Effects of Macrolides on Nontypeable Haemophilus influenzae Biofilm Formation

OBJECTIVE To study the treatment effect of macrolides on nontypeable Haemophilus influenzae biofilm formation.METHODS Two strains of H.influenzae were isolated from sputum specimens from patients with acute exacerbation of chronic obstructive pulmonary diseases.Formation of bacterial biofilm was examined by crystal violet assay and scanning electron microscope.The biofilms were measured under varying concentrations of macrolides in vitro.RESULTS Biofilm synthesis was observed at subMIC and became thicker in roxithromycin and erythromycin at 1/8 MIC,Disruption of mature biofilms could be achieved at relatively higher concentration,Azithromycin displayed more powerful activity.CONCLUSIONS H.influenzae is capable to form biofilm in vitro,especially in subconcentration.Sufficient antibiotics dosage might affact early formation of biofilms.Azithromycin exerts better effects on biofilm formation than other macrolides.