Pyometra, characterized by the accumulation of purulent exudate in the uterus, is the most prevalent reproductive disease in canines. While the disease often begins with mild local symptoms, it can escalate into peritonitis, sepsis, and multi-organ dysfunction, thereby posing a significant threat to life. Despite the high incidence and recognized significance of canine pyometra, gaps persist in our understanding of its epidemiology, etiology, and pathogenesis. Recent studies have, however, broadened our comprehension of this disease, shedding light on potential new infection sources, etiologies, and the application of clinical predictive biomarkers and new therapeutic protocols. This study aimed to review the current understanding of canine pyometra, with particular emphasis on the latest research concerning its etiology and epidemiology. Furthermore, it addressed key research questions and proposed directions for future investigations into various facets of canine pyometra.

Methicillin-resistant Staphylococci (MRS) cause infections at various sites and exhibit multidrug resistance. Despite their importance in veterinary medicine, only little is known about Staphylococcus spp. colonizing and infecting cats. Therefore, in this study, we aimed to isolate and identify Staphylococcus spp. colonizing hospitalized and non-hospitalized domestic cats and analyze their antimicrobial resistance profiles, genetic diversity, and risk factors associated with MRS colonization. A total of 218 oral and axillary swabs were obtained from 109 cats, including 77 non-hospitalized and 32 hospitalized cats. After plating on selective media, the isolates were identified via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and rpoB and 16S rRNA gene sequencing. Subsequently, antimicrobial sensitivity of the strains was assessed, and they were screened for mecA gene. Methicillin-resistant S. haemolyticus (MRSH) isolates were subjected to multilocus sequence typing, whereas methicillin-resistant S. pseudintermedius (MRSP) and S. felis isolates were subjected to whole genome sequencing. S. felis was most commonly isolated from non-hospitalized cats (28.1%), whereas S. pseudintermedius and MRS were commonly isolated from hospitalized cats (25%). MRSH isolates from hospitalized animals were classified as ST3. The identified MRSP strains belonged to two well-known sequence types, ST551 and ST71. Moreover, antimicrobial use (p = 0.0001), hospitalization (p = 0.0141), and comorbidities (p = 0.002) were associated with increased MRS prevalence in cats.

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.

The Amazonian manatee (Trichechusinunguis) is an aquatic mammal threatened with extinction. However, few studies have investigated the pathogens in this species, which may affect both animal and human health. This study aimed to evaluate the frequency, distribution, and patterns of antimicrobial susceptibility of Staphylococcus spp. and Escherichiacoli colonizing the nasal and rectal cavities of Amazonian manatees kept in captivity at the National Institute for Amazonian Research (INPA) in the state of Amazonas, Brazil. Rectal and nasal swabs from 44 manatees of different ages were used in this study. The genus Staphylococcus was isolated from the nasal swabs of 32 (72.7%) animals, with two individuals harboring more than one species of Staphylococcus. S. sciuri was the most commonly isolated species. Resistance to penicillin was observed in 13 (40.6%) isolates, more frequent than the other antimicrobials tested (P = 0.01). E. coli was isolated from the rectal swabs of all animals, with phylogroup B1 being the most frequent among the strains obtained (P = 0.0008). Four isolates (6.8%) were positive for virulence factors, three of which were classified as enterotoxigenicE. coli (ETEC) and one as enteropathogenicE. coli (EPEC). To our knowledge, this is the first study to evaluate Staphylococcus spp. and E. coli in Amazonian manatee samples. This study revealed nasal colonization by Staphylococcus spp., mainly S. sciuri, and diarrheagenicE. coli isolates, including antimicrobial-resistant strains.

Enterococcus faecium is globally recognized as a major causative agent of hospital-acquired infections in humans, particularly isolates belonging to clonal complex 17 (CC17). However, its role as a causative agent of severe infections in dogs remains poorly understood. This study investigated two cases of sepsis caused by E. faecium CC17 in dogs, combining clinical and pathological characterization with genomic analysis of the isolates. The first case involved a dog presenting with lameness and swelling of the left pelvic limb, which progressed to an open wound, sepsis, and death. The second case was a nosocomial infection in a dog following radical mastectomy. Post mortem examinations revealed lesions consistent with bacterial infection and sepsis, including hemorrhagic diathesis, thrombosis, endocarditis, and splenitis. E. faecium was isolated in pure culture from ventricular blood and peritoneal fluid swabs in both animals. Antimicrobial susceptibility testing revealed that the E. faecium isolates were multidrug-resistant, showing susceptibility only to chloramphenicol, fosfomycin, and vancomycin. Genomic sequencing identified both isolates as members of CC17, a clonal complex commonly associated with sepsis in humans. Single nucleotide polymorphism analysis showed that the isolates clustered with other canine strains and were closely related to human-derived isolates, including vancomycin-resistant enterococci (VRE). This report provided a comprehensive pathological and genomic characterization of two cases of E. faecium-associated sepsis in dogs. The findings highlighted the importance of implementing strict infection control protocols to mitigate nosocomial infections in veterinary hospitals.

Clostridioides difficile is an anaerobic bacterium that causes disease in both animals and humans. Despite the known significance of this agent, there are no commercial vaccines available for humans, and only one immunogen is marketed for swine. However, no studies have evaluated this vaccine. Background/Objectives: Therefore, the aim of this study was to assess the potency of the first commercial vaccine for C. difficile infection in piglets and to compare the humoral response in rabbits and sows. Methods: Pregnant sows were divided into two groups: a vaccinated group (n = 12), receiving two doses before farrowing, according to the manufacturer’s recommendation, and an unvaccinated control group (n = 6). Blood samples were taken from sows and also from piglets up to two days after birth. In addition, two groups of New Zealand rabbits (Oryctolagus cuniculus) received either a half-dose (G1) or a full-dose (G2) of the vaccine, with a control group receiving sterile saline (0.85%). Rabbits were vaccinated twice, 21 days apart, with blood samples collected before each dose and 14 days after the final dose. A serum neutralization assay in Vero cells was performed to evaluate the titers of neutralizing antibodies. Results: The vaccine demonstrated immunogenicity by stimulating the production of neutralizing antibodies in both rabbits and sows. Additionally, these antibodies were passively transferred to piglets through colostrum, reaching levels comparable to those found in sows. Furthermore, vaccinated rabbits developed antibody titers that do not significantly differ from those obtained in sows and piglets. Conclusions: The tested vaccine can induce a humoral immune response against C. difficile A/B toxins in sows and these antibodies are passively transferred to neonatal piglets through colostrum. Also, the vaccination of rabbits might be a useful alternative for evaluating the potency of vaccines against C. difficile.