Antibiotic resistance pattern of Acinetobacter baumannii strains: A retrospective study from Oman

Background: Multidrug-resistant (MDR) Acinetobacter baumannii is of serious health concern and associated with high mortality. Data regarding the antibiotic resistance pattern of A. baumannii strains in Oman is limited. Objectives: To determine the antibiotic resistance pattern of A. baumannii from various clinical samples in a tertiary care hospital in the North-Batinah region of Oman. Methods: A. baumannii isolates recovered from various clinical samples in the Microbiology laboratory of Sohar Hospital, Oman, during 2015-2019 were retrospectively analyzed. Organism identification and their antibiotic resistance patterns were performed as recommended by the Clinical and Laboratory Standards Institute. Results: A total of 1890 A. baumannii nonduplicate isolates were found from clinical samples of 1326 patients. The isolates were more frequently isolated from elderly patients (40%) and in-patient department patients (67%). Infection/colonization was more common among patients treated in the medicine, intensive-care unit, and surgery departments. A. baumannii strains were highly resistant (50-83%) to most of the tested antibiotics, with the highest against ceftriaxone (83%) and ceftazidime (75%), and lowest against colistin (1%) and tigecycline (8%). Among the isolates, 67% (1265) were MDR strains. Of these, 22%, 32% and 16% were resistant to all six, five and four classes of the tested antibiotics. Conclusion: The study found that the frequency of isolation of MDR A. baumannii isolates in the northern region of Oman is high.