D-062. Identification of an Exopolysaccharide Involved in Biofilm Formation of Acinetobacter baumannii 307-0294

K. A. Brossard, A. A. Campagnari;
State Univ. of New York, Buffalo, NY.

Acinetobacter baumannii is a Gram-negative aerobic coccobaccillus found ubiquitous in nature. Numerous studies have documented this organism as a cause of community acquired and nosocomial infections, and recent outbreaks among military personnel stationed in the Middle East. Individuals infected with A. baumannii may develop pneumonia, urinary tract, wound, and other infections. Treatment is difficult because of the multi-drug resistant characteristic of A. baumannii strains. Nosocomial infections, specifically those associated with the respiratory and urinary tracts, are primarily associated with the use of indwelling catheters and mechanical ventilation. A. baumannii can persist on abiotic surfaces for days to weeks and this persistence may be due to an ability to form a biofilm. Biofilm formation is an important survival mechanism in harsh environments. In pathogenic and nonpathogenic bacteria, formation of a biofilm provides a mechanism for long term colonization, evasion of the host immune system and resistance to treatment with antibiotics. It has recently been demonstrated that A. baumannii attaches to and forms biofilms on abiotic surfaces similar to other pathogenic organisms that produce an exopolysaccharide which acts as an intercellular adhesin. We have identified a locus in A. baumannii 307-0294 that is involved in production of this exopolysaccharide. Disruption of this locus leads to a phenotypic difference in colony morphology between the mutant and wild type strains. Furthermore, analysis of colony lift assays using wheat germ agglutinin showed detection of an N-acetyl glucosamine polymer surrounding the wild type colonies and the absence of detection in the mutant strain. Disruption of the locus in the mutant resulted in reduced biofilm formation as compared to wild type in static assay. This study suggests that the locus involved in the formation of an exopolysaccharide is significant to the process of biofilm formation in Acinetobacter baumannii 307-0294.