eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2025-06-30 18 2 1571 1579 10.13005/bpj/3194 65977 article Bindu Dhanapal 1 Mymoonah Risha 1 Chitralekha Saikumar 1 Department of Microbiology, Sree Balaji Medical College and Hospital, Chrompet, Chennai, Tamilnadu, India Acinetobacter species are emerging pathogens in healthcare settings, responsible for many infections, including bacteremia, pneumonia, meningitis, peritonitis, and wound infections. Their ability to develop multidrug resistance through various resistance determinants poses significant challenges for treatment. This study aimed to isolate and speciate Acinetobacter using simple phenotypic tests, determine their antibiotic susceptibility profiles, and conduct molecular characterization of resistance genes. This prospective cross-sectional study was conducted from January 2023 to December 2023 to isolate and identify Acinetobacter isolates from confirmed infections using phenotypic methods, followed by antibiotic susceptibility testing. Among 108 confirmed cases of Acinetobacter infection, 73 were male patients, 49 were over 50 years old, and 49 were from the Intensive Care Unit (ICU). The most common specimens were endotracheal aspirates (36.1%) and sputum (34.2%). Levofloxacin and meropenem were the most effective antibiotics, with 81.5% sensitivity each, while ceftriaxone (81.4%), gentamicin (71.3%), cefepime (77%), and ceftazidime (70.3%) exhibited high resistance rates.All the isolates were sensitive to colistin and tigecycline.  In terms of speciation, Acinetobacterbaumannii was predominant, accounting for 97.2% of isolates. Notably, Acinetobacter species were more frequently isolated from ICU patients (38%) than other wards. These findings underscore the critical need for vigilant infection control practices and tailored antibiotic stewardship programs in healthcare settings. https://biomedpharmajournal.org/vol18no2/emerging-drug-resistance-in-acinetobacter-species-a-study-on-isolation-speciation-and-antimicrobial-susceptibility-patterns-in-a-tertiary-care-hospital/ Acinetobacterbaumannii Acinetobacter infections Antibiotic susceptibility test Colistin Ceftazidime-avibactam+aztreonam ICU MDR Synergistic effect