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

Keli Cristine Reiter1, Gustavo Enck Sambrano, Bárbara Villa

  • 1Programa de Pós-graduação em Ciências da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brasil. kelicrisr@gmail.com

Revista Da Sociedade Brasileira De Medicina Tropical
|August 30, 2012
PubMed
Abstract

Insights

Rifampicin showed limited efficacy against biofilm-forming methicillin-resistant Staphylococcus aureus (MRSA). While vancomycin and rifampicin combination inhibited biofilm, neither eradicated mature MRSA biofilms effectively.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Pharmacology

Background:

  • Antimicrobial activity against biofilms is influenced by molecular properties.
  • Vancomycin is a standard treatment for methicillin-resistant Staphylococcus aureus (MRSA) infections.
  • Rifampicin exhibits potential antibiofilm properties, but its effectiveness requires further definition.

Purpose of the Study:

  • To investigate the activity of rifampicin, alone and in combination with vancomycin, against biofilm-forming MRSA.
  • To determine the efficacy of these agents in eradicating and inhibiting mature MRSA biofilms.

Main Methods:

  • Utilized a twofold serial broth microtiter method for determining antimicrobial concentrations.
  • Assessed biofilm challenge and bacterial count recovery to evaluate efficacy.
  • Determined Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), and Minimum Biofilm Eradication Concentration (MBEC).

Main Results:

  • Rifampicin and vancomycin MICs and MBCs were determined for planktonic MRSA.
  • MBEC values for mature biofilms were significantly higher (64 to 32,000-fold for rifampicin, 32 to 512-fold for vancomycin) compared to planktonic cells.
  • Vancomycin combined with rifampicin demonstrated biofilm inhibitory capacity, reducing bacterial load (1.43 and 0.56 log10 CFU/ml for weak and strong biofilm producers, respectively), but did not achieve in vitro eradication.

Conclusions:

  • Rifampicin alone was ineffective in killing biofilm-forming MRSA in this study.
  • Rifampicin demonstrated a lower ability to eradicate mature MRSA biofilms compared to vancomycin.
  • Combined vancomycin and rifampicin showed biofilm inhibition but not complete eradication of mature MRSA biofilms.

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