Sage Journals: Discover world-class research

Abstract

Clostridium (Clostridioides) difficile is a gram-positive, spore-forming bacterium that is an important cause of disease in people, a variably important cause of disease in some animal species, and an apparently harmless commensal in others. Regardless of whether it is a known pathogen in a particular species, it can also be found in healthy individuals, sometimes at high prevalences and typically with higher rates of carriage in young individuals. As it is investigated in more animal species, it is apparent that this bacterium is widely disseminated in a diverse range of domestic and wild animal species. Although it can be found in most species in which investigations have been performed, there are pronounced intra- and inter-species differences in prevalence and clinical relevance. A wide range of strains can be identified, some that appear to be animal associated and others that are found in humans and animals. A large percentage of strains that cause disease in people can at least sporadically be found in animals. It is a potentially important zoonotic pathogen, but there is limited direct evidence of animal–human transmission. Although C. difficile has been studied extensively over the past few decades, it remains an enigmatic organism in many ways.

Keywords

diarrhea epidemiology gastrointestinal microbiome microbiology zoonoses

Introduction

Clostridium (Clostridioides)⁸⁰ difficile is a gram-positive, anaerobic, spore-forming bacterium that can be found in humans, a wide range of animal species, and the environment. It is the cause of C. difficile infection (CDI), a critically important disease in humans. Its role as an animal pathogen ranges from important to unclear to apparently irrelevant, depending on the animal species.

As a spore-former, the bacterium can be found in 2 states, the fastidious vegetative form that reproduces in the gastrointestinal tract, and as a hardy spore that is passed in feces and can survive for prolonged periods outside the host. The spore is the infectious form, whereas vegetative cells are the metabolically active form that can produce toxins, cause disease, and produce more spores. Virulence is classically attributed to 2 main toxins, toxin A (TcdA) and toxin B (TcdB), with some strains producing a binary toxin (CDT). Most strains produce TcdA and TcdB, or TcdA, TcdB, and CDT, but toxin-variant strains that produce some but not all of these toxins (e.g., TcdA–/TcdB+) can cause disease. Strains that lack genes encoding TcdA, TcdB, and CDT are considered nontoxigenic and clinically irrelevant.

C. difficile is a genetically diverse bacterial species that is estimated to have diverged 1.1–85 million years ago.⁵³ Most isolates are able to be assigned to 1 of 6 main phylogenetic clades (Table 1), 5 of which (clades 1–5) contain toxigenic strains,¹²⁷ although classification has been evolving. Nontoxigenic strains are intermixed with toxigenic strains in 3 clades (clades 1, 4, and 5). PCR ribotyping, a typing method that involves PCR amplification of the spacer region between the 16S and 23S rRNA genes, and subsequent analysis of gel banding pattern or capillary PCR product,^26,61 is the most widely used typing method. Although > 300 ribotypes are formally classified and many others have been identified, a relatively small number of strains are of greatest concern. Clade 1 contains the most common human pathogens in most regions (ribotypes 001, 012, and 014). Clade 2 contains ribotype 027 (NAP1), a hypervirulent strain associated with widespread disease in humans internationally. Clade 4 contains the toxin variant (TcdA–, TcdB+) ribotype 017 and related strains, which are important causes of disease in humans in some regions. Most of these ribotypes can also be found in animals; however, the main animal concerns are livestock-associated strains in clade 5, particularly ribotype 078. This clade is highly divergent from other clades, and ribotype 078 has emerged as an important cause of community-associated CDI in humans, raising concerns about zoonotic or food origins.^63,73,113 C. difficile is an important cause of disease in some domestic animal species, a potential but unclear cause of disease, or apparently clinically relevant in others.

Table 1.

Clostridium (Clostridioides) difficile clades.

Clade	Common pathogenic PCR ribotypes	Comment
1	001, 012, 014	Most diverse clade; toxigenic and nontoxigenic strains.
2	027, 016, 036, 176	Contains the hypervirulent ribotype 027/NAP1 strain.
3	023	Uncommon clade dominated by one ribotype (023).
4	017	Toxigenic and nontoxigenic strains, includes toxin A–, B+ strains such as 017.
5	078, 126, 033	Toxigenic and nontoxigenic strains; evolutionarily highly divergent from other clades; contains the livestock-associated ribotype 078 (sequence type 11).
6		Nontoxigenic strains; highly diverged; consideration has been given to whether this should represent a separate species.

Horses

Some of the earliest evidence of clinical relevance of C. difficile in domestic animals involved horses, and CDI is an important cause of disease in both adult horses and foals.^25,138 Initial study of C. difficile in horses involved foals, in which the presence of the bacterium was associated with diarrhea.⁶⁴ Subsequent studies demonstrated associations between the presence of TcdA and/or TcdB and diarrhea in adult horses and foals.^42,138 Enterocolitis was later reproduced experimentally through administration of C. difficile spores or vegetative cells to foals.¹² CDI is strongly associated with antimicrobial exposure in humans⁹¹ and, although such an association has been suggested in horses,²⁵ antimicrobial exposure is an inconsistent risk factor and has not always been identified as a risk factor for CDI in horses.¹⁴⁰ Of particular interest have been older reports of severe CDI in mares whose foals were treated with erythromycin and rifampin,^23,48 with subsequent reproduction of CDI in mares given low oral doses of those drugs meant to mimic the concentrations they might be exposed to when their foals were treated.⁴⁸ Interestingly, this phenomenon has not been reported elsewhere, suggesting regional differences in susceptibility, perhaps because of differences in the gut microbiota. In contrast to human medicine, in which CDI is an important hospital-associated infection, hospital-associated CDI appears to be uncommon in horses, with only one report implicating it in a cluster of hospital-associated infections.⁸⁷ Anecdotally, outbreaks are not uncommon in foals on large breeding farms; however, objective data are lacking.

The clinical spectrum of CDI has not been well described in horses, but it can range from mild, self-limiting diarrhea to rapidly fatal, peracute hemorrhagic enterocolitis. It is most often manifest as diarrhea with various degrees of dehydration, toxemia, and abdominal pain.

