Molecular characterization and clinical significance of New Delhi metallo-beta-lactamases-1 producing Escherichia coli recovered from a South Indian tertiary care hospital

Context: The increased rate of infection by New Delhi metallo-beta-lactamases-1 (NDM1) producing Escherichia coli is a major concern since they show a high rate of drug resistance and are responsible for mortality and morbidity. Aims: To characterize the NDM1 producing E. coli isolates and their impact on patients' clinical outcome. Settings and Design: This descriptive study was carried out in a multi-specialty tertiary care hospital. Materials and Methods: Three hundred nonrepeat strains of E. coli from inpatients were included in the study. Modified Hodge test and metallo-beta-lactamases (MBL) e-test were performed to detect carbapenemase and MBL activity. Polymerase chain reaction (PCR) technique was performed to detect NDM1. NDM1 positive isolates were further tested for plasmid mediated AmpC, bla(CTX), bla(SHV), bla(TEM) genes and also for phylogrouping by PCR methods. Treatment and patients' clinical outcome were also analyzed. Results: Out of 300 isolates, 21 (7%) were MBL producers by phenotypic methods. Of this, 17 (81%) were NDM1 positives, among the NDM1 producers 6 (35%) isolates were belongs to phylogroups D followed by A 5 (29%), B1 4 (24%) and B2 2 (12%), 15 (88%) isolates were bla(CTX-M) positive suggestive of extended-spectrum beta lactamase producing strain and 7 (47%) were positive with CIT type of AmpC. With the follow-up of the patients, it was found that 12 (71%) recovered and 3 (18%) developed relapses, and mortality was seen in 2 (12%) patients. Conclusions: NDM1 producing isolates showed a high degree of drug resistance but can be treated with suitable antimicrobials, in the majority. Early detection and choice of appropriate antibiotics may help in reducing mortality and morbidity.