Clostridium difficile: a new zoonotic agent?

Antimicrobial resistance of Clostridioides difficile in veterinary medicine around the world: A scoping review of minimum inhibitory concentrations

Objective

To provide a comprehensive characterization of Clostridioides difficile antimicrobial resistance (AMR) data in veterinary medicine based on the minimum inhibitory concentrations (MICs) of all antimicrobial agents tested in relation to the techniques used.

Methods

A systematic scoping review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews (PRISMA-ScR) and its associated checklist. The objective was to provide a synthesis of the evidence in a summarized and analyzed format.To this end, three scientific databases were consulted: Scopus, PubMed, and Web of Science, up until December 2021. Subsequently, all identified literature was subjected to screening and classification in accordance with the established study criteria, with the objective of subsequent evaluation.

Study selection and data extraction

A comprehensive analysis was conducted on studies regarding Clostridioides difficile antimicrobial resistance (AMR) in veterinary medicine across various animal species and related sources. The analysis included studies that presented data on antimicrobial susceptibility testing using the E-test, agar dilution, or broth microdilution techniques. The extracted data included minimum inhibitory concentration (MIC) values and a comprehensive characterization analysis.

Results

A total of 1582 studies were identified in scientific databases, of which only 80 were subjected to analysis. The research on Clostridioides difficile antimicrobial resistance (AMR) in veterinary medicine is most prolific in Europe and North America. The majority of isolates originate from production animals (55%) and pets (15%), with pigs, horses, and cattle being the most commonly studied species. The tested agents' minimum inhibitory concentrations (MICs) and resulting putative antimicrobial resistance profiles exhibited considerable diversity across animal species and sources of isolation. Additionally, AMR characterization has been conducted at the gene and genomic level in animal strains. The E-test was the most frequently utilized method for antimicrobial susceptibility testing (AST). Furthermore, the breakpoints for interpreting the MICs were found to be highly heterogeneous and frequently observed regardless of the geographical origin of the publication.

Conclusions

Antimicrobial susceptibility testing techniques and results were found to be diverse and heterogeneous. There is no evidence of an exclusive antimicrobial resistance pattern in any animal species. Despite the phenotypic and genomic data collected over the years, further interdisciplinary studies are necessary. Our findings underscore the necessity for international collaboration to establish uniform standards for C. difficile antimicrobial susceptibility testing (AST) methods and reporting. Such collaboration would facilitate a "One Health" approach to surveillance and control, which is of paramount importance.

Non-human Clostridioides difficile Reservoirs and Sources: Animals, Food, Environment

Clostridioides difficile is ubiquitous and is found in humans, animals and in variety of environments. The substantial overlap of ribotypes between all three main reservoirs suggests the extensive transmissions. Here we give the overview of European studies investigating farm, companion and wild animals, food and environments including water, soil, sediment, wastewater treatment plants, biogas plants, air, and households. Studies in Europe are more numerous especially in last couple of years, but are still fragmented in terms of countries, animal species, or type of environment covered. Soil seem to be the habitat of divergent unusual lineages of C. difficile. But the most important aspect of animals and environment is their role in C. difficile transmissions and their potential as a source for human infection is discussed.

Global prevalence of Clostridioides difficile in 17,148 food samples from 2009 to 2019: a systematic review and meta-analysis

BACKGROUND

Clostridioides (Clostridium) difficile is an important infectious pathogen, which causes mild-to-severe gastrointestinal infections by creating resistant spores and producing toxins. Spores contaminated foods might be one of the most significant transmission ways of C. difficile-associated infections. This systematic review and meta-analysis study were conducted to investigate the prevalence of C. difficile in food.

METHODS

Articles that published the prevalence of C. difficile in food in PubMed, Web of Science, and Scopus databases were retrieved using selected keywords between January 2009 and December 2019. Finally, 17,148 food samples from 60 studies from 20 countries were evaluated.

RESULTS

The overall prevalence of C. difficile in various foods was 6.3%. The highest and lowest levels of C. difficile contamination were detected to seafood (10.3%) and side dishes (0.8%), respectively. The prevalence of C. difficile was 4% in cooked food, 6.2% in cooked chicken and 10% in cooked seafood.

CONCLUSIONS

There is still little known concerning the food-borne impact of C. difficile, but the reported contamination might pose a public health risk. Therefore, to improve the food safety and prevent contamination with C. difficile spores, it is necessary to observe hygienic issues during foods preparation, cooking and transfer.

The Environment, Farm Animals and Foods as Sources of Clostridioides difficile Infection in Humans

The recent discovery of the same Clostridioides difficile ribotypes associated with human infection in a broad range of environments, animals and foods, coupled with an ever-increasing rate of community-acquired infections, suggests this pathogen may be foodborne. The objective of this review was to examine the evidence supporting this hypothesis. A review of the literature found that forty-three different ribotypes, including six hypervirulent strains, have been detected in meat and vegetable food products, all of which carry the genes encoding pathogenesis. Of these, nine ribotypes (002, 003, 012, 014, 027, 029, 070, 078 and 126) have been isolated from patients with confirmed community-associated C. difficile infection (CDI). A meta-analysis of this data suggested there is a higher risk of exposure to all ribotypes when consuming shellfish or pork, with the latter being the main foodborne route for ribotypes 027 and 078, the hypervirulent strains that cause most human illnesses. Managing the risk of foodborne CDI is difficult as there are multiple routes of transmission from the farming and processing environment to humans. Moreover, the endospores are resistant to most physical and chemical treatments. The most effective current strategy is, therefore, to limit the use of broad-spectrum antibiotics while advising potentially vulnerable patients to avoid high-risk foods such as shellfish and pork.