The bacterium has also been implicated as a cause of duodenitis/proximal jejunitis.¹⁴ Clinical and histologic changes consistent with that disease were reproduced experimentally by administration of a C. difficile toxin suspension.¹³

Although C. difficile has been clearly established as an equine pathogen, toxigenic strains can also be found commonly in healthy foals and adult horses. Shedding rates have been reported of 0–29% in healthy foals,^24,118,138 44% of antibiotic-treated foals,²⁴ 4.9–8.4% in hospitalized horses,^65,93 and 0–7.6% of healthy adult horses.^{24,93,132,138} Risk factors for C. difficile shedding have been explored in adult horses and have focused on young age and antibiotic exposure.^24,47 Reasons why CDI develops in some individuals but not others are unknown, but the intestinal microbiota probably plays an important role.

Various strains have been found in horses. In some studies, the livestock-associated ribotype 078 has been present or predominant.^{93,96,117,119} Other clade 5 strains found predominantly in livestock such as TcdA–, TcdB–, CDT+ ribotype 033⁶⁵ have also been found as common strains in some populations. More common human strains such as ribotypes 001, 012, 014, 017, and 027 have been identified in some regions.^93,119,132 Overall, most strains found in horses are also found in humans; however, the zoonotic disease risk is unclear.

Pigs

As in horses, C. difficile is clearly a pathogen in pigs. However, in contrast, disease seems to predominantly, if not exclusively, affect piglets 10 d of age or younger.^{15,33,134,146,147} Clinical manifestations are variable. Sudden death can occur, with or without evident diarrhea. In less severely affected animals, diarrhea, abdominal distension, decreased appetite, and poor growth may be evident. Pathologically, it is manifest predominantly as typhlocolitis and mesocolonic edema.¹⁴⁷

Similar to clinical observations, disease has been reproduced experimentally in young piglets but not in older piglets.¹⁵ Antimicrobial exposure is not required for development of CDI.

Although disease in piglets is the animal health concern, most studies of C. difficile in pigs has involved surveillance aimed at estimating prevalence and characteristics of C. difficile from pigs of various ages, with a focus on potential zoonotic risks. Shedding of C. difficile is common in many pig populations, with a clear impact of age. Shedding rates are high in young pigs and typically decline to lower levels by the time of slaughter. Rates in 1- to 14-d-old piglets of 27–100% have been reported,^{4,6,17,19,46,52,57,71,75,78,97,98,115,126,128,137} with rates declining rapidly to 0–4% in finisher pigs.^{4,16,34,52,55,69,98,108} However, isolation rates from sows of 4–50% have been reported,^{46,57,69,78,97,98,128} perhaps related to the stress of pregnancy and parturition. Reasons for the marked effect of age have not been investigated, but this pattern is consistent with various other species and is likely related to the protective gut microbiota, which becomes established in the first weeks to months of life.¹²⁵ Beyond age, no factors have been clearly associated with C. difficile shedding, including conventional versus organic production.⁶⁷

A variety of strains can be found; however, a few livestock-associated strains predominate. At the forefront is ribotype 078, a toxinotype V, clade 5 strain that is strongly associated with pigs, and to a lesser degree the closely related ribotypes 126 and 066. These 3 ribotypes have been the sole or predominant strains identified in studies of livestock in North America, Europe, and Asia.^{4,6,9,17,56,66,67,69,78,98,115,128,137,141,148} Yet, although ribotype 078 predominates, a wide range of strains can be identified, including other strains found in humans with CDI.^6,8,97 As in some other animal species, the ribotype distribution is different in Australia, where ribotype 078 is rare to nonexistent and various strains can be found, including some unusual strains such as ribotype 237.^95,126

Further characterization of ribotype 078 isolates by multilocus variable number tandem repeat analysis (MLVA) or whole genome sequencing has shown that human and porcine isolates are indistinguishable,^40,68,70 furthering concerns about zoonotic and foodborne exposure.

Cattle

Increasing attention has been paid to C. difficile in cattle, but mainly because of zoonotic disease concerns rather than animal health concerns. The role of C. difficile in cattle health is unclear and probably minimal. In calves, an association between the presence of C. difficile or its toxins in feces and diarrhea has been reported.^49,88,106 However, disease could not be reproduced experimentally in neonatal calves.¹⁰⁷ There is no evidence of a role in disease in adult cattle.

As with other species, C. difficile can be found in a variable percentage of healthy individuals. There is a strong influence of age, with young calves having the highest shedding rates.^{20,21,37,58,72,88,109} Shedding rates for adult dairy cattle (10%),²⁰ adult beef cattle (3.3–18%),^{38,50,109,110} adult cattle of unknown type (1.5%),¹¹¹ and calves (2–60%)^{20,37,43,72,74,88,101} have been reported. Farm management and health status factors, such as diet change, mastitis, number of calves, and antimicrobial exposure, have been associated with increased risk of C. difficile shedding.^20,21,88

Strain data have been variable, and there may be pronounced regional differences in ribotype distribution. Some authors, mainly from North America and Europe, have reported a predominance or exclusive isolation of livestock-associated ribotype 078.^{37,38,49,88,110,114} The closely related ribotype 126 has also been found in Australian cattle.^72,74 Other studies have reported more diversity, including various common human strains such as ribotypes 033, 001, 014/020, and 027 as well as strains rarely or never recognized in humans.^{20,21,50,72,74,88}

Small ruminants

There has been very little study of sheep and goats, although C. difficile has been identified in a small (2–9.5%) percentage of healthy individuals.^18,44,71,111 As with other species, the prevalence may be higher in young individuals.⁷¹ Strain data are very limited, but a variety of strains have been reported, including strains that have been found in humans and other animal species (e.g., ribotypes 014, 010, 045).^18,71,111 There is no evidence that CDI is a relevant disease in these species.

