Clostridium perfringens: A review of enteric diseases in dogs, cats and wild animals

Carriage of Clostridium perfringens in domestic and farm animals across the central highlands of Colombia: implications for gut health and zoonotic transmission

Clostridium perfringens inhabits the guts of humans and animal species. C. perfringens can proliferate and express an arsenal of toxins, promoting the development of multiple gut illnesses. Healthy animals carrying C. perfringens represents a risk of transmission to other animals or humans through close contact and an increased likelihood of acquisition of toxin plasmids. The aim of this study was to evaluate the frequency of C. perfringens carriage in domestic and farm animals in the central highlands of Colombia. C. perfringens was detected in six animal species using PCR targeting alpha toxin (cpa) and 16S ribosomal RNA (16S-rRNA) genes from 347 fecal samples collected in two Departments: 177 from farm animals of Boyacá and 170 from domestic animals of both Cundinamarca and Boyacá. The overall frequency of C. perfringens detection was 22.1% (n = 77/347), with the highest frequency observed in cats 34.2% (n = 41/120), followed by dogs 30.0% (n = 15/50). The lowest frequency was detected in ruminants: goats 11.1% (n = 3/27), sheep 8.0% (n = 4/50) and cattle 6.0% (n = 6/50). Domestic animals showed a higher frequency of C. perfringens carriage than farm animals. This difference could be associated with dietary patterns, as domestic animals have diets rich in proteins and carbohydrates, while ruminants have low-carbohydrate diets, resulting in high production of endopeptidase-type enzymes and differences in pH due to the anatomy of gastrointestinal tract, which can influence bacterial proliferation. These findings indicate a potential risk of transmission of C. perfringens among animals and from animals to humans through close contact.

Zoonotic bacterial and parasitic intestinal pathogens in foxes, raccoons and other predators from eastern Germany

In this study, we investigated faecal specimens from legally hunted and road-killed red foxes, raccoons, raccoon dogs, badgers and martens in Germany for parasites and selected zoonotic bacteria. We found that Baylisascaris procyonis, a zoonotic parasite of raccoons, had spread to northeastern Germany, an area previously presumed to be free of this parasite. We detected various pathogenic bacterial species from the genera Listeria, Clostridium (including baratii), Yersinia and Salmonella, which were analysed using whole-genome sequencing. One isolate of Yersinia enterocolitica contained a virulence plasmid. The Salmonella Cholerasuis isolate encoded an aminoglycoside resistance gene and a parC point mutation, conferring resistance to ciprofloxacin. We also found tetracycline resistance genes in Paeniclostridium sordellii and Clostridium baratii. Phylogenetic analyses revealed that the isolates were polyclonal, indicating the absence of specific wildlife-adapted clones. Predators, which scavenge from various sources including human settlements, acquire and spread zoonotic pathogens. Therefore, their role should not be overlooked in the One Health context.

Occurrence of Clostridium perfringens in Wild Mammals in the Amazon Biome

The objective of this study was to evaluate the occurrence of Clostridium perfringens in stool samples and swabs collected from wild mammals in the Amazon biome. Sixty-five faecal and swab samples were collected in situ and ex situ from 16 species and three genera of wild mammals, some of which were in good health and some of which had diarrhoea. After pre-enrichment, the samples were plated on selective agar for C. perfringens. Characteristic colonies were subjected to multiplex PCR for the detection of genes encoding the main C. perfringens toxins (alpha, beta, epsilon, and iota toxin and enterotoxin). Among the 65 samples, 40 (61.5%) were positive for the gene encoding the alpha toxin and were classified as type A, 36 of which were asymptomatic animals and four were diarrheal. No other toxinotypes were found. The findings of this study suggest that C. perfringens type A is commonly found in mammal species of the Amazon biome. This seems to be the first study to identify C. perfringens type A in species such as B. variegatus (common ground sloth), C. didactylus (two-toed sloth), P. flavus (Jupará), T. tetradactyla (anteater), S. collinsi (squirrel monkey), S. niger (black marmoset), and S. apella (Guyana capuchin) and in the genus Didelphis sp. (opossum).

In vitro activity of fidaxomicin and combinations of fidaxomicin with other antibiotics against Clostridium perfringens strains isolated from dogs and cats

BACKGROUND

Previous studies have demonstrated that fidaxomicin, a macrocyclic lactone antibiotic used to treat recurrent Clostridioides difficile-associated diarrhea, also displays potent in vitro bactericidal activity against Clostridium perfringens strains isolated from humans. However, to date, there is no data on the susceptibility to fidaxomicin of C. perfringens strains of animal origin. On the other hand, although combination therapy has become popular in human and veterinary medicine, limited data are available on the effects of antibiotic combinations on C. perfringens. We studied the in vitro response of 21 C. perfringens strains obtained from dogs and cats to fidaxomicin and combinations of fidaxomicin with six other antibiotics.

RESULTS

When tested by an agar dilution method, fidaxomicin minimum inhibitory concentrations (MICs) ranged between 0.004 and 0.032 µg/ml. Moreover, the results of Etest-based combination assays revealed that the incorporation of fidaxomicin into the test medium at a concentration equivalent to half the MIC significantly increased the susceptibility of isolates to metronidazole and erythromycin in 71.4% and 61.9% of the strains, respectively, and the susceptibility to clindamycin, imipenem, levofloxacin, and vancomycin in 42.9-52.4% of the strains. In contrast, ¼ × MIC concentrations of fidaxomicin did not have any effect on levofloxacin and vancomycin MICs and only enhanced the effects of clindamycin, erythromycin, imipenem, and metronidazole in ≤ 23.8% of the tested strains.

CONCLUSIONS

The results of this study demonstrate that fidaxomicin is highly effective against C. perfringens strains of canine and feline origin. Although fidaxomicin is currently considered a critically important antimicrobial that has not yet been licensed for veterinary use, we consider that the results reported in this paper provide useful baseline data to track the possible emergence of fidaxomicin resistant strains of C. perfringens in the veterinary setting.

