Molecular characterization and antimicrobial susceptibility profile of New Delhi metallo-beta-lactamase-1-producing Escherichia coli among hospitalized patients

BACKGROUND: Carbapenemase-producing microorganisms are becoming a major concern among hospital-acquired infections. There is also increased multidrug resistance seen among these isolates. AIMS: We have conducted this study to determine the prevalence of New Delhi metallo-beta-lactamase-1 (NDM-1) gene-producing Escherichia coli among hospitalized patients in a tertiary care hospital in Northern India. SETTINGS AND DESIGN: The study was conducted in the Department of Microbiology with the tertiary care hospital settings. It was a prospective cross-sectional observational study conducted during January 2014-August 2014. MATERIALS AND METHODS: A total of 500 nonduplicate E. coli samples were processed. The isolates with reduced susceptibility to ertapenem, i.e., zone diameter between 19 and 21 mm, were considered carbapenemase producers. These isolates were subjected to modified Hodge test for phenotypic confirmation. Polymerase chain reaction was performed on all the screened isolates for molecular detection of NDM-1 gene. STATISTICAL ANALYSIS USED: Chi-square test was used to analyze the data and P < 0.05 was considered statistically significant. RESULTS: Out of 500 E. coli isolates, 61 (12.2%) were screened for carbapenemase production. 47 (9.4%) isolates were positive by modified Hodge test and 36 (7.2%) isolates showed the presence of blaNDM-1 gene (P < 0.05). CONCLUSION: There is an increased prevalence of NDM-1 gene-producing E. coli isolates. These carbapenemase-producing isolates are more resistant to other group of antibiotics (aminoglycosides, fluoroquinolones along with beta-lactam group). Early detection of blaNDM-1 gene can help in choosing the effective treatment options for hospitalized patients in time, thereby reducing the risk of mortality.