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

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.

Evaluation of disk diffusion method for testing the rifampicin, erythromycin, and tetracycline susceptibility of Clostridioides (prev. Clostridium) difficile

INTRODUCTION

Antimicrobial resistance (AMR) is one of the greatest threats to animal and public health. Clostridioides (prev. Clostridium) difficile is a major burden to healthcare and a relevant AMR gene reservoir. Despite the known importance of AMR in C. difficile epidemiology and treatment, antimicrobial susceptibility testing for this pathogen is still based on the determination of the minimal inhibitory concentration (MIC) by the agar dilution method, which is technically demanding and labor-intensive. In this study, the disk diffusion method was used to evaluate the susceptibility of C. difficile to erythromycin, rifampicin, and tetracycline.

MATERIAL AND METHODS

A total of 155 isolates isolated between 2011 and 2022 from humans and animals in Brazil were simultaneously tested using the disk diffusion method and the epsilometer test (Etest) for these three antimicrobials on Brucella blood agar supplemented with vitamin K and hemin.

RESULTS

The results suggest that disk diffusion can be an interesting routine tool to identify erythromycin- and rifampicin-resistant C. difficile isolates (≥20 mm cut-off) and wild type (WT) strains (≥28 mm). However, the disk diffusion protocol tested in this study does not seem suitable for tetracycline because of the common misclassification of resistant strains.

Molecular epidemiology of Clostridioides difficile in companion animals: Genetic overlap with human strains and public health concerns

Introduction

The changing epidemiology of Clostridioides difficile reflects a well-established and intricate community transmission network. With rising numbers of reported community-acquired infections, recent studies tried to identify the role played by non-human reservoirs in the pathogen's transmission chain. This study aimed at describing the C. difficile strains circulating in canine and feline populations, and to evaluate their genetic overlap with human strains to assess the possibility of interspecies transmission.

Methods

Fecal samples from dogs (n = 335) and cats (n = 140) were collected from two populations (group A and group B) in Portugal. C. difficile isolates were characterized for toxigenic profile and PCR-ribotyping. The presence of genetic determinants of antimicrobial resistance was assessed in all phenotypically resistant isolates. To evaluate the genetic overlap between companion animals and human isolates from Portugal, RT106 (n = 42) and RT014/020 (n = 41) strains from both sources were subjected to whole genome sequencing and integrated with previously sequenced RT106 (n = 43) and RT014/020 (n = 142) genomes from different countries. The genetic overlap was assessed based on core-single nucleotide polymorphism (SNP) using a threshold of 2 SNP.

Results

The overall positivity rate for C. difficile was 26% (76/292) in group A and 18.6% (34/183) in group B. Toxigenic strains accounted for 50% (38/76) and 52.9% (18/34) of animal carriage rates, respectively. The most prevalent ribotypes (RT) were the toxigenic RT106 and RT014/020, and the non-toxigenic RT010 and RT009. Antimicrobial resistance was found for clindamycin (27.9%), metronidazole (17.1%) and moxifloxacin (12.4%), associated with the presence of the ermB gene, the pCD-METRO plasmid and point mutations in the gyrA gene, respectively. Both RT106 and RT014/020 genetic analysis revealed several clusters integrating isolates from animal and human sources, supporting the possibility of clonal interspecies transmission or a shared environmental contamination source.

Discussion

This study shows that companion animals may constitute a source of infection of toxigenic and antimicrobial resistant human associated C. difficile isolates. Additionally, it contributes with important data on the genetic proximity between C. difficile isolates from both sources, adding new information to guide future work on the role of animal reservoirs in the establishment of community associated transmission networks and alerting for potential public health risk.

Characterization of the virulence of three novel clade 2 Clostridioides (Clostridium) difficile strains and a two-year screening in animals and humans in Brazil

Clostridioides (Clostridium) difficile infection (CDI) is an evolving global healthcare problem, and owing to the diverse and dynamic molecular epidemiology of C. difficile, new strains continue to emerge. In Brazil, only two cases of CDI due to the so called hypervirulent PCR ribotype (RT) 027 belonging to clade 2 have ever been reported, whereas incidence of CDI due to another “hypervirulent” RT078 (clade 5) has not yet been reported. In contrast, novel clade 2 strains have been identified in different hospitals. To better understand the epidemiology of CDIs in Brazil, this study aimed to genotypically and phenotypically characterize three novel Brazilian clade 2 strains (RT883, 884, and 885) isolated from patients with confirmed CDI. In addition, to better understand the circulating RTs, a two-year sampling was conducted in patients from the same hospital and in several domestic and wild animal species. The three strains examined showed lower production of A/B toxins than the control RT027, although two of these strains harbored a truncated tcdC gene. All strains showed swimming motility similar to that of RT027, while RT883 showed higher spore production than the reference strain. In the in vivo hamster model, the lethality of all strains was found to be similar to that of RT027. Both cgMLST and cgMLSA analyses revealed a high genetic similarity among the three-novel clade 2 isolates. In the two-year survey in animals and humans, RT883, 884, and 885 were not detected; however, three new RTs (RT988, RT989, and RT990) were isolated, two of which were genetically related to the three previously reported clade 2 strains. RT106 and RT126 were most frequently detected in humans (47.9%) and animals (57.9%), respectively. Furthermore, RT027 and RT078 were not detected in humans. The results of this study suggest that these novel clade 2 strains have virulence potential and that new strains from clade 2 continue to emerge in our setting, indicating the need for long-term local surveillance.

