Effects of erythromycin, nystatin and their combination on Pseudomonas aeruginosa and Candida albicans biofilms

Introduction: Pseudomonas aeruginosa is frequently found to coexist and interact with Candida albicans in the polymicrobial biofilms. Considering the pathogenicity of polymicrobial biofilms in many persistent infections, this study was aimed to evaluate the combined effects of antibiotics erythromycin and nystatin on P. aeruginosa-C. albicans polymicrobial biofilm under both aerobic and anaerobic conditions. Methods and Results: Treatment with single (erythromycin or nystatin) and combined antibiotics caused subtle reductions in the number of viable biofilm cells as well as protein and extracellular DNA content of the biofilm extracellular polymeric substance (EPS). Protein profiling demonstrated differential expression of biofilm proteins following exposure to the antimicrobial treatments. Conclusion: These findings suggest that erythromycin and nystatin, either single or in combination affect EPS composition (protein and extracellular DNA) as well as biofilm protein expression