DETECTION OF METALLO BETA - LACTAMASES AMONG ENTEROBACTERIACEAE ISOLATES AT A TERTIARY CARE HOSPITAL, SOUTH INDIA

Background: 

The spread of carbapenem resistant bacteria has caused grave concern due to the limited choice in antibiotics for treating infections caused by them. The emergence of  metallo beta-lactamse (MBL) producing  gram negative bacilli poses a therapeutic challenge and is of  serious concern for infection control in hospital environment.

Materials & Methods:

A total of 475 non repeat clinical isolates of family Enterobacteriaceae were included in the study. Resistance to imipenem was determined in isolates by disc diffusion & minimum inhibitory concentration (MIC) method. Imipenem resistant  isolates  were tested for MBL production by combined disc diffusion test and modified Hodge test.

Results:

Out of the 475 Enterobacteriaceae strains,  20 showed resistance to imipenem. MBL activity was detected in all 20 (4.2%) isolates by combined disc diffusion test, in 18 isolates by modified Hodge test. The MBL producing isolates included clinical strains of Klebsiella spp (45%), E. coli (40%), Citrobacter spp (15%).  Majority of the MBL isolates were from Intensive care unit (65%), from patients with comorbid conditions and with invasive devices.  MBL producing isolates showed high level of resistance to aminoglycosides and fluoroquinolones but all were susceptible to colistin.

Conclusion:

The need of the hour is to detect MBL producing isolates for better patient outcomes, to execute prompt infection control measures and decrease the escalation of resistance.