Phenotypic characterization of multidrug-resistant Acinetobacter baumannii with special reference to metallo-β-lactamase production from the hospitalized patients in a tertiary care hospital in Nepal.

Abstract

Introduction: Acinetobacter baumanniiis an important cause of nosocomial infection and has been associated with a wide variety of illnesses in hospitalized patients, especially patients in the intensive care units. The emergence of carbapenem-resistant clones of A. baumannii has been the most serious problem worldwide. After the carbapenem resistant clones have emerged, leaving the hope of treatment of A. baumannii infection is by the last resort of antibiotics such as tigecycline, polymyxin-B and colistin. The purpose of this study is to determine the antibiotic resistance patterns of A. baumannil isolates, prevalence of multidrug resistance, extended spectrum beta lactamase production and metallo-beta lactamase production.

Methods: This is a prospective study conducted at the department of Clinical Microbiology. Tribhuvan University Teaching Hospital, from December 2013 to September 2014. Ethical approval was taken from the Institutional Review Board of Institute of Medicine. Two hundred and forty six Acinetobacterisolates were identified by standard microbiological testing. Antimicrobial susceptibility testing was performed by Kirby Bauer method as per the CLSI guidelines. Multidrug resistance was determined. ESBL production was detected by combination disc method and confirmed by Clinical and Laboratory Standerd Institute confirmatory test. MBL production was detected by using imipenem and imipenem/EDTA disc.

Result: All 122 Multidrug-resistant A. baumannii isolateswere resistant to majority of the drugs used. All the isolates were completely sensitive to polymyxin B, colistin and tigecycline only. Fifteen (12.29%) isolates of A. baumannii were extended spectrum beta-lactamase producers and 50 (40.98%) were metallo-beta-lactamase producers. Multidrug resistance was common in A. baumannii

Conclusion: Multidrug resistance in A. baumannii is becoming more common ESBL and MBL production should be promptly detected and reported to control the spread of resistant phenotypes to other individuals.