Dogs

The role of C. difficile in enteric disease in dogs remains enigmatic. An association between the presence of C. difficile toxins in feces and diarrhea has been reported in some studies,¹³⁹ but not others.^32,35 Additionally, disease could not be reproduced experimentally.³⁶ Accurate diagnosis of CDI is a challenge in dogs because of limited information about optimal methods, interpretation of results, and the potentially high background colonization rate in some dog populations. Whether C. difficile is a common cause of disease, a rare cause of disease, a relevant coinfection, or a harmless commensal remains to be determined.

Regardless of its role (or lack thereof) in disease in dogs, C. difficile can be found in a small percentage of healthy individuals. Prevalences of 0–6% tend to be reported in healthy adult dogs,^{82,83,102,116,130,139,144} but higher rates have also been identified (e.g., 17%).¹²⁹ Specific groups from which higher rates of shedding have been identified include hospitalized dogs (19–22%),^35,130 veterinary hospital outpatients (14–33%),^60,130,133 dogs that visit human healthcare facilities (41–58%),^83,84 and racing sled dogs (58%).⁹² Colonization rates can be high in young puppies, as highlighted by a 62% prevalence in neonates³⁰ and a small longitudinal study that reported a cumulative prevalence of 100% in 2 litters.³ Shedding rates of 6.7–12% have been reported in dogs with gastrointestinal disease,^{10,41,100,139} similar to the range seen in healthy dog populations. Reported risk factors for C. difficile shedding include contact with human healthcare facilities,⁸³ exposure to groups of children,⁸³ antimicrobial treatment,^35,60,82,83 and administration of immunosuppressive drugs during hospitalization.^35,60,82,83 There may be a major human influence on C. difficile shedding in dogs, given that living with an owner that has been treated with antibiotics⁸³ and living with an immunocompromised owner¹³⁶ have been associated with increased risk of C. difficile shedding. These presumably are related to an increased risk of the owner shedding C. difficile, with subsequent direct or indirect transmission to their dogs. A study that combined dog and cat data identified proton pump inhibitor (PPI) administration as a risk factor,¹⁰² an interesting finding given increasing recognition of the association of PPI administration with C. difficile shedding in humans.^11,89 That study also reported antimicrobial exposure, and contact with a person with diarrhea as risk factors.

Strains identified in dogs tend to mimic those found in people, including some of the most common strains found in human CDI, such as ribotypes 001, 014, and 106.^{5,10,100,102,116,136} The livestock-associated ribotype 078 has been reported less commonly,^100,102 and, although rare, the hypervirulent human pathogen ribotype 027 has also been found.^81,102 Whether colonization with the same strains represents human–dog transmission or common source exposure is unclear. Likely intra-house transmission of C. difficile from infected owners to their dogs was identified in 2 of 5 of dogs in a small study of households of people with CDI.⁸⁵ In that study, dogs were negative on baseline testing then acquired C. difficile that had an indistinguishable pulsed-field gel electrophoresis (PFGE) type compared to the infected person. However, in a study of households with healthy people and pets, the same strain of C. difficile was not identified in people and pets in any of 415 households.¹⁰²

Cats

C. difficile has been isolated from healthy and diarrheic cats.^{2,29,35,86,90,104,116,143} Prevalence data are limited and sometimes hard to discern because some studies do not differentiate diarrheic versus healthy cats. Overall rates of 2.5–38.1% have been reported,^{35,86,102,116,135} with the low end of that range (i.e., < 5%) likely representing the shedding rate for the general, healthy, homed cat population. Typing data are limited, but as for dogs, common human strains are often found, such as ribotypes 010, 106, and 014/020.^102,116,122 In a small study of people with CDI, likely human–animal transmission (based on the cat being negative on an initial sample then later harboring C. difficile with an indistinguishable PFGE type compared to the person) was identified in 1 of 8 cats.⁸⁵

The clinical relevance of C. difficile in cats is unclear. Diagnosis of CDI has been made in diarrheic cats,¹⁴³ but the true role in disease is unclear because of the presence of the bacterium in healthy animals. Evidence of an association between C. difficile and diarrhea in cats is currently lacking.

Poultry

There is no evidence that C. difficile is a relevant pathogen in poultry. Surveillance studies have investigated shedding of the bacterium in healthy birds, where, as in other species, it can be found in an age-dependent manner^59,124 and perhaps of greatest relevance from a potential zoonotic disease standpoint. Prevalences of 0–62% have been reported in healthy chickens.^{1,51,59,76,103,105,149} High strain diversity has been identified, with perhaps a higher proportion of nontoxigenic strains compared to other species. Strains that have been identified include common human strains (e.g., ribotypes 001, 014, 039), livestock-associated ribotype 078 or related strains, and various nontoxigenic strains.^{1,51,59,76,105} As with some other livestock species, there appear to be regional differences in strain distribution.

Wildlife

Given the estimate that C. difficile evolved well before humans (and perhaps before mammals),⁵³ it should be unsurprising that the bacterium can be found in wildlife. It has been isolated from an impressive array of wildlife species, including wild carnivores, omnivores, herbivores, and insectivores, including skunks, opossums, raccoons, coatis, bats, bears, rats, and other rodents, feral swine, various bird species, and wild canids.^{22,27,45,54,62,77,94,112,121,123,131,142} It is likely that it has been isolated from most species for which a concerted effort has been made to identify it. Whether C. difficile is a pathogen in wildlife species is difficult to discern. Most of the available information is from surveillance of healthy animals or animals with unknown health status, something that precludes assessment of its role as a potential opportunistic (as opposed to obligate) pathogen. Sporadic case reports have implicated C. difficile in disease of individual animals (e.g., ocelot, captive Kodiak bear, harbor seal)^7,99,120; however, it can be difficult to put results of detection of the organism or even its toxins into context without understanding the prevalence of the bacterium in healthy cohorts.

Strains found in wildlife often reflect their degree of exposure to human habitats. Three different types of wildlife can be considered, with potential differences in the epidemiology and ecology of the bacterium. These consist of urban wildlife, wildlife associated with farms, and wildlife more removed from humans and domestic animals.