Examining the Extent of Contamination, Antibiotic Resistance, and Genetic Diversity of Clostridioides (Clostridium) difficile Strains in Meat and Feces of Some Native Birds of Iran

Clostridioides (Clostridium) difficile (C. difficile) is one of the essential enteropathogens in humans and livestock and is a severe health threat, according to the Centre for Disease Control and Prevention. Also, antimicrobials are one of the most critical risk factors for C. difficile infection (CDI). The present study examined the infection, antibiotic resistance, and genetic diversity of the C. difficile strains in the meat and feces of some native birds (chicken, duck, quail, and partridge) in the Shahrekord region, Iran, from July 2018 to July 2019. Samples were grown on CDMN agar after an enrichment step. To determine the toxin profile, the tcdA, tcdB, tcdC, cdtA, and cdtB genes were detected via multiplex PCR. The antibiotic susceptibility of these isolates was examined using the disk diffusion method and followed based on MIC and epsilometric test. 300 meat samples of chicken, duck, partridge, and quail and 1100 samples of bird feces were collected from six traditional farms in Shahrekord, Iran. Thirty-five meat samples (11.6%) and 191 fecal samples (17.36%) contained C. difficile. Moreover, five toxigenic samples isolated had 5, 1, and 3 tcdA/B, tcdC, and cdtA/B genes. Out of the studied strains isolated from the 226 samples, two isolates belonging to ribotype RT027 and one isolated RT078 profile related to native chicken feces were observed from chicken sample. The antimicrobial susceptibility testing showed that all the strains are resistant to ampicillin, 28.57% are resistant to metronidazole, and 100% were susceptible to vancomycin. Based on the results, it can be concluded that the raw meat of birds might be a source of resistant C. difficile that poses a hygienic threat to the consumption of native bird meat. Nevertheless, further studies are essential to understand additional epidemiological features of C. difficile in bird meat.

Presence of Clostridioides difficile in cattle feces, carcasses, and slaughterhouses: Molecular characterization and antibacterial susceptibility of the recovered isolates

The aims of this study were to isolate and identify Clostridioides difficile from cattle feces and carcasses, and slaughterhouse samples, and to determine the molecular characteristics and antibacterial susceptibility of the recovered isolates. A total of 220 samples, including 100 cattle fecal samples, 100 cattle carcass surface samples, and 20 slaughterhouse samples were used as the study material. In total, 12 (5.45%) samples, including 11 (11%) cattle fecal samples and 1 (5%) slaughterhouse sample, were found to be positive for C. difficile. On the other hand, all of the carcass samples were negative for C. difficile. A total of 11 (91.66%) isolates, including 10 fecal isolates and 1 slaughterhouse wastewater isolate, were found to be positive for the presence of the toxin genes tcdA and tcdB, whilst 1 fecal isolate was found to be negative for both genes. In addition, 3 different ERIC-PCR profiles were identified in the 11 fecal isolates. The ERIC-PCR profile of the slaughterhouse wastewater isolate was found to be similar to one of the ERIC-PCR profiles obtained from the fecal isolates. All of the isolates were resistant to ciprofloxacin and levofloxacin. Considering that the agent is a spore-forming bacterium shed in feces, the detection of C. difficile isolates of different genotypes, some carrying toxin genes, suggests that feces and slaughterhouse wastewater carrying this bacterium may pose a risk for the contamination of carcasses. The current study revealed that hygiene conditions should be performed to the maximum extent in slaughterhouses.

Clostridioides difficile infection: an emerging zoonosis?

INTRODUCTION

Clostridioides difficile (C. difficile) infection (CDI) is the most common cause of antibiotic-associated diarrhea and one of the common infections in healthcare facilities. In recent decades, there has been an emerging threat of community-acquired CDI (CA-CDI). Environmental transmission of C. difficile in the community setting has become a major concern, and animals are an important reservoir for C. difficile causing human diseases.

AREAS COVERED

In this article, the molecular epidemiology of C. difficile in animals and recent evidences of zoonotic transfer to humans are reviewed based on an electronic search in the databases of PubMed and Google Scholar.

EXPERT OPINION

C. difficile can be found in stool from diarrheal dogs and cats; therefore, household pets could be a potential source. C. difficile will threaten human health because hypervirulent C. difficile ribotype 078 strains have been found in retail chickens, pig farms, and slaughterhouses. Risk factors for fecal C. difficile carriage in animals include young age, dietary changes, and antibiotic abuse in domestic animals. With the advent of whole genome sequencing techniques, there will be more solid evidence indicating zoonotic transfer of C. difficile from animals to humans.

Agricultural fertilization with poultry manure results in persistent environmental contamination with the pathogen Clostridioides difficile

During a field experiment applying broiler manure for fertilization of agricultural land, we detected viable Clostridioides (also known as Clostridium) difficile in broiler faeces, manure, dust and fertilized soil. A large diversity of toxigenic C. difficile isolates was recovered, including PCR ribotypes common from human disease. Genomic relatedness of C. difficile isolates from dust and from soil, recovered more than 2 years after fertilization, traced their origins to the specific chicken farm that had delivered the manure. We present evidence of long-term contamination of agricultural soil with manure-derived C. difficile and demonstrate the potential for airborne dispersal of C. difficile through dust emissions during manure application. Clostridioides genome sequences virtually identical to those from manure had been recovered from chicken meat and from human infections in previous studies, suggesting broiler-associated C. difficile are capable of zoonotic transmission.

