Genetic linkage of bla_NDM among nosocomial isolates of Acinetobacter baumannii from a tertiary referral hospital in northern India

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• 作者：Shweta Mishra^a ; Malay Ranjan Sen^a ; ^{mr_senbhu@yahoo.com} ; Supriya Upadhyay^a ; Amitabha Bhattacharjee^b
• 关键词：Acinetobacter baumannii ; NDM ; ISAba125
• 刊名：International Journal of Antimicrobial Agents
• 出版年：2013
• 出版时间：May, 2013
• 年：2013
• 卷：41
• 期：5
• 页码：452-456
• 全文大小：276 K

文摘

The aim of this study was to evaluate the emergence of bla_NDM-1 among clinical isolates of Acinetobacter baumannii isolated from a north Indian tertiary care hospital and to assess the gene cassettes and resistance determinants located within them. In total, 74 A. baumannii were screened for MBL production by the imipenem-EDTA method and were characterised for antibiotic sensitivity. PCR was performed to detect the presence of bla_NDM and the co-existence of ESBL and AmpC genes. NDM-producing isolates were typed by ERIC-PCR, and the association of integrons with bla_NDM-1 and the presence of gene cassettes were determined using specific primers. The genetic location of bla_NDM in ISAba125 was also determined. Transformation was performed using a heat-shock method. Three isolates were found to harbour bla_NDM, all of which co-produced bla_EBC, bla_DHA and bla_CIT AmpC ¦Â-lactamases. All MBL-producers showed resistance to cephalosporins, carbapenems, aminoglycosides, fluoroquinolones and tigecycline but were susceptible to polymyxin B. Presence of class 1 integrons was demonstrated in all three bla_NDM-harbouring isolates, whilst linkage between the integron and bla_NDM could not be established. Detection of gene cassettes revealed the presence of dihydrofolate reductase (dhfr) and aminoglycoside 6¡ä-N-acetyltransferase [aac(6¡ä)] genes. Presence of bla_NDM in ISAba125 was also observed. These findings suggest that ISAba125 appears to be the main genetic component for dissemination of bla_NDM in A. baumannii. The association of bla_NDM-1 with ISAba125 and the mobility of other multiresistance region (gene cassette)-carrying integrons provide an easy way to cross species barriers and reach a level that places the patients at risk.