Dissemination of Clostridium difficile in food and the environment: Significant sources of C. difficile community-acquired infection?

Clostridium difficile is a significant pathogen with over 300 000 cases reported in North America annually. Previously, it was thought that C. difficile was primarily a clinically associated infection. However, through the use of whole genome sequencing it has been revealed that the majority of cases are community acquired. The source of community-acquired C. difficile infections (CDI) is open to debate with foodborne being one route considered. Clostridium difficile fits the criteria of a foodborne pathogen with respect to being commonly encountered in a diverse range of foods that includes meat, seafood and fresh produce. However, no foodborne illness outbreaks have been directly linked to C. difficile there is also no conclusive evidence that its spores can germinate in food matrices. This does not exclude food as a potential vehicle but it is likely that the pathogen is also acquired through zoonosis and the environment. The most significant factor that defines susceptibility to CDI is the host microbiome and functioning immune system. In this respect, effective control can be exercised by reducing the environmental burden of C. difficile along with boosting the host defences against the virulent enteric pathogen.

Persistence of Clostridium difficile in wastewater treatment-derived biosolids during land application or windrow composting.

AIMS: To determine the persistence of Clostridium difficile spores in biosolids during composting or when amended into soil and held under natural environmental climatic conditions. METHODS AND RESULTS: Five log CFU g(-1) Cl. difficile spores (ribotypes 027 or 078) were inoculated into agricultural soils (sandy loam or loam) amended with 10% w/w anaerobically digested biosolids. The inoculated soil : biosolids mixture was then placed into sentinel vials which were introduced at a depth of 15 cm within the field plot consisting of the corresponding soil type. Two trials were performed, the first of which started in late spring (May 2013 through to August 2014) and second from November 2013 through to October 2014 (fall trial). Ribotype 078 endospores in loam or sandy loam soil decreased during the summer but then increased in numbers towards the fall. At the end of the trial, levels of ribotype 078 spores had decreased by 1·5 log CFU g(-1) , with 027 spores decreasing by <1 log CFU g(-1) over the same time period. Windrow composting of biosolids decreased Cl. difficile levels from 3·7 log CFU g(-1) down to 0·3 log CFU g(-1) with the greater reduction occurring during the curing phase. In comparison, Cl. perfringens decreased from 6·3 log CFU g(-1) down to 2·4 log CFU g(-1) but mainly in the thermal phase of the composting process. CONCLUSIONS: Composting of biosolids is a more effective means of inactivating Cl. difficile compared to land application. SIGNIFICANCE AND IMPACT OF THE STUDY: Windrow composting represents an effective method to reduce the environmental burden of Cl. difficile associated with biosolids.

Prevalence of methicillin-resistant Staphylococcus aureus in Canadian commercial pork processing plants.

AIMS: This study investigated the prevalence of Methicillin-resistant Staphylococcus aureus (MRSA), their spa-types, and antimicrobial resistance profiles at various steps during commercial pork production from three plants designated as A, B and C. METHODS AND RESULTS: Over a period of 1 year 2640 samples from three commercial pork plants were obtained on a rotating basis. Sample sources were: nasal swabs after bleeding (NSAB), nasal swab after scalding (NSASs, plant C) or skinning (NSASk, plants A, B), carcass swabs after pasteurization (CSAP, plant C) or washing (CSAW, plants A, B) and retail pork (RP). Overall MRSA prevalence at each sampling point in the pork plants after adjusting for clustering was: 61·93, 28·38 7·58 and 1·21% for NSAB, NSASc/Sk, CSAP/CSAW and RP respectively. The majority of MRSA isolates from the three pork plants belonged to livestock-associated MRSA spa-types t034 and t011 (3·8%; ST398). The mainly human spa-type t002 (15%) was also recovered. All MRSA isolates were resistant to ß-lactam and tetracycline antibiotics. Overall resistance to tigecycline was found in about 10% of MRSA isolates while <3% isolates were resistant to daptomycin, gentamicin, quinupristin/dalfopristin and trimethoprim/sulfamethoxazole. CONCLUSION: A higher prevalence of MRSA in the nasal cavity of incoming pigs was observed at all three plants, but a notable reduction in MRSA along the pork processing steps occurred. SIGNIFICANCE AND IMPACT OF THE STUDY: The highest prevalence of MRSA was found in the nasal cavity of incoming pigs in three commercial pig slaughter and pork processing plants. A reduction in MRSA prevalence occurred along the processing chain, and pork products from these plants showed significantly lower MRSA than the initial steps of slaughter and processing, suggesting a reduction in MRSA during the slaughter process with minimal cross-contamination.

Immune status of children with phenylketonuria.

OBJECTIVE: To determine the effect of differences in plasma phenylalanine (Phe) concentrations (< 363 umol/L, 363 to 605 umol/L, and > 605 umol/L) on hematological and immunological parameters in 22 children with phenylketonuria (PKU). METHODS: Children with PKU were divided into one of three groups based on fasting plasma Phe levels. Hematologic and immunologic parameters of the children with PKU were compared between the groups and also compared with published values from age-matched children without PKU. RESULTS: Hematologic and immunologic parameters did not differ among children with different plasma Phe concentrations. Specifically, no significant differences between groups of PKU children with differing plasma Phe levels were found for plasma levels of albumin, hemoglobin, amino acids, IgM, complement C3, interleukins 1 and 2, erythrocyte, leukocyte and differential cell counts, hematocrit, percentages and numbers of CD4+, CD8+, CD3+ and total lymphocytes, or CD4 to CD8 ratio. Mean plasma IgG and IgA concentrations of the PKU children were, however, significantly lower than values from similar aged children. Moreover, positive correlations were obtained between plasma albumin and percentages and numbers of CD3+ and CD4+, between plasma IgG and interleukins 1 and 2, and between intakes of energy, protein, iron and plasma IgG levels. No correlations were found between plasma Phe and immunological parameters. CONCLUSION: While differences in plasma Phe concentrations up to concentrations of 866 umol/L do not appear to affect selected immune system parameters, further studies are needed to investigate the relationship between dietary nutrient intake, nutritional status, antibody biosynthesis and cytokine production. Assessment of plasma and cell membrane lipids and trace mineral status of PKU children would be helpful to determine if relationships exist between these nutrients and antibody production.