The prevalence of Clostridioides difficile on farms, in abattoirs and in retail foods in Ireland

An increasing proportion of Clostridioides difficile infections (CDI) are community acquired. This study tested farm, abattoir and retail food samples for C. difficile, using peer reviewed culture and molecular methods. The contamination rate on beef, sheep and broiler farms ranged from 2/30 (7%) to 25/30 (83%) in faeces, soil and water samples, while concentrations ranged from 2.9 log₁₀ cfu/ml to 8.4 log₁₀ cfu/g. The prevalence and associated counts were much lower in abattoir samples. Although 26/60 were C. difficile positive by enrichment and PCR, only 6 samples yielded counts by direct plating (1.1 log₁₀ cfu/cm² to 5.1 log₁₀ cfu/g). At retail, 9/240 samples were C. difficile positive, including corned beef (1), spinach leaves (2), iceberg lettuce, little gem lettuce, wild rocket, coleslaw, whole milk yogurt and cottage cheese (1 sample each), with counts of up to 6.8 log₁₀ cfu/g. The tcdA, tcdB, cdtA, cdtB, tcdC and tcdR genes were detected in 41%, 99.2%, 33.6%, 32%, 46.7% and 31.1%, respectively, of the 122 C. difficile isolates obtained. It was concluded that although the prevalence of C. difficile decreased along the food chain, retail foods were still heavily contaminated. This pathogen may therefore be foodborne, perhaps necessitating dietary advice for potentially vulnerable patients.

Characterisation and Antibiotic Susceptibility Profile of Clostridioides (Clostridium) Difficile Isolated from Chicken Carcasses

Introduction

Clostridioides (Clostridium) difficile is a Gram+, anaerobic, spore-forming, rod-shaped bacterium that can produce toxins, and it is mainly because its virulence is attributed. The objective of this study was to evaluate the presence of C. difficile and hyper virulent ribotypes in chicken carcasses and the antibiotic susceptibility of isolated strains.

Material and Methods

C. difficile was isolated from chicken carcasses by microbiological methods, its ribotypes were identified by means of PCR, the toxin production ability was defined by ELISA, and the susceptibility of the isolates to selected antibiotics was determined by minimum inhibitory concentration evaluator strips.

Results

The bacterium was isolated from 69 out of 185 (37.3%) examined chicken carcass samples, and six out of the 69 (8.7%) isolates were identified as ribotype 027. All isolates were susceptible to amoxicillin-clavulanic acid (100.0%), vancomycin (97.1%), metronidazole (88.4%), and tetracycline (95.7%), whereas they were resistant to cefotaxime (97.1%) and imipenem (89.9%).

Conclusion

The results of this study demonstrate the presence of toxigenic C. difficile isolates such as ribotype 027 (one of the most common causes of C. difficile infection in humans) in chicken carcasses. Although there is no case for stating that C. difficile is a food-borne pathogen, the presence of C. difficile in chicken may be considered to be a potential risk to consumers.

One Health approach to Clostridioides difficile in Japan

Clostridioides difficile infections (CDIs) are predominantly a healthcare-associated illness in developed countries, with the majority of cases being elderly and hospitalize patients who used antibiotic therapy. Recently, the incidence of community-associated CDIs (CA-CDIs) in younger patients without a previous history of hospitalization or antibiotic treatment has been increasing globally. C. difficile is sometimes found in the intestine of many animals, such as pigs, calves, and dogs. Food products such as retail meat products and vegetables sometimes contain C. difficile. C. difficile has also been isolated from several environments such as compost manure, rivers, and soils. Yet, direct transmission of C. difficile from animals, food products, and environments to humans has not been proven, although these strains have similar molecular characteristics. Therefore, it has been suggested that there is a relationship between CA-CDIs and C. difficile from animals, food products, and the environment. To clarify the importance of the presence of C. difficile in several sources, characterization of C. difficile in these sources is required. However, the epidemiology of C. difficile in animals, food products, and the environment is not well studied in Japan. This review summarizes recent trends of CDIs and compares the molecular characteristics of C. difficile in Japanese animals, food products, and the environment. The prevalence trends of C. difficile in Japan are similar to those in the rest of the world. Therefore, I recommend using a One Health approach to CDI surveillance, monitoring, and control.

Clostridioides difficile in national food surveillance, Slovenia, 2015 to 2017

BackgroundClostridioides difficile is an important human and animal intestinal pathogen. Because of increasing indications of an association between C. difficile and food, in 2015, the Administration of the Republic of Slovenia for Food Safety, Veterinary Sector and Plant Protection (UVHVVR) included C. difficile in its national food surveillance.AimWe aim to report the results and experience with a nationwide and long-term testing of food for C. difficile as a part of a regular national food surveillance programme.MethodsRetail minced meat and meat preparations (beef, pork and poultry) were sampled within a three-year period, 2015 to 2017. Selected raw retail vegetables, leaf salads and root vegetables, and ready-to-eat salads were only sampled during 2016 and 2017. Seafood was only sampled in 2017.ResultsAltogether, 434 samples were tested, with 12 of 336 (3.6%) meat samples and 6 of 98 (6.1%) raw vegetables contaminated with C. difficile. Twelve of 18 recovered food isolates were toxigenic (toxinotypes 0, III, V, XII). The isolates belonged to 13 different PCR ribotypes, 001 being most common (5 isolates). Several food types with an increased potential of being contaminated with C. difficile were detected by surveillance.ConclusionThe three-year C. difficile testing within the national food surveillance revealed a low proportion of C. difficile-contaminated food and high genotype variability. Because the risk of C. difficile infection associated with C. difficile-contaminated food is unknown, no measures were recommended in the case of positive results.

