Rifampicin fails to eradicate mature biofilm formed by methicillin-resistant Staphylococcus aureus

Revista da Sociedade Brasileira de Medicina Tropical

Keli Cristine Reiter²  Gustavo Enck Sambrano¹  Bárbara Villa¹  Thiago Galvão Da Silva Paim²  Caio Fernando De Oliveira²  Pedro Alves D'azevedo² 

[1] ,Universidade Federal de Ciências da Saúde de Porto Alegre Programa de Pós-graduação em Ciências da Saúde Porto Alegre RS

关键词: Staphylococcus aureus;    Rifampicin;    Vancomycin;    Biofilm;    Resistance;    Staphylococcus aureus;    Rifampicina;    Vancomicina;    Biofilme;    Resistência;   

DOI  :  10.1590/S0037-86822012000400011

来源: SciELO

【 摘 要 】

INTRODUCTION: Antimicrobial activity on biofilms depends on their molecular size, positive charges, permeability coefficient, and bactericidal activity. Vancomycin is the primary choice for methicillin-resistant Staphylococcus aureus (MRSA) infection treatment; rifampicin has interesting antibiofilm properties, but its effectivity remains poorly defined. METHODS: Rifampicin activity alone and in combination with vancomycin against biofilm-forming MRSA was investigated, using a twofold serial broth microtiter method, biofilm challenge, and bacterial count recovery. RESULTS: Minimal inhibitory concentration (MIC) and minimal bactericidal concentration for vancomycin and rifampicin ranged from 0.5 to 1mg/l and 0.008 to 4mg/l, and from 1 to 4mg/l and 0.06 to 32mg/l, respectively. Mature biofilms were submitted to rifampicin and vancomycin exposure, and minimum biofilm eradication concentration ranged from 64 to 32,000 folds and from 32 to 512 folds higher than those for planktonic cells, respectively. Vancomycin (15mg/l) in combination with rifampicin at 6 dilutions higher each isolate MIC did not reach in vitro biofilm eradication but showed biofilm inhibitory capacity (1.43 and 0.56log10 CFU/ml reduction for weak and strong biofilm producers, respectively; p<0.05). CONCLUSIONS: In our setting, rifampicin alone failed to effectively kill biofilm-forming MRSA, demonstrating stronger inability to eradicate mature biofilm compared with vancomycin.

【 授权许可】

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