prevalence of is256 among icapositive and biofilm non-producing staphylococcus epidermidis clinical isolates

Background: s. epidermidis is one of predominant members of human normal microflora, however it may be the main cause of nosocomial infections related to medical devices put into the body and thus the biofilm formation is a main route for pathogenesis which is affected by icaadbc operon. in this study, the prevalence of is256 sequence among ica-positive and biofilm non-producer clinical isolates of s. epidermidis was investigated. methods: in this study, 100 clinical isolates of s. epidermidis were collected from different infections. the is256 sequence, icaadbc operon and biofilm formation by microtiter plate assay were evaluated among them. the antibiotic susceptibility of these isolates was done with disc diffusion by using c efoxitin, ciprofloxacin, erythromycin, gentamycin, oxacillin and tetracycline discs. results: of 100 isolates, 18 (18%) were ica operon-positive from which 18%, 14%, 16% and 17% contained icaa, icad, icab and icac genes, respectively. moreover, 14 of 18 (77.77%) ica-positive isolates amplified the is256 gene. the biofilm formation by microtiter plate assay showed that 18 (18%) isolates were strong biofilm producers, 21 (21%) produced intermediate level biofilm and 14 (14%) and 47 (47%) isolates were weak and non-biofilm producers, respectively. in the antibiotic susceptibility test, the majority of isolates were resistant to oxacillin and lowest resistance was against ciprofloxacin. conclusion: the statistical analysis with p<0.05 exhibited that there was a reverse relation between biofilm production and the insertion of is256, and in fact the higher prevalence of is256 among isolates, the biofilm formation declined. data showed that amongst most of ica-positive isolates, the is256 was detected and therefore other genetic factors affect the expression of this operon.