Gut microbiota and age shape susceptibility to clostridial enteritis in lorikeets under human care

Background

Enteritis is a common cause of morbidity and mortality in lorikeets that can be challenging to diagnose and treat. In this study, we examine gut microbiota in two lorikeet flocks with enteritis (Columbus Zoo and Aquarium—CZA; Denver Zoo—DZ). Since 2012, the CZA flock has experienced repeated outbreaks of enteritis despite extensive diet, husbandry, and clinical modifications. In 2018, both CZA and DZ observed a spike in enteritis. Recent research has revealed that the gut microbiota can influence susceptibility to enteropathogens. We hypothesized that a dysbiosis, or alteration in the gut microbial community, was making some lorikeets more susceptible to enteritis, and our goal was to characterize this dysbiosis and determine the features that predicted susceptibility.

Results

We employed 16S rRNA sequencing to characterize the cloacal microbiota in lorikeets (CZA n = 67, DZ n = 24) over time. We compared the microbiota of healthy lorikeets, to lorikeets with enteritis, and lorikeets susceptible to enteritis, with “susceptible” being defined as healthy birds that subsequently developed enteritis. Based on sequencing data, culture, and toxin gene detection in intestinal contents, we identified Clostridium perfringens type A (CZA and DZ) and C. colinum (CZA only) at increased relative abundances in birds with enteritis. Histopathology and immunohistochemistry further identified the presence of gram-positive bacilli and C. perfringens, respectively, in the necrotizing intestinal lesions. Finally, using Random Forests and LASSO models, we identified several features (young age and the presence of Rhodococcus fascians and Pseudomonas umsongensis) associated with susceptibility to clostridial enteritis.

Conclusions

We identified C. perfringens type A and C. colinum associated with lorikeet necrohemorrhagic enteritis at CZA and DZ. Susceptibility testing of isolates lead to an updated clinical treatment plan which ultimately resolved the outbreaks at both institutions. This work provides a foundation for understanding gut microbiota features that are permissive to clostridial colonization and host factors (e.g. age, prior infection) that shape responses to infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42523-021-00148-7.

Stress-Related Herpesvirus Reactivation in Badgers Can Result in Clostridium Proliferation

Clostridium perfringens is an important food-borne zoonotic pathogen and a member of the commensal gut microbiome of many mammals. Predisposing factors such as coinfection with other pathogens or diet change can, however, cause overgrowth and subsequent disease development. Here we investigated the occurrence of C. perfringens in a free-ranging badger population with up to 100% prevalence of herpesvirus infection. Herpesvirus reactivation is known to be associated with increased susceptibility bacterial infections. PCR screening of rectal swabs from 69 free-ranging badgers revealed 15.9% (11/69, 95% CI = 9.1-26.3%) prevalence of detectable C. perfringens (Type A) DNA in the digestive tracts of assymptomatic animals. The results of Fisher's exact test revealed C. perfringens detection was not biased by age, sex and seasons. However, badgers with genital tract gammaherpesvirus (MusGHV-1) reactivation (p = 0.007) and infection with a specific MusGHV-1 genotype (p = 0.019) were more prone to of C. perfringens proliferation, indicating coinfection biased dynamics of intestinal C. perfringens. An inclusion pattern analysis further indicated that, causally, MusGHV-1 reactivation potentiated C. perfringens detection. Whether or not specific MusGHV-1 genotype infection or reactivation plays a role in C. perfringens overgrowth or disease development in badgers will require further investigation. Nevertheless, a postmortem examination of a single badger that died of fatal disease, likely associated with C. perfringens, revealed MusGHV-1 detection in the small intestine.

Antimicrobial Drug-Resistant Salmonella in Urban Cats: Is There an Actual Risk to Public Health?

The present study was undertaken to investigate the presence of Salmonella spp. in the faeces of client-owned cats in urban areas and to evaluate the risk that is posed to public health. Fresh faecal samples were collected directly from the rectums from 53 diarrhoeic and 32 non-diarrhoeic cats. The samples were individually screened for the presence of Salmonella spp. using standard methods and, in the case of positive findings, the resulting typical colonies were then biochemically confirmed using the VITEK^®2 automated system. Subsequently, all of the Salmonella spp. isolates were molecularly tested for the presence of the invA gene. All of the isolates were serotyped using the slide agglutination technique according to the White–Kauffmann–Le Minor scheme. The phenotypic antimicrobial susceptibility profile of the isolated strains was obtained from the VITEK^®2 system using specific cards from the Gram-negative bacteria. A total of 16 of the samples (18.82%) tested positive for Salmonella spp. according to conventional and molecular testing methods. Serotyping of the Salmonella isolates showed the presence of three serotypes, namely S. enteritidis (n = 9; 56.3%), S. typhimurium (n = 4; 25%), and S. kentucky (n = 3; 18.8%). All of the tested strains showed strong resistance towards cefazolin, cefepime, ceftazidime, and ceftriaxone. Additionally, resistance (listed in descending order of strength) was observed to trimethoprim/sulfamethoxazole (11/16; 68.8%), ampicillin (10/16; 62.5%), ampicillin/sulbactam (9/16; 56.3%), gentamicin (9/16; 56.3%), nitrofurantoin (8/16; 50.0%), and amikacin (5/16; 31.3%). No resistance was expressed against ciprofloxacin, ertapenem, imipenem, levofloxacin, piperacillin/tazobactam, and tobramycin. The results of this study highlight a substantial public health issue and medical concern, especially in vulnerable people, such as children, the elderly, and immunocompromised individuals.

Enteric Organisms Detected in Feces of Dogs With Bloody Diarrhea: 45 Cases

Bloody diarrhea is a common condition in dogs, but studies evaluating the enteropathogens involved specifically in adult dogs are scarce. In the present study, stool samples from 45 adult dogs with bloody diarrhea were evaluated for the four enteric organisms mainly reported in these cases: canine parvovirus type 2 (CPV-2), Clostridioides difficile, Clostridium perfringens, and Salmonella spp. In addition, the samples were also tested for coronavirus, rotavirus, Giardia spp., and Escherichia coli pathotypes to provide a better understanding of possible co-occurrence. Vaccination status, diet, and clinical outcome were also obtained when available. CPV-2b was identified in 17 dogs (37.8%), being the most frequent cause of bloody diarrhea, including completely vaccinated adult dogs. Toxigenic C. difficile and C. perfringens netF⁺ were detected in 6 (13.3%) and 5 (11.1%) dogs, in some cases in a co-occurrence with other enteric organisms. Three fatal cases of salmonellosis were identified in dogs fed a raw meat-based diet, raising the risks associated with this increasing practice.

