Genomic Analysis of Clostridioides difficile Recovered from Horses in Western Australia

Clostridioides difficile poses an ongoing threat as a cause of gastrointestinal disease in humans and animals. Traditionally considered a human healthcare-related disease, increases in community-associated C. difficile infection (CDI) and growing evidence of inter-species transmission suggest a wider perspective is required for CDI control. In horses, C. difficile is a major cause of diarrhoea and life-threatening colitis. This study aimed to better understand the epidemiology of CDI in Australian horses and provide insights into the relationships between horse, human and environmental strains. A total of 752 faecal samples from 387 Western Australian horses were collected. C. difficile was isolated from 104 (30.9%) horses without gastrointestinal signs and 19 (37.8%) with gastrointestinal signs. Of these, 68 (55.3%) harboured one or more toxigenic strains, including C. difficile PCR ribotypes (RTs) 012 (n = 14), 014/020 (n = 10) and 087 (n = 7), all prominent in human infection. Whole-genome analysis of 45 strains identified a phylogenetic cluster of 10 closely related C. difficile RT 012 strains of equine, human and environmental origin (0-62 SNP differences; average 23), indicating recent shared ancestry. Evidence of possible clonal inter-species transmission or common-source exposure was identified for a subgroup of three horse and one human isolates, highlighting the need for a One Health approach to C. difficile surveillance.

Clostridioides (Clostridium) difficile-associated disease, epiploic foramen entrapment, and gastric rupture in a Thoroughbred racehorse: case report and literature review

Epiploic foramen entrapment (EFE) is a common cause of small intestinal colic in horses and may lead to intestinal strangulation. Strangulating intestinal obstruction impairs the gastrointestinal outflow and can lead to secondary gastric rupture and endotoxemia. Clostridioides difficile can cause enterotyphlocolitis with colic in horses of all ages, and the process is commonly referred to as C. difficile-associated disease (CDAD). Here we report the results of the postmortem examination of a 7-y-old Thoroughbred racehorse with concurrent CDAD, EFE, and gastric rupture that was euthanized following a history of colic over several days. A segment of distal jejunum and proximal ileum had passed through the epiploic foramen, and the intestinal wall was thickened and dark-red. The remaining small intestinal loops were distended and filled with blood-tinged contents. Peritonitis had resulted from escape of gastric contents into the abdominal cavity through a tear in the major curvature of the stomach. Histologically, the incarcerated segment had acute transmural hemorrhage with congestion and mucosal necrosis; neutrophilic infiltrates with fibrin thrombi were in the mucosa of the non-incarcerated small intestinal segments. C. difficile toxins were detected in the small intestinal contents, and C. difficile was isolated from the small intestine, colon, and cecum.

Laboratory diagnosis of Clostridioides (Clostridium) difficile infection in domestic animals: A short review

Despite the known importance of Clostridioides (Clostridium) difficile infection (CDI) in animals, there are no published guidelines for the diagnosis of CDI. The performance of the available commercial methods, all standardized for human stool samples, can vary according to the animal species. Thus, the aim of the present study was to review the literature on the detection of C. difficile in pigs, horses, and dogs. The detection of toxins A and B using enzyme immunoassays seems to have low performance in piglet and dog samples, while it shows high sensitivity for the diagnosis of CDI in foals. On the other hand, tests for the detection of glutamate dehydrogenase (GDH) have a high sensitivity towards detection of C. difficile in animal samples, suggesting that it can be an adequate screening method. A few studies have evaluated real-time PCR or nucleic acid amplification tests in animal samples and, so far, these methods have also shown a low performance for the detection of C. difficile in animals. Although the intestinal lesions caused by CDI can vary among animal species, histopathology can be a useful auxiliary tool for postmortem diagnosis in animals.

Clostridial Diseases of Horses: A Review

The clostridial diseases of horses can be divided into three major groups: enteric/enterotoxic, histotoxic, and neurotoxic. The main enteric/enterotoxic diseases include those produced by Clostridium perfringens type C and Clostridioides difficile, both of which are characterized by enterocolitis. The main histotoxic diseases are gas gangrene, Tyzzer disease, and infectious necrotic hepatitis. Gas gangrene is produced by one or more of the following microorganisms: C. perfringens type A, Clostridium septicum, Paeniclostridium sordellii, and Clostridium novyi type A, and it is characterized by necrotizing cellulitis and/or myositis. Tyzzer disease is produced by Clostridium piliforme and is mainly characterized by multifocal necrotizing hepatitis. Infectious necrotic hepatitis is produced by Clostridium novyi type B and is characterized by focal necrotizing hepatitis. The main neurotoxic clostridial diseases are tetanus and botulism, which are produced by Clostridium tetani and Clostridium botulinum, respectively. Tetanus is characterized by spastic paralysis and botulism by flaccid paralysis. Neither disease present with specific gross or microscopic lesions. The pathogenesis of clostridial diseases involves the production of toxins. Confirming a diagnosis of some of the clostridial diseases of horses is sometimes difficult, mainly because some agents can be present in tissues of normal animals. This paper reviews the main clostridial diseases of horses.

