[Effect of macrolides on biofilm of mucoid Pseudomonas aeruginosa].

OBJECTIVE: To observe the effect of macrolides with different structures on biofilm of mucoid Pseudomonas aeruginosa so as to provide a theoretical basis for treatment of bacterial biofilm diseases.

METHODS: Modified plate culture method was used to establish in vitro bacterial biofilm model, which was identified by silver nitrate staining. After the biofilm was treated by gatifloxacin and/or macrolides with different structures and of different concentrations, the number of viable bacteria was measured by MTT method and bacterial adherence was measured by crystal violet staining.

RESULTS: Clarithromycin and azithromycin of 1/4 and 1/16 MIC combined with gatifloxacin significantly inhibited the adherence of mucoid Pseudomonas aeruginosa (P < 0.05) and reduced the number of viable mucoid Pseudomonas aeruginosa compared with gatifloxacin alone (P < 0.05), while such effects could not be seen for rovamycin.

CONCLUSION: Inhibiting the adherence of mucoid Pseudomonas aeruginosa may be one of the mechanisms by which macrolides such as clarithromycin and azithromycin enhance the antibacterial activity of gatifloxacin against mucoid Pseudomonas aeruginosa.