributes to the growth and adherence of type F NFD strains in the presence of adherent mucus. Consequently, the current study first demonstrated greater growth of nanI-carrying versus non-nanI-carrying type F strains in the presence of HT29-MTX-E12 cells, which produce an adherent mucus layer, versus their parental HT29 cells, which make minimal mucus. Demonstrating the specific importance of NanI for this effect, type F NFD strain F4969 or a complementing strain grew and adhered better than an isogenic nanI null mutant in the presence of HT29-MTX-E12 cells versus HT29 cells. Those effects involved mucus production by HT29-MTX-E12 cells since mucus reduction using N-acetyl cysteine reduced F4969 growth and adherence. Consistent with those in vitro results, NanI contributed to growth of F4969 in the mouse small intestine. By demonstrating a growth and adherence role for NanI in the presence of adherent mucus, these results further support NanI as a potential virulence factor during type F NFDs.

NanH Is Produced by Sporulating Cultures of Clostridium perfringens Type F Food Poisoning Strains and Enhances the Cytotoxicity of C. perfringens Enterotoxin

Clostridium perfringens type F strains cause the second most common bacterial foodborne illness in the United States. C. perfringens enterotoxin (CPE) is responsible for the diarrhea and cramping symptoms of this food poisoning (FP). Previous studies showed that NanI sialidase can enhance CPE activity in vitro.

Clostridium perfringens type F food poisoning (FP) strains cause one of the most common foodborne illnesses. This FP develops when type F FP strains sporulate in the intestines and produce C. perfringens enterotoxin (CPE), which is responsible for the diarrhea and abdominal cramps of this disease. While C. perfringens can produce up to three different sialidases, the current study surveyed FP strains, which confirmed the results of a previous study that they consistently carry the nanH sialidase gene, often as their only sialidase gene. NanH production was found to be associated with sporulating cultures of the surveyed type F FP strains, including SM101 (a transformable derivative of a FP strain). The sporulation-associated regulation of NanH production by strain SM101 growing in modified Duncan-Strong medium (MDS) was shown to involve Spo0A, but it did not require the completion of sporulation. NanH production was not necessary for either the growth or sporulation of SM101 when cultured in MDS. In those MDS cultures, NanH accumulated in the sporulating mother cell until it was released coincidently with CPE. Since CPE becomes extracellular when mother cells lyse to release their mature spores, this indicates that mother cell lysis is also important for NanH release. The copresence of NanH and CPE in supernatants from lysed sporulating cultures was shown to enhance CPE cytotoxicity for Caco-2 cells. This enhancement was attributable to NanH increasing CPE binding and could be replicated with purified recombinant NanH. These in vitro findings suggest that NanH may be an accessory virulence factor during type F FP.

IMPORTANCEClostridium perfringens type F strains cause the second most common bacterial foodborne illness in the United States. C. perfringens enterotoxin (CPE) is responsible for the diarrhea and cramping symptoms of this food poisoning (FP). Previous studies showed that NanI sialidase can enhance CPE activity in vitro. While many type F FP strains do not produce NanI, they do consistently make NanH sialidase. This study shows that, like CPE, NanH is produced by sporulating type F FP strains and then released extracellularly when their sporulating cells lyse to release their mature spore. NanH was shown to enhance CPE cytotoxicity in vitro by increasing CPE binding to cultured Caco-2 cells. This enhancement could be important because many type F FP strains produce less CPE than necessary (in a purified form) to cause intestinal pathology in animal models. Therefore, NanH represents a potential accessory virulence factor for type F FP.

Innovative and Highly Sensitive Detection of Clostridium perfringens Enterotoxin Based on Receptor Interaction and Monoclonal Antibodies

Clostridium perfringens enterotoxin (CPE) regularly causes food poisoning and antibiotic-associated diarrhea; therefore, reliable toxin detection is crucial. To this aim, we explored stationary and mobile strategies to detect CPE either exclusively by monoclonal antibodies (mAbs) or, alternatively, by toxin-enrichment via the cellular receptor of CPE, claudin-4, and mAb detection. Among the newly generated mAbs, we identified nine CPE-specific mAbs targeting five distinct epitopes, among them mAbs recognizing CPE bound to claudin-4 or neutralizing CPE activity in vitro. In surface plasmon resonance experiments, all mAbs and claudin-4 revealed excellent affinities towards CPE, ranging from 0.05 to 2.3 nM. Integrated into sandwich enzyme-linked immunosorbent assays (ELISAs), the most sensitive mAb/mAb and claudin-4/mAb combinations achieved similar detection limits of 0.3 pg/mL and 1.0 pg/mL, respectively, specifically detecting recombinant CPE from spiked feces and native CPE from 30 different C. perfringens culture supernatants. The implementation of mAb- and receptor-based ELISAs into a mobile detection platform enabled the fast detection of CPE, which will be helpful in clinical laboratories to diagnose diarrhea of assumed bacterial origin. In conclusion, we successfully employed an endogenous receptor and novel high affinity mAbs for highly sensitive and specific CPE-detection. These tools will be useful for both basic and applied research.

Comparative in silico genome analysis of Clostridium perfringens unravels stable phylogroups with different genome characteristics and pathogenic potential

Clostridium perfringens causes a plethora of devastating infections, with toxin production being the underlying mechanism of pathogenicity in various hosts. Genomic analyses of 206 public-available C. perfringens strains´ sequence data identified a substantial degree of genomic variability in respect to episome content, chromosome size and mobile elements. However, the position and order of the local collinear blocks on the chromosome showed a considerable degree of preservation. The strains were divided into five stable phylogroups (I–V). Phylogroup I contained human food poisoning strains with chromosomal enterotoxin (cpe) and a Darmbrand strain characterized by a high frequency of mobile elements, a relatively small genome size and a marked loss of chromosomal genes, including loss of genes encoding virulence traits. These features might correspond to the adaptation of these strains to a particular habitat, causing human foodborne illnesses. This contrasts strains that belong to phylogroup II where the genome size points to the acquisition of genetic material. Most strains of phylogroup II have been isolated from enteric lesions in horses and dogs. Phylogroups III, IV and V are heterogeneous groups containing a variety of different strains, with phylogroup III being the most abundant (65.5%). In conclusion, C. perfringens displays five stable phylogroups reflecting different disease involvements, prompting further studies on the evolution of this highly important pathogen.