Global and Historical Distribution of Clostridioides difficile in the Human Diet (1981-2019): Systematic Review and Meta-Analysis of 21886 Samples Reveal Sources of Heterogeneity, High-Risk Foods, and Unexpected Higher Prevalence Toward the Tropic

Clostridioides difficile (CD) is a spore-forming bacterium that causes life-threatening intestinal infections in humans. Although formerly regarded as exclusively nosocomial, there is increasing genomic evidence that person-to-person transmission accounts for only <25% of cases, supporting the culture-based hypothesis that foods may be routine sources of CD-spore ingestion in humans. To synthesize the evidence on the risk of CD exposure via foods, we conducted a systematic review and meta-analysis of studies reporting the culture prevalence of CD in foods between January 1981 and November 2019. Meta-analyses, risk-ratio estimates, and meta-regression were used to estimate weighed-prevalence across studies and food types to identify laboratory and geographical sources of heterogeneity. In total, 21886 food samples were tested for CD between 1981 and 2019 (96.4%, n = 21084, 2007–2019; 232 food-sample-sets; 79 studies; 25 countries). Culture methodology, sample size and type, region, and latitude were sources of heterogeneity (p < 0.05). Although non-strictly-anaerobic methods were reported in some studies, and we confirmed experimentally that improper anaerobiosis of media/sample-handling affects CD recovery in agar (Fisher, p < 0.01), most studies (>72%) employed the same (one-of-six) culture strategy. Because the prevalence was also meta-analytically similar across six culture strategies reported, all studies were integrated using three meta-analytical methods. At the study level (n = 79), the four-decade global cumulative-prevalence of CD in the human diet was 4.1% (95%CI = −3.71, 11.91). At the food-set level (n = 232, mean 12.9 g/sample, similar across regions p > 0.2; 95%CI = 9.7–16.2), the weighted prevalence ranged between 4.5% (95%CI = 3–6%; all studies) and 8% (95%CI = 7–8%; only CD-positive-studies). Risk-ratio ranking and meta-regression showed that milk was the least likely source of CD, while seafood, leafy green vegetables, pork, and poultry carried higher risks (p < 0.05). Across regions, the risk of CD in foods for foodborne exposure reproducibly decreased with Earth latitude (p < 0.001). In conclusion, CD in the human diet is a global non-random-source of foodborne exposure that occurs independently of laboratory culture methods, across regions, and at a variable level depending on food type and latitude. The latitudinal trend (high CD-food-prevalence toward tropic) is unexpectedly inverse to the epidemiological observations of CD-infections in humans (frequent in temperate regions). Findings suggest the plausible hypothesis that ecologically-richer microbiomes in the tropic might protect against intestinal CD colonization/infections despite CD ingestion.

Clostridioides (Clostridium) Difficile in Food-Producing Animals, Horses and Household Pets: A Comprehensive Review

Clostridioides (Clostridium) difficile is ubiquitous in the environment and is also considered as a bacterium of great importance in diarrhea-associated disease for humans and different animal species. Food animals and household pets are frequently found positive for toxigenic C. difficile without exposing clinical signs of infection. Humans and animals share common C. difficile ribotypes (RTs) suggesting potential zoonotic transmission. However, the role of animals for the development of human infection due to C. difficile remains unclear. One major public health issue is the existence of asymptomatic animals that carry and shed the bacterium to the environment, and infect individuals or populations, directly or through the food chain. C. difficile ribotype 078 is frequently isolated from food animals and household pets as well as from their environment. Nevertheless, direct evidence for the transmission of this particular ribotype from animals to humans has never been established. This review will summarize the current available data on epidemiology, clinical presentations, risk factors and laboratory diagnosis of C. difficile infection in food animals and household pets, outline potential prevention and control strategies, and also describe the current evidence towards a zoonotic potential of C. difficile infection.

Isolation and toxin gene detection of Clostridium (Clostridioides) difficile from traditional and commercial quail farms and packed quail meat for market supply - Short communication

Clostridium (Clostridioides) difficile is a Gram-positive anaerobic rod-shaped bacterium and the main cause of nosocomial diarrhoea in humans. In recent years, the transmission of C. difficile from environmental reservoirs (e.g. food) to humans has become a major focus of research. The aim of this study was to investigate the prevalence and corresponding toxin genes of C. difficile in faecal samples and meat of quails. Thirty samples of packed quail meat in Mashhad, Iran and 500 faecal samples (pooled to n = 5) were collected on quail farms in the Northeastern Khorasan region for further investigation. Of 100 pooled quail faecal samples 10% showed cultural growth of C. difficile. In meat samples two out of 30 specimens (7%) showed cultural growth. In six of ten isolates from faecal samples toxin genes (tcdB and tcdA) were present, while four isolates harboured no toxin genes. However, in meat isolates no toxin genes were present. Mutations in the tcdC gene were not detected, indicating that 'hypervirulent' strains such as RT027 and RT078 were not present. The data suggest that quail and quail products might hold a potential for the spread of C. difficile.

Impact of early-life events on the susceptibility to Clostridium difficile colonisation and infection in the offspring of the pig

Clostridium difficile has been documented as a major cause of uncontrolled outbreaks of enteritis in neonatal pigs and antibiotic-associated infections in clinical settings. It belongs to the natural cohort of early colonisers of the gastrointestinal tract of pigs and can be detected in faeces up to two weeks post-partum. In older pigs, it often remains under the detection limit. Most neonatal pigs show no clinical signs of disease although C. difficile and its toxins can be detected at high levels in faeces. Increased mortality rates associated with C. difficile on pig farms are, so far, considered "spontaneous" and the predisposing factors are mostly not defined. The infection caused by C. difficile is multifactorial and it is likely that the repertoire of maternal factors, host physiology, the individually developing gut microbiota, co-infections and environmental stress define the conditions for disease development. In this addendum to our recently published work on CDI in neonatal piglets, we discuss the "early-life events" that influence C. difficile spread and infection in neonatal piglets.

Epidemiological and genomic characterization of community-acquired Clostridium difficile infections

BACKGROUND

Clostridium difficile infection (CDI) is a major cause of morbidity and mortality in North America and Europe. The aim of this study was to identify epidemiologically-confirmed cases of community-acquired (CA)-CDI in a large North American urban center and analyze isolates using multiple genetic and phenotypic methods.

