The industrial processing of broiler chickens has become increasingly automated to scale up meat production. However, certain procedures may cause rupture of the gastrointestinal tract, contaminating the products. The objective of this study was to evaluate the efficiency of the removal of visible contaminated broiler carcasses from the slaughter line based on their microbiological quality compared to non-contaminated ones. Carcasses were analyzed for Escherichia coli and aerobic mesophilic microorganisms counts, as well as Salmonella spp. detection. Carcasses with gastrointestinal contamination had significantly higher counts of aerobic mesophilic microorganisms and E. coli than those without contamination. However, carcasses without visible contamination also showed high counts of bacteria, indicative of the hygiene and sanitary concerns during slaughter. Salmonella spp. were detected in both types of carcasses, with no significant difference in the frequency of positive samples. The most frequently identified serovar was Salmonella Minnesota. The most frequently detected bacteria were E. coli, Klebsiella pneumoniae, Citrobacter freundii, and Pseudomonas aeruginosa. In conclusion, both contaminated and non-contaminated carcasses exhibited high bacterial counts, including potentially pathogenic microorganisms, highlighting the need for post-evisceration steps to reduce microbial contamination.

Salmonella Dublin is a serovar that causes severe infections and cattle. Despite the importance of this agent, research on achieving its elimination from dairy farms is limited, which complicates risk mitigation and control efforts. This study thus aimed to assess the prevalence of S. Dublin on a farm with a history of outbreaks, to understand the dynamics of the infection, characterize the antimicrobial resistance of the isolates, and evaluate their genetic similarity. Multiparous cows in the postpartum phase are nearly five times more likely to shed Salmonella sp. A total of 39 cases of fatal septicemic salmonellosis caused by S. Dublin were confirmed in calves aged 3–5 months. Antimicrobial susceptibility was evaluated in 45 strains of S. Dublin, with 48.9% of the isolates classified as multidrug resistant, including resistance to penicillin (48.9%), tetracyclines (42.2%), and fluoroquinolones (33.3%). Seven multidrug-resistant isolates were selected for genomic sequencing. Among the resistance determinants identified, a mutation in the gyrA gene, present in all sequenced isolates, was notable. Analyses of cgMLST and SNPs revealed that the isolates from healthy animals were closely related to those found in animals with confirmed cases of S. Dublin, confirming that the agent was circulating among healthy animals across various categories. A high similarity was also found between the isolates in this study and strains causing salmonellosis in humans in Brazil, thus reinforcing the zoonotic nature and possible epidemiological link between cattle, and the occurrence of this disease in humans.

Salmonella enterica serotype Dublin is a major concern for livestock, particularly due to its high morbidity and mortality rates in cattle herds. In Brazil, limited research has explored the epidemiology of this serovar, including outbreak characterization, antimicrobial susceptibility profiles, and genetic similarity of isolates. This study aimed to describe the clinical and epidemiological features of confirmed S. Dublin outbreaks across multiple Brazilian cattle herds, as well as to assess antimicrobial resistance profiles, identify resistance genes, and evaluate genetic similarity among isolates. Between 2018 and 2025, S. Dublin outbreaks were confirmed on 19 farms, most of which (84.2%) were dairy facilities involving calves. In 57.9% of the outbreaks, calves aged 90–180 days were affected. Notably, 68.4% of the farms reported S. Dublin outbreaks following or coinciding with an increase in cases of bovine tick fever (babesiosis and/or anaplasmosis). The majority of isolates (79.5%) were resistant to at least one antimicrobial, and 20.5% were classified as multidrug-resistant. Among the resistance determinants identified, a point mutation in gyrA, detected in more than a quarter of the sequenced isolates, was particularly notable. Single-nucleotide polymorphism (SNP) and core genome multilocus sequence typing (cgMLST) analyses revealed marked genetic similarity among isolates from related outbreaks, highlighting the risk of introducing S. Dublin through the purchase of untested animals. A high similarity was also observed between outbreak isolates and strains previously associated with human infections in Brazil, underscoring the zoonotic potential of S. Dublin. IMPORTANCE: Salmonella Dublin is a cattle-adapted serovar capable of causing disease and substantial economic losses in the livestock sector. In humans, this serotype is also associated with serious illness and has the highest reported fatality rate among Salmonella enterica serotypes. In this study, we aimed to describe 19 outbreaks of S. Dublin in cattle herds and to characterize the clinical and epidemiological features of the disease in cattle, given the scarcity of information in the literature. Alongside this, we sequenced at least one isolate per farm to investigate antimicrobial resistance genes, mobile genetic elements, and the similarity between our strains and those from bovine and human sources in Brazil and elsewhere. Overall, this is the first study to assess the clinical aspects of S. Dublin in cattle herds from tropical regions, accompanied by the antimicrobial profiles of these isolates and their genomic relatedness to strains isolated from human clinical infections.

