Antibiotic Resistance of Acinetobacter Isolated in a Spanish Veterinary Teaching Hospital

Acinetobacter is one of the most relevant pathogenic and nosocomial bacteria in human medicine. However, in veterinary medicine, particularly in Spain, there are very few studies on the impact and frequency of infections due to this genus. The main objective of this study was to characterise Acinetobacter isolates recovered at the Complutense Veterinary Teaching Hospital of the Complutense University of Madrid (HCV-UCM), with special emphasis on detecting antimicrobial resistance. A total of 23 isolates obtained from different animal species and samples over a 25-year period were included in the study, based on their identification as Acinetobacter by VITEK-2. Identification was made by using MALDI-TOF, VITEK-2, whole-genome sequencing (WGS) and a chromogenic medium. WGS confirmed that 13 of the 23 isolates belonged to Acinetobacter spp. Antimicrobial susceptibility was interpreted according to CLSI guidelines using the Kirby–Bauer disk diffusion and broth microdilution method. The proportion of clinical isolates identified as Acinetobacter spp. at the HCV-UCM was 0.3%. Of these, 15.4% (2/13 isolates) were classified as multidrug-resistant. Two isolates with the highest MIC for tigecycline carried the tet(X) gene, and two isolates harboured mutations in both gyrA and parC QRDR regions. The results of this study suggest that, in this hospital, antimicrobial resistance among Acinetobacter isolates may not yet be widespread.