Urban wildlife can have close contact with humans, human environments, human waste, and discarded food products, creating the potential for exposure to a variety of C. difficile strains. Most study of urban wildlife has involved rodents. Over 13% of rats from a low socioeconomic status area of Vancouver, Canada, were shedding C. difficile in one study, with a combination of known human strains (including ribotypes 001 and 014), livestock- (and food)-associated ribotype 078, and previously unknown strains,⁵⁴ suggesting exposure through contact with human environments or feces and food waste, as well as endemic rat- or wildlife-associated strains. A lower prevalence (1%), with no isolate characterization, was identified in rats from New York City.⁴⁵ However, a study of house mice in New York and mice caught in the Dutch city of Utrecht yielded prevalences of 4% and 35%, respectively, consisting predominantly of ribotypes that have been found in people.^31,145

Animals living on or near farms can be exposed to pathogens from livestock, direct contact with farming areas, or indirectly through manure spread on fields or via runoff. Unsurprisingly, C. difficile can be isolated from species such as raccoons and rats that live on or near farms, sometimes at high prevalences (up to 32%).^9,39,62,77 The livestock-associated ribotype 078 predominates in wildlife from farms; however, isolates more often associated with humans can also be found.^{9,28,39,62,77} Birds also have contact with farm environments, as potentially highlighted by detection of C. difficile, including ribotype 078, in 4% of migrating European barn swallows.²²

Although human or domestic animal contact is common for many wildlife populations, C. difficile has been identified in animals well removed from human influences. For example, it was isolated from 15% of polar bears in the Canadian Arctic, with isolates being strains that had not been previously identified in humans.¹⁴² More study of remote wildlife is needed to help understand the natural (non-human–associated) ecology of this organism.

The role of wildlife in the epidemiology of human or domestic animal CDI is unclear. However, there is some potential for wildlife to be a reservoir of novel strains, to bridge agricultural and urban habitats, and to transmit C. difficile over long distances.

Conclusion

Clostridium difficile is a genetically, evolutionarily, and ecologically diverse organism that can be found in a multitude of animal hosts. Why it can cause devastating disease in some species and be an innocuous commensal in others remains unclear and could offer insight into the pathophysiology of CDI.

Although there are marked differences in reported prevalences and strain distributions between studies, species, and regions, a few common themes emerge. The bacterium can be found in a variable and sometimes high prevalence, even in species in which it is a clear pathogen. Shedding is much more common in young animals, particularly neonates, likely as a result of a less well-developed protective gut microbiota, with rapid decreases in shedding with increasing age.

Strain distributions are variable between and within species. Of significant concern is the predominance of the livestock-associated ribotype 078 and related clade 5 strains because of increasing recognition of community-associated disease in people caused by this lineage.^68,76,79 However, a diverse range of other types can be found, including some of the most common human strains. The natural ecology of C. difficile and its movement between different species remains unclear. Similarity in strains found in some species (including humans and animals) supports some degree of interspecies movement or common source of exposure; however, the dynamics of interspecies (including zoonotic) transmission of this important and enigmatic bacterium remain to be clarified.

Footnotes

Declaration of conflicting interests

The author declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

J. Scott Weese

References

Abdel-Glil

, et al. Presence of Clostridium difficile in poultry and poultry meat in Egypt. Anaerobe 2018;51:21–25.

Álvarez-Pérez

, et al. Data from a survey of Clostridium perfringens and Clostridium difficile shedding by dogs and cats in the Madrid region (Spain), including phenotypic and genetic characteristics of recovered isolates. Data Brief 2017;14:88–100.

Álvarez-Pérez

, et al. Faecal shedding of antimicrobial-resistant Clostridium difficile strains by dogs. J Small Anim Pract 2015;56:190–195.

Alvarez-Perez

, et al. Prevalence of Clostridium difficile in diarrhoeic and non-diarrhoeic piglets. Vet Microbiol 2009;137:302–305.

Alvarez-Perez

, et al. Prevalence and characteristics of Clostridium perfringens and Clostridium difficile in dogs and cats attended in diverse veterinary clinics from the Madrid region. Anaerobe 2017;48:47–55.

Alvarez-Perez

, et al. High prevalence of the epidemic Clostridium difficile PCR ribotype 078 in Iberian free-range pigs. Res Vet Sci 2013;95:358–361.

Anderson

, et al. Clinical and epidemiologic considerations of Clostridium difficile in harbor seals (Phoca vitulina) at a marine mammal rehabilitation center. J Zoo Wildl Med 2015;46:191–197.

Andino-Molina

, et al. Multidrug-resistant Clostridium difficile ribotypes 078 and 014/5-FLI01 in piglets from Costa Rica. Anaerobe 2019;55:78–82.

Andrés-Lasheras

, et al. Presence of Clostridium difficile in pig faecal samples and wild animal species associated with pig farms. J Appl Microbiol 2017;122:462–472.

10.

Andrés-Lasheras

, et al. Preliminary studies on isolates of Clostridium difficile from dogs and exotic pets. BMC Vet Res 2018;14:77.

11.

Anjewierden

, et al. Risk factors for Clostridium difficile infection in pediatric inpatients: a meta-analysis and systematic review. Infect Control Hosp Epidemiol 2019;40:420–426.

12.

Arroyo

, et al. Experimental Clostridium difficile enterocolitis in foals. J Vet Intern Med 2004;18:734–738.

13.

Arroyo

, et al. Duodenitis-proximal jejunitis in horses after experimental administration of Clostridium difficile toxins. J Vet Intern Med 2017;31:158–163.

14.

Arroyo

, et al. Potential role of Clostridium difficile as a cause of duodenitis-proximal jejunitis in horses. J Med Microbiol 2006;55:605–608.

15.

Arruda

PHE

, et al. Effect of age, dose and antibiotic therapy on the development of Clostridium difficile infection in neonatal piglets. Anaerobe 2013;22:104–110.

16.

Asai

, et al. Clostridium difficile isolated from the fecal contents of swine in Japan. J Vet Med Sci 2013;75:539–541.

17.

Avbersek

, et al. Diversity of Clostridium difficile in pigs and other animals in Slovenia. Anaerobe 2009;15:252–255.

18.

