Résumé
Objective To investigate the effects of levofloxacin,ciprofloxacin,ceftazidime,pip-eracillin,cefoperazone/sulbactam,erythromycin,sulfamethoxazole and gentamycin on the bacterial biofilms of Stenotrophomonas mahophilia.Methotis Biofilm and conventional susceptibilities were determined for S.maltophilia isolates from 42 patients.The model of S.maltophilia biofflms in vitro was developed in the Mueller-Hinton broth--micmtiter inoculator or silica films.After antibiotic challenge plate 20 h,each plate was sonicated and the absorbance value at 620 nm(A620)was measured on a microtiter plate colorimeter be-fore and after incubation for 6 h.Then the biofilm inhibitory concentrations were calculated.Finally,based on the acquired data.the experiments of combinafion effects of erythromycin with the 3 antibiotic agents on the formed biofilms of 5 picked strains were designed and worked out.Results The sensitive rate of 42 S.maltaphilia to levofloxacin.sulfamethoxazole and piperacillin were 83.33%,66.67%and 54.76%,re-spectively.The bilfilm inhibitory concentrations were much higher than the corresponding minimal inhibitory concentrateion after formed biofflms.Conclusion Forty-two S.maltophilia are multi-resistant to antibiotic agent.And levofioxacin may have a better effect against biofilms compared with others.The inhibition effect of combination erythromycin with levofloxacin is more obvious among all the 3 antibiotic agents.