Prevalence of pgaABCD locus in biofilm formation Acinetobacter baumannii

Abstract

 

Acinetobacter baumannii is a common cause of nosocomial infections. This bacterium has the ability to survive in different environmental conditions and colonize on biotic and abiotic surfaces to produce biofilm. Biofilm is a structure with three-dimensional of a multicellular complex in which the cells are embedded in an extracellular polymeric substance that was produced by the organism itself. The matrix of biofilm includes ions, proteins, nucleic acids, and polymers of polysaccharides. The crucial factor to form biofilm in A. baumannii is the induction of poly-1,6-N-acetylglucosamine (PNAG), which is a surface polysaccharides and considers a virulence factor essential for adherence and aggregation by many Gram-negative bacteria. Several studies concluded that PNAG is crucial factor to keep the robustness of A. baumannii under stressful and dynamic environmental conditions. A. baumannii pgaABCD locus of four genes (pgaA, pgaB, pgaC, and pgaD) encode proteins, which are involved in the synthesis of PNAG. Using PCR analysis concluded that 91.7% of A. baumannii clinical isolates had pgaABCD genes and microtitration plate method indicated that 25% of the isolates produced strong-biofilm, 71% produced moderate-biofilm and 4% of isolates were nonforming biofilm. Statistical analysis showed a significant correlation P less than 0.0001 between biofilm production and the functional role of four genes of the pgaABCD loci.