METHODS

Seventy-eight patients testing positive for C. difficile from outpatient clinics were further investigated by telephone questionnaire. CA-CDI isolates were characterized by antibiotic susceptibility, pulsed-field gel electrophoresis and whole genome sequencing. CA-CDI was defined as testing positive greater than 12 weeks following discharge or no previous hospital admission in conjunction with positive toxin stool testing.

RESULTS

51.3% (40/78) of the patients in this study were found to have bona fide CA-CDI. The majority of patients were female (71.8% vs. 28.2%) with 50-59 years of age being most common (21.8%). Common co-morbidities included ulcerative colitis (1/40; 2.5%), Crohn's disease (3/40; 7.5%), celiac disease (2/40; 5.0%) and irritable bowel syndrome (8/40; 20.0%). However, of 40 patients with CA-CDI, 9 (29.0%) had been hospitalized between 3 and 6 months prior and 31 (77.5%) between 6 and 12 months prior. The hypervirulent North American Pulostype (NAP) 1-like (9/40; 22.5%) strain was the most commonly identified pulsotype. Whole genome sequencing of CA-CDI isolates confirmed that NAP 1-like pulsotypes are commonplace in CA-CDI. From a therapeutic perspective, there was universal susceptibility to metronidazole and vancomycin.

CONCLUSIONS

All CA-CDI cases had some history of hospitalization if the definition were modified to health care facility exposure in the last 12 months and is supported by the genomic analysis. This raises the possibility that even CA-CDI may have nosocomial origins.

Porcine and bovine Clostridium difficile ribotype 078 isolates demonstrate similar growth and toxigenic properties

Clostridioides (C.) difficile are found in cows, pigs and poultry suggesting that this pathogen is present and more importantly animals could act as a reservoir, via food or environment, of human C. difficile infection. Molecular methods together with phenotypical characterisation bring integrated and important tools to describe diversity and nature of bacteria including C. difficile. Moreover, similar or identical C. difficile types are found in different farm animals. This study aimed to phenotypically characterise C. difficile isolates belonging to ribotype 078 and to identify differences such as growth and toxicity between porcine and bovine isolates. C. difficile isolates were assessed for the growth behaviour (turbidimetry), metabolic potential (Biolog AN) and toxin production (ELISA method) in vitro. The concentration of released either toxin A (TcdA) or toxin B (TcdB) varied greatly between the isolates tested; however, it did not differ between the porcine and bovine ribotypes. Also, the TcdA/TcdB ratio of the isolates did not show a difference either. The most common metabolised substrates were pyruvic acid followed by α-ketobutyric acid. The results show that both porcine and bovine C. difficile RT 078 share similar phenotypical characteristics including growth and production of toxins. The findings may help understand the virulence of C. difficile RT 078 in porcine and bovine species.

A Comparative Study on the Faecal Bacterial Community and Potential Zoonotic Bacteria of Muskoxen (Ovibos moschatus) in Northeast Greenland, Northwest Greenland and Norway

Muskoxen (Ovibos moschatus) are ruminants adapted to a high-fibre diet. There is increasing interest in the role that gut microbes play in the digestion and utilization of these specialized diets but only limited data available on the gut microbiome of high-Arctic animals. In this study, we metabarcoded the 16S rRNA region of faecal samples from muskoxen of Northeast Greenland, Northwest Greenland and Norway, and quantified the effects of physiological and temporal factors on bacterial composition. We found significant effects of body mass, year of sampling and location on the gut bacterial communities of North East Greenland muskoxen. These effects were however dwarfed by the effects of location, emphasizing the importance of the local ecology on the gut bacterial community. Habitat alterations and rising temperatures may therefore have a considerable impact on muskoxen health and reproductive success. Moreover, muskoxen are hunted and consumed in Greenland, Canada and Alaska; therefore, this study also screened for potential zoonoses of food safety interest. A total of 13 potentially zoonotic genera were identified, including the genera Erysipelothrix and Yersinia implicated in recent mass die-offs of the muskoxen themselves.

Pathogens of Food Animals: Sources, Characteristics, Human Risk, and Methods of Detection

Pathogens associated with food production (livestock) animals come in many forms causing a multitude of disease for humans. For the purpose of this review, these infectious agents can be divided into three broad categories: those that are associated with bacterial disease, those that are associated with viruses, and those that are parasitic in nature. The goal of this chapter is to provide the reader with an overview of the most common pathogens that cause disease in humans through exposure via the food chain and the consequence of this exposure as well as risk and detection methods. We have also included a collection of unusual pathogens that although rare have still caused disease, and their recognition is warranted in light of emerging and reemerging diseases. These provide the reader an understanding of where the next big outbreak could occur. The influence of the global economy, the movement of people, and food makes understanding production animal-associated disease paramount to being able to address new diseases as they arise.

Molecular characterisation of Czech Clostridium difficile isolates collected in 2013-2015