Avbersek

, et al. Clostridium difficile in goats and sheep in Slovenia: characterisation of strains and evidence of age-related shedding. Anaerobe 2014;28:163–167.

19.

Baker

, et al. Prevalence and diversity of toxigenic Clostridium perfringens and Clostridium difficile among swine herds in the midwest. Appl Environ Microbiol 2010;76:2961–2967.

20.

Bandelj

, et al. Identification of risk factors influencing Clostridium difficile prevalence in middle-size dairy farms. Vet Res 2016;47:41.

21.

Bandelj

, et al. Quantification of Clostridioides (Clostridium) difficile in feces of calves of different age and determination of predominant Clostridioides difficile ribotype 033 relatedness and transmission between family dairy farms using multilocus variable-number tandem-repeat analysis. BMC Vet Res 2018;14:298.

22.

Bandelj

, et al. Prevalence and molecular characterization of Clostridium difficile isolated from European barn swallows (Hirundo rustica) during migration. BMC Vet Res 2014;10:40.

23.

Båverud

, et al. Clostridium difficile associated with acute colitis in mares when their foals are treated with erythromycin and rifampicin for Rhodococcus equi pneumonia. Equine Vet J 1998;30:482–488.

24.

Båverud

, et al. Clostridium difficile: prevalence in horses and environment, and antimicrobial susceptibility. Equine Vet J 2003;35:465–471.

25.

Båverud

, et al. Clostridium difficile associated with acute colitis in mature horses treated with antibiotics. Equine Vet J 1997;29:279–284.

26.

Bidet

, et al. Development of a new PCR-ribotyping method for Clostridium difficile based on ribosomal RNA gene sequencing. FEMS Microbiol Lett 1999;175:261–266.

27.

Bondo

, et al. Salmonella, Campylobacter, Clostridium difficile, and anti-microbial resistant Escherichia coli in the faeces of sympatric meso-mammals in southern Ontario, Canada. Zoonoses Public Health 2019;66:406–416.

28.

Bondo

, et al. Longitudinal study of Clostridium difficile shedding in raccoons on swine farms and conservation areas in Ontario, Canada. BMC Vet Res 2015;11:254.

29.

Borriello

, et al. Household pets as a potential reservoir for Clostridium difficile infection. J Clin Pathol 1983;36:84–87.

30.

Buogo

, et al. Présence de Campylobacter spp., Clostridium difficile, C. perfringens et salmonelles dans des nichées de chiots et chez des chiens adultes d’un refuge [Presence of Campylobacter spp., Clostridium difficile, C. perfringens and salmonellae in litters of puppies and in adult dogs in a shelter]. Schweiz Arch Tierheilkd 1995;137:165–171. French.

31.

Burt

, et al. Wild mice in and around the city of Utrecht, the Netherlands, are carriers of Clostridium difficile but not ESBL-producing Enterobacteriaceae, Salmonella spp. or MRSA. Lett Appl Microbiol 2018;67:513–519.

32.

Busch

, et al. Clostridium perfringens enterotoxin and Clostridium difficile toxin A/B do not play a role in acute haemorrhagic diarrhoea syndrome in dogs. Vet Rec 2015;176:253.

33.

Chan

, et al. A retrospective study on the etiological diagnoses of diarrhea in neonatal piglets in Ontario, Canada, between 2001 and 2010. Can J Vet Res 2013;77:254–260.

34.

Cho

, et al. Low prevalence of Clostridium difficile in slaughter pigs in Korea. J Food Prot 2015;78:1034–1036.

35.

Clooten

, et al. Prevalence and risk factors for Clostridium difficile colonization in dogs and cats hospitalized in an intensive care unit. Vet Microbiol 2008;129:209–214.

36.

Clooten

, et al. Genotypic and phenotypic characterization of Clostridium perfringens and Clostridium difficile in diarrheic and healthy dogs. J Vet Intern Med 2003;17:123; author reply 123.

37.

Costa

, et al. Epidemiology of Clostridium difficile on a veal farm: prevalence, molecular characterization and tetracycline resistance. Vet Microbiol 2011;152:379–384.

38.

Costa

, et al. Prevalence and molecular characterization of Clostridium difficile isolated from feedlot beef cattle upon arrival and mid-feeding period. BMC Vet Res 2012;8:38.

39.

de Oliveira

, et al. Rodents are carriers of Clostridioides difficile strains similar to those isolated from piglets. Anaerobe 2018;51:61–63.

40.

Debast

, et al. Clostridium difficile PCR ribotype 078 toxinotype V found in diarrhoeal pigs identical to isolates from affected humans. Environ Microbiol 2009;11:505–511.

41.

Diniz

, et al. The incidence of Clostridioides difficile and Clostridium perfringens netF-positive strains in diarrheic dogs. Anaerobe 2018;49:58–62.

42.

Donaldson

Palmer

JE.

Prevalence of Clostridium perfringens enterotoxin and Clostridium difficile toxin A in feces of horses with diarrhea and colic. J Am Vet Med Assoc 1999;215:358–361.

43.

Doosti

Mokhtari-Farsani

Study of the frequency of Clostridium difficile tcdA, tcdB, cdtA and cdtB genes in feces of calves in south west of Iran. Ann Clin Microbiol Antimicrob 2014;13:21.

44.

Esfandiari

, et al. Isolation and characterization of Clostridium difficile in farm animals from slaughterhouse to retail stage in Isfahan, Iran. Foodborne Pathog Dis 2015;12:864–866.

45.

Firth

, et al. Detection of zoonotic pathogens and characterization of novel viruses carried by commensal Rattus norvegicus in New York City. MBio 2014;5:e01933–14.

46.

Fry

, et al. Antimicrobial resistance, toxinotype, and genotypic profiling of Clostridium difficile isolates of swine origin. J Clin Microbiol 2012;50:2366–2372.

47.

Gustafsson

, et al. Study of faecal shedding of Clostridium difficile in horses treated with penicillin. Equine Vet J 2004;36:180–182.

48.

