Preliminary investigation of the molecular mechanisms of imipenem-resistance in clinical isolates of Acinetobacter baumannii in Xi'an.
- Author:
Xiang-Shu TAN
1
;
Yuan LIU
;
Xing-Peng HAN
Author Information
- Publication Type:Journal Article
- MeSH: Acinetobacter baumannii; drug effects; genetics; isolation & purification; Anti-Bacterial Agents; pharmacology; Bacterial Proteins; genetics; China; Humans; Imipenem; pharmacology; beta-Lactam Resistance; beta-Lactamases; genetics
- From: Journal of Southern Medical University 2009;29(7):1393-1396
- CountryChina
- Language:Chinese
-
Abstract:
OBJECTIVETo investigate the molecular mechanism of carbapenem resistance in the clinical isolates of Acinetobacter baumannii from Xi'an and their profile of carbapenemase production.
METHODSA total of 146 Acinetobacter baumannii strains were isolated from 6 general hospitals in Xi'an. Antimicrobial susceptibility test was performed for all the strains, followed by detection of imipenem resistance using E-test for metallo-beta-lactamase (MBL) and NaCl inhibition test for OXA type carbapenemase. Bla(OXA-23)and bla(OXA-58) were amplified by PCR, and the positive products were sequenced.
RESULTSFrom the collected strains, 15 non-repetitive imipenem-resistant Acinetobacter baumannii strains were identified, among which 14 yielded negative results in E-test for MBL production. All the resistant strains showed increased sensitivity to imipenem after NaCl inhibition, suggesting the presence of carbapenemase production. Eleven of the strains harbored OXA -23 type gene and 1 harbored OXA -58 type gene. The concordance rate of the results by NaCl inhibition test and PCR was 85.7%.
CONCLUSIONSProduction of OXA-type carbapenemase is the most important reason for carbapenem resistance in Acinetobacter baumannii in Xi'an. The OXA-58 type gene is a novel carbapenemase genotype in China. NaCl inhibition test is a convenient and cost-effective method for detecting carbapenemase in Acinetobacter baumannii.