Clostridium difficile is a leading nosocomial pathogen and molecular typing is a crucial part of monitoring its occurrence and spread. Over a three-year period (2013-2015), clinical C. difficile isolates from 32 Czech hospitals were collected for molecular characterisation. Of 2201 C. difficile isolates, 177 (8%) were non-toxigenic, 2024 (92%) were toxigenic (tcdA and tcdB) and of these, 677 (33.5%) carried genes for binary toxin production (cdtA, cdtB). Capillary-electrophoresis (CE) ribotyping of the 2201 isolates yielded 166 different CE-ribotyping profiles, of which 53 were represented by at least two isolates for each profile. Of these, 29 CE-ribotyping patterns were common to the Leeds-Leiden C. difficile reference strain library and the WEBRIBO database (83.7% isolates), and 24 patterns were recognized only by the WEBRIBO database (11.2% isolates). Isolates belonging to these 53 CE-ribotyping profiles comprised 94.9% of all isolates. The ten most frequent CE-ribotyping profiles were 176 (n=588, 26.7%), 001 (n=456, 20.7%), 014 (n=176, 8%), 012 (n=127, 5.8%), 017 (n=85, 3.9%), 020 (n=68, 3.1%), 596 (n=55, 2.5%), 002-like (n=45, 2.1%), 010 (n=35, 1.6%) and 078 (n=34, 1.6%). Multi-locus sequence typing (MLST) of seven housekeeping genes performed in one isolate of each of 53 different CE-ribotyping profiles revealed 40 different sequence types (STs). We conclude that molecular characterisation of Czech C. difficile isolates revealed a high diversity of CE-ribotyping profiles; the prevailing RTs were 001 (20.7%) and 176 (027-like, 26.7%).

Clostridium difficile infection: Early history, diagnosis and molecular strain typing methods

Recognised as the leading cause of nosocomial antibiotic-associated diarrhoea, the incidence of Clostridium difficile infection (CDI) remains high despite efforts to improve prevention and reduce the spread of the bacterium in healthcare settings. In the last decade, many studies have focused on the epidemiology and rapid diagnosis of CDI. In addition, different typing methods have been developed for epidemiological studies. This review explores the history of C. difficile and the current scope of the infection. The variety of available laboratory tests for CDI diagnosis and strain typing methods are also examined.

Effect of passive immunotherapy against Clostridium difficile infection: a systematic review and meta-analysis

This systematic review aimed to determine the effect of antibody therapy against Clostridium difficile infection (CDI) using meta-analysis. In total, 28 studies (animals - 12; human - 17) were identified from the database on the basis of inclusion criteria; then selected studies were systematically reviewed and statistically analyzed. In animal experiments, the pooled relative risk of eight potential studies suggested that the antibody treatment could reduce the risk of CDI. However, the methodological heterogeneity was moderately higher. In human subjects, the majority of reports demonstrated the beneficial effect of passive immunotherapy against CDI. However, this systematic review and meta-analysis recommends that more intensive controlled studies are indispensable for legitimate confirmation.

Identification of risk factors influencing Clostridium difficile prevalence in middle-size dairy farms

Farm animals have been suggested to play an important role in the epidemiology of Clostridium difficile infection (CDI) in the community. The purpose of this study was to evaluate risk factors associated with C. difficile dissemination in family dairy farms, which are the most common farming model in the European Union. Environmental samples and fecal samples from cows and calves were collected repeatedly over a 1 year period on 20 mid-size family dairy farms. Clostridium difficile was detected in cattle feces on all farms using qPCR. The average prevalence between farms was 10% (0–44.4%) and 35.7% (3.7–66.7%) in cows and calves, respectively. Bacterial culture yielded 103 C. difficile isolates from cattle and 61 from the environment. Most C. difficile isolates were PCR-ribotype 033. A univariate mixed effect model analysis of risk factors associated dietary changes with increasing C. difficile prevalence in cows (P = 0.0004); and dietary changes (P = 0.004), breeding Simmental cattle (P = 0.001), mastitis (P = 0.003) and antibiotic treatment (P = 0.003) in calves. Multivariate analysis of risk factors found that dietary changes in cows (P = 0.0001) and calves (P = 0.002) increase C. difficile prevalence; mastitis was identified as a risk factor in calves (P = 0.001). This study shows that C. difficile is common on dairy farms and that shedding is more influenced by farm management than environmental factors. Based on molecular typing of C. difficile isolates, it could also be concluded that family dairy farms are currently not contributing to increased CDI incidence.

Clostridium difficile in Food and Animals: A Comprehensive Review

Zoonoses are infections or diseases that can be transmitted between animals and humans through direct contact, close proximity or the environment. Clostridium difficile is ubiquitous in the environment, and the bacterium is able to colonise the intestinal tract of both animals and humans. Since domestic and food animals frequently test positive for toxigenic C. difficile, even without showing any signs of disease, it seems plausible that C. difficile could be zoonotic. Therefore, animals could play an essential role as carriers of the bacterium. In addition, the presence of the spores in different meats, fish, fruits and vegetables suggests a risk of foodborne transmission. This review summarises the current available data on C. difficile in animals and foods, from when the bacterium was first described up to the present.

Diversity and Evolution in the Genome of Clostridium difficile

Clostridium difficile infection (CDI) is the leading cause of antimicrobial and health care-associated diarrhea in humans, presenting a significant burden to global health care systems. In the last 2 decades, PCR- and sequence-based techniques, particularly whole-genome sequencing (WGS), have significantly furthered our knowledge of the genetic diversity, evolution, epidemiology, and pathogenicity of this once enigmatic pathogen. C. difficile is taxonomically distinct from many other well-known clostridia, with a diverse population structure comprising hundreds of strain types spread across at least 6 phylogenetic clades. The C. difficile species is defined by a large diverse pangenome with extreme levels of evolutionary plasticity that has been shaped over long time periods by gene flux and recombination, often between divergent lineages. These evolutionary events are in response to environmental and anthropogenic activities and have led to the rapid emergence and worldwide dissemination of virulent clonal lineages. Moreover, genome analysis of large clinically relevant data sets has improved our understanding of CDI outbreaks, transmission, and recurrence. The epidemiology of CDI has changed dramatically over the last 15 years, and CDI may have a foodborne or zoonotic etiology. The WGS era promises to continue to redefine our view of this significant pathogen.