Gustafsson

, et al. The association of erythromycin ethylsuccinate with acute colitis in horses in Sweden. Equine Vet J 1997;29:314–318.

49.

Hammitt

, et al. A possible role for Clostridium difficile in the etiology of calf enteritis. Vet Microbiol 2008;127:343–352.

50.

Hampikyan

, et al. The prevalence of Clostridium difficile in cattle and sheep carcasses and the antibiotic susceptibility of isolates. Meat Sci 2018;139:120–124.

51.

Harvey

, et al. Clostridium difficile in poultry and poultry meat. Foodborne Pathog Dis 2011;8:1321–1323.

52.

Hawken

, et al. Longitudinal study of Clostridium difficile and methicillin-resistant Staphylococcus aureus associated with pigs from weaning through to the end of processing. J Food Prot 2013;76:624–630.

53.

, et al. Evolutionary dynamics of Clostridium difficile over short and long time scales. Proc Natl Acad Sci U S A 2010;107:7527–7532.

54.

Himsworth

, et al. Carriage of Clostridium difficile by wild urban Norway rats (Rattus norvegicus) and black rats (Rattus rattus). Appl Environ Microbiol 2014;80:1299–1305.

55.

Hoffer

, et al. Low occurrence of Clostridium difficile in fecal samples of healthy calves and pigs at slaughter and in minced meat in Switzerland. J Food Prot 2010;73:973–975.

56.

Hopman

NEM

, et al. High occurrence of various Clostridium difficile PCR ribotypes in pigs arriving at the slaughterhouse. Vet Q 2011;31:179–181.

57.

Hopman

NEM

, et al. Acquisition of Clostridium difficile by piglets. Vet Microbiol 2011;149:186–192.

58.

Houser

, et al. Prevalence of Clostridium difficile toxin genes in the feces of veal calves and incidence of ground veal contamination. Foodborne Pathog Dis 2012;9:32–36.

59.

Hussain

, et al. Molecular characteristics of Clostridium difficile isolates from human and animals in the north eastern region of India. Mol Cell Probes 2016;30:306–311.

60.

Hussain

, et al. Isolation and characterization of Clostridium difficile from pet dogs in Assam, India. Anaerobe 2015;36:9–13.

61.

Indra

, et al. Characterization of Clostridium difficile isolates using capillary gel electrophoresis-based PCR ribotyping. J Med Microbiol 2008;57:1377–1382.

62.

Jardine

, et al. Detection of Clostridium difficile in small and medium-sized wild mammals in Southern Ontario, Canada. J Wildl Dis 2013;49:418–421.

63.

Jhung

, et al. Toxinotype V Clostridium difficile in humans and food animals. Emerg Infect Dis 2008;14:1039–1045.

64.

Jones

, et al. Isolation of Clostridium difficile and detection of cytotoxin in the feces of diarrheic foals in the absence of antimicrobial treatment. J Clin Microbiol 1987;25:1225–1227.

65.

Kecerova

, et al. Clostridium difficile isolates derived from Czech horses are resistant to enrofloxacin; cluster to clades 1 and 5 and ribotype 033 predominates. Anaerobe 2019;56:17–21.

66.

Keel

, et al. Prevalence of PCR ribotypes among Clostridium difficile isolates from pigs, calves, and other species. J Clin Microbiol 2007;45:1963–1964.

67.

Keessen

, et al. The relation between farm specific factors and prevalence of Clostridium difficile in slaughter pigs. Vet Microbiol 2011;154:130–134.

68.

Keessen

, et al. Clostridium difficile infection associated with pig farms. Emerg Infect Dis 2013;19:1032–1034.

69.

Kim

, et al. High prevalence of Clostridium difficile PCR ribotype 078 in pigs in Korea. Anaerobe 2018;51:42–46.

70.

Knetsch

, et al. Whole genome sequencing reveals potential spread of Clostridium difficile between humans and farm animals in the Netherlands, 2002 to 2011. Euro Surveill 2014;19:20954.

71.

Knight

Riley

TV.

Prevalence of gastrointestinal Clostridium difficile carriage in Australian sheep and lambs. Appl Environ Microbiol 2013;79:5689–5692.

72.

Knight

, et al. Clostridium difficile carriage in Australian cattle: a cross-sectional study reveals high prevalence of non-PCR ribotype 078 strains in veal calves at slaughter. Appl Environ Microbiol 2013;79:2630–2635.

73.

Knight

, et al. Evolutionary and genomic insights into Clostridioides difficile sequence type 11: a diverse zoonotic and antimicrobial-resistant lineage of global one health importance. MBio 2019;10:e00446–19.

74.

Knight

, et al. Contamination of Australian newborn calf carcasses at slaughter with Clostridium difficile. Clin Microbiol Infect 2016;22:266.e1–e7.

75.

Knight

, et al. Nationwide surveillance study of Clostridium difficile in Australian neonatal pigs shows high prevalence and heterogeneity of PCR ribotypes. Appl Environ Microbiol 2015;81:119–123.

76.

Koene

MGJ

, et al. Clostridium difficile in Dutch animals: their presence, characteristics and similarities with human isolates. Clin Microbiol Infect 2012;18:778–784.

77.

Krijger

, et al. Clostridium difficile in wild rodents and insectivores in The Netherlands. Lett Appl Microbiol 2019;69:35–40.

78.

Krutova

, et al. The emergence of Clostridium difficile PCR ribotype 078 in piglets in the Czech Republic clusters with Clostridium difficile PCR ribotype 078 isolates from Germany, Japan and Taiwan. Int J Med Microbiol 2018;308:770–775.

79.

Kuijper

van Dissel

JT.

Spectrum of Clostridium difficile infections outside health care facilities. CMAJ 2008;179:747–748.

80.

Lawson

, et al. Reclassification of Clostridium difficile as Clostridioides difficile (Hall and O’Toole 1935) Prévot 1938. Anaerobe 2016;40:95–99.

81.

Lefebvre

, et al. Epidemic Clostridium difficile strain in hospital visitation dog. Emerging Infect Dis 2006;12:1036–1037.

82.

