05) (Figure  6A). In order to understand the effects of DNAse at different stages of biofilm formation, we exposed developing biofilms to DNAse (0.65 mg/ml) at 0, 6 and 18 hrs and developed the biofilms up to 24 hrs (Figure  6B). At all Inflammation related inhibitor starting exposures, DNAse decreased biofilm formation at 24 hrs significantly compared to controls (p < 0.05). Percentage reduction

in biofilms was more pronounced for mixed species biofilms compared to single species biofilms, indicating the higher eDNA content of the mixed species biofilms (Figure  6C). Figure 6 Biofilm disruption of eDNA by DNAse. Twenty four hr single species and mixed species biofilms were exposed to DNAse for 16 hr at concentrations from 0 (buffer) to 1.25 mg/ml (Figure 6 A). Biofilm formation was significantly decreased by DNAse at 1.25 mg/ml compared to buffer (p < 0.05) and the biofilm AZD1480 mouse disruption effect was concentration dependent. A time course experiment was performed by the addition of DNAse (0.65 mg/ml) at 0, 6 or 18 hrs and biofilm development continued

till 24 hr and quantitated (Figure 6 B). Both S. epidermidis and mixed species biofilm formation were significantly decreased Omipalisib supplier (p < 0.05) after addition of DNAse at the three time-points of DNAse exposure. Percentage reduction in biofilms was more pronounced in mixed species biofilms compared to single species S. epidermidis biofilms (Figure 6 C). S. epidermidis biofilms are represented in white squares and bars and mixed species biofilms in gray squares and bars. Discussion We evaluated the morphology of mixed species biofilms of S. epidermidis and C. albicans, in vitro. We observed enhancement of biofilms in a mixed species environment. In a mouse subcutaneous catheter model of biofilm infection, we noted increased catheter infection and systemic dissemination of S. epidermidis in a mixed species environment. To further explore the reasons for increased pathogenicity of S. epidermidis in mixed species biofilm infections with C. albicans, we evaluated the transcriptome of S. epidermidis in a mixed species environment and found that the repressors of autolysis, lrgA and lrgB were highly down regulated. Down regulation of repressors of autolysis,

is associated with increased eDNA in the biofilm matrix, possibly by increased enough bacterial autolysis. We confirmed the significance of increased biofilm eDNA by evaluating its degradation by DNAse. Mixed species biofilms of S. epidermidis and C. albicans were significantly thicker and voluminous compared to single species biofilms of either organism in vitro. Increased thickness of mixed species biofilms can be due to increase in the number of organisms or increase in the extracellular matrix or possibly both. In mixed species biofilm infections in vivo, at 8 days of infection, we observed increase in catheter CFU/ml of S. epidermidis associated with blood dissemination. Mixed species biofilms in vivo may further be modified by environmental milieu e.g.