Clostridioides difficile infection and One Health: An Equine Perspective

Clostridioides (Clostridium) difficile presents a significant health risk to humans and animals. The complexity of the bacterial–host interaction affecting pathogenesis and disease development creates an ongoing challenge for epidemiological studies, control strategies and prevention planning. The recent emergence of human disease caused by strains of C. difficile found in animals adds to mounting evidence that C. difficile infection (CDI) may be a zoonosis. In equine populations, C. difficile is a known cause of diarrhoea and gastrointestinal inflammation, with considerable mortality and morbidity. This has a significant impact on both the well‐being of the animal and, in the case of performance and production animals, it may have an adverse economic impact on relevant industries. While C. difficile is regularly isolated from horses, many questions remain regarding the impact of asymptomatic carriage as well as optimization of diagnosis, testing and treatment. This review provides an overview of our understanding of equine CDI while also identifying knowledge gaps and the need for a holistic One Health approach to a complicated issue.

Bacterial and viral enterocolitis in horses: a review

Enteritis, colitis, and enterocolitis are considered some of the most common causes of disease and death in horses. Determining the etiology of these conditions is challenging, among other reasons because different causes produce similar clinical signs and lesions, and also because some agents of colitis can be present in the intestine of normal animals. We review here the main bacterial and viral causes of enterocolitis of horses, including Salmonella spp., Clostridium perfringens type A NetF-positive, C. perfringens type C, Clostridioides difficile, Clostridium piliforme, Paeniclostridium sordellii, other clostridia, Rhodococcus equi, Neorickettsia risticii, Lawsonia intracellularis, equine rotavirus, and equine coronavirus. Diarrhea and colic are the hallmark clinical signs of colitis and enterocolitis, and the majority of these conditions are characterized by necrotizing changes in the mucosa of the small intestine, colon, cecum, or in a combination of these organs. The presumptive diagnosis is based on clinical, gross, and microscopic findings, and confirmed by detection of some of the agents and/or their toxins in the intestinal content or feces.

The comparative pathology of enterocolitis caused by Clostridium perfringens type C, Clostridioides difficile, Paeniclostridium sordellii, Salmonella enterica subspecies enterica serovar Typhimurium, and nonsteroidal anti-inflammatory drugs in horses

To determine if there were significant differences produced by 5 of the most prevalent causes of equine enterocolitis, we studied retrospectively the gross and microscopic pathology of 90 cases of enterocolitis submitted to the San Bernardino laboratory of the California Animal Health and Food Safety Laboratory. Included were cases caused by Clostridium perfringens type C (CP; n = 20), Clostridioides difficile (CD; n = 20), Paeniclostridium sordellii (PS; n = 15), Salmonella enterica subspecies enterica serovar Typhimurium (ST; n = 20), and NSAID intoxication (NS; n = 15). Grossly, necrotizing hemorrhagic typhlocolitis was seen most frequently in cases of CD, ST, and NS disease. Cases of CP and PS had enteritis or colitis in similar percentages. Congestion, hemorrhage, and pleocellular inflammatory infiltrates followed by mucosal and submucosal necrosis were the main lesions found in horses with enteritis or colitis produced by any of the etiologic agents investigated. Severe lesions were more frequent in cases of CD and CP than in cases associated with any of the other 3 etiologies. Pseudomembranes were observed with similar prevalence in the small intestine and colon affected by all agents studied. Thrombosis of the lamina propria and/or submucosa was observed in ~50% of the cases of enteritis and colitis by all etiologies, except for PS, in which the majority of the cases had thrombosis. Gross and microscopic lesions of enterocolitis were not sufficiently specific for any of these etiologic agents to enable these enteritides to be distinguished by gross and/or histologic examination.