Lefebvre

, et al. Evaluation of the risks of shedding Salmonellae and other potential pathogens by therapy dogs fed raw diets in Ontario and Alberta. Zoonoses Public Health 2008;55:470–480.

83.

Lefebvre

, et al. Incidence of acquisition of methicillin-resistant Staphylococcus aureus, Clostridium difficile, and other health-care-associated pathogens by dogs that participate in animal-assisted interventions. J Am Vet Med Assoc 2009;234:1404–1417.

84.

Lefebvre

, et al. Prevalence of zoonotic agents in dogs visiting hospitalized people in Ontario: implications for infection control. J Hosp Infect 2006;62:458–466.

85.

Loo

, et al. Household transmission of Clostridium difficile to family members and domestic pets. Infect Control Hosp Epidemiol 2016;37:1342–1348.

86.

Madewell

, et al. Clostridium difficile: a survey of fecal carriage in cats in a veterinary medical teaching hospital. J Vet Diagn Invest 1999;11:50–54.

87.

Madewell

, et al. Apparent outbreaks of Clostridium difficile-associated diarrhea in horses in a veterinary medical teaching hospital. J Vet Diagn Invest 1995;7:343–346.

88.

Magistrali

, et al. Prevalence and risk factors associated with Clostridium difficile shedding in veal calves in Italy. Anaerobe 2015;33:42–47.

89.

Mallia

, et al. Examining the epidemiology and microbiology of Clostridium difficile carriage in elderly patients and residents of a healthcare facility in southern Ontario, Canada. J Hosp Infect 2018;99:461–468.

90.

Marks

, et al. Genotypic and phenotypic characterization of Clostridium perfringens and Clostridium difficile in diarrheic and healthy dogs. J Vet Intern Med 2002;16:533–540.

91.

McDonald

, et al. Recommendations for surveillance of Clostridium difficile-associated disease. Infect Control Hosp Epidemiol 2007;28:140–145.

92.

McKenzie

, et al. Prevalence of diarrhea and enteropathogens in racing sled dogs. J Vet Intern Med 2010;24:97–103.

93.

Medina-Torres

, et al. Prevalence of Clostridium difficile in horses. Vet Microbiol 2011;152:212–215.

94.

Miller

, et al. Enteric bacterial pathogen detection in southern sea otters (Enhydra lutris nereis) is associated with coastal urbanization and freshwater runoff. Vet Res 2010;41:1.

95.

Moono

, et al. Persistence of Clostridium difficile RT 237 infection in a Western Australian piggery. Anaerobe 2016;37:62–66.

96.

Niwa

, et al. Postoperative Clostridium difficile infection with PCR ribotype 078 strain identified at necropsy in five Thoroughbred racehorses. Vet Rec 2013;173:607.

97.

Norén

, et al. Clostridium difficile PCR ribotype 046 is common among neonatal pigs and humans in Sweden. Clin Microbiol Infect 2014;20:O2–O6.

98.

Norman

, et al. Varied prevalence of Clostridium difficile in an integrated swine operation. Anaerobe 2009;15:256–260.

99.

Orchard

, et al. Antibiotic-associated colitis due to Clostridium difficile in a Kodiak bear. Am J Vet Res 1983;44:1547–1548.

100.

Orden

, et al. Isolation of Clostridium difficile from dogs with digestive disorders, including stable metronidazole-resistant strains. Anaerobe 2017;43:78–81.

101.

Pirs

, et al. Isolation of Clostridium difficile from food animals in Slovenia. J Med Microbiol 2008;57:790–792.

102.

Rabold

, et al. The zoonotic potential of Clostridium difficile from small companion animals and their owners. PLoS One 2018;13:e0193411.

103.

Razmyar

, et al. Toxigenic Clostridium difficile in retail packed chicken meat and broiler flocks in northeastern Iran. Iran J Vet Res 2017;18:271–274.

104.

Riley

, et al. Gastrointestinal carriage of Clostridium difficile in cats and dogs attending veterinary clinics. Epidemiol Infect 1991;107:659–665.

105.

Rodriguez-Palacios

, et al. Three-week summer period prevalence of Clostridium difficile in farm animals in a temperate region of the United States (Ohio). Can Vet J 2014;55:786–789.

106.

Rodriguez-Palacios

, et al. Clostridium difficile PCR ribotypes in calves, Canada. Emerging Infect Dis 2006;12:1730–1736.

107.

Rodriguez-Palacios

, et al. Natural and experimental infection of neonatal calves with Clostridium difficile. Vet Microbiol 2007;124:166–172.

108.

Rodriguez

, et al. Presence of Clostridium difficile in pigs and cattle intestinal contents and carcass contamination at the slaughterhouse in Belgium. Int J Food Microbiol 2013;166:256–262.

109.

Rodriguez

, et al. Clostridium difficile in beef cattle farms, farmers and their environment: assessing the spread of the bacterium. Vet Microbiol 2017;210:183–187.

110.

Rodriguez

, et al. Clostridium difficile in young farm animals and slaughter animals in Belgium. Anaerobe 2012;18:621–625.

111.

Romano

, et al. Prevalence and genotypic characterization of Clostridium difficile from ruminants in Switzerland. Zoonoses Public Health 2012;59:545–548.

112.

Rothenburger

, et al. Livestock-associated methicillin-resistant Staphylococcus aureus and Clostridium difficile in wild Norway rats (Rattus norvegicus) from Ontario swine farms. Can J Vet Res 2018;82:66–69.

113.

Rupnik

Is Clostridium difficile-associated infection a potentially zoonotic and foodborne disease?

Clin Microbiol Infect 2007;13:457–459.

114.

Schneeberg

, et al. Presence of Clostridium difficile PCR ribotype clusters related to 033, 078 and 045 in diarrhoeic calves in Germany. J Med Microbiol 2013;62:1190–1198.

115.

Schneeberg

, et al. Clostridium difficile genotypes in piglet populations in Germany. J Clin Microbiol 2013;51:3796–3803.

116.