Epidemiological and genetic characterization of Clostridium butyricum cultured from neonatal cases of necrotizing enterocolitis in China

Objective:

Laboratory-based characterization and traceback of Clostridium butyricum isolates linked to outbreak cases of neonatal necrotizing enterocolitis (NEC) in a hospital in China.

Methods:

In total, 37 samples were collected during the NEC outbreak. Classical bacteriological methods were applied to isolate and identify Clostridium spp. Meanwhile, 24 samples collected after an outbreak were similarly tested. All Clostridium isolates were identified to species level as either C. butyricum or C. sporogenes. These isolates were subsequently subtyped using pulsed-field gel electrophoresis (PFGE). Genomic DNA was purified from 2 representative C. butyricum isolates and sequenced to completion.

Results:

Of 37 samples collected during the NEC outbreak, 17 (45.95%) were positive for Clostridium spp. One species, C. butyricum, was cultured from 10 samples. Another species cultured from 2 other samples was identified as C. sporogenes. Both of these species were cocultured from 5 samples. Pulsotyping showed that the 15 C. butyricum and the 7 C. sporogenes isolates produced indistinguishable DNA profiles. No NEC cases were reported after disinfection following the outbreak, and all samples collected after the outbreak were negative for Clostridium spp. Whole-genome sequencing (WGS) indicated that sialidase, hemolysin, and enterotoxin virulence factors were located on the chromosomes of 2 C. butyricum isolates.

Conclusions:

The outbreak of NEC was epidemiologically linked to C. butyricum contamination within the hospital. This is the first report of an NEC outbreak associated with C. butyricum infection in China.

Development of a bivalent food poisoning vaccine: augmented antigenicity of the C-terminus of Clostridium perfringens enterotoxin by fusion with the B subunit of Escherichia coli Shiga toxin 2

Food poisonings caused by Clostridium perfringens and Shiga toxin (Stx)-producing Escherichia coli (STEC) occur frequently worldwide; however, no vaccine is currently available. Therefore, we aimed to develop a bivalent vaccine against C. perfringens and STEC infections. Although it has been considered that the C-terminal region of C. perfringens enterotoxin (C-CPE) could be a good vaccine antigen to block the binding to its receptor, it was insufficient for induction of a protective immune response because of the low antigenicity. However, the fusion of C-CPE with Stx2 B subunit (Stx2B) augmented the antigenicity of C-CPE without affecting the antigenicity of Stx2B. Indeed, high levels of C-CPE-specific neutralizing IgG were found in the serum of mice immunized with the fusion protein Stx2B-C-CPE. Additionally, comparable and substantial levels of Stx2B-specific neutralizing IgG were induced in mice receiving Stx2B-C-CPE or Stx2B alone. These antibody responses against C-CPE and Stx2B lasted for at least 48 weeks, which were sufficient for protective immunity in vitro and in vivo, indicating that Stx2B-C-CPE could induce long-term protective immunity. As an underlying mechanism, ex vivo stimulation with Stx2B, but not with C-CPE, induced cytokine production from splenic T cells collected from mice immunized with Stx2B-C-CPE, suggesting that Stx2B-specific, but not C-CPE-specific, T cells were induced by the immunization with Stx2B-C-CPE and plausibly promoted immunoglobulin class switching of both Stx2B- and C-CPE-specific B cells from IgM to IgG. These findings collectively indicate that Stx2B-C-CPE is a T-cell-antigen-supplement-type bivalent vaccine, which could be an efficient against C. perfringens and STEC infections.

Food-to-Humans Bacterial Transmission

Microorganisms vehiculated by food might benefit health, cause minimal change within the equilibrium of the host microbial community or be associated with foodborne diseases. In this chapter we will focus on human pathogenic bacteria for which food is conclusively demonstrated as their transmission mode to human. We will describe the impact of foodborne diseases in public health, the reservoirs of foodborne pathogens (the environment, human and animals), the main bacterial pathogens and food vehicles causing human diseases, and the drivers for the transmission of foodborne diseases related to the food-chain, host or bacteria features. The implication of food-chain (foodborne pathogens and commensals) in the transmission of resistance to antibiotics relevant to the treatment of human infections is also evidenced. The multiplicity and interplay of drivers related to intensification, diversification and globalization of food production, consumer health status, preferences, lifestyles or behaviors, and bacteria adaptation to different challenges (stress tolerance and antimicrobial resistance) from farm to human, make the prevention of bacteria-food-human transmission a modern and continuous challenge. A global One Health approach is mandatory to better understand and minimize the transmission pathways of human pathogens, including multidrug-resistant pathogens and commensals, through food-chain.

RIP1, RIP3, and MLKL Contribute to Cell Death Caused by Clostridium perfringens Enterotoxin

C. perfringens type F strains are a common cause of food poisoning and antibiotic-associated diarrhea. Type F strain virulence requires production of C. perfringens enterotoxin (CPE). In Caco-2 cells, high CPE concentrations cause necrosis while low enterotoxin concentrations induce apoptosis. The current study determined that receptor-interacting serine/threonine-protein kinases 1 and 3 are involved in both CPE-induced apoptosis and necrosis in Caco-2 cells, while mixed-lineage kinase domain-like pseudokinase (MLKL) oligomerization is involved in CPE-induced necrosis, thereby indicating that this form of CPE-induced cell death involves necroptosis. High CPE concentrations also caused necroptosis in T84 and Vero cells. Calpain activation was identified as a key intermediate for CPE-induced necroptosis. These results suggest inhibitors of RIP1, RIP3, MLKL oligomerization, or calpain are useful therapeutics against CPE-mediated diseases.

