title: Distribution of erm genes among Staphylococcus aureus isolates with inducible resistance to clindamycin in Isfahan, Iran.
abstract: BACKGROUND
  The rising frequency of methicillin resistant Staphylococcus aureus (MRSA) has led to an increased use of antibiotics such as macrolide, lincosamide, streptogramin B (MLSB) for the treatment of S. aureus infections. Resistance to MLSB in S. aureus is commonly encoded by erm genes, which can be constitutive MLSB (cMLSB) or inducible MLSB (iMLSB). The purpose of this study was to determine the frequency of cMLSB, iMLSB, and MS phenotypes using D-test and polymerase chain reaction (PCR) methods.
  
  
  METHODS
  A total of 215 isolates of S. aureus were collected from January 2010 to May 2012 from Al-Zahra Hospital in Isfahan. PCR was performed for detection of mecA gene on all isolates using specific primers. The frequency of MLSB-resistant isolates was determined using D-test, and then a multiplex PCR was performed for detection of ermA, ermB, and ermC genes.
  
  
  RESULTS
  Among 215 S. aureus isolates examined, 82 (40.9%) were MRSA, and iMLSB, cMLSB, and MS resistance phenotypes had a frequency of 9 (4.18%), 58 (26.9%), and 11 (5.1%), respectively. Among nine isolates with iMLSB resistance phenotype, four isolates contained ermC gene, two isolates ermB gene, and one isolate ermA gene. Two isolates did not have any erm gene.
  
  
  CONCLUSIONS
  In the current study, cMLSB was the most frequent phenotype and ermC was the most common gene in iMLSB resistant phenotypes.
authors.affiliation: Department of Microbiology, Faculty of Bioscience, Falavarjan Branch, Islamic Azad University, Isfahan, Iran.
authors.forename: Fahimeh
authors.initials: F
authors.lastname: Ghanbari
authors.affiliation: Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Hasan
authors.initials: H
authors.lastname: Ghajavand
authors.affiliation: Department of Endodontics, School of Dentistry, Zahedan University of Medical Sciences, Zahedan, Iran.
authors.forename: Roholla
authors.initials: R
authors.lastname: Havaei
authors.affiliation: Cellular and Molecular Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran.
authors.forename: Mohammad-Saeid
authors.initials: MS
authors.lastname: Jami
authors.affiliation: Department of Medical Bacteriology and Virology, Ghaem Hospital, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Farzad
authors.initials: F
authors.lastname: Khademi
authors.affiliation: Department of Microbiology, Faculty of Bioscience, Falavarjan Branch, Islamic Azad University, Isfahan, Iran.
authors.forename: Leila
authors.initials: L
authors.lastname: Heydari
authors.affiliation: Department of Microbiology, School of Medicine, Ahvaz University of Medical Sciences, Ahvaz, Iran.
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Shahin
authors.affiliation: Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Seyed Asghar
authors.initials: SA
authors.lastname: Havaei
keywords: Clindamycin; D-test; Staphylococcus aureus; erm genes; inducible resistance