Indeed, the abundance of polysaccharides in virulent clinical isolates emphasizes their importance in colonization

(Ammendolia et al., 1999). Several reports have demonstrated that PIA synthesis, as well as biofilm formation by S. aureus, are significantly affected by a number of environmental stresses (Cramton et al., 2001; Pamp et al., 2006; Rode et al., 2007; Agostinho et al., 2009). The present study showed diverse patterns of biofilm formation for four S. aureus strains exposed to a different range of culture conditions, including time, temperature, pH, reducing conditions and atmosphere. The MTP method was useful as a quantitative technique to measure the biofilm developed from these studies. Although it is clear that the formation of biofilms had selleck chemicals llc an optimal time (18–24 h), temperature (37 °C) and pH (lightly acidic), it is also evident that this bacterium could form biofilms under a wide range of conditions. This property could explain the ability of this pathogen to persist successfully in medical environments, where cells persist on various surfaces such as those of hospital furniture, medical devices or food installations, where small numbers of many different organisms initially

attach to microirregularities on surfaces, which in time are able to form micro- and macrocolonies that can enter the blood stream and cause septicemia (Herrera et al., 2007). Although S. aureus is now known to produce biofilm, little is known about the environmental factors that triggers this formation. We observed that biofilm Z-VAD-FMK clinical trial formation was influenced by different conditions, with there being a close relation with extracellular stress (eROS and NO). The NBT assay was useful in determining the iROS and eROS

production in S. aureus biofilm and allowed us to observe that the increase in the extracellular stress (eROS and ON) was more significant than that of iROS. NO is obtained from a product of the anaerobic reduction, with of this process resulting in a switch from O2 to NO3−, NO2− or nitrous oxide (N2O) as the electron acceptor. Barraud et al. (2006) detected ONOO− inside microcolonies in Pseudomonas aeruginosa biofilms, with ONOO− being formed from NO oxidation only in the presence of ROS (Barraud et al., 2006). Although it is not clear how ONOO− is produced inside the microcolonies, O2 gradients can occur, with simultaneous O2 and NO3− respiration having recently been demonstrated for P. aeruginosa populations (Chen et al., 2006). Schlag et al. (2007) characterized the response of S. aureus to nitrite-induced stress and showed that it involved the impairment of PIA synthesis and biofilm formation. They also provided evidence that nitrite-derived NO played a role in the inhibition of biofilm formation and that biofilm-embedded staphylococci could be efficiently killed by nitrite in an acidic environment. Despite NO exposure being able to reduce staphylococcal viability (Kaplan et al., 1996), S.