Dogs in Rio de Janeiro as reservoirs of Clostridioides difficile ribotypes causing CDI in humans.

INTRODUCTION: In the past decade, the incidence of community-acquired Clostridioides difficile infection (CA-CDI) has increased, suggesting a role for animal species in its spread. OBJECTIVE: This study aimed to isolate and characterize C. difficile strains from domestic dogs at veterinary clinics to enhance our understanding of C. difficile epidemiology in Rio de Janeiro. MATERIAL AND METHODS: For this study 90 stool samples from dogs were collected and cultured in a selective medium (Clostridioides difficile Brucella agar - CDBA) for isolation. Species were identified by MALDI-TOF MS, with confirmation provided by PCR targeting the tpi gene. The antibiotic susceptibility test of the strains was performed using five antibiotics: vancomycin, metronidazole, moxifloxacin, rifampicin, and erythromycin. Strains resistant to metronidazole were further analyzed for the presence of the plasmid pCD-METRO using PCR. The presence of toxin genes (tcdA, tcdB, and cdtB) was investigated, alongside ribotyping and tcdC sequencing analyses. The strains were also tested for biofilm formation and motility. RESULTS: C. difficile was isolated in 15.5% (14/90) of the samples. Among the strains analyzed, 87.71% (12/14) tested positive for both toxin genes A and B and belonged to ribotypes 106 (10/14) and 014/020 (2/14). The remaining 14.3% (2/14) were non-toxigenic and were identified as RT010. Regarding the antibiotic profile, 42.85% (6/14) of the strains exhibited resistance to at least one antibiotic, including vancomycin (1/14) and metronidazole (1/14). The metronidazole-resistant strain was also positive for the plasmid pCD-METRO. All strains exhibited both biofilm formation and motility. Among the 10 toxigenic strains sequenced for the tcdC gene, two exhibited a deletion in the same region as the epidemic strain, NAP1 (RT027). CONCLUSION: Our study found that C. difficile most of the ribotypes isolated from dogs are involved in cases of CDI in humans, and the prevalence was higher in dogs with diarrhea (p = 0.034). Although we could not confirm that diarrhea in these dogs was solely due to C. difficile, their colonization may represent a common transmission route for human C. difficile infections.

Colitis caused by Clostridioides difficile infection in a domestic dog: A case report.

Clostridioides difficile has been identified as one of the primary etiologic agents of nosocomial diarrhea and pseudomembranous colitis in humans and other mammals associated following broad-spectrum antibiotics use. In Rio de Janeiro, Brazil we describe a case of C. difficile infection (CDI) in a 13-year-old male dog.

Mercury concentration in the freshwater bonefish Cyphocharax gilbert (Curimatidae) and its parasite the crustacean Riggia paranensis (Cymothoidae)

Fish parasites can accumulate heavy metals reaching higher concentrations than the host and may affect the host's bioaccumulation. The present study compared total mercury concentration in the liver and muscle of Cyphocharax gilbert and in the parasite Riggia paranensis sampled in the middle Itabapoana River, Brazil, also considering the reproductive stages of both fish and parasite. Mean concentrations of mercury in muscle of fish varied from 20.8 ng.g-1 in mature females to 38.1 ng.g-1 in post-spawning females. The mean concentrations in fish liver varied from 60.9 ng/g in post-spawning females to 110.4 ng.g-1 in infested males. The mean concentration of mercury in parasites varied from 26.2 ng.g-1 in specimens carrying early embryo to 39.5 ng.g-1 in specimens with eggs. Positive and significant associations (P<0.05) were found between the total mercury concentrations in parasites and muscle of host (both females and males), and between concentrations in parasites and in the liver of male hosts. These results suggest that R. paranensis can be used to indicate mercury levels in edible parts of C. gilbert.

Parasitos de peixes podem acumular metais pesados em concentrações acima dos hospedeiros, podendo afetar a bioacumulação nestes. O presente estudo comparou a concentração total do mercúrio no fígado e no músculo de Cyphocharax gilbert e no parasito Riggia paranensis, coletados no trecho médio do rio Itabapoana, Brasil, considerando o estágio reprodutivo tanto dos peixes como dos parasitos. A concentração média do mercúrio nos músculos dos peixes variou entre 20,8 ng.g-1 nas fêmeas maturas e 38,1 ng.g-1 nas fêmeas desovadas. As concentrações médias nos fígados dos peixes variaram entre 60,9ng/g em fêmeas desovadas e 110,4 ng.g-1 em machos parasitados. Entre os parasitos, as concentrações médias de mercúrio variaram entre 26,2 ng.g-1 em espécimes com embriões iniciando o desenvolvimento to 39,5 ng.g-1 em espécimes com ovos . Associações positivas e significativas (P<0.05) foram encontradas entre as concentrações totais de mercúrio em parasitos e músculos dos hospedeiros (tanto em macho como em fêmeas) e entre as concentrações nos parasitos e os fígados dos hospedeiros machos. Estes resultados sugerem que o parasito R. paranensis pode ser utilizado como bioindicador dos níveis de mercúrio nas partes comestíveis de C. gilbert.