Klebsiella infections in the oral cavities of both humans and dogs have been increasingly reported and are associated with various buccal infections, as well as systemic infections. These infections appear to be rising particularly among pets and their owners, suggesting a possible bidirectional transmission between humans and dogs. Therefore, this study aimed to investigate the potential link of mixed infections involving Klebsiella pneumoniae and Enterococcus spp. Buccal cavity samples were collected from humans (n = 25) and dogs (n = 25). Samples were initially enriched in tryptic soy broth and subsequently cultured on tryptic soy agar, MacConkey agar, and blood agar. All isolates were identified using the VITEK 2 system, and eight selected isolates were further analyzed by 16S rRNA gene PCR. In humans, Klebsiella spp. were detected in 24% of samples by primary isolation, 44% by VITEK 2 analysis, and 12% were confirmed by 16S rRNA PCR. In dogs, primary isolation and VITEK 2 identification both showed a prevalence of 28%, while 20% were confirmed by 16S rRNA PCR. Among human samples, isolates were detected in 10% of males and 13.3% of females, whereas in dogs, 14.3% of males and 27.3% of females were positive. The results revealed that K. pneumoniae accounted for 66.7% and Enterococcus faecalis for 33.3% of isolates from humans, while in dogs, K. pneumoniae represented 80% and E. faecalis 20% of the isolates. These findings highlight the potential significance of transmission of these bacterial species between humans and dogs.
