title: Variability in gene cassette patterns of class 1 and 2 integrons associated with multi drug resistance patterns in Staphylococcus aureus clinical isolates in Tehran-Iran.
abstract: BACKGROUND
  To investigate antibiotic resistance, the occurrence and distribution of class 1 and 2 integrons in multidrug- resistant Staphylococcus aureus isolates from hospitals in Tehran, Iran. The isolates were examined for susceptibility to antimicrobial agents. The mecA gene, class 1 and 2 integrons were detected by PCR. Integrase positive strains were further analysed for the presence of resistance gene cassettes using specific primers and were sequenced.
  
  
  RESULTS
  Among 139 S.aureus isolates, 109 (78.4 %) and 112 (80.5 %) strains were considered as multidrug resistant and mecA positive, respectively. Class 1 integrons and internal variable regions were found in 72.6 % (101/139) and 97 % (98/101) and class 2 integrons and variable regions also in 35.2 % (49/139) and 65.3 % (32/49) of S.aureus clinical isolates, respectively. Twelve distinct cassette arrays were found, containing genes encoding resistance to β-lactams, aminoglycosides, streptothricin, trimethoprim, chloramphenicol,a putative glucose dehydrogenase precursor and a protein with unknown function. Gene cassette arrays aadB, aadA2 and dhfrA1-sat2-aadA1 were common in S.aureus isolates. We detected a completely new gene cassettes which contained aadB, oxa2, aacA4, orfD-aacA4-catB8, aadB-catB3, orfD-aacA4 and aadB-aadA1-cmlA6 of class 1 and dhfrA1-sat2-aadA1, dhfrA11, dhfrA1-sat2 of class 2 integrons.
  
  
  CONCLUSIONS
  This is the first study to report carriage of class 1 and 2 integrons and associated gene cassettes among in S.aureus isolates from Iran.
authors.affiliation: Department of Mycobacteriology & Pulmonary Research, Pasteur Institute of Iran, Tehran-Iran, No. 358, 12th Farwardin Ave, Jomhhoori St, Tehran, 1316943551, Iran. m.mostafa@yahoo.com.|Department of Microbiology, Karaj branch, Islamic Azad University, Karaj, Iran. m.mostafa@yahoo.com.
authors.forename: Mahdi
authors.initials: M
authors.lastname: Mostafa
authors.affiliation: Department of Mycobacteriology & Pulmonary Research, Pasteur Institute of Iran, Tehran-Iran, No. 358, 12th Farwardin Ave, Jomhhoori St, Tehran, 1316943551, Iran. d.siadat@gmail.com.
authors.forename: Seyed Davar
authors.initials: SD
authors.lastname: Siadat
authors.affiliation: Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran. shahcheraghifereshteh@yahoo.com.
authors.forename: Fereshteh
authors.initials: F
authors.lastname: Shahcheraghi
authors.affiliation: Department of Mycobacteriology & Pulmonary Research, Pasteur Institute of Iran, Tehran-Iran, No. 358, 12th Farwardin Ave, Jomhhoori St, Tehran, 1316943551, Iran. farzam_vaziri@yahoo.com.
authors.forename: Farzam
authors.initials: F
authors.lastname: Vaziri
authors.affiliation: Department of Mycobacteriology & Pulmonary Research, Pasteur Institute of Iran, Tehran-Iran, No. 358, 12th Farwardin Ave, Jomhhoori St, Tehran, 1316943551, Iran. alizh63@yahoo.com.
authors.forename: Alireza
authors.initials: A
authors.lastname: Japoni-Nejad
authors.affiliation: Department of Microbiology, Karaj branch, Islamic Azad University, Karaj, Iran. j.Yousefi@yahoo.com.
authors.forename: Jalil
authors.initials: J
authors.lastname: Vand Yousefi
authors.affiliation: National Institute of Genetic Engineering and Biotechnology, Tehran, Iran. Rajaei@yahoo.com.
authors.forename: Bahareh
authors.initials: B
authors.lastname: Rajaei
authors.affiliation: Department of Mycobacteriology & Pulmonary Research, Pasteur Institute of Iran, Tehran-Iran, No. 358, 12th Farwardin Ave, Jomhhoori St, Tehran, 1316943551, Iran. elnazharifimood@gmail.com.
authors.forename: Elnaz
authors.initials: E
authors.lastname: Harifi Mood
authors.affiliation: Department of Mycobacteriology & Pulmonary Research, Pasteur Institute of Iran, Tehran-Iran, No. 358, 12th Farwardin Ave, Jomhhoori St, Tehran, 1316943551, Iran. nebrahimzadeh50@gmail.com.
authors.forename: Nayyereh
authors.initials: N
authors.lastname: Ebrahim zadeh
authors.affiliation: Biotechnology Department, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. arfa.moshiri@gmail.com.
authors.forename: Arfa
authors.initials: A
authors.lastname: Moshiri
authors.affiliation: Department of Anesthesiology, Iran University of Medical Sciences, Tehran, Iran. s.siamdoust@yahoo.com.
authors.forename: Seyed Alireza
authors.initials: SA
authors.lastname: Seyed Siamdoust
authors.affiliation: Department of Microbiology, Reference Health Laboratories Research Center, Ministry of Health and Medical Education, Tehran, Iran. m.rahbar@yahoo.com.
authors.forename: Mohamad
authors.initials: M
authors.lastname: Rahbar
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000145:classification / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D023061:Gene Order; D005798:Genes, Bacterial; D005838:Genotype; D032023:Integrons; D007492:Iran; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial