Maryam Danesh - Department of Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran
Fateh Rahimi - Department of Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran

Background: Staphylococcus epidermidis isolates are among the most important causes of nosocomial infections and could be classified as health threatening agents. This study aimed to determine the biofilm formation ability and clonal dissemination of S. epidermidis strains isolated from patients and healthy people in Isfahan during ۲۰۱۶ and ۲۰۱۷. Materials & Methods: A total of ۱۳۹ and ۱۲۳ suspected colonies of S. epidermidis were collected from different clinical specimens and the arm of healthy people, respectively. The ability to form biofilm was determined using a combination of Congo-red agar (CRA) and microtiter plate (MTP) assays. The presence of genes involved in biofilm formation was also tested by the polymerase chain reaction (PCR) test. The susceptibility of all strains to ۱۲ antibiotics was evaluated using the disk diffusion method according to the Clinical & Laboratory Standards Institute (CLSI) guidelines. Moreover, all biofilm-producing strains were typed using PhenePlate system as well as cassette chromosome mec (SCCmec) and accessory gene regulator (agr) locus typing method. Findings: A total of ۴۳ biofilm-producing S. epidermidis strains were identified among ۱۰۷ and ۱۲۳ confirmed strains isolated from hospitalized patients and healthy people, respectively; all of which were positive for aap gene, and the presence of ica operon was limited to ۸۶ and ۲۷% of the strains isolated from patients and healthy people, respectively. All the strains showed susceptibility to vancomycin, quinupristin-dalfopristin, and linezolid. Moreover, SCCmec Types III, IV, and V were detected among all methicillin-resistant S. epidermidis (MRSE) strains, and agr Type I was the most frequent one. Among all biofilm-positive strains, ۳ common types (CTs) and ۷ single types (STs) were determined;  CT۱ and CT۲ were the most common types among the strains isolated from hospitalized patients and healthy people. Conclusion: These findings indicated the presence and persistence of diverse clone types of biofilm-producing S. epidermidis strains with common types of PhP, agr, and SCCmec in the hospital and the community of Isfahan.

Staphylococcus epidermidis, Biofilm, Congo red, Hospitals, Healthy people, Bacterial typing.