Clostridium perfringens type F strains cause gastrointestinal disease when they produce a pore-forming toxin named C. perfringens enterotoxin (CPE). In human enterocyte-like Caco-2 cells, low CPE concentrations cause caspase-3-dependent apoptosis, while high CPE concentrations cause necrosis. Since necrosis or apoptosis sometimes involves receptor-interacting serine/threonine-protein kinase-1 or 3 (RIP1 or RIP3), this study examined whether those kinases are important for CPE-induced apoptosis or necrosis. Highly specific RIP1 or RIP3 inhibitors reduced both CPE-induced apoptosis and necrosis in Caco-2 cells. Those findings suggested that the form of necrosis induced by treating Caco-2 cells with high CPE concentrations involves necroptosis, which was confirmed when high, but not low, CPE concentrations were shown to induce oligomerization of mixed-lineage kinase domain-like pseudokinase (MLKL), a key late step in necroptosis. Furthermore, an MLKL oligomerization inhibitor reduced cell death caused by high, but not low, CPE concentrations. Supporting RIP1 and RIP3 involvement in CPE-induced necroptosis, inhibitors of those kinases also reduced MLKL oligomerization during treatment with high CPE concentrations. Calpain inhibitors similarly blocked MLKL oligomerization induced by high CPE concentrations, implicating calpain activation as a key intermediate in initiating CPE-induced necroptosis. In two other CPE-sensitive cell lines, i.e., Vero cells and human enterocyte-like T84 cells, low CPE concentrations also caused primarily apoptosis/late apoptosis, while high CPE concentrations mainly induced necroptosis. Collectively, these results establish that high, but not low, CPE concentrations cause necroptosis and suggest that RIP1, RIP3, MLKL, or calpain inhibitors can be explored as potential therapeutics against CPE effects in vivo.

Effects of Claudin-1 on the Action of Clostridium perfringens Enterotoxin in Caco-2 Cells

Clostridium perfringens enterotoxin (CPE) contributes to diarrhea and an often-lethal enterotoxemia. CPE action starts when it binds to claudin receptors, forming a small complex (90 kDa). Six small complexes then oligomerize to create prepores, followed by insertion of beta-hairpins from CPE to form beta-barrel pores named CH-1 or CH-2. Of the ~27 members of the human claudin protein family, only some bind CPE. However, both receptor claudins and the nonreceptor claudin-1 (CLDN-1) are associated with the small and CH-1/CH-2 CPE complexes. Therefore, this study evaluated whether claudin-1 affects CPE action by generating a CLDN-1 null mutant in Caco-2 cells using CRISPR-Cas9. Compared to wild-type Caco-2 cells, paracellular permeability of the CLDN-1 mutant was significantly enhanced, suggesting that claudin-1 may reduce CPE absorption during enterotoxemia. The CLDN-1 mutant was also markedly more sensitive than wild-type Caco-2 cells to apically-applied CPE. The mechanism behind this increased sensitivity involved higher CPE binding by the CLDN-1 mutant vs. wild-type Caco-2 cells, which led to more CH-1/CH-2 complex formation. However, the CH-1/CH-2 complexes formed by the CLDN-1 mutant were less stable or trypsin resistant than those of wild-type cells. These results indicate that, although a nonreceptor, CLDN-1 positively and negatively influences CPE action.

Dangers of Clostridium perfringens food poisoning in psychiatric patients

Clostridium perfringens food poisoning can be fatal in patients with chronic constipation. We report the investigation and management of a probable outbreak of C. perfringens food poisoning among psychiatric patients in Cape Town, South Africa, in 2013.

Guideline for the Antibiotic Use in Acute Gastroenteritis

Acute gastroenteritis is common infectious disease in community in adults. This work represents an update of 'Clinical guideline for the diagnosis and treatment of gastrointestinal infections' that was developed domestically in 2010. The recommendation of this guideline was developed regarding the following; epidemiological factors, test for diagnosis, the indications of empirical antibiotics, and modification of antibiotics after confirming pathogen. Ultimately, it is expected to decrease antibiotic misuse and prevent antibiotic resistance.

Potential Therapeutic Effects of Mepacrine against Clostridium perfringens Enterotoxin in a Mouse Model of Enterotoxemia

Clostridium perfringens enterotoxin (CPE) is a pore-forming toxin that causes the symptoms of common bacterial food poisoning and several non-foodborne human gastrointestinal diseases, including antibiotic-associated diarrhea and sporadic diarrhea. In some cases, CPE-mediated disease can be very severe or fatal due to the involvement of enterotoxemia. Therefore, the development of potential therapeutics against CPE action during enterotoxemia is warranted. Mepacrine, an acridine derivative drug with broad-spectrum effects on pores and channels in mammalian membranes, has been used to treat protozoal intestinal infections in human patients. A previous study showed that the presence of mepacrine inhibits CPE-induced pore formation and activity in enterocyte-like Caco-2 cells, reducing the cytotoxicity caused by this toxin in vitro Whether mepacrine is similarly protective against CPE action in vivo has not been tested. When the current study evaluated whether mepacrine protects against CPE-induced death and intestinal damage using a murine ligated intestinal loop model, mepacrine protected mice from the enterotoxemic lethality caused by CPE. This protection was accompanied by a reduction in the severity of intestinal lesions induced by the toxin. Mepacrine did not reduce CPE pore formation in the intestine but inhibited absorption of the toxin into the blood of some mice. Protection from enterotoxemic death correlated with the ability of this drug to reduce CPE-induced hyperpotassemia. These in vivo findings, coupled with previous in vitro studies, support mepacrine as a potential therapeutic against CPE-mediated enterotoxemic disease.