Densitometric analysis of rep-PCR data: Insight into genetic variability and transmission of Clostridium perfringens typed with an improved multiplex PCR

An epidemiological study was conducted in North-East India (part of Indo-Burma biodiversity hotspot) to better understand the distribution, diversity, and transmission of Clostridium perfringens among livestock, pets, wild animals (captive), and humans. A total of 160 C. perfringens isolates were recovered from 642 diarrhoeic faecal samples with an isolation rate of 24.92%. Isolation rate was the highest among captive wild animals (37.5%) followed by dog (34.6%), human (33.8%), pig (32.7%), cattle (20.8%), goat (18.3%) and poultry (9.3%). Isolates were toxin typed using a seven gene multiplex PCR designed for simultaneous detection of cpa, cpb, cpb2, etx, iap, cpe and netB. The majority of isolates, 128 (80%) were of type A, followed by 17 (10.62%), 5 (3.12%), 4 (2.5%), 3 (1.87%), 2 (1.25%) and 1 (0.63%) isolates of type C, D, E, G, F and B, respectively. Beta 2 toxin gene was present in 65 (50%) of type A isolates, followed by 7 (41.2%), 4 (80%), 1(25%), and 1 (100%) of type C, D, G and B isolates, respectively. Beta 2 toxin has a high prevalence among dogs (28.6%), cattle (27.3%), and pig (20.8%) compared to humans, goat, wild animals, and poultry (1.2-14.3%). The prevalence of CPE and NetB toxin-positive strains was low, with only 3 (1.8%) and 5 (3.1%) isolates, respectively. Association of C. perfringens with diarrhoea in Civet Cat, Golden Langur, and Gray Langur has been reported for the first time. The genetic diversity and transmission of isolates were investigated using automated rep-PCR (Diversilab®, bioMérieux) using two densitometry-based matrices: modified Kullback-Leibler (KL) and Pearson's correlation (PC). The PC and modified KL matrices formed three distinct clusters with 59% and 27.2% similarity, respectively. C. perfringens diversity and transmission were best studied using modified KL matrix that placed more emphasis on the presence of bands rather than intensity. However, the PC method was found to be more suitable for differentiating strains within a toxin type, with slightly higher D-values.

Clostridium perfringens-Associated Necrotic Enteritis-Like Disease in Coconut Lorikeets (Trichoglossus haematodus)

Several outbreaks of necrotic enteritis-like disease in lorikeets, from which Clostridium perfringens was consistently isolated, are described. All lorikeets had acute, segmental, or multifocal fibrinonecrotizing inflammatory lesions in the small and/or the large intestine, with intralesional gram-positive rods. The gene encoding C. perfringens alpha toxin was detected by PCR (polymerase chain reaction) on formalin-fixed, paraffin-embedded (FFPE) tissues in 20 out of 24 affected lorikeets (83%), but it was not amplified from samples of any of 10 control lorikeets (P < .0001). The second most prevalent C. perfringens toxin gene detected was the beta toxin gene, which was found in FFPE from 7 out of 24 affected lorikeets (29%). The other toxin genes were detected inconsistently and in a relatively low number of samples. These cases seem to be associated with C. perfringens, although the specific type involved could not be determined.

Faecal PCR panel results and clinical findings in Western Australian dogs with diarrhoea

AIM

To describe faecal PCR (fPCR) results and clinical findings of dogs seen at a university teaching hospital for diarrhoea.

DESIGN

Retrospective case series (April 2015 to July 2018).

PROCEDURE

Data were collected from the hospital electronic medical records. Data extracted included signalment, history, clinical signs, treatment, fPCR panel results, other faecal diagnostic test results and antimicrobial use.

RESULTS

One hundred and sixty-eight dogs with diarrhoea had a fPCR panel submitted. Most dogs (115, 68.5%) had diarrhoea of 3 days or less duration. Clostridium perfringens alpha toxin gene was most frequently detected (156, 92.9%) by fPCR, followed by Campylobacter spp. (55, 32.7%), canine parvovirus (CPV) (29, 17.3%), Salmonella spp. (14, 8.3%) and Giardia spp. (9, 5.4%). For the 45 dogs that had a negative point-of-care CPV test, 13 were CPV fPCR positive; some of which were adult dogs with current vaccination status. A total of 94/168 (56%) dogs received antimicrobials at some time during the treatment of diarrhoea.

CONCLUSION

Faecal PCR panels can identify dogs with enteric organisms in their faeces that traditional faecal diagnostics may miss, thus contributing additional information to the diagnostic process. Nonetheless, fPCR results should be interpreted in light of the clinical findings, and particular consideration given to avoiding inappropriate use of antimicrobials. This study highlights that testing for C. perfringens alpha toxin gene is not likely to be diagnostically helpful, and that adult dogs with diarrhoea might be identified as CPV positive with PCR testing, despite a negative point-of-care CPV test result and a current vaccination status.

Fecal shedding of Salmonella spp., Clostridium perfringens, and Clostridioides difficile in dogs fed raw meat-based diets in Brazil and their owners' motivation

The present study aimed to explore the motivations of Brazilian dog owners and their knowledge about the risks related to raw meat-based diets (RMBD) as well as to evaluate important enteropathogens such as Salmonella spp., C. perfringens, and C. difficile, in feces of dogs fed different diets. The majority of the pet owners (69.3%) reported to have chosen this diet for their dogs, considering it to be more “natural”. A large number of owners declared that RMBD do not pose health risks for their animals (87.9%) or humans (98.8%), even though almost one third of the respondents (34.8%) declared having at least one individual at high risk of infection in contact with RMBD-fed dogs. Stool samples from 46 RMBD-fed dogs and 192 dogs fed commercial dry feed were collected. The present study revealed that dogs fed raw meat diets were almost 30 times more likely to be positive for Salmonella spp. than dogs on a conventional diet. Some of the serovars detected were commonly associated with human salmonellosis, such as S. Typhimurium and S. Saintpaul, and were multidrug resistant. RMBD-fed dogs were more likely to be positive for C. perfringens type A (p = 0.008) and one C. perfringens type F was isolated from these animals. Two toxigenic strains (4.3%) of C. difficile were isolated only from raw meat-fed dogs, all of which were under antibiotic therapy. These toxigenic C. difficile isolates were classified as RT106/ST54 and RT600/ST149, previously associated with infection in dogs and humans. The present work revealed that the owners have a tendency to ignore or are unaware of the risks associated with raw meat diets for dogs. Also, the higher fecal shedding of important enteropathogens in dogs fed RMBD suggests that this diet poses a risk for the animals and the people in contact with them.

