Fatemeh Iranpour - Department of Microbiology and virology, Faculty of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran.
Peyman Faridifar - Department of Microbiology, Zanjan Branch, Islamic Azad University, Zanjan, Iran.
Fatemeh Mohammadi - Department of Microbiology, Islamic Azad University, Tehran branch, Tehran, Iran.
Bahman Mirzaei - Department of Microbiology, Microbial research center, Pasteur Institute of Iran, Tehran.
Mostafa Shahmoradi - Department of Microbiology, Microbial research center, Pasteur Institute of Iran, Tehran.
Seyed Fazlollah Mousavi - Department of Microbiology, Microbial research center, Pasteur Institute of Iran, Tehran.

Introduction and Objectives: Staphylococcus epidermidis as an important opportunistic pathogen and a major reason for foreign body infections owing to antibiotic resistance to the greatest of the antibiotics is looked upon as a health threat in hospitalized patients. The present study aimed to investigate the in vitro biofilm formation capacity, the presence of biofilm related genes (icaA, icaB, icaC, icaD, sdrG and atlE) and antibiotic susceptibility patterns of clinical S. epidermidis isolates. Materials and Methods: Following the isolation of coagulase-negative staphylococci taking advantage of traditional biochemical procedure, S. epidermidis isolates were identified by molecular approaches. The frequency of biofilm related genes was assessed by multiplex colony PCR. Biofilm formation and antibiotic susceptibility testing were assessed by microtiter plate and disk diffusion methods, respectively. Results: 54 isolates of S. epidermidis were identified according to molecular detection of sesC gene. Biofilm formation phenotype was detected in all S. epidermidis isolates; 45 (83.33%) of isolates produced strong biofilm and 5 (9.26%) of isolates formed the moderate biofilm and 4 (7.41%) strains as weak biofilm producer. The most frequent biofilm related gene was sdrG (98%), followed by atlE (84%), icaC (80%) and icaD (70%). Basing on the susceptibility testing, Cefamandole and Amikacin are the most effective antibiotics against and the least effects belonged to Methicillin and Amoxicillin/Clavulanic Acid. Conclusion: Because of the increasing frequency of biofilm forming S. epidermidis and antibiotic resistance, a prompt determination is essential for eradication of introduced strains that have the ability of biofilm-forming and resistance to an antibiotic for avoiding other medical devices related infections.

Staphylococcus epidermidis, Biofilm-related genes, Multiplex Colony PCR, atlE, sdrG, icaADCB