Enterotoxic Clostridia: Clostridium perfringens Enteric Diseases

In humans and livestock, Clostridium perfringens is an important cause of intestinal infections that manifest as enteritis, enterocolitis, or enterotoxemia. This virulence is largely related to the toxin-producing ability of C. perfringens. This article primarily focuses on the C. perfringens type F strains that cause a very common type of human food poisoning and many cases of nonfoodborne human gastrointestinal diseases. The enteric virulence of type F strains is dependent on their ability to produce C. perfringens enterotoxin (CPE). CPE has a unique amino acid sequence but belongs structurally to the aerolysin pore-forming toxin family. The action of CPE begins with binding of the toxin to claudin receptors, followed by oligomerization of the bound toxin into a prepore on the host membrane surface. Each CPE molecule in the prepore then extends a beta-hairpin to form, collectively, a beta-barrel membrane pore that kills cells by increasing calcium influx. The cpe gene is typically encoded on the chromosome of type F food poisoning strains but is encoded by conjugative plasmids in nonfoodborne human gastrointestinal disease type F strains. During disease, CPE is produced when C. perfringens sporulates in the intestines. Beyond type F strains, C. perfringens type C strains producing beta-toxin and type A strains producing a toxin named CPILE or BEC have been associated with human intestinal infections. C. perfringens is also an important cause of enteritis, enterocolitis, and enterotoxemia in livestock and poultry due to intestinal growth and toxin production.

Evidence that Clostridium perfringens Enterotoxin-Induced Intestinal Damage and Enterotoxemic Death in Mice Can Occur Independently of Intestinal Caspase-3 Activation

Clostridium perfringens enterotoxin (CPE) is responsible for the gastrointestinal symptoms of C. perfringens type A food poisoning and some cases of nonfoodborne gastrointestinal diseases, such as antibiotic-associated diarrhea. In the presence of certain predisposing medical conditions, this toxin can also be absorbed from the intestines to cause enterotoxemic death. CPE action in vivo involves intestinal damage, which begins at the villus tips. The cause of this CPE-induced intestinal damage is unknown, but CPE can induce caspase-3-mediated apoptosis in cultured enterocyte-like Caco-2 cells. Therefore, the current study evaluated whether CPE activates caspase-3 in the intestines and, if so, whether this effect is required for the development of intestinal tissue damage or enterotoxemic lethality. Using a mouse ligated small intestinal loop model, CPE was shown to cause intestinal caspase-3 activation in a dose- and time-dependent manner. Most of this caspase-3 activation occurred in epithelial cells shed from villus tips. However, CPE-induced caspase-3 activation occurred after the onset of tissue damage. Furthermore, inhibition of intestinal caspase-3 activity did not affect the onset of intestinal tissue damage. Similarly, inhibition of intestinal caspase-3 activity did not reduce CPE-induced enterotoxemic lethality in these mice. Collectively, these results demonstrate that caspase-3 activation occurs in the CPE-treated intestine but that this effect is not necessary for the development of CPE-induced intestinal tissue damage or enterotoxemic lethality.

Mechanisms of Action and Cell Death Associated with Clostridium perfringens Toxins

Clostridium perfringens uses its large arsenal of protein toxins to produce histotoxic, neurologic and intestinal infections in humans and animals. The major toxins involved in diseases are alpha (CPA), beta (CPB), epsilon (ETX), iota (ITX), enterotoxin (CPE), and necrotic B-like (NetB) toxins. CPA is the main virulence factor involved in gas gangrene in humans, whereas its role in animal diseases is limited and controversial. CPB is responsible for necrotizing enteritis and enterotoxemia, mostly in neonatal individuals of many animal species, including humans. ETX is the main toxin involved in enterotoxemia of sheep and goats. ITX has been implicated in cases of enteritis in rabbits and other animal species; however, its specific role in causing disease has not been proved. CPE is responsible for human food-poisoning and non-foodborne C. perfringens-mediated diarrhea. NetB is the cause of necrotic enteritis in chickens. In most cases, host–toxin interaction starts on the plasma membrane of target cells via specific receptors, resulting in the activation of intracellular pathways with a variety of effects, commonly including cell death. In general, the molecular mechanisms of cell death associated with C. perfringens toxins involve features of apoptosis, necrosis and/or necroptosis.

2017 Infectious Diseases Society of America Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea

These guidelines are intended for use by healthcare professionals who care for children and adults with suspected or confirmed infectious diarrhea. They are not intended to replace physician judgement regarding specific patients or clinical or public health situations. This document does not provide detailed recommendations on infection prevention and control aspects related to infectious diarrhea.

The Potential Therapeutic Agent Mepacrine Protects Caco-2 Cells against Clostridium perfringens Enterotoxin Action

Clostridium perfringens enterotoxin (CPE) causes the gastrointestinal (GI) symptoms of a common bacterial food poisoning and several nonfoodborne human GI diseases. A previous study showed that, via an undetermined mechanism, the presence of mepacrine blocks CPE-induced electrophysiologic activity in artificial membranes. The current study now demonstrates that mepacrine also inhibits CPE-induced cytotoxicity in human enterocyte-like Caco-2 cells and that mepacrine does not directly inactivate CPE. Instead, this drug reduces both CPE pore formation and CPE pore activity in Caco-2 cells. These results suggest mepacrine as a therapeutic candidate for treating CPE-mediated GI diseases.