Isolation of Clostridium perfringens and Clostridioides difficile in diarrheic and nondiarrheic cats

The occurrence and characteristics of Clostridioides (previously Clostridium) difficile and Clostridium perfringens in the feces of diarrheic and non-diarrheic cats was investigated. Apparently healthy animals were more likely to be positive for C. perfringens type A (p = 0.009). Two isolates (0.7%), one each from a diarrheic and an apparently healthy cat, were positive for the enterotoxin-encoding gene but negative for the NetF-encoding gene. Six toxigenic C. difficile isolates were isolated, all RT106 and ST42, which is commonly reported in humans with C. difficile infection.

Gas gangrene in mammals: a review

Gas gangrene is a necrotizing infection of subcutaneous tissue and muscle that affects mainly ruminants and horses, but also other domestic and wild mammals. Clostridium chauvoei, C. septicum, C. novyi type A, C. perfringens type A, and C. sordellii are the etiologic agents of this disease, acting singly or in combination. Although a presumptive diagnosis of gas gangrene can be established based on clinical history, clinical signs, and gross and microscopic changes, identification of the clostridia involved is required for confirmatory diagnosis. Gross and microscopic lesions are, however, highly suggestive of the disease. Although the disease has a worldwide distribution and can cause significant economic losses, the literature is limited mostly to case reports. Thus, we have reviewed the current knowledge of gas gangrene in mammals.

First Microbiological and Molecular Identification of Rhodococcus equi in Feces of Nondiarrheic Cats

Rhodococcus equi is responsible for infections in multiple-host animals. In humans, the prevalence of rhodococcus has increased worldwide and represents an emergent risk. R. equi is a soil-borne opportunistic bacterium isolated from feces of a wide variety of domestic species, except cats; thus, there is no known potential risk of its transmission from humans. Here, the mono- and cooccurrence of Rhodococcus equi and other bacteria and selected virulence markers were investigated in feces of nondiarrheic cats from urban (n=100) and rural (n=100) areas. Seven (7/200=3.5%) R. equi isolates were recovered in ceftazidime, novobiocin, and cycloheximide (CAZ-NB) selective media, exclusively of cats from three distinct farms (p=0.01), and these cats had a history of contact with horses and their environment (p=0.0002). None of the R. equi isolates harbored hosted-adapted plasmid types associated with virulence (pVAPA, pVAPB, and pVAPN). One hundred seventy-five E. coli isolates were identified, and 23 atypical enteropathogenic E. coli (aEPEC), 1 STEC (Shiga-toxin producing E. coli), and 1 EAEC (enteroaggregative E. coli) were detected. Eighty-six C. perfringens type A isolates were identified, and beta-2 and enterotoxin were detected in 21 and 1 isolates, respectively. Five C. difficile isolates were identified, one of which was toxigenic and ribotype 106. The main cooccurring isolates in cats from urban areas were E. coli and C. perfringens A (26/100=26%), E. coli and C. perfringens type A cpb2⁺ (8/100=8%), and aEPEC (eae+/escN+) and C. perfringens type A (5/100=5%). In cats from farms, the main cooccurring isolates were E. coli and C. perfringens type A (21/100=21%), E. coli and C. perfringens type A cpb₂⁺ 8/100=8%), and E. coli and R. equi (4/100=4%). We identified, for the first time, R. equi in nondiarrheic cats, a finding that represents a public health issue because rhodococcus has been reported in both immunosuppressed and immunocompetent humans, particularly people living with HIV/AIDS.

Galleria mellonella Infection Model Identifies Both High and Low Lethality of Clostridium perfringens Toxigenic Strains and Their Response to Antimicrobials

Research progress into mechanisms of the anaerobe Clostridium perfringens and associated diseases has been frustrated by the lack of reliable infection models. Wax moth larvae (Galleria mellonella) have emerged as a viable alternative to other models of infection since they are economic, survive at 37°C and require no specialist equipment. This study aims to establish to what extent G. mellonella larvae can be used to study the virulence of C. perfringens strains and its suitability for studying novel treatment strategies by an improved time-lapse approach to data collection. Mortality and morbidity rates of larvae challenged with 10⁵ CFU of C. perfringens isolates from various sources were observed over 72 h and dose response data obtained. Phenoloxidase enzyme activity was investigated as a marker for immune response and tissue burden assessed by histopathological techniques. Results demonstrate that C. perfringens is pathogenic toward G. mellonella although potency varies dramatically between C. perfringens isolates and the reference strain ATCC 13124 was shown to be avirulent. Infection with C. perfringens strains activated the melanisation pathway resulting in melanin deposition but no increase in enzyme activity was observed. Efficacy of antibiotic therapy (penicillin G, bacitracin, neomycin, and tetracycline) administered parenterally to some extent correlates with that of in vitro analysis. The findings suggest G. mellonella might be a useful in vivo model of infection and convenient as a pre-screening assay for virulence of C. perfringens strains or as a simple, cheap and rapid in vivo assay in the first stage development of novel therapeutics against anaerobes.

HIGHLIGHTS

-Potential novel in vivo model for the study of Clostridium perfringens infection.-Novel time-lapse approach to data collection.-First report of the pathogenicity of C. perfringens toward G. mellonella.-First report of the efficacy of antibiotic therapy in response to C. perfringens infection in G. mellonella.

A Randomized Double Blinded Placebo-Controlled Clinical Trial of a Probiotic or Metronidazole for Acute Canine Diarrhea

Acute diarrhea is a common, often self-limiting, cause of presentation for veterinary care, yet there is a paucity of data on frequently-prescribed treatments. The purpose of this randomized, double blinded placebo-controlled clinical trial was to compare two anecdotally-recommended treatments: a probiotic combination and metronidazole. Sixty dogs without concurrent comorbidities were randomized into three treatment groups. The time to resolution of diarrheal signs was evaluated using owner surveys and fecal scoring charts. Dogs presenting with acute diarrhea achieved acceptable fecal consistency after 3.5 ± 2.2 days when receiving probiotic, 4.6 ± 2.4 days with oral metronidazole, and 4.8 ± 2.9 days with placebo; statistically significant differences were not identified between treatment groups (p = 0.17). These findings failed to provide evidence for the common use of metronidazole in this cohort of dogs with acute canine diarrhea, and a larger study population would be required to identify a statistically significant effect of probiotics.

