Antimicrobial resistance of Acinetobacter baumannii isolates from internal medicine wards, intensive care unit, and surgery wards and their homogeneous study by cluster analysis

Objective: To investigate the antimicrobial resistance of Acinetobacter baumannii clinical isolates and study the homogeneity of isolates by cluster analysis. Methods: Disc diffusion test (K-B method) was used to study the antimicrobial resistance, and WHONET 5 was used for statistics analysis; the homogeneous relations among the isolates was analyzed by cluster analysis of SPSS 10.0; and significant differences were identified by χ 2 test among the resistance incidences to antibiotics. Results: Among 82 isolates of Acinetobacter baumannii collected from Huaxi Hospital of Sichuan university, sputum was the major specimen samples, percentage was 91.5% in total isolates; The rates of antimicrobial resistance were 12.5%, 37.8%, 40.7% and 42.0% to imipenem, ciprofloxacin, ceftazidime and amikacin, respectively; Resistant incidences were different significantly (P < 0.05) between the isolates from intensive care unit, surgery departments and the isolates from internal medicine departments to cefotaxime, amikacin, gentamicin, aztreonam and trimethoprim/sulfamethoxazole. The cluster analysis revealed that the homogeneous strains were identified for 762332 and 769317, 54744 and 28081, 30073 and 30200 from internal medicine departments; 18681, 787232, 731161 and 785010, 781.971 and 786090, 785246 and 770010, 786110 and 764616 from intensive care unit; as well as 766969 and 783141 from surgery departments; These strains were isolated from the same wards or neighbor wards in short interval. Most of them were multi-drug resistant strains. Conclusions: Resistant incidences were different significantly between the isolates from intensive care unit, surgery departments and the isolates frominternal medicine departments to cefotaxime, amikacin, gentamicin, aztreonam and trimethoprim/sulfamethoxazole; Cluster analysis is of importance to identify the homogeneous isolates of Acinetobacter baumannii, and for monitoring as well as controlling the infections in hospital.