evaluation of anti-biofilm activity of lactobacillus rhamnosus gg and nisin on the expression of aap, ica-a and ica-d as biofilm-associated genes of staphylococcus epidermidis

Background and objectives: in the present study, the anti-biofilm activity of lactobacillus rhamnosus gg and nisin was investigated on biofilm-forming abilities of staphylococcus epidermidis strains and the expression of the biofilm-associated genes. materials and methods: in this study, the standard strain of l. rhamnosus gg (atcc 53103) and nisin were used to assess their anti-microbial and anti-biofilm effects on s. epidermidis (rp62a). results: the mic and mbc analysis showed that nisin at 256 μg/ml and 512 μg/ml, and l. rhamnosus gg at 1×107 cfu/ ml and 1×108 cfu/ml have anti-microbial activity compared to the negative control respectively. l. rhamnosus gg bacteria and nisin inhibited the biofilm formation of s. epidermidis based on optical density of at 570 nm (p <0.001). the relative mrna expression of aap, icaa, and icad genes was significantly reduced compared to the negative control after treating s. epidermidis with sub-mic of nisin (0.44, 0.25 and 0.6 fold, respectively) (p>0.05). in addition, the relative expression of aap and icaa genes, but not icad (p>0.05), was significantly lower than the negative control (0.62 and 0.7 fold, respectively) (p>0.05), after exposure to the sub mic of l. rhamnosus gg. conclusion: nisin and l. rhamnosus gg exhibit potent activity against biofilm-forming abilities of s. epidermidis and these agents could be utilized as an anti-biofilm agents against s. epidermidis infections. .