Identification and Characterization of Escherichia coli, Salmonella Spp., Clostridium perfringens, and C. difficile Isolates from Reptiles in Brazil

Considering the increasing popularity of reptiles as pets and their possible role as reservoirs of pathogenic microorganisms, the aim of this study was to isolate Escherichia coli, Salmonella spp., Clostridium perfringens, and C. difficile strains from reptiles in Brazil and to characterize the isolated strains. The characterization was based on phylogenetic typing of E. coli, identification of virulence genes of E. coli, C. perfringens, and C. difficile, serotyping of Salmonella spp., ribotyping and MLST of C. difficile and antimicrobial susceptibility test of pathogenic strains. Cloacal swabs were collected from 76 reptiles, of which 15 were lizards, 16 chelonians, and 45 snakes, either living in captivity, in the wild, or as companion animals. E. coli was isolated from 52 (68.4%) reptiles, of which 46 (88.4%) were characterized as phylogroup B1. The virulence factor CNF1 of E. coli was found in seven (9.2%) sampled animals, whereas the gene of EAST1 was found in isolates from two (2.6%) reptiles. Three isolates positive for CNF1 were resistant to cephalothin, one of which was also resistant to ciprofloxacin, trimethoprim/sulfamethoxazole, and chloramphenicol, being then classified as multidrug resistant strain (MDR). Salmonella enterica was identified in 26 (34.2%) reptiles, of which 13 belonged to the subspecies enterica. Serotypes such as S. Mbandaka, S. Panama, S. Infantis, S. Heidelberg, and S. Anatum were identified. One isolate of S. enterica subsp. houtenae was resistant to cephalothin and ciprofloxacin. C. perfringens type A was isolated from six (7.8%) animals. C. difficile was isolated from three (3.9%) reptiles. Two of these isolates were toxigenic and classified into ribotypes/MLST 081/ST9 and 106/ST42, which have been previously reported to infect humans. In conclusion, reptiles in Brazil can harbor toxigenic C. difficile and potentially pathogenic E. coli and Salmonella enterica subsp. enterica, thus representing a risk to human and animal health.

Recent progress in electrochemical biosensors as point of care diagnostics in livestock health

Livestock are critical component for supporting the sustainable agriculture in the current global scenario. In the era of artificial intelligence and automation in field of livestock, sensors play an important role. Electrochemical sensor is the type of sensor which holds reliability and tremendous promise in raising the animal productivity in developing world. An early and accurate diagnosis of the animal pathogen and metabolic status are the cornerstone for better animal productivity. The available diagnostic techniques require tedious sample preparation, sophisticated instrument, dedicated laboratory, trained personnel and it is time consuming also. The electrochemical biosensor technology might be a smart solution because of its sensitivity, simplicity, low cost, possible miniaturization and potential ability for real-time analysis. In the veterinary disease diagnostics, various biosensors including electrochemical biosensors have been developed recently, based on disease specific biomarkers. The main focus of article is on reviewing the research in detection of animal infectious and metabolic diseases, hormonal analysis and sweat analysis with electrochemical biosensor.

Isolation of Clostridium perfringens and C. difficile in crab-eating fox ( Cerdocyon thous - Linnaeus 1776) from Northeastern Brazil

ABSTRACT The aim of the present study was to isolate Clostridium perfringens and C. difficile in crab-eating fox (Cerdocyon thous) from Northeastern Brazil. Stool samples of 18 captive crab-eating foxes from four states of Northeastern Brazil (Alagoas, Bahia, Paraíba e Pernambuco) were collected and subjected to C. perfringens and C. difficile isolation. Suggestive colonies of C. perfringens were then analyzed for genes encoding the major C. perfringens toxins (alpha, beta, epsilon and iota), beta-2 toxin (cpb2), enterotoxin (cpe), and NetB- (netB) and NetF- (netF) encoding genes. C. difficile strains were analyzed by multiplex-PCR for a housekeeping gene (tpi), toxins A (tcdA) and B (tcdB) and a binary toxin gene (cdtB). Unthawed aliquots of stool samples positive for toxigenic C. difficile were subjected to a commercial ELISA to evaluate the presence of A/B toxins. Clostridium perfringens (type A) was isolated from five (27%) samples, and only one sample was positive for beta-2 enconding gene (cpb2). Two (11%) stool samples were positive for C. difficile, but negative for A/B toxins. These two wild canids were also positive for C. perfringens type A. This is the first report of C. difficile in crab-eating fox.

Prevalence, toxin gene profile, antibiotic resistance, and molecular characterization of Clostridium perfringens from diarrheic and non-diarrheic dogs in Korea

Clostridium perfringens causes diarrhea and other diseases in animals and humans. We investigated the prevalence, toxin gene profiles, and antibiotic resistance of C. perfringens isolated from diarrheic dogs (DD) and non-diarrheic dogs (ND) in two animal hospitals in Seoul, Korea. Fecal samples were collected from clinically DD (n = 49) and ND (n = 34). C. perfringens was isolated from 31 of 49 DD (63.3%) and 21 of 34 ND dogs (61.8%). All C. perfringens strains were positive for the α toxin gene, but not for the β, ε, or ι toxin genes; therefore, all strains were identified as type A C. perfringens. All isolates were cpe-negative, whereas the β2 toxin gene was identified in 83.9% and 61.9% of isolates from DD and ND, respectively. Most isolates were susceptible to ampicillin (94%), chloramphenicol (92%), metronidazole (100%), moxifloxacin (96%), and imipenem (100%). However, 25.0% and 21.2% of isolates were resistant to tetracycline and clindamycin, respectively. Molecular subtyping of the isolated strains was performed by using pulsed-field gel electrophoresis. Fifty-two isolates were classified into 48 pulsotypes based on more than 90% similarity of banding patterns. No notable differences were observed among the isolates from DD and ND.

