Overexpression of Gene Driven by IS Is Associated with Imipenem Resistance in a Clinical Isolate from Vietnam.

The aim of this study was to investigate genetic structures and expression of gene in five clinical isolates recovered from two hospitals in southern Vietnam during 2012-2014. isolates were identified by automated microbiology systems and confirmed by PCR. All isolates were characterized as multidrug resistant by antimicrobial testing using the disk diffusion method. Four imipenem susceptible and one nonsusceptible isolates (MIC > 32 g·ml) were identified by E-test. PCR amplification of gene upstream and downstream sequences revealed the presence of IS at both locations in one multidrug-resistant isolate. Semiquantitation of and gene expression was performed by the 2 method. The gene expression of five isolates showed little difference, but the isolate bearing IS- -IS exhibited significantly higher mRNA level. Higher -lactamases activity in periplasmic than cytoplasmic fraction was found in most isolates. The isolate overexpressing gene possessed very high periplasmic enzyme activity. In conclusion, the isolate bearing IS- gene exhibited high resistance to imipenem, corresponding to an overexpression of gene and very high periplasmic -lactamase activity.