Phenotypic and Genotypic Characterization of Resistance Mechanisms of Invasive Isolates of Carbapenem Resistant Acinetobacter baumannii in a Tertiary Care Centre in India

Abstract

The current study documents the reduced susceptibility rates against the available antimicrobial agents including colistin in carbapenem-resistant A. baumannii. To combat such scenario combination therapy is preferred over monotherapy. To understand the changing trend in the susceptibility profile, ontinuous monitoring of prevailing MDR or XDR A. baumannii is the need of the hour. The present study documents only chromosomal mediated colistin resistance. Though synergistic activity of various novel antimicrobial agents are shown in-vitro, further in-vivo and clinical studies are warranted. Further, mobile genetic elements plays an important in disseminating antibiotic resistance genes and corroborates the rate of genetic variations associated with acquisition of various genetic determinants in A. baumannii. Recent rapid expansion of International clonal lineage of A. baumannii emphasizes the need for epidemiological studies to understand the spread of high risk clones involved in the dissemination of antibiotic resistance genes. Comparative genomic studies using WGS provides comprehensive and accurate information on the diverse genome of A. baumannii to understand the evolution, resistance mechanisms and epidemiology. Future Recommendations: Accurate phenotypic identification of Acinetobacter baumannii from Acb complex is difficult. A universal molecular-based detection method has to be implemented. Continuous monitoring of anti-microbial susceptibility profile and anti-microbial resistance pattern of A.baumannii is crucial: to track the change in the trend, to implement proper infection control and to guide appropriate empirical anti-microbial therapy. Comparative genomic analysis using complete genomes will be helpful in the characterization of resistome, virulome, mobilome and to understand the newlineepidemiology of clinical isolates of A. baumannii. Combination of drugs targeting different resistance mechanisms will be helpful for the treatment of Acinetobacter infections.