Schneeberg

, et al. Prevalence and distribution of Clostridium difficile PCR ribotypes in cats and dogs from animal shelters in Thuringia, Germany. Anaerobe 2012;18:484–488.

117.

Schoster

, et al. Longitudinal study of Clostridium difficile and antimicrobial susceptibility of Escherichia coli in healthy horses in a community setting. Vet Microbiol 2012;159:364–370.

118.

Schoster

, et al. Effect of a probiotic on prevention of diarrhea and Clostridium difficile and Clostridium perfringens shedding in foals. J Vet Intern Med 2015;29:925–931.

119.

Schoster

, et al. Presence and molecular characterization of Clostridium difficile and Clostridium perfringens in intestinal compartments of healthy horses. BMC Vet Res 2012;8:94.

120.

Silva

, et al. Clostridium difficile-associated diarrhea in an ocelot (Leopardus pardalis). Anaerobe 2013;20:82–84.

121.

Silva

, et al. Carriage of Clostridium difficile in free-living South American coati (Nasua nasua) in Brazil. Anaerobe 2014;30:99–101.

122.

Silva

, et al. Clostridium difficile ribotypes in humans and animals in Brazil. Mem Inst Oswaldo Cruz 2015;110:1062–1065.

123.

Silva

ROS

, et al. Clostridium difficile and Clostridium perfringens from wild carnivore species in Brazil. Anaerobe 2014;28:207–211.

124.

Skraban

, et al. Changes of poultry faecal microbiota associated with Clostridium difficile colonisation. Vet Microbiol 2013;165:416–424.

125.

Slifierz

, et al. Longitudinal study of the early-life fecal and nasal microbiotas of the domestic pig. BMC Microbiol 2015;15:184.

126.

Squire

, et al. Novel molecular type of Clostridium difficile in neonatal pigs, Western Australia. Emerg Infect Dis 2013;19:790–792.

127.

Stabler

, et al. Comparative phylogenomics of Clostridium difficile reveals clade specificity and microevolution of hypervirulent strains. J Bacteriol 2006;188:7297–7305.

128.

Stein

, et al. PCR-ribotype distribution of Clostridium difficile in Irish pigs. Anaerobe 2017;48:237–241.

129.

Stone

, et al. More than 50% of Clostridium difficile isolates from pet dogs in Flagstaff, USA, carry toxigenic genotypes. PLoS One 2016;11:e0164504.

130.

Struble

, et al. Fecal shedding of Clostridium difficile in dogs: a period prevalence survey in a veterinary medical teaching hospital. J Vet Diagn Invest 1994;6:342–347.

131.

Thakur

, et al. Detection of Clostridium difficile and Salmonella in feral swine population in North Carolina. J Wildl Dis 2011;47:774–776.

132.

Thean

, et al. Clostridium difficile in horses in Australia—a preliminary study. J Med Microbiol 2011;60:1188–1192.

133.

Usui

, et al. Distribution and characterization of Clostridium difficile isolated from dogs in Japan. Anaerobe 2016;37:58–61.

134.

Waters

, et al. Typhlocolitis caused by Clostridium difficile in suckling piglets. J Vet Diagn Invest 1998;10:104–108.

135.

Weber

, et al. Untersuchungen zum Vorkommen von Clostridium difficile in Kotproben von Hunden und Katzen [The occurrence of Clostridium difficile in fecal samples of dogs and cats]. Zentralbl Veterinarmed B 1989;36:568–576. German.

136.

Weese

, et al. Evaluation of Clostridium difficile in dogs and the household environment. Epidemiol Infect 2010;138:1100–1104.

137.

Weese

, et al. Clostridium difficile and methicillin-resistant Staphylococcus aureus shedding by slaughter-age pigs. BMC Vet Res 2011;7:41.

138.

Weese

, et al. A prospective study of the roles of Clostridium difficile and enterotoxigenic Clostridium perfringens in equine diarrhoea. Equine Vet J 2001;33:403–409.

139.

Weese

, et al. The roles of Clostridium difficile and enterotoxigenic Clostridium perfringens in diarrhea in dogs. J Vet Intern Med 2001;15:374–378.

140.

Weese

, et al. Clostridium difficile associated diarrhoea in horses within the community: predictors, clinical presentation and outcome. Equine Vet J 2006;38:185–188.

141.

Weese

, et al. Longitudinal investigation of Clostridium difficile shedding in piglets. Anaerobe 2010;16:501–504.

142.

Weese

, et al. Clostridium (Clostridioides) difficile shedding by polar bears (Ursus maritimus) in the Canadian Arctic. Anaerobe 2019;57:35–38.

143.

Weese

, et al. Suspected Clostridium difficile-associated diarrhea in two cats. J Am Vet Med Assoc 2001;218:1436–1439.

144.

Wei

, et al. Prevalence, genotype and antimicrobial resistance of Clostridium difficile isolates from healthy pets in Eastern China. BMC Infect Dis 2019;19:46.

145.

Williams

, et al. New York City house mice (Mus musculus) as potential reservoirs for pathogenic bacteria and antimicrobial resistance determinants. MBio 2018;9:e00624–18.

146.

Yaeger

, et al. A survey of agents associated with neonatal diarrhea in Iowa swine including Clostridium difficile and porcine reproductive and respiratory syndrome virus. J Vet Diagn Invest 2002;14:281–287.

147.

Yaeger

, et al. A prospective, case control study evaluating the association between Clostridium difficile toxins in the colon of neonatal swine and gross and microscopic lesions. J Vet Diagn Invest 2007;19:52–59.

148.

Zhang

, et al. The first isolation of Clostridium difficile RT078/ST11 from pigs in China. PLoS One 2019;14:e0212965.

149.

Zidaric

, et al. High diversity of Clostridium difficile genotypes isolated from a single poultry farm producing replacement laying hens. Anaerobe 2008;14:325–327.

Clostridium ( Clostridioides ) difficile in animals

Abstract

Keywords

Introduction

Horses

Pigs

Cattle

Small ruminants

Dogs

Cats

Poultry

Wildlife

Conclusion

Footnotes

Declaration of conflicting interests

Funding

ORCID iD

References