Clostridium perfringens enterotoxin (CPE) causes the diarrhea associated with a common bacterial food poisoning and many antibiotic-associated diarrhea cases. The severity of some CPE-mediated disease cases warrants the development of potential therapeutics. A previous study showed that the presence of mepacrine inhibited CPE-induced electrophysiology effects in artificial lipid bilayers lacking CPE receptors. However, that study did not assess whether mepacrine inactivates CPE or, instead, inhibits a step in CPE action. Furthermore, CPE action in host cells is complex, involving the toxin binding to receptors, receptor-bound CPE oligomerizing into a prepore on the membrane surface, and β-hairpins in the CPE prepore inserting into the membrane to form a pore that induces cell death. Therefore, the current study evaluated the ability of mepacrine to protect cells from CPE. This drug was found to reduce CPE-induced cytotoxicity in Caco-2 cells. This protection did not involve mepacrine inactivation of CPE, indicating that mepacrine affects one or more steps in CPE action. Western blotting then demonstrated that mepacrine decreases CPE pore levels in Caco-2 cells. This mepacrine-induced reduction in CPE pore levels did not involve CPE binding inhibition but rather an increase in CPE monomer dissociation due to mepacrine interactions with Caco-2 membranes. In addition, mepacrine was also shown to inhibit CPE pores when already present in Caco-2 cells. These in vitro studies, which identified two mepacrine-sensitive steps in CPE-induced cytotoxicity, add support to further testing of the therapeutic potential of mepacrine against CPE-mediated disease.

IMPORTANCEClostridium perfringens enterotoxin (CPE) causes the gastrointestinal (GI) symptoms of a common bacterial food poisoning and several nonfoodborne human GI diseases. A previous study showed that, via an undetermined mechanism, the presence of mepacrine blocks CPE-induced electrophysiologic activity in artificial membranes. The current study now demonstrates that mepacrine also inhibits CPE-induced cytotoxicity in human enterocyte-like Caco-2 cells and that mepacrine does not directly inactivate CPE. Instead, this drug reduces both CPE pore formation and CPE pore activity in Caco-2 cells. These results suggest mepacrine as a therapeutic candidate for treating CPE-mediated GI diseases.

Toxinotyping and Antimicrobial Resistance of Clostridium Perfringens Isolated from Processed Chicken Meat Products

Introduction

The toxinotyping and antimicrobial susceptibility of Clostridium perfringens strains isolated from processed chicken meat were determined.

Material and Methods

Two hundred processed chicken meat samples from luncheon meats, nuggets, burgers, and sausages were screened for Clostridium perfringens by multiplex PCR assay for the presence of alpha (cpa), beta (cpb), epsilon (etx), iota (ia), and enterotoxin toxin (cpe) genes. The C. perfringens isolates were examined in vitro against eight antibiotics (streptomycin, amoxicillin, ampicillin, ciprofloxacin, lincomycin, cefotaxime, rifampicin, and trimethoprim-sulfamethoxazole)

Results

An overall of 32 C. perfringens strains (16%) were isolated from 200 processed chicken meat samples tested. The prevalence of C. perfringens was significantly dependent on the type of toxin genes detected (P = 0.0), being the highest in sausages (32%), followed by luncheon meats (24%), burgers (6%), and nuggets (2%). C. perfringens type A was the most frequently present toxinotype (24/32; 75%), followed by type D (21.9 %) and type E (3.1%). Of the 32 C. perfringens strains tested, only 9 (28%) were enterotoxin gene carriers, with most representing type A (n = 6). C. perfringens strains differed in their resistance/susceptibility to commonly used antibiotics. Most of the strains tested were sensitive to ampicillin (97%) and amoxicillin (94%), with 100% of the strains being resistant to streptomycin and lincomycin. It is noteworthy that the nine isolates with enterotoxigenic potential had a higher resistance than the non-enterotoxigenic ones.

Conclusion

The considerably high C. perfringens isolation rates from processed chicken meat samples and resistance to some of the commonly used antibiotics indicate a potential public health risk. Recent information about the isolation of enterotoxigenic C. perfringens type E from chicken sausage has been reported.

Bystander Host Cell Killing Effects of Clostridium perfringens Enterotoxin

Clostridium perfringens enterotoxin (CPE) binds to claudin receptors, e.g., claudin-4, and then forms a pore that triggers cell death. Pure cultures of host cells that do not express claudin receptors, e.g., fibroblasts, are unaffected by pathophysiologically relevant CPE concentrations in vitro. However, both CPE-insensitive and CPE-sensitive host cells are present in vivo. Therefore, this study tested whether CPE treatment might affect fibroblasts when cocultured with CPE-sensitive claudin-4 fibroblast transfectants or Caco-2 cells. Under these conditions, immunofluorescence microscopy detected increased death of fibroblasts. This cytotoxic effect involved release of a toxic factor from the dying CPE-sensitive cells, since it could be reproduced using culture supernatants from CPE-treated sensitive cells. Supernatants from CPE-treated sensitive cells, particularly Caco-2 cells, were found to contain high levels of membrane vesicles, often containing a CPE species. However, most cytotoxic activity remained in those supernatants even after membrane vesicle depletion, and CPE was not detected in fibroblasts treated with supernatants from CPE-treated sensitive cells. Instead, characterization studies suggest that a major cytotoxic factor present in supernatants from CPE-treated sensitive cells may be a 10- to 30-kDa host serine protease or require the action of that host serine protease. Induction of caspase-3-mediated apoptosis was found to be important for triggering release of the cytotoxic factor(s) from CPE-treated sensitive host cells. Furthermore, the cytotoxic factor(s) in these supernatants was shown to induce a caspase-3-mediated killing of fibroblasts. This bystander killing effect due to release of cytotoxic factors from CPE-treated sensitive cells could contribute to CPE-mediated disease.

