In Vitro Study of bactericidal activity of β-lactam and aminoglycoside antibiotics against biofilm cells of Pseudomonas aeruginosa

Pseudomonas aeruginosa is gram negative and opportunistic bacteria, causing a wide variety of infections.This bacteria produces biofilm. A biofilm is a population of cells growing on a surface and enclosed in an exopolysaccharide matrix. Biofilm infections are difficult to eradicate with antimicrobial treatment. In this study 42 clinical isolates of P. aeruginosa were collected from hospital. P. aeruginosa strain 214 producing higher biofilm was selected for further study. We investigated biofilm production with scanning electeron microscope and the bactericidal activity of β-lactam and aminoglycoside against biofilm and planktonic cells. The result showed high difference in antibiotic susceptibility between planktonic and biofilm populations.Biofilm cells were complety eradication by treatment with 128 MIC gentamicin and 64MIC amikacin,whereas the biofilm still remained during treatment at a concetration 2560μg/ml of β-lactam (Imipenem and ceftazidim).