Antimicrobial Susceptibility of New Delhi Metallo Beta Lactamase - 1(NDM-1) producing Bacteria isolated from major hospitals in Kano-Nigeria to Colistin and Tigecycline

Abstract

The continued rise in the rate of resistance of clinical pathogens to common antibiotics in our hospitals has left the prescribers with option of using colistin, tigecycline and related drugs in treating serious infections. Resistance mediated by New Delhi Metallo Beta lactamase (NDM-1) is widely underreported especially in our facilities. This study aimed at screening for carbapenemase, metallo beta lactamase (MBL) and specific NDM-1 producing clinical isolates from major tertiary hospitals in Kano-Nigeria and determining their susceptibility to colistin and tigecycline. A total of 500 antibiotic resistant bacterial isolates belonging to the family Enterobacteriaceaea and Pseudomonasea were screened phenotypically for carbapenemase and MBL production using Modified Hodges and EDTA Disc Synergy tests respectively. BlaNDM-1 gene was detected among potential NDM-1 producers by Polymerase Chain Reaction (PCR) using NDM-1 specific primers. Susceptibility of the carbapenemase, MBL and confirmed NDM-1 producing bacteria to colistin and tigecycline
was carried out using disc diffusion method. Of the total isolates screened, 162 (32.4%) and 43(8.6%) were carbapenemase and MBL producers respectively. While highest prevalence of carbapenemase was found in S. typhi (66.7%), followed by S. paratyphi (50%), K.
pneumoniae (36.9%), K. oxytoca (33.3%), and E. coli (31%), MBL prevalence was higher in Proteus mirabilis, K. pneumoniae, and Ps. aeruginosa. Among the isolates positive in phenotypic confirmation test (i.e. carbapenemase and MBL), gene bla NDM-1 was detected
in 3 E. coli and 1 K. pneumoniae bringing the overall frequency of NDM-1 producers to0.8%. While the carbapenemase producing isolates are about 96% sensitive to colistin and tigecycline, MBL and NDM-1 were all 100% sensitive using disc diffusion method.
Carbapenemase, MBL and NDM-1 producing isolates occurred among the pathogens commonly isolated in the study area and are highly susceptible to Colistin and tigecycline.