Changing trends in the antimicrobial susceptibility of clinical isolates of Acinetobacter baumannii.
Acinetobacter baumannii has recently emerged as an important nosocomial pathogen because of its resistance to the majority of commonly used antimicrobial agents. Therefore, the pattern of isolation of Acinetobacter baumannii in our laboratory and the in vitro susceptibilities to various antimicrobial agents were studied. One hundred and two clinical isolates of previously identified Acinetobacter calcoaceticus var. anitratus from different patients were collected from the Diagnostic Bacteriology section of the Department of Pathology, Singapore General Hospital. The strains were reclassified according to recent taxonomic changes using phenotypic tests and tested for beta-lactamase production using Cefinase disks. In vitro sensitivities to various antimicrobial agents were determined using the disk diffusion method. Of the 103 A. calcoaceticus var. anitratus species, 99 were identified as A. baumannii, 2 as A. junii and 1 as A. haemolyticus. Majority of the A. baumannii isolates were from wound sites (63.6%) and from patients in the general wards (70.7%). beta-lactamase activity was present in all these isolates. The most active agent against all A. baumannii isolates was imipenem. However, 14 of the strains were resistant to imipenem, 8 of which came from the burns ward. Two-thirds of isolates from burn patients were completely resistant to all the antimicrobial agents tested. Almost all isolates previously identified as A. calcoaceticus var. anitratus in our laboratory are A. baumannii strains. Imipenem is the most effective antimicrobial agent; however, the high rate of imipenem resistance especially among burn patients is a source of major concern.
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L H
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Department of Pathology, Singapore General Hospital, Singapore.
Yeo
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D016954:Acinetobacter calcoaceticus / Q000187:drug effects* / Q000201:enzymology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D018432:Drug Resistance, Multiple; D006801:Humans; D015378:Imipenem / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000639:trends; D013845:Thienamycins / Q000494:pharmacology; D001618:beta-Lactamases / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D013845:Thienamycins; D015378:Imipenem; D001618:beta-Lactamases