The Presence of gram-negative bacteria carrying the New Delhi metallo-β-lactamase gene on abiotic touch surfaces at a tertiary care center

Abstract

Objectives: New Delhi metallo-β-lactamase (NDM), which has emerged as a major mechanism of resistance to carbapenems in Gram-negative bacteria (GNB), challenges effective patient management of health-care systems. Nonpathogenic environmental bacteria present on abiotic touch surfaces in hospitals may serve as reservoirs for the NDM gene and contribute to the emergence and spread of resistance to carbapenems. The aim of this study was to determine the presence of NDM-positive GNB in the environment of a tertiary care center. Materials and Methods: Fifty-eight swab samples were collected from various touch surfaces in 12 different wards between January and February 2017. The swabs were cultured in nutrient broth and subsequently subcultured onto McConkey agar plates. Both lactose and nonlactose fermenting colonies grown were identified by biochemical methods. The polymerase chain reaction method was used to detect NDM carriage. Results: Twenty-seven (46%) of the samples were positive for microbial growth, of which 21 (36%) samples yielded bacterial growth on McConkey agar plates. Of the 30 isolates identified, 25 (83%) were nonfermenting GNB (NFGNB) and 5 (17%) were Klebsiella spp., of which 1 was Klebsiella oxytoca. NFGNB were isolated mostly from tables and infusion stands in various wards. Four of the five Klebsiella spp. were from patients' beds. Two isolates of NFGNB and one Klebsiella spp. were positive for the NDM gene. Conclusion: In addition to serving as potential pathogens of nosocomial infections, environmental bacteria present on abiotic touch surfaces in hospitals may serve as reservoirs for the NDM gene.

Keywords

• hospital environment
• klebsiella
• new delhi metallo-β-lactamase
• nonfermenting gram-negative bacteria
• touch surfaces