Immunochromatographic test and ELISA for the detection of glutamate dehydrogenase (GDH) and A/B toxins as an alternative for the diagnosis of Clostridioides (Clostridium) difficile-associated diarrhea in foals and neonatal piglets

Considering the lack of studies evaluating the performance of commercially available methods for diagnosis of Clostridioides (Clostridium) difficile infection (CDI) in animals, the present study aimed to assess an immunochromatographic test for detection of glutamate dehydrogenase (GDH) and A/B toxins of C. difficile, also evaluated by an ELISA kit, in foals and neonatal piglets. Intestinal contents of 47 piglets and feces of 35 foals were tested to GDH antigen and A/B toxins in a lateral flow method (Ecodiagnostica, Brazil). Also, these samples were submitted to A/B toxin detection by an ELISA kit (C. difficile Tox A/B II, Techlab Inc., USA), using the toxigenic culture (TC) as the reference method. The GDH component of the lateral flow test showed sensitivity and negative predictive value (NPV) of 100% and a high specificity in samples of piglets (82.61%) and foals (100%). Detection of A/B toxins using the lateral flow test and the ELISA resulted in a specificity of 100% in samples of both species. On the other hand, the sensibility ranged from 54.2 to 90% for the ELISA and from 12.5 to 60% for the lateral flow test for piglets' and foals' samples, respectively. In conclusion, the present work suggests that the lateral flow test for GDH detection could be a useful method for diagnosing CDI in these species. On the other hand, the low sensitivity of the lateral flow test for A/B toxins might compromise its utility in piglets.

Fatal intestinal inflammatory lesions in equids in California: 710 cases (1990-2013)

OBJECTIVE

To determine incidences and underlying causes of fatal intestinal inflammatory lesions (FIILs) and demographic characteristics of affected equids necropsied at any of the California Animal Health and Food Safety Laboratory facilities between January 1, 1990, and April 16, 2013.

ANIMALS

710 equids with FIILs, including colitis, duodenitis, enteritis, enterocolitis, enteropathy, enterotyphlitis, gastritis, gastroenteritis, ileitis, jejunitis, typhlitis, or typhlocolitis, alone or in combination.

PROCEDURES

The medical records were reviewed, and data collected included animal age, sex, geographic origin, necropsy submission date, and breed, purpose, or characteristic of use. Descriptive statistics were compiled and reported as numbers and percentages.

RESULTS

Colitis (323/710 [45.5%]), enteritis (146/710 [20.6%]), and typhlocolitis (138/710 [19.4%]) were the most common FIILs, and the underlying cause of most FIILs was categorized as either undetermined (465/710 [65.5%]) or bacterial (167/710 [23.5%]). The most common bacteria responsible for FIILs were Clostridium spp and Salmonella spp.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that the underlying cause for most FIILs could not be identified; however, when it was identified, it was most commonly bacterial and typically Clostridium spp or Salmonella spp, which could be useful information for practitioners when evaluating and managing horses and other equids with intestinal distress. In addition, results underscored the need for improved diagnostic procedures and strategies to determine underlying causes of FIILs in equids. Knowledge of the most common FIILs and their underlying causes may help in diagnosing and mitigating intestinal disease in equids.

NetF-producing Clostridium perfringens and its associated diseases in dogs and foals

The role of type A Clostridium perfringens in canine acute hemorrhagic diarrhea syndrome and foal necrotizing enteritis is poorly characterized. However, a highly significant association between the presence of novel toxigenic C. perfringens and these specific enteric diseases has been described. These novel toxigenic strains produce 3 novel putative toxins, which have been designated NetE, NetF, and NetG. Although not conclusively demonstrated, current evidence suggests that NetF is likely the major virulence factor in strains responsible for canine acute hemorrhagic diarrhea syndrome and foal necrotizing enteritis. NetF is a beta-pore-forming toxin that belongs to the same toxin superfamily as CPB and NetB toxins produced by C. perfringens. The netF gene is encoded on a conjugative plasmid that, in the case of netF, also carries another putative toxin gene, netE. In addition, these strains consistently also carry a cpe tcp-conjugative plasmid, and a proportion also carry a separate netG tcp-conjugative plasmid. The netF and netG genes form part of a locus with all the features of the pathogenicity loci of tcp-conjugative plasmids. The netF-positive isolates are clonal in origin and fall into 2 clades. Disease in dogs or foals can be associated with either clade. Thus, these are strains with unique virulence-associated characteristics associated with serious and sometimes fatal cases of important enteric diseases in 2 animal species.

Paeniclostridium (Clostridium) sordellii-associated enterocolitis in 7 horses

Enteric disease in horses may be caused by a variety of microorganisms, including several clostridial species. Paeniclostridium sordellii (previously Clostridium sordellii) has been frequently associated with gas gangrene in humans and several animal species, including horses. However, its role in enteric diseases of animals has not been fully determined. We describe herein 7 cases of enteric disease in horses associated with P. sordellii infection. Grossly, the small and/or large intestines were necrotic, hemorrhagic, and edematous. Microscopically, there was severe mucosal necrosis and hemorrhage of the small and/or large intestine of all horses. P. sordellii was isolated and/or demonstrated by immunohistochemistry and/or PCR in the intestine of all horses. All other known causes of enteric disease in horses were ruled out in these 7 cases. P. sordellii should be considered among the differential diagnoses in cases of enteric disease in horses.

