Pathogenic effects of biofilm with chronic pseudomonas aeruginosa lung infection in rats

ObjectiveTo establish an animal model of P.aeruginosa biofilm associated with chronic pulmonary infection and investigate the pathogenic effects of biofilm.MethodsExperiments in vitro, measuring the MICS, MBCS of levofloxacin(LFX), ceftazidime(CAZ) in PAO579 in alginate beads and planktonic PAO579. Rats were challenged with 0.1 ml of PAO579(109CFU/ml) in alginate beads or 0.1 ml of planktonic PAO579(109 CFU/ml), 3,7,14 days after challenging, bacteriological, pathological features were observed.ResultsThe MICS, MBCS of LFX, CAZ in PAO579 in alginate beads were higher than those in planktonic PAO579 in vitro. CFU/lung in alginate beads group was significantly higher than that in planktonic bacteria group(P =0.002, P =0.004, P = 0.002, respectively); macroscopic lung pathology and the inflammation in alginate beads group were significantly more severe compared to those in planktonic bacteria group in vivo.ConclusionP.aeruginosa biofilm protected bacterium from killing of antibiotics and might mediate the host immune damage in the lung tissue and made bacterium evade the host immune defense.