In susceptible host cells, Clostridium perfringens enterotoxin (CPE) binds to claudin receptors and then forms pores that result in cell death. Using cocultures of CPE receptor-expressing sensitive cells mixed with CPE-insensitive cells lacking receptors for this toxin, the current study determined that CPE-treated sensitive cells release soluble cytotoxic factors, one of which may be a 10- to 30-kDa serine protease, to cause apoptotic death of cells that are themselves CPE insensitive. These findings suggest a novel bystander killing mechanism by which a pore-forming toxin may extend its damage to affect cells not directly responsive to that toxin. If confirmed to occur in vivo by future studies, this bystander killing effect may have significance during CPE-mediated disease and could impact the translational use of CPE for purposes such as cancer therapy.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Toxinotypes of Clostridium Perfringens Isolated from Sick and Healthy Avian Species

Currently, the factors/toxins responsible for Clostridium perfringens-associated avian enteritis are not well understood. To assess whether specific C. perfringens' toxinotypes are associated with avian enteritis, the isolates of C. perfringens from 31 cases of avian necrotic or ulcerative enteritis submitted between 1997 and 2005 were selected for retrospective analysis using multiplex PCR. C. perfringens was isolated from chickens, turkeys, quail, and psittacines. The toxinotypes of isolates from diseased birds were compared against the toxinotype of 19 C. perfringens isolates from avian cases with no evidence of clostridial enteritis. All C. perfringens isolates were classified as type A regardless of species or disease history. Although many isolates (from all avian groups) had the gene encoding the C. perfirngens beta2 toxin, only 54% produced the toxin in vitro when measured using Western blot analysis. Surprisingly, a large number of healthy birds (90%) carried CPB2-producing isolates, whereas over half of the cpb2-positive isolates from diseased birds failed to produce CPB2. These data from this investigation do not suggest a causal relationship between beta2 toxin and necrotic enteritis in birds.

The interaction of Clostridium perfringens enterotoxin with receptor claudins

Clostridium perfringens enterotoxin (CPE) has significant medical importance due to its involvement in several common human gastrointestinal diseases. This 35 kDa single polypeptide toxin consists of two domains: a C-terminal domain involved in receptor binding and an N-terminal domain involved in oligomerization, membrane insertion and pore formation. The action of CPE starts with its binding to receptors, which include certain members of the claudin tight junction protein family; bound CPE then forms a series of complexes, one of which is a pore that causes the calcium influx responsible for host cell death. Recent studies have revealed that CPE binding to claudin receptors involves interactions between the C-terminal CPE domain and both the 1st and 2nd extracellular loops (ECL-1 and ECL-2) of claudin receptors. Of particular importance for this binding is the docking of ECL-2 into a pocket present in the C-terminal domain of the toxin. This increased understanding of CPE interactions with claudin receptors is now fostering the development of receptor decoy therapeutics for CPE-mediated gastrointestinal disease, reagents for cancer therapy/diagnoses and enhancers of drug delivery.

Clostridium perfringens Enterotoxin: Action, Genetics, and Translational Applications

Clostridium perfringens enterotoxin (CPE) is responsible for causing the gastrointestinal symptoms of several C. perfringens food- and nonfood-borne human gastrointestinal diseases. The enterotoxin gene (cpe) is located on either the chromosome (for most C. perfringens type A food poisoning strains) or large conjugative plasmids (for the remaining type A food poisoning and most, if not all, other CPE-producing strains). In all CPE-positive strains, the cpe gene is strongly associated with insertion sequences that may help to assist its mobilization and spread. During disease, CPE is produced when C. perfringens sporulates in the intestines, a process involving several sporulation-specific alternative sigma factors. The action of CPE starts with its binding to claudin receptors to form a small complex; those small complexes then oligomerize to create a hexameric prepore on the membrane surface. Beta hairpin loops from the CPE molecules in the prepore assemble into a beta barrel that inserts into the membrane to form an active pore that enhances calcium influx, causing cell death. This cell death results in intestinal damage that causes fluid and electrolyte loss. CPE is now being explored for translational applications including cancer therapy/diagnosis, drug delivery, and vaccination.

Collagen degradation and MMP9 activation by Enterococcus faecalis contribute to intestinal anastomotic leak

Even under the most expert care, a properly constructed intestinal anastomosis can fail to heal, resulting in leakage of its contents, peritonitis, and sepsis. The cause of anastomotic leak remains unknown, and its incidence has not changed in decades. We demonstrate that the commensal bacterium Enterococcus faecalis contributes to the pathogenesis of anastomotic leak through its capacity to degrade collagen and to activate tissue matrix metalloproteinase 9 (MMP9) in host intestinal tissues. We demonstrate in rats that leaking anastomotic tissues were colonized by E. faecalis strains that showed an increased collagen-degrading activity and also an increased ability to activate host MMP9, both of which contributed to anastomotic leakage. We demonstrate that the E. faecalis genes gelE and sprE were required for E. faecalis-mediated MMP9 activation. Either elimination of E. faecalis strains through direct topical antibiotics applied to rat intestinal tissues or pharmacological suppression of intestinal MMP9 activation prevented anastomotic leak in rats. In contrast, the standard recommended intravenous antibiotics used in patients undergoing colorectal surgery did not eliminate E. faecalis at anastomotic tissues nor did they prevent leak in our rat model. Finally, we show in humans undergoing colon surgery and treated with the standard recommended intravenous antibiotics that their anastomotic tissues still contained E. faecalis and other bacterial strains with collagen-degrading/MMP9-activating activity. We suggest that intestinal microbes with the capacity to produce collagenases and to activate host metalloproteinase MMP9 may break down collagen in the intestinal tissue contributing to anastomotic leak.

An epidemiological review of gastrointestinal outbreaks associated withClostridium perfringens, North East of England, 2012–2014

An anecdotal increase inC. perfringensoutbreaks was observed in the North East of England during 2012–2014. We describe findings of investigations in order to further understanding of the epidemiology of these outbreaks and inform control measures. All culture-positive (>105c.f.u./g) outbreaks reported to the North East Health Protection Team from 1 January 2012 to 31 December 2014 were included. Epidemiological (attack rate, symptom profile and positive associations with a suspected vehicle of infection), environmental (deficiencies in food preparation or hygiene practices and suspected vehicle of infection) and microbiological investigations are described. Forty-six outbreaks were included (83% reported from care homes). Enterotoxin (cpe) gene-bearerC. perfringenswere detected by PCR in 20/46 (43%) and enterotoxin (by ELISA) and/or enterotoxigenic faecal/food isolates with indistinguishable molecular profiles in 12/46 (26%) outbreaks. Concerns about temperature control of foods were documented in 20/46 (43%) outbreaks. A suspected vehicle of infection was documented in 21/46 (46%) of outbreaks (meat-containing vehicle in 20/21). In 15/21 (71%) identification of the suspected vehicle was based on descriptive evidence alone, in 5/21 (24%) with supporting evidence from an epidemiological study and in 2/21 (10%) with supporting microbiological evidence.C. perfringens-associated illness is preventable and although identification of foodborne outbreaks is challenging, a risk mitigation approach should be taken, particularly in vulnerable populations such as care homes for the elderly.

