The distribution of carbapenem- And colistin-resistance in Gram-negative bacteria from the Tamil Nadu region in India

Prasanth Manohar, Thamaraiselvan Shanthini, Ramankannan Ayyanar, Bulent Bozdogan, Aruni Wilson, Ashok J. Tamhankar, Ramesh Nachimuthu, Bruno S. Lopes

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38 Citations (Scopus)


Purpose. The occurrence of carbapenem- and colistin-resistance among Gram-negative bacteria is increasing worldwide. The aim of this study was to understand the distribution of carbapenem- and colistin-resistance in two areas in Tamil Nadu, India. Methodology. The clinical isolates (n=89) used in this study were collected from two diagnostic centres in Tamil Nadu, India. The bacterial isolates were screened for meropenem- and colistin-resistance. Further, resistance genes blaNDM-1, blaOXA-48- like, blaIMP, blaVIM, blaKPC, mcr-1 and mcr-2 and integrons were studied. The synergistic effect of meropenem in combination with colistin was assessed. Results. A total of 89 bacterial isolates were studied which included Escherichia coli (n=43), Klebsiella pneumoniae (n=18), Pseudomonas aeruginosa (n=10), Enterobacter cloacae (n=6), Acinetobacter baumannii (n=5), Klebsiella oxytoca (n=4), Proteus mirabilis (n=2) and Salmonella paratyphi (n=1). MIC testing showed that 58/89 (65 %) and 29/89 (32 %) isolates were resistant to meropenem and colistin, respectively, whereas 27/89 (30 %) isolates were resistant to both antibiotics. Escherichia coli, K. pneumoniae, K. oxytoca, Pseudomonas aeruginosa, and Enterobacter cloacae isolates were blaNDM-1-positive (n=20). Some strains of Escherichia coli, K. pneumoniae and K. oxytoca were blaOXA-181-positive (n=4). Class 1, 2 and 3 integrons were found in 24, 20 and 3 isolates, respectively. Nine NDM-1-positive Escherichia coli strains could transfer carbapenem resistance via plasmids to susceptible Escherichia coli AB1157. Meropenem and colistin showed synergy in 10/20 (50 %) isolates by 24 h time-kill studies. Conclusion. Our results highlight the distribution of carbapenem- and colistin-resistance in Gram-negative bacteria isolated from the Tamil Nadu region in South India.

Original languageEnglish
Article number000508
Pages (from-to)874-883
Number of pages10
JournalJournal of Medical Microbiology
Issue number7
Publication statusPublished - 1 Jul 2017

Bibliographical note

Funding Information:
This research work was funded by DST-SERB, Govt of India, New Delhi, Ref. No. SERB/LS-930/2012. The authors would like to thank VIT University for providing research facilities.

Publisher Copyright:
© 2017 The Authors.


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