Collaborating genomic, transcriptomic and microbiomic alterations lead to canine extreme intestinal polyposis

Extreme intestinal polyposis in pet dogs has not yet been reported in literature. We identified a dog patient who developed numerous intestinal polyps, with the severity resembling human classic familial adenomatous polyposis (FAP), except the jejunum-ileum junction being the most polyp-dense. We investigated this dog, in comparison with 22 other dogs with spontaneous intestinal tumors but no severe polyposis, and with numerous published human cancers. We found, not APC mutation, but three other alteration pathways as likely reasons of this canine extreme polyposis. First, somatic truncation mutation W411X of FBXW7, a component of an E3 ubiquitin ligase, over-activates MYC and cell cycle-promoting network, accelerating crypt cell proliferation. Second, genes of protein trafficking and localization are downregulated, likely associated with germline mutation G406D of STAMBPL1, a K63-deubiquitinase, and MYC network activation. This inhibits epithelial apical-basolateral polarity establishment, preventing crypt cell differentiation. Third, Bacteroides uniformis, a commensal gut anaerobe, thrives and expresses abundantly thioredoxin and nitroreductase. These bacterial products could reduce oxidative stress linked to host germline mutation R51X of CYB5RL, a cytochrome b5 reductase homologue, decreasing cell death. Our work emphasizes the close collaboration of alterations across the genome, transcriptome and microbiome in promoting tumorigenesis.

Pulsed-field gel electrophoresis of enterotoxic Clostridium perfringens type A isolates recovered from humans and animals in Kolkata, India

Clostridium perfringens is one of the most important globally recognised gastroenteric pathogen in humans as well as animals. The present study was aimed to know the similarities/divergence among C. perfringens type A isolates of human and animal origin using the pulsed-field gel electrophoresis (PFGE) as a molecular tool. The enterotoxic isolates obtained by screening of human diarrhoeal cases (n = 130), diarrhoeal cases of pig (n = 52) and goat (n = 50), meat samples viz., pork (n = 59) and chevon (n = 57) were characterized by standard cultural and biochemical methods followed by PCR Assays. Accordingly, a total of 11 C. perfringens type A characterized isolates (16S rRNA+, cpa+, cpb2+ and cpe+) recovered from human diarrhoeal cases (n = 3); diarrhoeal cases of pig (n = 2) and goat (n = 2); meat samples viz. pork (n = 2) and chevon (n = 2) were examined employing PFGE. The observed clustering pattern in PFGE analysis showed the relatedness between isolates from diarrhoeal goat and chevon (90-100%); diarrhoeal pig and pork (65-68%); moreover, isolates from human diarrhoeal cases were exhibiting lineage to cases from goat and pig diarrhoea as well pork and chevon by 62-68% relatedness. The outcome of the present study indicates the probable contamination of this pathogen to the human food chain through faeces from suspected food animals viz. goat and pig and their improperly cooked meat.

Prevalence of enteropathogens in cats with and without diarrhea in four different management models for unowned cats in the southeast United States

•

Most cats in shelters, sanctuaries, foster homes, and trap-neuter-return programs carried at least one enteropathogen.

•

Tritrichomonas foetus and coronavirus were more common in cats with diarrhea.

•

Other bacterial, viral, protozoal, and helminth enteropathogens were present in cats with normal feces and diarrhea.

The objective of this study was to determine the prevalence of enteropathogens in cats with and without diarrhea in four different models for managing unowned cats: short-term animal shelter, long-term sanctuary, home-based foster care, and trap-neuter-return. Fecal samples from 482 cats, approximately half of the cats with normal fecal consistency and half with diarrhea, were tested by zinc sulfate centrifugation and by real-time PCR for a panel of enteropathogens.

At least one enteropathogen of feline or zoonotic importance was detected in a majority of cats, regardless of management model. For most enteropathogens, the presence or absence of diarrhea was not significantly associated with infection, the exceptions being Tritrichomonas foetus in sanctuary cats with diarrhea (26%) and normal fecal consistency (10%), respectively (P ≤ 0.04), and feline coronavirus in foster cats (80% and 58%) (P ≤ 0.001). The types of enteropathogens detected were related to the type of management model, e.g., viral and protozoal infections were most common in shelters, sanctuaries, and foster homes (confinement systems), whereas helminth infections were most common in trap-neuter-return programs (free-roaming cats).

These results suggest that management practices for unowned cats are inadequate for control of enteropathogens and that the presence of diarrhea is a poor indicator of enteropathogen carriage. Risk-management strategies to reduce transmission to people and other animals should focus on sanitation, housing, compliance with preventive care guidelines, periodic surveillance, response to specific enteropathogens, humane population management of free-roaming community cats, public health education, and minimizing the duration and number of cats in mass confinement.

Spatial Organization of the Gastrointestinal Microbiota in Urban Canada Geese

Recent reviews identified the reliance on fecal or cloacal samples as a significant limitation hindering our understanding of the avian gastrointestinal (gut) microbiota and its function. We investigated the microbiota of the esophagus, duodenum, cecum, and colon of a wild urban population of Canada goose (Branta canadensis). From a population sample of 30 individuals, we sequenced the V4 region of the 16S SSU rRNA on an Illumina MiSeq and obtained 8,628,751 sequences with a median of 76,529 per sample. These sequences were assigned to 420 bacterial OTUs and a single archaeon. Firmicutes, Proteobacteria, and Bacteroidetes accounted for 90% of all sequences. Microbiotas from the four gut regions differed significantly in their richness, composition, and variability among individuals. Microbial communities of the esophagus were the most distinctive whereas those of the colon were the least distinctive, reflecting the physical downstream mixing of regional microbiotas. The downstream mixing of regional microbiotas was also responsible for the majority of observed co-occurrence patterns among microbial families. Our results indicate that fecal and cloacal samples inadequately represent the complex patterns of richness, composition, and variability of the gut microbiota and obscure patterns of co-occurrence of microbial lineages.

The incidence of Clostridioides difficile and Clostridium perfringens netF-positive strains in diarrheic dogs

The aim of this study was to examine the incidence of Clostridioides (previously Clostridium) difficile and Clostridium perfringens in the feces of diarrheic and non-diarrheic dogs. Also, the presence of other common canine enteropathogens was examined. Toxigenic C. difficile and C. perfringens positive for the NetF-encoding gene (netF) were detected in 11 (11.9%) and seven (7.6%) diarrheic dogs, respectively. Three dogs were diagnosed simultaneously with toxigenic C. difficile and netF-positive C. perfringens. Among other enteropathogens, Giardia sp. was the most common agent detected in dogs positive for toxigenic C. difficile or netF-positive C. perfringens. The results suggest that C. difficile and C. perfringens occur more frequently as a primary cause of diarrhea.