Clostridium difficile ribotypes in Austria: a multicenter, hospital-based survey

A prospective, noninterventional survey was conducted among Clostridium difficile positive patients identified in the time period of July until October 2012 in 18 hospitals distributed across all nine Austrian provinces. Participating hospitals were asked to send stool samples or isolates from ten successive patients with C.difficile infection to the National Clostridium difficile Reference Laboratory at the Austrian Agency for Health and Food Safety for PCR-ribotyping and in vitro susceptibility testing. A total of 171 eligible patients were identified, including 73 patients with toxin-positive stool specimens and 98 patients from which C. difficile isolates were provided. Of the 159 patients with known age, 127 (74.3 %) were 65 years or older, the median age was 76 years (range: 9–97 years), and the male to female ratio 2.2. Among these patients, 73 % had health care-associated and 20 % community-acquired C. difficile infection (indeterminable 7 %). The all-cause, 30-day mortality was 8.8 % (15/171). Stool samples yielded 46 different PCR-ribotypes, of which ribotypes 027 (20 %), 014 (15.8 %), 053 (10.5 %), 078 (5.3 %), and 002 (4.7 %) were the five most prevalent. Ribotype 027 was found only in the provinces Vienna, Burgenland, and Lower Austria. Severe outcome of C. difficile infection was found to be associated with ribotype 053 (prevalence ratio: 3.04; 95 % CI: 1.24, 7.44), not with the so-called hypervirulent ribotypes 027 and 078. All 027 and 053 isolates exhibited in vitro resistance against moxifloxacin. Fluoroquinolone use in the health care setting must be considered as a factor favoring the spread of these fluoroquinolone resistant C. difficile clones.

Low Prevalence of Clostridium difficile in Slaughter Pigs in Korea

Clostridium difficile is an important cause of enteric disease in humans and animals. The prevalence of C. difficile infection is increasing, and the bacterium is frequently found in meat products, suggesting the possibility of animal-to-human transmission. Therefore, food animals must be assessed for their role as reservoirs of C. difficile. In this study, C. difficile was isolated from 2 (0.3%) of 659 slaughtered pigs in Korea. Both isolates were characterized as ribotype 078 and were multidrug resistant. The low occurrence suggests only a limited risk of C. difficile transmission from porcine food products; however, C. difficile ribotype 078 is an important pathogen in both pigs and humans, and further studies are necessary to investigate the occurrence of C. difficile in retail meats and other food animals.

Community-acquired Clostridium difficile infection and Australian food animals

Clostridium difficile is an anaerobic Gram positive spore-forming bacterium, the leading cause of infectious diarrhoea (C. difficile infection; CDI) in hospitalised humans. The assumption that CDI is primarily a hospital-acquired infection is being questioned. Community-acquired CDI (CA-CDI) is increasing1 particularly in groups previously considered at low risk2,3. In Australia, CA-CDI rates doubled during 2011 and increased by 24% between 2011 and 20124. Two potentially high-risk practices in Australian food animal husbandry may present a risk for CA-CDI: slaughtering of neonatal animals for food, and effluent recycling to agriculture.

Community-acquired Clostridium difficile infection: an increasing public health threat

There has been a startling shift in the epidemiology of Clostridium difficile infection over the last decade worldwide, and it is now increasingly recognized as a cause of diarrhea in the community. Classically considered a hospital-acquired infection, it has now emerged in populations previously considered to be low-risk and lacking the traditional risk factors for C. difficile infection, such as increased age, hospitalization, and antibiotic exposure. Recent studies have demonstrated great genetic diversity for C. difficile, pointing toward diverse sources and a fluid genome. Environmental sources like food, water, and animals may play an important role in these infections, apart from the role symptomatic patients and asymptomatic carriers play in spore dispersal. Prospective strain typing using highly discriminatory techniques is a possible way to explore the suspected diverse sources of C. difficile infection in the community. Patients with community-acquired C. difficile infection do not necessarily have a good outcome and clinicians should be aware of factors that predict worse outcomes in order to prevent them. This article summarizes the emerging epidemiology, risk factors, and outcomes for community-acquired C. difficile infection.

Humans and cattle: a review of bovine zoonoses

Infectious disease prevention and control has been among the top public health objectives during the last century. However, controlling disease due to pathogens that move between animals and humans has been challenging. Such zoonotic pathogens have been responsible for the majority of new human disease threats and a number of recent international epidemics. Currently, our surveillance systems often lack the ability to monitor the human-animal interface for emergent pathogens. Identifying and ultimately addressing emergent cross-species infections will require a "One Health" approach in which resources from public veterinary, environmental, and human health function as part of an integrative system. Here we review the epidemiology of bovine zoonoses from a public health perspective.

Occurrence of zoonotic clostridia and Yersinia in healthy cattle

Zoonotic pathogens are a frequent cause of disease worldwide. This study was designed to determine the occurrence of Clostridium difficile, Clostridium botulinum, and Yersinia enterocolitica in cattle in southern Bavaria, Germany. The study population included 49 farms; 34 were dairy farms (30 also fattening beef cattle) and 15 were solely beef cattle farms. Fecal and dust samples were collected from summer 2011 to summer 2012 and analyzed using a combination of enrichment procedures and real-time PCR. For the detection of C. difficile, samples were screened for the presence of the tpi gene and toxin genes tcdA, tcdB, and cdtA. Samples also were screened for genes for C. botulinum toxins A through F and for the ail gene of Y. enterocolitica. Of 506 samples, C. difficile genes were found in 29 samples (5.7%): 25 samples from dairy farms and 4 samples from beef cattle farms. Toxin genes were identified in 17 samples, with toxigenic profiles of A(+)B(+)CDT(-), A(+)B(-)CDT(+), and A(+)B(+)CDT(+). C. botulinum toxin genes were not detected in fecal samples from cattle, but the gene for toxin B was detected in 1 (0.8%) of 125 dust samples. Y. enterocolitica genes were found in 6 (1.6%) of 382 fecal samples from three dairy farms and one beef cattle farm. This study revealed that C. difficile and Y. enterocolitica are rare on cattle farms in Bavaria, Germany. In contrast to results of previous studies, C. botulinum was not detected in fecal samples but was found very rarely in dust samples from the cattle environment.

