detection of intracellular adhesion (ica) gene and biofilm formation staphylococcus aureus isolates from clinical blood cultures

b a ckground : in fact the biofilms are composed of bacterial cells living inmulticellular structures such as tissues and organs embedded within a self-produced matrix of extracellular polymeric substance (eps). ability to attach and biofilm formation are the most important virulence factors staphylococcus aureus isolates. the aims of this study were to detect intracellular adhesion (ica) locus and its relation to the biofilm formation phenotype in clinical isolates of s. aureus isolated from bloodcultures. methods : a total of 31 clinical s. aureus isolates were collected from loghman hospital of tehran, iran. in vitro biofilm formation ability was determined by microliter tissue culture plates. all clinical isolates were examined for determination the ica locus by using pcr method. r esults: twelve (38.7%) of the isolates were strong biofilm producers. the results showed that 18(80.6%) of the isolates carried icad gene, whereas the prevalence of icaa, icab and icac were 51.6%, 45.1% and 77.4% respectively. c o nclusions : s. aureus clinical isolates have different ability to form biofilm. this may be caused by the differences in the expression of biofilm related genes, genetic make-up and physiological conditions.