Identification and Antimicrobial Susceptibility Testing of Anaerobic Bacteria: Rubik's Cube of Clinical Microbiology?

Anaerobic bacteria have pivotal roles in the microbiota of humans and they are significant infectious agents involved in many pathological processes, both in immunocompetent and immunocompromised individuals. Their isolation, cultivation and correct identification differs significantly from the workup of aerobic species, although the use of new technologies (e.g., matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, whole genome sequencing) changed anaerobic diagnostics dramatically. In the past, antimicrobial susceptibility of these microorganisms showed predictable patterns and empirical therapy could be safely administered but recently a steady and clear increase in the resistance for several important drugs (β-lactams, clindamycin) has been observed worldwide. For this reason, antimicrobial susceptibility testing of anaerobic isolates for surveillance purposes or otherwise is of paramount importance but the availability of these testing methods is usually limited. In this present review, our aim was to give an overview of the methods currently available for the identification (using phenotypic characteristics, biochemical testing, gas-liquid chromatography, MALDI-TOF MS and WGS) and antimicrobial susceptibility testing (agar dilution, broth microdilution, disk diffusion, gradient tests, automated systems, phenotypic and molecular resistance detection techniques) of anaerobes, when should these methods be used and what are the recent developments in resistance patterns of anaerobic bacteria.

Highly suspected cases of salmonellosis in two cats fed with a commercial raw meat-based diet: health risks to animals and zoonotic implications

BACKGROUND

Feeding raw meat-based diets (RMBD) to companion animals raises public health concerns for both animals and humans. While considerable attention has been paid to bacterial contamination of commercial pet food, few literature studies have investigated foodborne disease in companion animals. Salmonellosis is reported to be infrequent in cats but no known data or studies estimating feline salmonellosis are available or large-scale epidemiological studies assessing Salmonella risk factors.

CASE PRESENTATION

Two highly suspected cases of salmonellosis in two cats fed with a commercial frozen poultry RMBD are presented, for the first time from the same household. The clinical presentation, diagnostics, treatment and follow-up are reported and the zoonotic implications are discussed.

CONCLUSIONS

This case highlights the health risks posed to both animals and owners by feeding RMBD to pets, and suggests that these risks should be considered by veterinary practitioners.

Clostridium perfringens and C. difficile in parvovirus-positive dogs

The aim of this study was to investigate Clostridium difficile and Clostridium perfringens in 82 diarrheic dogs positive for canine parvovirus type 2 (CPV). Enterotoxigenic C. perfringens type A was isolated from three (3.6%) dogs. One (1.2%) strain was also positive for NetE- and NetF-encoding genes, which are commonly associated with diarrhea in dogs. Toxigenic C. difficile was isolated from one animal (1.2%), which was also positive for A/B toxins. The present study identified C. difficile and C. perfringens infection in CPV-positive dogs. Further studies are necessary to clarify if clostridial infections may predispose or potentiate CPV-infection in dogs or vice versa.

•

The co-infection of canine parvovirus (CPV) and toxigenic clostridia is still poorly understood.

•

82 CPV-positive dogs were tested for C. perfringens netF+ and C. difficile infection (CDI).

•

C. perfringens type A positive for NetF-encoding gene (netF) was recovered from an adult dog (1.2%).

•

C. difficile was isolated from ten 12.2% (10/82) dogs, but in only one CDI was confirmed.

•

To our knowledge, this is the first study that report C. perfringen netF positive in CPV-positive dogs.

Prevalence and characteristics of Clostridium perfringens and Clostridium difficile in dogs and cats attended in diverse veterinary clinics from the Madrid region

Despite extensive research on the epidemiology of pathogenic clostridia in dogs and cats, most published studies focus on a selected animal population and/or a single veterinary medical centre. We assessed the burden of Clostridium perfringens and C. difficile shedding by small animals in 17 veterinary clinics located within the Madrid region (Spain) and differing in size, number and features of animals attended and other relevant characteristics. In addition, we studied the genetic diversity and antibiotic susceptibility of recovered isolates. Selective culture of all fecal specimens collected during a single week from dogs (n = 105) and cats (n = 37) attended in participating clinics yielded C. perfringens/C. difficile from 31%, 4.8% of the dogs, and 20%, 0% of the cats analyzed, respectively, and three dogs yielded both species. Furthermore, 17 animals (15 dogs and two cats) that yielded a positive culture for either species were recruited for a follow-up survey and C. perfringens was again obtained from nine dogs. Considerable differences in prevalence were observed among participating clinics for both clostridial species. C. perfringens isolates (n = 109) belonged to toxinotypes A (97.2%) and E (three isolates from one dog), whereas C. difficile isolates (n = 18) belonged to the toxigenic ribotypes 106 (33.3%) and 154 (16.7%), a 009-like ribotype (33.3%) and an unknown non-toxigenic ribotype (16.7%). Amplified fragment length polymorphism-based fingerprinting classified C. perfringens and C. difficile isolates into 105 and 15 genotypes, respectively, and tested isolates displayed in vitro resistance to benzylpenicillin (2.8%, 88.8%), clindamycin (0%, 16.7%), erythromycin (0.9%, 16.7%), imipenem (1.8%, 100%), levofloxacin (0.9%, 100%), linezolid (5.5%, 0%), metronidazole (4.6%, 0%) and/or tetracycline (7.3%, 0%). All animals from which multiple isolates were retrieved yielded ≥2 different genotypes and/or antimicrobial susceptibility profiles. Future studies should focus on the seasonal and geographical variations of prevalence and diversity patterns of clostridial species in small animals.

In vitro and in vivo antagonistic activity of new probiotic culture against Clostridium difficile and Clostridium perfringens

BACKGROUND

Genus Clostridium accompanies more than 200 known species and at least 30 among them are associated with human and animal diseases. At the moment, the treatment of clostridial infections is based on use of antibiotics. However, due to the European ban on the use of antibiotics in livestock production, novel therapeutic strategies for treatment of these hardly curable infections have been evaluated. Hence, in this study the antimicrobial effect of newly designed probiotic culture consisted of natural isolates Lactobacillus helveticus BGRA43, Lactobacillus fermentum BGHI14 and Streptococcus thermophilus BGVLJ1-44 against Clostridium difficile and Clostridium perfringens was analyzed.

