Expression of β-Lactamase in Pseudomonas aeruginosa Biofilms

OBJECTIVE To explore production of β-lactamase induced by antibiotics in Pseudomonas aeruginosa biofilm and planktonic bacteria.METHODS In vitro models of P.aeruginosa biofilm were built up.The planktonic bacteria and P.aeruginosa biofilms were exposed to different concentrations of imipenem and ceftazidime.The quantitative analysis of β-lactamase was undertaken.The class of β-lactamase was verified by modified cefoxitin three-dimensional test.RESULTS Both P.aeruginosa biofilm and planktonic bacteria showed significant β-lactamase activity in the presence of antibiotics.The maximal β-lactamase activities of both were significantly different with the statistic method of test(P0.05).The β-lactamase induced was found to be AmpC β-lactamase with modified cefoxitin three-dimensional test.CONCLUSIONS P.aeruginosa biofilm showed stronger ability for β-lactamase production induced by antibiotics than planktonic bacteria.Imipenem is a stronger inducer for of ampC expression than ceftazidime.