Microbiological Food Safety for Vulnerable People

Foodborne pathogens are more likely to cause infection and to result in serious consequences in vulnerable people than in healthy adults. People with some increase in susceptibility may form nearly 20% of the population in the UK and the USA. Conditions leading to increased susceptibility are listed. The main factors leading to foodborne disease caused by major pathogens are outlined and examples are given of outbreaks resulting from these factors. Measures to prevent foodborne disease include procedures based on Hazard Analysis Critical Control Point principles and prerequisite programmes and, especially for vulnerable people, the use of lower-risk foods in place of higher-risk products.

Antibiotic Sensitivity of Clostridium perfringens Isolated From Faeces in Tabriz, Iran

BACKGROUND

Clostridium perfringens, a Gram-positive, anaerobic bacterium that produces at least 16 virulence factors including 12 toxins (α-ν), enterotoxin, hemolysin and neuraminidase, can create variable pathogenic condition, ranging from a food poisoning to life-threatening myonecrosis. Among C. perfringens strains, resistance to the drug choices such as penicillin as well as to alternatives of penicillin like metronidazole and clindamycin has also been observed.

OBJECTIVES

The aim of this study was to determine the resistance of isolated toxigenic and non-toxigenic C. perfringens strains against common antimicrobial agents.

MATERIALS AND METHODS

In this descriptive study, a total of 136 stool specimens were collected. At first, cooked meat medium enrichment method was performed on samples at 45°C. Thereafter, a loopful of the enriched culture was transferred to blood agar and incubated anaerobically at 37°C for 24-72 hours. Colonies with double zone of hemolysis were identified by different biochemical tests such as phospholipase C (lecithinase) test, indole and urease production. The Minimum Inhibitory Concentration (MIC) for common antibiotics was determined by Etests (Epsilometer) and duplex Polymerase Chain Reaction (PCR) reaction was performed with specific primers for amplification of cpe (426 bp) and plc (283 bp) Genes.

RESULTS

Of 136 stool samples including diarrhea [48] and non-diarrhea [88] ones, 83 (61.02%) C. perfringens were cultured. Of these 83, 79 C. perfringens isolates showed the alpha-toxin (phospholipase C) production gene by PCR. Respectively, 3 (9.09%) and 2 (4.34%) cpe genes were present in diarrhea and non-diarrhea samples. Of 79 isolates of C. perfringens, 34 (43.03%) cases showed no resistance, 18 (22.78%) had one resistance and 27 (34.17%) isolates had multiple resistance to imipenem, metronidazole, ceftriaxone, clindamycin, chloramphenicol, and penicillin.

CONCLUSIONS

Periodic evaluation of antimicrobial susceptibility for C. perfringens should be performed. Harboring of enterotoxigenic C. perfringens in individuals not necessarily results in diarrhea.

Enforcement of science-using a Clostridium perfringens outbreak investigation to take legal action

BACKGROUND

We report an outbreak of Clostridium perfringens in a care home in North East England.

METHODS

A retrospective cohort study was used to investigate this outbreak. Faecal samples were obtained from symptomatic residents. Environmental Health Officers carried out a food hygiene inspection and formal statements were taken.

RESULTS

Fifteen residents reported illness and the epidemic curve was suggestive of a point source outbreak. Results suggest that illness was associated with consumption of mince & vegetable pie and/or gravy. There were a number of issues with food served, in particular the mince products had been cooked, cooled, reheated and served again over a period of several days. Faecal sampling revealed the presence of C.perfringens enterotoxin gene and four samples were indistinguishable by fluorescent amplified fragment length polymorphism, indicating a likely common source. The operator of the home was charged with three offences under the General Food Regulations 2004 and the Food Hygiene (England) Regulations 2006 and was convicted on all counts.

CONCLUSIONS

An outbreak of C.perfringens occurred in a care home. The likely cause was consumption of mince & vegetable pie and/or gravy. Epidemiological evidence can be used to help prosecute businesses with food safety offences in such circumstances.

Animal models to study the pathogenesis of human and animal Clostridium perfringens infections

The most common animal models used to study Clostridium perfringens infections in humans and animals are reviewed here. The classical C. perfringens-mediated histotoxic disease of humans is clostridial myonecrosis or gas gangrene and the use of a mouse myonecrosis model coupled with genetic studies has contributed greatly to our understanding of disease pathogenesis. Similarly, the use of a chicken model has enhanced our understanding of type A-mediated necrotic enteritis in poultry and has led to the identification of NetB as the primary toxin involved in disease. C. perfringens type A food poisoning is a highly prevalent bacterial illness in the USA and elsewhere. Rabbits and mice are the species most commonly used to study the action of enterotoxin, the causative toxin. Other animal models used to study the effect of this toxin are rats, non-human primates, sheep and cattle. In rabbits and mice, CPE produces severe necrosis of the small intestinal epithelium along with fluid accumulation. C. perfringens type D infection has been studied by inoculating epsilon toxin (ETX) intravenously into mice, rats, sheep, goats and cattle, and by intraduodenal inoculation of whole cultures of this microorganism in mice, sheep, goats and cattle. Molecular Koch's postulates have been fulfilled for enterotoxigenic C. perfringens type A in rabbits and mice, for C. perfringens type A necrotic enteritis and gas gangrene in chickens and mice, respectively, for C. perfringens type C in mice, rabbits and goats, and for C. perfringens type D in mice, sheep and goats.

