Genomics of Acinetobacter baumannii

Nosocomial bacterial infection is a formidable public health problem that has become particularly alarming in recent decades as antibiotic resistance has proliferated and multi-drug resistant (MDR) strains of various bacterial pathogens have emerged. Within this milieu, a dramatic increase in the frequency of nosocomial MDR Acinetobacter baumannii infections in US hospitals has been reported, resulting in limited therapeutic options since some isolates of A. baumannii are resistant to almost all currently available antibacterial agents. Infections with MDR A. baumannii-calcoaceticus complex (ABC) and other MDR bacteria have also complicated the care of US combat casualties from recent engagements in Iraq, where the acquisition of MDR appears to be significantly increased compared with past wars. Based on current epidemiological data, specific strains and isolates of MDR ABC may be more closely associated with greater morbidity and mortality than others. Consequently there exists a critical need to rapidly distinguish between different strains of MDR ABC to enhance infection control practices and assist in tracking the proliferation of more virulent strains, and to reveal the underlying molecular basis for virulence differences between strains. 

The genomes of 12 high priority A. baumannii-calcoaceticus complex (ABC) isolates, from both clinical and environmental origins, will be completed using the latest 454 Titanium paired-end technologies. In addition, to better understand the ABC pan genome and to aid in future development of a comprehensive A. baumannii species microarray, we will use subtractive hybridization techniques developed at the PFGRC to sequence only the unique DNA fragments from each of 38 isolates. We hope to elucidate the mechanisms underlying the differences in virulence associated with different strains of multi-drug resistant ABC as well as provide the framework for the development and deployment of a species microarray that will serve as a tool for the comprehensive genetic characterization of A. baumannii and other MDR isolates for epidemiology and infection control purposes by the U.S. military and civilian health care providers.

White Paper Access

The initial white paper submitted can be downloaded here. Since white papers are not always approved exactly as submitted, this document may not exactly describe the final form of the project. Please contact if you have any questions.


This project has been funded in whole or part with federal funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services under contract numbers N01-AI30071 and/or HHSN272200900007C.

Principal Investigator


Mikeljon Nikolich, PhD
Microbiologist Walter Reed Army Institute of Research


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