The Study of removing resistant factor of chronic lower respiratory tract infection

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This study was designed to investigate the in vitro effects of the macrolide erythromycin (EM) on biofilm formation by Pseudomonas aeruginosa. In addition the PMN phagocytosis of macrolide pretreated P.aeruginosa during biofilm formation was investigated.Non-mucoid or mucoid P.aeruginosa adhered silicone pieces were cultured with or without 1/4 MIC of EM.Alginic acid and glycocalyx production were measured by HPLC method and tryptophan assay. The human PMN phagocytosis of EM pretreated P.aeruginosa embedded in the biofilm was examined using flow cytometric analysis and chemiluminescence assay.The alginic acid and glycocalyx production of P.aeruginosa were suppressed by EM at concentrations below the minimum inhibitory concentration (sub-MIC), and biofilm formation was found to be reduced. PMN phagocytosis of EM pretreated non-mucoid or mucoid P.aeruginosa embedded in biofilm was significantly higher than that of untreated organisms.These findings confirmed that macrolides can reduce biofilm formation by P.aeruginosa and suggested that this reduction may enhance PMN phago-cytosis of mucoid and non-mucoid strains of P.aeruginosa. As conclusion, it is suggested that macrolides may be useful in the treatment of chronic respiratory tract infection caused by P.aeruginosa.