Clostridium difficile isolates derived from Czech horses are resistant to enrofloxacin; cluster to clades 1 and 5 and ribotype 033 predominates

Clostridium difficile has been recovered from the faeces of several animal species as well as horses. Between April 2015 and October 2016, 213 samples of faeces from non-hospitalized (n = 138) and hospitalized horses (n = 75) were investigated and eighteen C. difficile isolates were cultured using an enrichment method. Sixteen C. difficile positive samples were identified from hospitalised horses (p < 0.01). Molecular typing revealed seven ribotypes and sequence types (RT033/ST11 n = 8, 44.4%; RT081/ST9 n = 4, 22.2%; RT009/ST3 n = 2, 11.1%; RT003/ST12 n = 1, 5.6%; RT010/ST15 n = 1, 5.6%; RT012/ST54 n = 1, 5.6%; RT039/ST26 n = 1, 5.6%). Seven identified STs clustered to two clades (1 and 5). All C. difficile isolates were susceptible to amoxicillin, metronidazole, moxifloxacin, and vancomycin. One isolate (RT039) exhibited a high level of resistance to erythromycin and clindamycin (256 mg/L) and carried the ermB, adenine methylase gene. Five isolates were resistant to clindamycin at lower minimal inhibitory concentrations (MICs = 8-16 mg/L) and were susceptible to erythromycin and also ermB negative. All isolates were resistant to enrofloxacin (MICs ranged between 4 and 32 mg/L). Eight isolates were resistant to tetracycline (MICs 12-32 mg/L). Of them, four isolates carried the tetM gene and four isolates the tetW gene. In addition, the tetracycline resistance determinants identified were: tetA (P) (n = 4); tetB (P); and tetL (n = 1 each). The presence of tetW or tetM, together with other tet-class mechanisms, lead to an increase in the MICs to tetracycline. C. difficile isolates derived from Czech horses are identical to the ribotypes identified in humans and carry acquired antimicrobial resistance genes whose dissemination from veterinary healthcare sector to humans should be monitored by the "One health" approach.

Equine salmonellosis in southern Brazil

The Salmonella sp. genus is identified in several species, and the zoonosis it causes is one of the most important types worldwide. The specifics of salmonellosis vary according to the function of the serovar involved, the species affected, age and predisposing factors. However, few cases of equine salmonellosis have been reported. This study presents ten confirmed salmonellosis cases in equines in southern Brazil. Six were adult animals with stress factors preceding the disease, while four were foals, three of which presented with hyperacute manifestations. The main clinical signs were diarrhea, anorexia, and hyperthermia. Lesions varied in distribution and severity, although fibrinonecrotic or necrohemorrhagic enteritis was observed in all animals, mainly in the large intestine (large colon and cecum-8/10) and small intestine (3/10). Substantial liquid content, mainly hemorrhagic, was observed in all animals. The most characteristic microscopic lesion was mucosa necrosis, which is often accompanied by fibrin deposition, followed by necrosis of follicular centers and vascular changes. Bacterial isolation revealed seven isolates. Five were serotyped, and the serovars Typhimurium and Anatum were associated with two cases each, while Muenster was associated with a case whose lesion pattern varied. Immunohistochemical staining was positive in all cases. All diagnoses were based on the clinical history, macroscopic and histological lesions, and the bacterial isolation and/or immunostaining associated with histological lesions.

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.

Gastritis, Enteritis, and Colitis in Horses

The gastrointestinal system of horses is affected by a large variety of inflammatory infectious and noninfectious conditions. The most prevalent form of gastritis is associated with ulceration of the pars esophagea. Although the diagnostic techniques for alimentary diseases of horses have improved significantly over the past few years, difficulties still exist in establishing the causes of a significant number of enteric diseases in this species. This problem is compounded by several agents of enteric disease also being found in the intestine of clinically normal horses, which questions the validity of the mere detection of these agents in the intestine.

