Pseudomonas aeruginosa biofilm and the properties of polysaccharide associated antibiotic resistance

High density growth of bacteria tend to form biofilms by excreting an extracellular matrix. This matrix is composed of adhesive components such as polysaccharides. The polysaccharides serve as cell-to-cell attachments and a selective filter for which outside material must pass. By forming the biofilm, the bacteria create a defense mechanism against antibiotic attacks and other abrasive environmental factors. Pseudomonas aeruginosa is a biofilm forming bacteria with known antibiotic resistance. Four strains were tested, ΔwspF, ΔwspF Δpel, ΔwspF Δpsl, and ΔwspF Δpel Δpsl. Each strain produced differing amounts of the polysaccharides PEL and PSL. The antibiotics gentamicin and ciprofloxacin were used to test antibiotic tolerance of the differing polysaccharides. The results showed that PSL provided antibiotic tolerance against gentamicin but was susceptible to ciprofloxacin. PEL provided antibiotic tolerance to ciprofloxacin but was susceptible to gentamicin