DRP006541
Emergence of multidrug-resistant Acinetobacter variabilis in Japan
The emergence and dissemination of drug-resistant Acinetobacter species have been recognized as a serious health concern worldwide. Drug-resistant Acinetobacter baumannii has been one of the most important nosocomial pathogens with the highest incidence rate of isolation among Acinetobacter species. The genus Acinetobacter composes 62 distinct species with validly published names and several species with effectively published names awaiting validation. Acinetobacter variabilis was originally classified as Acinetobacter DNA group 15 TU using DNA-DNA hybridization by Tjernberg and Ursing in 1989. Later, Acinetobacter DNA group 15 TU was proposed as Acinetobacter variabilis sp. nov. in 2015 by Krizova L., et al. Since NDM-1 metallo-beta-lactamase (MBL) producing Klebsiella pneumoniae and Escherichia coli was initially detected in 2008 in Sweden, NDM-type MBL producers have become endemic in the India, and these organisms were isolated in various countries and regions worldwide. Although NDM-type MBL producers seem to be not yet spreading in Japan, there is at least four reports of NDM producing clinical isolates, including an isolate of E. coli producing NDM-1 MBL obtained from a patient traveling India for business in March 2009, and two isolates of NDM-5 MBL producing E. coli and NDM-1 MBL producing K. pneumoniae obtained from two foreigners from Bangladesh and Indonesia, respectively, and an isolate of E. coli producing NDM-7 obtained from a patient with history of admission in India. In Acinetobacter species, an isolate of NDM-1 MBL producing A. baumannii was obtained from a patient in Japan. The methylation of 16S rRNA confers high resistance to all clinically important aminoglycosides in Gram-negative organism. Clinical isolates of Klebsiella pneumoniae harboring the armA, a 16S rRNA methylase, and Pseudomonas aeruginosa harboring the rmtA, another one, were identified in 2003 in France, Japan, and the other countries since 2003. To date, 10 plasmid-associated 16S rRNA methylase genes, armA, rmtA-H and npmA, have been identified in human and animal. In this study, we analysis a clinical isolate of A. variabilis producing both NDM-1 MBL and OXA-420 carbapenemases, and ArmA 16S rRNA methylase obtained from a patient in Japan.