Necrotizing Enteritis and Hyperammonemic Encephalopathy Associated With Equine Coronavirus Infection in Equids

Equine coronavirus (ECoV) is a Betacoronavirus recently associated clinically and epidemiologically with emerging outbreaks of pyrogenic, enteric, and/or neurologic disease in horses in the United States, Japan, and Europe. We describe the pathologic, immunohistochemical, ultrastructural, and molecular findings in 2 horses and 1 donkey that succumbed to natural infection with ECoV. One horse and the donkey (case Nos. 1, 3) had severe diffuse necrotizing enteritis with marked villous attenuation, epithelial cell necrosis at the tips of the villi, neutrophilic and fibrinous extravasation into the small intestinal lumen (pseudomembrane formation), as well as crypt necrosis, microthrombosis, and hemorrhage. The other horse (case No. 2) had hyperammonemic encephalopathy with Alzheimer type II astrocytosis throughout the cerebral cortex. ECoV was detected by quantitative polymerase chain reaction in small intestinal tissue, contents, and/or feces, and coronavirus antigen was detected by immunohistochemistry in the small intestine in all cases. Coronavirus-like particles characterized by spherical, moderately electron lucent, enveloped virions with distinct peplomer-like structures projecting from the surface were detected by negatively stained transmission electron microscopy in small intestine in case No. 1, and transmission electron microscopy of fixed small intestinal tissue from the same case revealed similar 85- to 100-nm intracytoplasmic particles located in vacuoles and free in the cytoplasm of unidentified (presumably epithelial) cells. Sequence comparison showed 97.9% to 99.0% sequence identity with the ECoV-NC99 and Tokachi09 strains. All together, these results indicate that ECoV is associated with necrotizing enteritis and hyperammonemic encephalopathy in equids.

Dominant components of the Thoroughbred metabolome characterised by (1) H-nuclear magnetic resonance spectroscopy: A metabolite atlas of common biofluids

REASONS FOR PERFORMING STUDY

Metabonomics is emerging as a powerful tool for disease screening and investigating mammalian metabolism. This study aims to create a metabolic framework by producing a preliminary reference guide for the normal equine metabolic milieu.

OBJECTIVES

To metabolically profile plasma, urine and faecal water from healthy racehorses using high resolution (1) H-nuclear magnetic resonance (NMR) spectroscopy and to provide a list of dominant metabolites present in each biofluid for the benefit of future research in this area.

STUDY DESIGN

This study was performed using 7 Thoroughbreds in race training at a single time point. Urine and faecal samples were collected noninvasively and plasma was obtained from samples taken for routine clinical chemistry purposes.

METHODS

Biofluids were analysed using (1) H-NMR spectroscopy. Metabolite assignment was achieved via a range of one- and 2-dimensional experiments.

RESULTS

A total of 102 metabolites were assigned across the 3 biological matrices. A core metabonome of 14 metabolites was ubiquitous across all biofluids. All biological matrices provided a unique window on different aspects of systematic metabolism. Urine was the most populated metabolite matrix with 65 identified metabolites, 39 of which were unique to this biological compartment. A number of these were related to gut microbial host cometabolism. Faecal samples were the most metabolically variable between animals; acetate was responsible for the majority (28%) of this variation. Short-chain fatty acids were the predominant features identified within this biofluid by (1) H-NMR spectroscopy.

CONCLUSIONS

Metabonomics provides a platform for investigating complex and dynamic interactions between the host and its consortium of gut microbes and has the potential to uncover markers for health and disease in a variety of biofluids. Inherent variation in faecal extracts along with the relative abundance of microbial-mammalian metabolites in urine and invasive nature of plasma sampling, infers that urine is the most appropriate biofluid for the purposes of metabonomic analysis.

Postoperative Clostridium difficile infection with PCR ribotype 078 strain identified at necropsy in five Thoroughbred racehorses

Clostridium difficile is an important cause of acute enterocolitis in horses. We describe five cases of C difficile infection occurring postoperatively in Thoroughbred racehorses. Following diarrhoea or colic accompanied by a marked increase in packed cell volume (to ≥60 per cent) and leucopenia (≤4000 cells/μl) within two to four days after surgery in all five horses, four of them died or were euthanased because of colitis or severe diarrhoea. In these four horses, necrotising entero-typhlo-colitis was revealed by postmortem examination, and C difficile was recovered from the contents of the small and/or large intestine. The remaining horse was euthanased because of marked decline in general condition and the presence of a lung abscess, from which C difficile was isolated. The horse had had severe postoperative diarrhoea before the onset of respiratory disorder; laboratory tests for C difficile were not performed on the faeces. All C difficile isolates were toxin-A-positive, toxin-B-positive and actin-specific ADP-ribosyltransferase (CDT)-positive. The isolates were indistinguishable by pulsed field gel electrophoresis analysis, PCR ribotyping, and slpA sequence typing, and the slpA sequences and PCR ribotype patterns were identical to those of known PCR type 078. This case sequence might have been healthcare-associated infection, although there was about a four-month interval between each disease onset.