Previous studies have shown that NAC could decrease biofilm formation by a variety of bacteria [4–6] and that it inhibited bacterial adherence, reduced the production of extracellular polysaccharide matrix, while promoting the disruption of mature biofilms, and reduced sessile cell viability [4, 7]. Olofsson [7] studied the biofilms of 10 bacterial strains isolated from a paper mill. These results showed that EPS production decreased significantly in the presence of NAC (0.25 mg/ml). Although the growth didn’t affected the most of tested bacteria, the average reduction in the #AZD2171 chemical structure randurls[1|1|,|CHEM1|]# amount of EPS produced was 58% ± 20%; the presence of NAC reduced

the number of attached multi-species community bacteria by as much as 76% ± 46%. There is only one article demonstrated the inhibitory effect of NAC on P. aeruginosa adherence and biofilm formation in vitro by the number of viable cell counts previously, and also revealed that ciprofloxacin/NAC combination showed the highest ability

to inhibit biofilm synthesis and disrupt preformed selleckchem mature biofilms [19]. In our research, inhibitory effects of drugs on biofilms not only determined by the viable count technique, but also were imaged using CLSM and quantified biofilm structures by COMSTAT program, EPS production in the presence of NAC also be examined quantitatively. CLSM can provide three-dimensional, noninvasive inspection and computer reconstruction of mature biofilms O-methylated flavonoid without

appreciable distortion of architecture in a manner similar to computer-assisted tomography and magnetic resonance imaging methods. COMSTAT comprises some features for quantifying three-dimensional biofilm image stacks [20]. Biomass represents the overall volume of the biofilm, substratum coverage reflects how efficiently the substratum is colonized by bacteria of the population, the surface area of biomass is the area which summation of all biomass voxel surfaces exposed to the background, the surface to volume ratio is the surface area divided by the bio-volume which indicates how the biofilm adapts to the environment, roughness provides a measure of how much the thickness of the biofilm varies, and it is also an indicator of biofilm heterogeneity. Our results showed that NAC dispersed the biofilms formed by P. aeruginosa. By visual inspection of CLSM images, NAC disrupted and inhibited PAO1 biofilms, fluorescence and thickness decreased after exposure to NAC and there were dose-dependent effects. Biofilms were nearly detached at 10 mg/ml NAC. Using COMSTAT software, the PAO1 biofilm biomass decreased and its heterogeneity increased gradually in direct proportion to the NAC concentration. NAC also had an independent anti-microbial effect on biofilm-associated P. aeruginosa at 2.5 mg/ml (P <0.01) and had a synergistic effect with CIP.