RESULTS

The probiotic culture showed strong in vitro antimicrobial effect on C. difficile (human clinical isolate). In addition, individual strains and the probiotic combination exhibited immunomodulatory activity. The probiotic combination significantly increased the proliferation of GALT lymphocytes. At the other hand, none of the bacterial treatments (individual strains and the combination) induced the production of proinflammatory cytokines IL-6 and IL-1β by intestinal epithelial cells, Caco-2. Interestingly, Caco-2 cells exposed to the probiotic combination produced significantly elevated amount of TGFβ pointing to potential protecting effect of the probiotic. In addition, the results of field trial on spontaneously infected goats revealed reduction of C. perfringens in goats (below the detection threshold) after the probiotic treatment.

CONCLUSIONS

The results of this study indicated that the novel probiotic deserves to be further investigated as a promising antimicrobial agent against C. difficile and C. perfringens.

Metataxonomics reveal vultures as a reservoir for Clostridium perfringens

The Old World vulture may carry and spread pathogens for emerging infections since they feed on the carcasses of dead animals and participate in the sky burials of humans, some of whom have died from communicable diseases. Therefore, we studied the precise fecal microbiome of the Old World vulture with metataxonomics, integrating the high-throughput sequencing of almost full-length small subunit ribosomal RNA (16S rRNA) gene amplicons in tandem with the operational phylogenetic unit (OPU) analysis strategy. Nine vultures of three species were sampled using rectal swabs on the Qinghai-Tibet Plateau, China. Using the Pacific Biosciences sequencing platform, we obtained 54 135 high-quality reads of 16S rRNA amplicons with an average of 1442±6.9 bp in length and 6015±1058 reads per vulture. Those sequences were classified into 314 OPUs, including 102 known species, 50 yet to be described species and 161 unknown new lineages of uncultured representatives. Forty-five species have been reported to be responsible for human outbreaks or infections, and 23 yet to be described species belong to genera that include pathogenic species. Only six species were common to all vultures. Clostridium perfringens was the most abundant and present in all vultures, accounting for 30.8% of the total reads. Therefore, using the new technology, we found that vultures are an important reservoir for C. perfringens as evidenced by the isolation of 107 strains encoding for virulence genes, representing 45 sequence types. Our study suggests that the soil-related C. perfringens and other pathogens could have a reservoir in vultures and other animals.

Water Sources in a Zoological Park Harbor Genetically Diverse Strains of Clostridium Perfringens Type A with Decreased Susceptibility to Metronidazole

The presence of Clostridium perfringens in water is generally regarded as an indicator of fecal contamination, and exposure to waterborne spores is considered a possible source of infection for animals. We assessed the presence and genetic diversity of C. perfringens in water sources in a zoological park located in Madrid (Spain). A total of 48 water samples from 24 different sources were analyzed, and recovered isolates were toxinotyped, genotyped by fluorophore-enhanced repetitive polymerase chain reaction (rep-PCR) fingerprinting and tested for antimicrobial susceptibility. C. perfringens was recovered from 43.8 % of water samples and 50 % of water sources analyzed. All isolates (n = 70) were type A and 42.9 % were β2-toxigenic (i.e., cpb2+), but none contained the enterotoxin-encoding gene (cpe). Isolates belonged to 15 rep-PCR genotypes and most genetic diversity (88 %) was distributed among isolates obtained from the same sample. Most isolates displayed intermediate susceptibility (57.1 %; MIC = 16 μg ml^-1) or resistance (5.7 %; MIC ≥ 32 μg ml^-1) to metronidazole. No resistance to other antimicrobials was detected, although some isolates showed elevated MICs to erythromycin and/or linezolid. Finally, a marginally significant association between absence of cpb2 and decreased susceptibility to metronidazole (MIC ≥ 16 μg ml^-1) was detected. In conclusion, our results reveal a high prevalence of C. perfringens type A in the studied water reservoirs, which constitutes a health risk for zoo animals. The elevated MICs to metronidazole observed for genetically diverse isolates is a cause of additional concern, but more work is required to clarify the significance of reduced metronidazole susceptibility in environmental strains.

Acute necrotizing colitis with pneumatosis intestinalis in an Amazonian manatee calf

On 25 January 2014, a 1 mo old female Amazonian manatee Trichechus inunguis calf weighing 12 kg was rescued by air transport in Guajará, Brazil, and transferred to Mamirauá Institute's Community-based Amazonian Manatee Rehabilitation Center. The calf presented piercing/cutting lesions on the back, neck, and head, in addition to dehydration and intermittent involuntary buoyancy. X-ray analysis revealed a large amount of gases in the gastrointestinal tract. Daily procedures included wound cleaning and dressing, clinical and laboratory monitoring, treatment for intestinal tympanism, and artificial feeding. Adaptation to the nursing formula included 2 kinds of whole milk. Up to 20 d post-rescue the calf presented appetite, was active, and gained weight progressively. Past this period the calf started losing weight and presented constant involuntary buoyancy and died after 41 d in rehabilitation. The major findings at necropsy were pneumatosis intestinalis in cecum and colon, pulmonary edema, and hepatomegaly. The microscopic examination revealed pyogranulomatous and necrohemohrragic colitis with multinucleated giant cells, acute multifocal lymphadenitis with lymphoid depletion in cortical and paramedullary regions of mesenteric lymph nodes, and diffuse severe acinar atrophy of the pancreas. Anaerobic cultures of fragments of cecum and colon revealed colonies genotyped as Clostridium perfringens type A. We speculate that compromised immunity, thermoregulatory failure, and intolerance to artificial diet may have been contributing factors to the infection, leading to enterotoxemia and death.

Clostridium perfringens type A netF and netE positive and Clostridium difficile co-infection in two adult dogs

The aim of this study was to report two cases of Clostridium perfringens type A and Clostridium difficile co-infection in adult dogs. Both animals were positive for A/B toxin. Toxigenic C. difficile and C. perfringens type A positive for NetE and NetF-encoding genes were isolated. This report reinforces the necessity of studying a possible synergism of C. difficile and C. perfringens in enteric disorders.