An assessment of the human health impact of seven leading foodborne pathogens in the United States using disability adjusted life years

We explored the overall impact of foodborne disease caused by seven leading foodborne pathogens in the United States using the disability adjusted life year (DALY). We defined health states for each pathogen (acute illness and sequelae) and estimated the average annual incidence of each health state using data from public health surveillance and previously published estimates from studies in the United States, Canada and Europe. These pathogens caused about 112 000 DALYs annually due to foodborne illnesses acquired in the United States. Non-typhoidal Salmonella (32 900) and Toxoplasma (32 700) caused the most DALYs, followed by Campylobacter (22 500), norovirus (9900), Listeria monocytogenes (8800), Clostridium perfringens (4000), and Escherichia coli O157 (1200). These estimates can be used to prioritize food safety interventions. Future estimates of the burden of foodborne disease in DALYs would be improved by addressing important data gaps and by the development and validation of US-specific disability weights for foodborne diseases.

Virulence Plasmids of Spore-Forming Bacteria

Plasmid-encoded virulence factors are important in the pathogenesis of diseases caused by spore-forming bacteria. Unlike many other bacteria, the most common virulence factors encoded by plasmids in Clostridium and Bacillus species are protein toxins. Clostridium perfringens causes several histotoxic and enterotoxin diseases in both humans and animals and produces a broad range of toxins, including many pore-forming toxins such as C. perfringens enterotoxin, epsilon-toxin, beta-toxin, and NetB. Genetic studies have led to the determination of the role of these toxins in disease pathogenesis. The genes for these toxins are generally carried on large conjugative plasmids that have common core replication, maintenance, and conjugation regions. There is considerable functional information available about the unique tcp conjugation locus carried by these plasmids, but less is known about plasmid maintenance. The latter is intriguing because many C. perfringens isolates stably maintain up to four different, but closely related, toxin plasmids. Toxin genes may also be plasmid-encoded in the neurotoxic clostridia. The tetanus toxin gene is located on a plasmid in Clostridium tetani, but the botulinum toxin genes may be chromosomal, plasmid-determined, or located on bacteriophages in Clostridium botulinum. In Bacillus anthracis it is well established that virulence is plasmid determined, with anthrax toxin genes located on pXO1 and capsule genes on a separate plasmid, pXO2. Orthologs of these plasmids are also found in other members of the Bacillus cereus group such as B. cereus and Bacillus thuringiensis. In B. thuringiensis these plasmids may carry genes encoding one or more insecticidal toxins.

Clostridium perfringens type A-E toxin plasmids

Clostridium perfringens relies upon plasmid-encoded toxin genes to cause intestinal infections. These toxin genes are associated with insertion sequences that may facilitate their mobilization and transfer, giving rise to new toxin plasmids with common backbones. Most toxin plasmids carry a transfer of clostridial plasmids locus mediating conjugation, which likely explains the presence of similar toxin plasmids in otherwise unrelated C. perfringens strains. The association of many toxin genes with insertion sequences and conjugative plasmids provides virulence flexibility when causing intestinal infections. However, incompatibility issues apparently limit the number of toxin plasmids maintained by a single cell.

Toxinotyping and antimicrobial susceptibility of enterotoxigenic Clostridium perfringens isolates from mutton, beef and chicken meat

A total of 300 meat samples comprising mutton, beef, and chicken meat (n = 100) collected from either local butcher shops or large meat outlets situated at various areas of Lahore City located in Punjab province of Pakistan were tested for the isolation of Clostridium perfringens. Prevalence of the organism was highest in the chicken (6 %) followed by mutton (5 %) and beef (1 %). Contamination level was high (10/150) in the samples collected from local butcher shops in comparison to the samples collected from large meat outlets (2/150). All of the raw meat samples were negative for the presence of alpha, beta and epsilon toxins of C. perfringens as detected through ELISA. Out of a total number of 12 isolates only half were capable of producing enterotoxins when cultured in trypticase glucose yeast (TGY) broth. Toxinotyping of the isolates showed that 3 were of type A while one each of the remaining three belonged to type B, C, and D. Antibiotic susceptibility testing of the toxin producing isolates revealed that C. perfringens were susceptible to chloramphenicol, ciprofloxacin, metronidazole, and ceftriaxone. All of the other drugs were relatively less effective with a least activity of amoxicillin against the isolates.

Contributions of NanI sialidase to Caco-2 cell adherence by Clostridium perfringens type A and C strains causing human intestinal disease

Previous studies showed that Clostridium perfringens type D animal disease strain CN3718 uses NanI sialidase for adhering to enterocyte-like Caco-2 cells. The current study analyzed whether NanI is similarly important when type A and C human intestinal disease strains attach to Caco-2 cells. A PCR survey determined that the nanI gene was absent from typical type A food poisoning (FP) strains carrying a chromosomal enterotoxin (CPE) gene or the genetically related type C Darmbrand (Db) strains. However, the nanI gene was present in type A strains from healthy humans, type A strains causing CPE-associated antibiotic-associated diarrhea (AAD) or sporadic diarrhea (SD), and type C Pig-Bel strains. Consistent with NanI sialidase being the major C. perfringens sialidase when produced, FP and Db strains had little supernatant sialidase activity compared to other type A or C human intestinal strains. All type A and C human intestinal strains bound to Caco-2 cells, but NanI-producing strains had higher attachment levels. When produced, NanI can contribute to host cell attachment of human intestinal disease strains, since a nanI null mutant constructed in type A SD strain F4969 had lower Caco-2 cell adhesion than wild-type F4969 or a complemented strain. Further supporting a role for NanI in host cell attachment, sialidase inhibitors reduced F4969 adhesion to Caco-2 cells. Collectively, these results suggest that NanI may contribute to the intestinal attachment and colonization needed for the chronic diarrhea of CPE-associated AAD and SD, but this sialidase appears to be dispensable for the acute pathogenesis of type A FP or type C enteritis necroticans.