Effect of Combination Antimicrobial Therapy on C. albicans-S. aureus Polymicrobial Biofilms

Ref ID: 18792

Author:

A. Shoyinka, MD (Doctor of Medicine) – Fellow1, N. Doyon-Reale, B SC – Research Assistant 1, M. P. Ponniah, B SC – Research Assistant 1, M. M. Harriot, PhD – Professor 1,2, J. A. Vazquez, MD – Professor 1;

Author address:

1Henry Ford Hlth. System, Detroit, MI, 2Oakland Univ. William Beaumont Sch. of Med., Rochester, MI.

Full conference title:

52nd Annual ICAAC

Date: 9 September 2014

Abstract:

Background: A significant proportion of human infections involve biofilms. Biofilm embedded organisms are more resistant to antimicrobial therapy and are able to withstand host immune defenses. It is established that C.albicans forms polymicrobial (PM) biofilms with S.aureus. In this study, our goal was to investigate the effects of combination antifungal and antibacterial therapy on C.albicans and S.aureus monomicrobial (MM) and PM biofilms. We hypothesized that combination therapy would be more effective than monotherapy in reducing the microbial load in PM biofilms. Methods: Laboratory and clinical strains of C.albicans (106) and S.aureus (107)(methicillin susceptible (MSSA) and resistant (MRSA)) alone and in combination were added to 96-well plates in 50% bovine serum and incubated at 35°C for 24 h. Biofilms were then treated for an additional 24h with amphotericin B (AmB), micafungin or caspofungin alone or in combination with vancomycin. CFUs assays were used to assess the effect of the drugs. Results: All strains of MSSA and MRSA were more resistant to vancomycin in the PM biofilm compared to the MM biofilm. However, both MSSA and MRSA in PM biofilm demonstrated increased susceptibility to vancomycin when treated simultaneously with vancomycin and either micafungin, caspofungin or AmB. Additionally, C.albicans/MRSA PM biofilms was more resistant to micafungin compared to C.albicans/MSSA PM and monomicrobial biofilms. Lastly, AmB had a greater effect than micafungin or caspofungin on C.albicans in PM biofilms. Overall, the patterns of response to these drug combinations in all strains of MRSA/C.albicans in biofilm were similar.Conclusions: Combination treatment of PM biofilms with antifungals and antibacterials resulted in better inhibition of these resistant communities. The results from this study indicate that combination therapy should be considered in the treatment of PM C.albicans/S.aureus biofilm infections.

Abstract Number: M-1713

Conference Year: 2012

Link to conference website: NULL

New link: NULL

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