title: The distribution of pathogenic and toxigenic genes among MRSA and MSSA clinical isolates.
abstract: Staphylococcus aureus (S. aureus) is considered as a notorious nosocomial pathogen among hospitalized patients and community-dwelling subjects. Its increasing morbidity and mortality is believed to be due to antibiotic resistance. However, the data concerning molecular properties of infecting strains are few. In this study, a total of 192 S. aureus strains, including 88 (45.8%) meticillin-sensitive S. aureus (MSSA) and 104 (54.2%) meticillin-resistant S. aureus (MRSA) were recovered from clinical samples. The prevalence of subtypes containing staphylococcal cassette chromosome mec (SSCmec), staphylococcal enterotoxins (SEs), toxic shock syndrome toxin (TSST) and exfoliative toxin was assessed by PCR. Antibiotic susceptibility pattern and vancomycin resistance of each isolate were evaluated by disk diffusion method and micro-dilution method, respectively. 9 (2.3%) strains required MIC > 2 mg/l of vancomycin, which significantly increased among multi drug resistant (MDR), MRSA and SCCmec type III strains (p < 0.05). 171 (89%), 140 (72.91%), 7 (3.6), 78 (48.6%), 5 (2.6%), 151 (78.64%), 129 (67.18%), 178 (92.7%) and 15 (7.8%) of 192 isolates harbored mecA, entA, entB, entC, entD, entE, eta, etb and tsst-1 genes, respectively. 31 (16.14%), 5 (2.6%), 95 (49.48%) and 7 (3.64%) of 192 isolates carried SCCmec type I, II, III and IV, respectively. We found a significantly higher rate of MRSA and resistance to all tested antibiotics, except to penicillin G, kanamycin and linezolide among the SCCmec type III class (p < 0.05). According to our findings, MSSA isolates should be taken as seriously as MRSA strains due to the potential presence of broad spectrum virulence factor genes.
authors.affiliation: Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Abbas Ali
authors.initials: AA
authors.lastname: Imani Fooladi
authors.affiliation: Microbiology Department, Islamic Azad University of Arak Branch, Arak, Iran.
authors.forename: Elnaz
authors.initials: E
authors.lastname: Ashrafi
authors.affiliation: Microbiology Department, Islamic Azad University of Zanjan Branch, Zanjan, Iran.
authors.forename: Shafie Gorbani
authors.initials: SG
authors.lastname: Tazandareh
authors.affiliation: Biology Department, Islamic Azad University of Jahrom Branch, Jahrom, Iran.
authors.forename: Roohollah Zarei
authors.initials: RZ
authors.lastname: Koosha
authors.affiliation: Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Hamid Sedighian
authors.initials: HS
authors.lastname: Rad
authors.affiliation: Department of Drug and Food Control, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Amin
authors.affiliation: Microbiology Department, Islamic Azad University of Zanjan Branch, Zanjan, Iran.
authors.forename: Mina
authors.initials: M
authors.lastname: Soori
authors.affiliation: Microbiology Department, Islamic Azad University of Tonekabon Branch, Jahrom, Iran.
authors.forename: Reza Abbasi
authors.initials: RA
authors.lastname: Larki
authors.affiliation: Applied Biotechnology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Choopani
authors.affiliation: Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran. Electronic address: hosseini361@yahoo.com.
authors.forename: Hamideh Mahmoodzadeh
authors.initials: HM
authors.lastname: Hosseini
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001427:Bacterial Toxins / Q000235:genetics; D004768:Enterotoxins / Q000235:genetics; D005083:Exfoliatins / Q000235:genetics; D006784:Hospitals, Teaching; D006801:Humans; D007492:Iran; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000235:genetics* / Q000302:isolation & purification; D018089:Superantigens / Q000235:genetics; D020713:Vancomycin Resistance; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D004768:Enterotoxins; D005083:Exfoliatins; D018089:Superantigens; D037521:Virulence Factors; C030107:enterotoxin F, Staphylococcal
keywords: Entorotoxin; MRSA; MSSA; SCCmec; Staphylococcus aureus; Superantigen