Effect of Porcine Clostridium perfringens on Intestinal Barrier, Immunity, and Quantitative Analysis of Intestinal Bacterial Communities in Mice

Clostridium perfringens (C. perfringens) is one of the main pathogens which can cause a range of histotoxic and enteric diseases in humans or animals (pigs, or broilers). The Centers for Disease Control and Prevention (CDC) estimates these bacteria cause nearly 1 million illnesses in the United States every year. For animal husbandry, necrotizing enteritis caused by C. perfringens can cost the global livestock industry between $2 billion and $6 billion per year. C. perfringens-infected animals can be isolated for its identification and pathology. A suitable animal model is one of the essential conditions for studying the disease pathogenesis. In previous studies, mice have been used as subjects for a variety of Clostridium perfringens toxicity tests. Thus, this study was designed to build a mouse model infected porcine C. perfringens which was isolated from the C.perfringens-infected pigs. A total of 32 6-week-old male C57BL/6 mice were randomly divided into four groups. Control group was orally administrated with PBS (200 μL) on day 0. Low group, Medium group, and High group were gavaged with 200 ul of PBS resuspension containing 8.0 × 10⁷ CFU, 4.0 × 10⁸ CFU, and 2.0 × 10⁹ CFU, respectively. We examined growth performance, immune status, intestinal barrier integrity, apoptosis-related genes expression, and copies of C. perfringens in mice. The results showed that the growth performance declined and intestinal structure was seriously damaged in High group. Meanwhile, pro-inflammatory factors (IL-1β, TNF-α, and IL-6) were significantly increased (P < 0.05) in High group compared to other groups. The tight junctions and pro-apoptosis related genes' expression significantly decreased (P < 0.05) in High group, and high dose caused a disruption of intestinal villi integrity and tissue injury in the jejunum of mice. In addition, the enumerations of C. perfringens, Escherichia coli, and Lactobacillus explained why the gut of High group mice was seriously damaged, because the C. perfringens and Escherichia coli significantly enriched (P < 0.05), and Lactobacillus dramatically decreased (P < 0.05). Overall, our results provide an experimental and theoretical basis for understanding the pathogenesis and exploring the effects of porcine C. perfringens on mice.

Molecular Detection of Toxigenic Clostridioides difficile among Diarrheic Dogs and Cats: A Mounting Public Health Concern

Nowadays, pet animals are known to be asymptomatic carriers of Clostridioidesdifficile. This study was conducted to investigate the burden of toxigenic C. difficile among diarrheic dogs and cats using direct PCR on fecal samples to reveal better insights about the epidemiology of such toxigenic strains referring to its public health significance. For this purpose, fecal samples were obtained from 58 dogs and 42 cats experiencing diarrhea. Following DNA extraction, the extracted DNA was examined for the occurrence of C. difficile as well as toxigenic strains through the detection of C. difficile 16S rRNA and toxin encoding genes (tcdA, tcdB, cdtA and cdtB) using PCR. Moreover, partial DNA sequencing of toxigenic strains retrieved from dog and cat was carried out. Of 100 examined diarrheic animals, 90 (90%) were C. difficile positive, including 93.1% and 85.7% of dogs and cats, respectively. In addition, toxigenic strains were detected in 13 animals, giving an overall prevalence 13% with the following prevalence rates among dogs and cats 12.1% and 14.3%, respectively. Furthermore, the phylogenetic analysis of the obtained sequence revealed high genetic relatedness of tcdA sequence obtained from a cat to strains of human diarrheic cases to point out the public health threat of such sequence. In conclusion, the direct detection of toxigenic C. difficile using PCR among dogs and cats highlights the potential role of household pets as a source for such strains to human contacts.

Pathological features of hepatic portal venous gas in a cat

An 8-year 8-month-old castrated male Munchkin presented with vomiting, anorexia and hypoactivity. Computed tomography revealed excessive gas accumulation within the intestinal lumen and gas bubbles in the liver, spleen, and portal venous system, indicating hepatic portal venous gas. The cat died without any significant improvement, and mild splenomegaly was found at necropsy. Histologically, multiple gas vacuoles were diffusely observed in the liver and spleen. In the stomach, multiple gas vacuoles and scattered focal ulcers were detected within the mucosa. Multifocal hemorrhage was noted in the small and large intestines, whereas gas vacuoles were not present. Based on these findings, a gastric ulcer under high gas pressure may have provided an entry point for gas into the portal venous system.

Prevalence, Colonization, Epidemiology, and Public Health Significance of Clostridioides difficile in Companion Animals

Clostridioides difficile, previously Clostrdium difficile, is a major cause of antibiotic-associated enteric disease in humans in hospital settings. Increased incidence of C. difficile infection (CDI) in community settings raises concerns over an alternative source of CDI for humans. The detection of genetically similar and toxigenic C. difficile isolates in companion animals, including asymptomatic pets, suggests the potential role of household pets as a source of community-associated CDI. The close association between companion animals and humans, in addition to the use of similar antibiotics in both species, could provide a selective advantage for the emergence of new C. difficile strains and thus increase the incidental transmission of CDI to humans. Therefore, screening household pets for C. difficile is becoming increasingly important from a public health standpoint and may become a part of routine testing in the future, for the benefit of susceptible or infected individuals within a household. In this review, we analyze available information on prevalence, pathophysiology, epidemiology, and molecular genetics of C. difficile infection, focusing on companion animals and evaluate the risk of pet-borne transmission of CDI as an emerging public health concern. Molecular epidemiological characterization of companion animal C. difficile strains could provide further insights into the interspecies transmission of CDI. The mosaic nature of C. difficile genomes and their susceptibility to horizontal gene transfer may facilitate the inter-mixing of genetic material, which could increase the possibility of the emergence of new community-associated CDI strains. However, detailed genome-wide characterization and comparative genome analysis are warranted to confirm this hypothesis.