Molecular Characterization of Acinetobacter baumannii with special reference to resistance mechanism & virulence factors: A study from the Andhra Pradesh

The genus Acinetobacter has undergone significant taxonomic modification over the last 30 years. Its most important representative, Acinetobacter baumannii, has emerged as one of the most troublesome pathogens for health care institutions globally. An opportunistic pathogen, A. baumannii has a high incidence among immune-compromised individuals, particularly those who have experienced a prolonged (> 90d) hospital stay. Commonly associated with aquatic environments, it has been shown to colonize the skin as well as being isolated in high numbers from the respiratory and oropharynx secretions of infected individuals.3 In recent years, it has been designated as a red alert human pathogen, generating alarm among the medical fraternity, arising largely from its extensive antibiotic resistance spectrum.The genus Acinetobacter, as currently defined, comprises gram-negative, strictly aerobic, nonfermenting, nonfastidious, nonmotile, catalase-positive, oxidase negative bacteria with a DNA GC content of 39% to 47%. Based on more recent taxonomic data, it was proposed that members of the genus Acinetobacter should be classified in the new family Moraxellaceae within the order Gammaproteobacteria, which includes the genera Moraxella, Acinetobacter, Psychrobacter, and related oraganisms. Acinetobacter species of human origin grow well on solid media that are routinely used in clinical microbiology laboratories, such as sheep blood agar or tryptic soy agar, at a 37 degree Celsius incubation temperature. These organisms form smooth, sometimes mucoid, greyish white colonies. Unfortunately, no single metabolic test distinguishes acinetobacters from other similar non-fermenting gram-negative bacteria. Following DNA-DNA hybridization studies performed by Bouvet and Grimnot in 1986, the Acinetobacter genus now consists of 26 named species and nine genomic species. In India, a retrospective analysis was performed on all patients, seeking medical assistance from the institutes, between January to December 2014, from whom clinical specimens yielded A. baumannii (excluding blood and urine). A. baumannii was isolated from 227 clinical specimens. Multi drug resistance was observed in 175 (77%) isolates and 30 (13%) were extensively drug resistant (XDR) being susceptible only to colistin. Another study highlights that, of the 100 clinical isolates of Acinetobacter species, 78 were A. baumannii, while 22 were A.lwoffi i. Forty six (59.0%) A. baumannii, 7 (31.8%) A. lwoffi i, 32 (31.1%) were found resistant to meropenem For first time we performed Denovo Hybrid Assembly using Illumina & Nanopore Approach to find the novel resistance mechanism and Virulence factors.This project was done in collaboration with Department of Microbiology, Saveetha Dental College & Hospitals, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai , Tamil Nadu India.Other submitters include Monika Ranjan Tatapudi ([e-mail]), Naveena latha J ([e-mail]), AS Smiline Girija ([e-mail])