Extracellular DNA-dependent biofilm formation by Staphylococcus epidermidis RP62A in response to subminimal inhibitory concentrations of antibiotics

• Published in: Research in microbiology 2011-06, Vol.162 (5), p.535-541
• Main Authors: Kaplan, Jeffrey B., Jabbouri, Saïd, Sadovskaya, Irina
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - pharmacology; Antibiotics; Bacteriology; Biofilm matrix; Biofilms; Biofilms - drug effects; Biological and medical sciences; Crystal violet binding assay; Deoxyribonuclease; DNA, Bacterial - genetics; DNA, Bacterial - metabolism; Enzymes; Extracellular Space - drug effects; Extracellular Space - metabolism; Fundamental and applied biological sciences. Psychology; Linezolid; Microbial Sensitivity Tests; Microbiology; Miscellaneous; Novobiocin; Polysaccharides; Pulmozyme; rhDNase; Species Specificity; Staphylococcus epidermidis; Staphylococcus epidermidis - drug effects; Staphylococcus epidermidis - genetics; Staphylococcus epidermidis - physiology; Staphylococcus epidermidis 1457; Staphylococcus epidermidis NJ9709; tigecycline; Vancomycin
• ISSN: 0923-2508; 1769-7123
• DOI: 10.1016/j.resmic.2011.03.008

We measured the ability of Staphylococcus epidermidis to form biofilms in the presence of subminimal inhibitory concentrations (sub-MICs) of vancomycin, tigecycline, linezolid and novobiocin. Six strains that produce different amounts of biofilm were tested. The three strains that produced the highest amounts of biofilm exhibited steady-state or decreased biofilm formation in the presence of sub-MIC antibiotics, whereas the three strains that produced lower amounts of biofilm exhibited up to 10-fold-increased biofilm formation in the presence of sub-MIC antibiotics. In two of the inducible strains (9142 and 456a), antibiotic-induced biofilm formation was inhibited by dispersin B, an enzyme that degrades poly- N-acetylglucosamine (PNAG) biofilm polysaccharide. In the third inducible strain (RP62A), dispersin B inhibited biofilm formation in response to sub-MIC vancomycin, but not to sub-MIC tigecycline. In contrast, DNase I efficiently inhibited biofilm formation by strain RP62A in response to sub-MIC tigecycline and vancomycin. DNase I had no effect on antibiotic-induced biofilm formation in strains 9142 and 456a. Our findings indicate that antibiotic-induced biofilm formation in S. epidermidis is both strain- and antibiotic-dependent and that S. epidermidis RP62A utilizes an extracellular DNA-dependent mechanism to form biofilms in response to sub-MIC antibiotics.