Molecular Detection of New Delhi Metallo Beta Lactamase 1 (NDM-1) Producing Bacterial Isolates in Kano- Northwestern Nigeria

Abstract

New Delhi Metallo Beta Lactamase 1 (NDM-1) is an enzyme with zinc ions at its active site that cleaves the amide bond of β-lactam ring and provides resistance against major classes of β-lactam antibiotics. The molecular detection of NDM-1 producing bacterial isolates from tertiary Hospitals in Kano was investigated. A total of 500 bacterial isolates of Enterobacteriaceae and Pseudomonas aeruginosa from samples of blood, urine, catheter tip were screened for NDM-1 over a period of 12 months. The isolates were screened preliminarily for carbapenemases using meropenem (10 µg) and imipenem (10 µg) by disc diffusion technique. Isolates of 23 mm and 21 mm for meropenem and imipenem respectively were confirmed by modified Hodge test then EDTA Disc Synergy Test using two meropenem discs, one with MEM (10 µg), and other containing 10 µl of 0.1 M anhydrous EDTA (292 µg) for Metallo Beta Lactamase (MBLs) and finally seventeen MBLs isolates were screened with NDM-1 specific primers by PCR then four PCR positive products were sequenced for blaNDM-1 gene. Of the 500 clinical bacterial isolates screened, 162(32.4%), 43(8.6%) and 4(0.8%) were found to produce carbapenemase, MBLs and NDM-1 respectively. The highest frequency of NDM-1 producers was found among Escherichia coli 3(1.6%) followed by Klebsiella pneumoniae 1(0.5%). Based on clinical samples, blood (25.0%) was found to have highest prevalence of MBLs followed by catheter tips (21.0%), wound swabs (11.1%) and urine (6.3%). Conclusively, NDM-1 was first detected in Kano, Nigeria.