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Introduction: Biofilm formation mediated by a polysaccharide intercellular adhesin (PIA) is considered a major pathogenic factor of staphylococcus epidermidis. PIA production is regulated by icaADBC operon. IS256 causes phase variation of biofilm formation by inactivation of ica operon. This study was aimed at investigating the prevalence of IS256 and biofilm formation in staphylococcus epidermidis isolated from healthy human skin.
 
Materials & Methods: 91 isolates of staphylococcus epidermidis were collected from the surface of healthy human skin. All the isolates were examined in terms of ability of biofilm formation by Microtiter plate assay. PCR technique with specific primers was used to determine the presence of IS2556. Additionally, all the isolates containing  IS256 were examined in term of aminoglycoside resistance, fluoro- quinolones, macrolides, and glycopeptides by disk diffusion method. Data were analyzed using SPSS software.
 
Findings: Out of the 91 isolates, only 8 (8/79%) cases contained IS256. The microtiter plate assay results showed that attachment abilities 58 (63/73%) lacked, 6 (6/6%) were weak, 14 (15/38%) were moderate and 13 (14/29%) were strong biofilm producers. The isolates containing IS256, 6 (75%) lacked, 1 (12/5%) was weak, and 1(12/5%) was moderate biofilm producer. The  isolates containing IS256, 3 (37/5%) were resistant to gentamicin, 2 (25%) to amikacin, 2 (25%) to streptomycin, 1(12/5%) to ciprofloxacin, 1(12/5%) to ofloxacin and 4 (50%)  were resistant to erythromycin, but no resistance to vancomycin was observed.
 
Discussion & Conclusions: The results demonstrated no relation  between the IS256 and biofilm formation. Not mutch resistance to aminoglycosides was observed in isolates containing IS256 hich. This is quite incompatible with the so-called role of IS256 in forming aminoglycoside resistance

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Introduction: Staphylococcus aureus is one of the critical pathogens resulted in hospital land community-acquired infections. Aminoglycosides are potent bactericidal agents that are often used in staphylococcal infection treatment in combination with a beta-lactam or glycopeptide antibiotics. The aim of this study was to determine the frequency of encoding gene ofaac (6΄)-Ie/aph (2˝).This gene is one of the important aminoglycoside modifying enzymes in combination with mecA which results in methicillin resistance. In doing so, disk diffusion and polymerase chain reaction (PCR) methods were utilized in clinical isolates of methicillin resistant staphylococcus aureus (MRSA).
 
Materials & Methods: In the current study, 174 clinical isolates of MRSA were obtained from different clinical specimens, including blood, sputum, trachea, brunch, pleura, urine, wound, and catheter. Antibiotic resistance of erythromycin, clindamycin, ciprofloxacin, gentamicin, cefazolin, rifampicin, doxycycline, cotrimoxazole and vancomycin was determined using Kirby-Bauer disk diffusion test method according to the CLSI guidelines. The presence of MRSA was confirmed using oxacillin and cefoxitin anti biotic disc diffusion. Subsequently, DNA of MRSA isolates was investigated to detect mecA and aminoglycoside resistance aac (6΄)-Ie/aph (2˝) genes using PCR.
 
Findings: The results obtained from biogram anti-microbial susceptibility test system indicated that all of the isolates were resistant to oxacillin and cefoxitin. All of the isolates were sensitive to vancomycin and majority of them were resistant to erythromycin (84.8%). According to PCR test results, 100 and 78.3% of the isolates were positive for the mecA and aac(6′)/aph(2˝)-Ia genes, respectively.
 
Discussion & Conclusions: According to the results, the aminoglycoside resistance geneswere highly prevalent in MRSA isolates.