Presence of Clostridium difficile PCR ribotype clusters related to 033, 078 and 045 in diarrhoeic calves in Germany

This study provides data on the distribution and relationship of C. difficile PCR ribotypes in diarrhoeic calves in Germany. C. difficile was isolated from 176 of 999 (17.6 %) faecal samples or swabs of diarrhoeic calves from 603 farms collected between January 2010 and August 2012 by eight federal laboratories of six states. Strains were assigned to 17 PCR ribotypes. PCR ribotypes 033 (57 %), 078 (17 %) and 045/FLI01 (closest match to 045 in the WEBRIBO database; 9 %) were found the most frequently. Nine per cent of all culture-positive tested animals shed more than one multiple locus variable number tandem repeat analysis (MLVA) or PCR ribotype. Eight PCR ribotypes with related profiles (including 033, 078 and 045/FLI01) representing 92 % of all isolates were grouped into three clusters. Molecular relatedness was supported by the absence of the MLVA locus A6 Cd only in clustered strains and identical toxin gene profiles for strains within each cluster. Previously reported mulitilocus sequence typing analysis for PCR ribotypes that were also recovered in this study found identical sequence types and a tcdC deletion (Δ39 bp) for 033, 045, 078 and 126 (ST-11), confirming this clustering. A different geographical occurrence of PCR ribotypes was shown for cluster 033 (found more frequently in southern Germany) and 045 (found more frequently in northern Germany). This study showed that clusters of C. difficile PCR ribotypes related to 033, 078 and 045 are predominant in diarrhoeic calves in Germany. The high number of strains belonging to PCR ribotype 078 demonstrated that diarrhoeic calves are also potential reservoirs for human pathogenic C. difficile strains.

Counterpoint: Is Clostridium difficile a food-borne disease?

The increase in community associated Clostridium difficile disease paired with recent data on C. difficile in retail foods has led to speculation that C. difficile is a food-borne pathogen. However, there is no current epidemiologic evidence (i.e. restaurant or food-associated outbreaks) to support this hypothesis. Rates of C. difficile recovery from food vary widely across laboratories and may be due to a number of confounding factors. This commentary discusses the results of two published investigations and suggests that higher prevalence rates observed in some food studies may be due to laboratory contamination. The conclusions are that prevalence of C. difficile in retail foods is relatively low and further investigations are required to determine if C. difficile is food-borne.

Clostridium difficile contamination of public tap water distribution system during a waterborne outbreak in Finland

Aims: In November through December 2007, the drinking water distribution system in the town of Nokia, Finland, was contaminated with treated sewage effluent that resulted in a large gastroenteritis outbreak in the community. The aim of the present study was to investigate if the contaminated water in this outbreak was also a potential source of Clostridium difficile infections. Methods: Samples from the contaminated tap water and treated sewage effluent were collected. Stool samples from a portion of patients that fell ill during the outbreak were examined for C. difficile. PCR ribotyping was performed on toxin positive C. difficile isolates and the genetic profiles of the water and patient isolates were compared. Results: Twelve toxin-positive C. difficile isolates were found in water samples: five from contaminated tap water and seven from treated sewage effluent. Among these, four and five distinct PCR ribotype profiles were identified, respectively. Four PCR ribotype profiles were found among nine human faecal C. difficile isolates. Two isolates, one from tap water and one from a patient, had an indistinguishable PCR ribotype profile. Conclusions: Our findings demonstrate for the first time C. difficile contamination of a tap water distribution system and waterborne transmission of toxigenic C. difficile seems possible.

Isolation of a toxigenic and clinical genotype of clostridium difficile in retail meats in Costa Rica

We isolated a regional toxigenic genotype of Clostridium difficile, previously found in human infection in 4 of 200 (2%) samples of retail meats for human consumption: 1 of 67 samples of beef, 2 of 66 of pork, and 1 of 67 of poultry meat. These four isolates were positive for the tcdA and tcdB genes but negative for deletion of the tcdC and cdtB genes. All strains induced cytopathic effects in HeLa cells. However, they were susceptible to some antibiotics to which clinical isolates are often resistant. All strains were susceptible to vancomycin, metronidazole, moxifloxacin, and rifampicin but resistant to clindamycin and ciprofloxacin. This first report of isolation of C. difficile in foodstuff from Latin America lends support to the notion that animal products serve as a reservoir for clinical strains of this pathogen in the community.

Clostridium difficile in foods and animals: history and measures to reduce exposure

Many articles have summarized the changing epidemiology of Clostridium difficile infections (CDI) in humans, but the emerging presence of C. difficile in foods and animals and possible measures to reduce human exposure to this important pathogen have been infrequently addressed. CDIs have traditionally been assumed to be restricted to health-care settings. However, recent molecular studies indicate that this is no longer the case; animals and foods might be involved in the changing epidemiology of CDIs in humans; and genome sequencing is disproving person-to-person transmission in hospitals. Although zoonotic and foodborne transmission have not been confirmed, it is evident that susceptible people can be inadvertently exposed to C. difficile from foods, animals, or their environment. Strains of epidemic clones present in humans are common in companion and food animals, raw meats, poultry products, vegetables, and ready-to-eat foods, including salads. In order to develop science-based prevention strategies, it is critical to understand how C. difficile reaches foods and humans. This review contextualizes the current understanding of CDIs in humans, animals, and foods. Based on available information, we propose a list of educational measures that could reduce the exposure of susceptible people to C. difficile. Enhanced educational efforts and behavior change targeting medical and non-medical personnel are needed.