Antibiotic resistance profile & extended spectrum beta-lactamase (ESBL) production in Acinetobacter species.

BACKGROUND & OBJECTIVES: Members of the genus Acinetobacter are an important cause of nosocomial infections and with widespread resistance to various antibiotics. Extended spectrum beta lactamase (ESBL) associated resistance among Acinetobacter species is now known. The aim of this study was to speciate clinical isolates of Acinetobacter, analyze their resistance patterns, identify the production ESBLs and compare the role of different cephalosporins in detecting ESBL production in the isolates.

METHODS

One hundred and fifty clinical isolates of Acinetobacter were speciated by various phenotypic tests. Antibiotic susceptibility was determined by the standard disc diffusion method. ESBL production was detected by the double disk approximation test using clavulanate containing disk and four different cephalosporin disks. Results of the above test were confirmed using the NCCLS phenotypic confirmatory test for ESBLs on a limited number of isolates.

RESULTS

Most of the isolates were of respiratory origin. A. calcoaceticus A. baumannii (Acb) complex was the predominant species isolated (75%). Most isolates were resistant to the antibiotics tested including the third generation cephalosporins. Most isolates were sensitive to carbapenems and cefoperazone-sulbactam. ESBL production was detected in 28 per cent of the isolates. In the double disc approximation test, cefepime and cefotaxime could detect most of the ESBLs in Acinetobacter isolates.

INTERPRETATION & CONCLUSION: A high level of antibiotic resistance was found in Acinetobacter in our study. Acb complex was the predominant and the more resistant species. Relatively high levels (28%) of ESBL have been detected in Acinetobacter and may reflect the scenario in India. ESBL production in Acinetobacter should be promptly detected and reported as it helps in treating individual cases and also in controlling the spread of these resistant phenotypes to other individuals.