[Influence of roxithromycin combined with fleroxacin on bacterial biofilm induced by Pseudomonas aeruginosa].
OBJECTIVE
To investigate the influence of roxithromycin (RXM) on the production of glycocalyx (GLX) and the synergic effect of RXM and fleroxacin (FLRX) on P. Aeruginosa biofilms.


METHODS
Bacterial biofilm (BF) was established and was influenced by RXM and FLRX with different concentrations. The samples were detected with scanning electron microscope and by a rapid method after BF was stained with AgNO3 solution. The synergism of antibacterial activities of RXM and FLRX to P. Aeruginosa was studied by computer image analysis and MTT method.


RESULTS
GLX production was reduced significantly by both 1/16 MIC and 1/4 MIC RXM (P < 0.01). 1/16 MIC and 1/4 MIC RXM showed no bactericidal activities to P. Aeruginosa in biofilms, while viable counts in biofilms almost had no difference. However, RXM could enhance the bactericidal activity of FLRX to P. Aeruginosa in biofilms. When FLRX of different concentrations was combined with 1/16 MIC and 1/4 MIC RXM respectively, the difference of the stained BF was counted up by computer image analysis system with significance of P < 0.05 and the viable counts were reduced significantly (P < 0.05). The results was in accordance with SEM pictures.


CONCLUSIONS
RXM has no direct bactericidal activities to P. Aeruginosa in biofilms, but it could inhibit GLX production. It can be considered that RXM could enhance antibacterial activities of FLRX by enhancing the permeability of FLRX into biofilms.
Chen
Q
Q
Department of Clinical Pharmacology, Department of Pulmonary, General Hospital of PLA, Beijing 100853, China.
Wang
R
R
Fang
X
X
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001422:Bacterial Adhesion; D018441:Biofilms / Q000187:drug effects*; D004357:Drug Synergism; D016576:Fleroxacin / Q000494:pharmacology*; D019276:Glycocalyx / Q000187:drug effects; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D015575:Roxithromycin / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D015575:Roxithromycin; D016576:Fleroxacin