Antimicrobial Susceptibility Profiles of Acinetobacter baumannii Strains, Isolated from Clinical Cases of Companion Animals in Greece

SIMPLE SUMMARY: Acinetobacter baumannii Complex is a worldwide distributed group of species responsible for several challenges in treating nosocomial infections in humans. The emergence of highly resistant strains, even to last-resort antibiotics, constitutes a severe threat, especially for hospitalized patients. In veterinary medicine, its role has not been comprehensively investigated yet. However, many recent studies indicate its ability to cause infections in multiple animal species, primarily pets. In this study, we obtained a significant number of A. baumannii isolates from canine and feline clinical samples during 2.5 years, in Greece. Data regarding the isolates’ sample origin, type of infection and resistance profile were collected and compared. High resistance rates against several antibiotics were detected, including agents of paramount clinical importance, such as carbapenems. This study indicates the emergence of Acinetobacter baumannii Complex bacteria as pathogens for companion animals, the prevalence of strains with acquired resistance to many of antibiotics, and the danger of circulation of these strains between animals, humans, and veterinary equipment and facilities. ABSTRACT: Acinetobacter baumannii–calcoaceticus (Abc) Complex bacteria are troublesome nosocomial pathogens in human medicine, especially during the last 30 years. Recent research in veterinary medicine also supports its emergence as an animal pathogen. However, relevant data are limited. In this study, we obtained 41 A. baumannii isolates from clinical samples of canine and feline origin collected in veterinary clinics in Greece between 2020 and 2023. Biochemical identification, antimicrobial susceptibility testing, molecular identification and statistical analysis were performed. Most of the samples were of soft tissue and urine origin, while polymicrobial infections were recorded in 29 cases. Minocycline was the most effective in vitro antibiotic, whereas high resistance rates were detected for almost all the agents tested. Notably, 20 isolates were carbapenem resistant and 19 extensively drug resistant (XDR). This is the first report of canine and feline infections caused by Abc in Greece. The results create concerns regarding the capability of the respective bacteria to cause difficult-to-treat infections in pets and persist in veterinary facilities through hospitalized animals, contaminated equipment, and surfaces. Moreover, the prevalence of highly resistant strains in companion animals constitutes a public health issue since they could act as a reservoir, contributing to the spread of epidemic clones in a community.