title: Clonal dissemination of methicillin-resistant Staphylococcus aureus in patients and the hospital environment.
abstract: BACKGROUND
  Methicillin is the drug of choice to treat infections caused by resistant strains of Staphylococcus aureus. However, methicillin-resistant S. aureus (MRSA) is now becoming endemic in many hospitals worldwide and is the cause of nosocomial outbreaks.
  
  
  METHODS
  To assess clonality and dissemination of MRSA strains in the hospitals of Tehran, a total of 60 MRSA strains were isolated from hospitalized patients (n=44) and hospital equipment and environment (n=16) of three metropolitan hospitals in Tehran between July 2009 and March 2010. These strains were subjected to antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), and biochemical fingerprinting using the PhPlate system.
  
  
  RESULTS
  Results showed the presence of between one and three dominant clonal groups within each hospital, with most equipment and environmental strains being identical to the dominant clones of hospitalized patient strains. The rate of resistance of these strains to the 13 antibiotics tested ranging from 2% to 100%, with resistance being highest for penicillin, ciprofloxacin, and tetracycline (>98% of the isolates). Comparison of the strains isolated from the three hospitals using a combination of PFGE and PhP types showed the presence of 11 clonal groups of MRSA among these hospitals; of these, three common clonal groups also had identical antibiotic resistance patterns and were found in more than one hospital.
  
  
  CONCLUSIONS
  These data suggest dissemination of a few dominant clonal groups of MRSA strains in hospitals in Tehran, with high level resistance to other commonly used antibiotics.
authors.affiliation: Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Sara
authors.initials: S
authors.lastname: Javidnia
authors.forename: Malihe
authors.initials: M
authors.lastname: Talebi
authors.forename: Mahnaz
authors.initials: M
authors.lastname: Saifi
authors.forename: Mohammad
authors.initials: M
authors.lastname: Katouli
authors.forename: Abdolaziz
authors.initials: A
authors.lastname: Rastegar Lari
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Pourshafie
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D006761:Hospitals; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antibiotic resistance; MRSA; Nosocomial infection; PFGE; PhPlate