Background/Objectives: Antimicrobial resistance is a major global health threat. Among the most problematic pathogens are carbapenem-resistant Acinetobacter baumannii and Klebsiella pneumoniae, which are significant causes of mortality in humans, particularly in the context of nosocomial infections. In companion animals, these bacteria have been reported mainly as colonizers of healthy animals or, less frequently, in community-acquired infections. However, no confirmed cases of healthcare-associated infections caused by these species have been documented in this population. This study reports the first confirmed fatal cases of infection with carbapenem-resistant A. baumannii and KPC-producing K. pneumoniae in dogs. Methods: Three hospitalized dogs developed infections associated with distinct anatomical devices, including a venous catheter, an endotracheal tube, and a Penrose drain. Bacterial isolation followed by antimicrobial susceptibility testing identified carbapenem-resistant A. baumannii and K. pneumoniae. The isolates were subsequently subjected to additional antimicrobial resistance tests and whole-genome sequencing (WGS). Results: WGS confirmed the presence of the OXA-23 carbapenemase gene in both A. baumannii isolates and the KPC-2 carbapenemase gene was detected in the K. pneumoniae strain. All three strains exhibited resistance to multiple antimicrobial classes, including β-lactams (amoxicillin-clavulanic acid, ampicillin, cephalotin, piperacillin-tazobactam, cefoxitin, ceftiofur, cefotaxime, ertapenem, imipenem and meropenem), aminoglycosides (gentamicin, neomycin), tetracyclines (doxycycline, tetracycline and oxytetracycline), fluoroquinolones (ciprofloxacin, enrofloxacin), and folate pathway antagonists (trimethoprim-sulfamethoxazole). Multilocus sequence typing identified two high-risk clones: K. pneumoniae ST340 (CC258) and A. baumannii ST15 (CC15). Single nucleotide polymorphism analysis confirmed a high degree of genetic similarity between these isolates and strains previously associated with human infections in Brazil. Conclusions: These findings provide the first evidence of fatal, healthcare-associated infections caused by these multidrug-resistant pathogens in dogs and underscore the need to strengthen surveillance and infection control practices in veterinary hospitals. Furthermore, the results raise concerns about the potential of companion animals to act as reservoirs for multidrug-resistant organisms of public health relevance.

Clostridioides difficile is a strictly anaerobic, spore-forming Gram-positive bacterium associated with diarrhea, known as C. difficile infection (CDI). In domestic animals, C. difficile is considered an important pathogen mostly in pigs and horses, but there are also reports in other domestic species. In wild animals, the epidemiology of C. difficile is largely unknown, and the role of the bacterium as a cause of diarrhea is unclear. The aim of this study was to determine the prevalence of C. difficile in the feces of wild animals referred to the Center of Medicine and Research in Wild Animals (CEMPAS). Fecal samples obtained from 100 animals of 34 different species were subjected to qPCR for the detection of the C. difficile 16S rRNA gene and two major toxin genes (tcdA and tcdB) and to anaerobic bacterial isolation. A total of 63 animals (63%) were positive for C. difficile by qPCR, and 16 isolates were recovered. The opossum (Didelphis spp.) had the highest number of positive animals in both tests (from 21 samples, 19 were qPCR positive, and four isolates were recovered). Three toxigenic strains (RT 002, 004, and 014), all previously described as infecting humans and animals, were isolated in the following species: bearded dragon (Pogona vitticeps), pampas fox (Lycalopex vetulus), and marmoset (Callithrix sp.). The presence of C. difficile in the feces of wild animals highlights the importance of wildlife as potential carriers of infection for production animals or humans.

Pyometra is the most common reproductive disease in female dogs, characterized by the accumulation of purulent content in the uterus. Its etiology is multifactorial, primarily involving hormonal and bacterial factors, with Escherichia coli being the most frequently isolated pathogen. International guidelines recommend bacterial culture and antimicrobial susceptibility testing of uterine content before or, if not feasible, after ovariohysterectomy. However, due to the time required to perform these tests, empirical antibiotic therapy is commonly prescribed, potentially contributing to antimicrobial resistance and treatment failure. Given that E. coli causing pyometra often originates from the intestinal microbiota, we hypothesized that isolates from rectal swabs could serve as predictors of the antimicrobial resistance profile of the E. coli causing pyometra. To evaluate this possibility, this study assessed the antimicrobial susceptibility of E. coli isolates from the uterine content and rectal swabs of bitches with pyometra and evaluated whether there is an association between the resistance profiles at these two sites. Samples from 72 dogs diagnosed with pyometra were collected for bacterial culture and antimicrobial susceptibility testing. E. coli was identified in 40 uterine content samples (55.6%) and 59 rectal swabs (81.9%) using species-specific PCR. E. coli isolates from rectal swabs exhibited higher resistance rates to commonly used antibiotics for pyometra treatment, including amoxicillin/clavulanic acid, ampicillin, enrofloxacin, and doxycycline (P < 0.05). The presence of susceptible isolates in rectal swabs is strongly associated with susceptibility in uterine isolates, yielding a positive predictive value up to 100%. These findings suggested that rectal swab isolates could serve as a reliable predictor of uterine E. coli susceptibility, providing a rapid and non-invasive tool to guide antimicrobial selection for pyometra treatment.