title: Antimicrobial resistance and virulence markers in methicillin sensitive Staphylococcus aureus isolates associated with nasal colonization.
abstract: Most Staphylococcus aureus infections occur in previously colonized persons who also act as reservoirs for continued dissemination. This study aimed to investigate the carriage of antimicrobial resistance and virulence markers in S. aureus isolates associated with nasal colonization. The study was conducted from December 2013-April 2014. Nasal swabs were collected and questionnaires administered to 97 medical students in Riyadh Saudi Arabia. Bacterial culture, identification and antimicrobial susceptibility testing were performed by conventional methods and chromogenic agar was used for methicillin resistant S. aureus (MRSA) screening. Molecular characterization of isolates was carried out using the StaphyType DNA microarray. Thirty two students (43%) had S. aureus nasal carriage (MSSA = 31; MRSA = 1). Seventeen clonal complexes (CC) were identified namely: CC15-MSSA (n = 5), CC1-MSSA-SCCfus (n = 4), CC8-MSSA (n = 3), CC22-MSSA (n = 3), CC25-MSSA (n = 3), CC101-MSSA (n = 2). Other CC found as single isolates were CC5-MSSA, CC6-MSSA, CC30-MSSA, CC45-MSSA, CC96-MSSA, CC188-MSSA, CC398-MSSA, CC942-MSSA/PVL+, CC1290-MSSA, ST2482-MSSA, CC80-MRSA-IV/PVL+. The CC1-SCCfus isolates harbored the Staphylococcal cassette chromosome (SCC) with ccrA-1; ccrB-1 and ccrB-3 genes plus the putative fusidic acid resistance marker Q6GD50. One MSSA isolate was genotyped as coagulase negative Staphylococcus spp with an irregular composite SCCmec element. Majority of the isolates harbored various virulence genes including the hemolysin, enterotoxin, and exfoliative genes as well as various adhesive protein producing genes. Although there was low carriage of MRSA, the MSSA isolates harbored various resistance and virulence genes including those usually seen in MRSA isolates. The presence of isolates with incomplete SCCmec elements plus putative resistance and virulence genes is of concern.
authors.affiliation: College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.
authors.forename: Abdullah
authors.initials: A
authors.lastname: Sarkar
authors.affiliation: College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.
authors.forename: Adeola
authors.initials: A
authors.lastname: Raji
authors.affiliation: College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.
authors.forename: Ghada
authors.initials: G
authors.lastname: Garaween
authors.affiliation: Department of Global Health, University of Washington, Seattle, WA, USA.
authors.forename: Olusegun
authors.initials: O
authors.lastname: Soge
authors.affiliation: College of Medicine, Alfaisal University, Riyadh, Saudi Arabia; Department of Infection and Immunity, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.
authors.forename: Jose
authors.initials: J
authors.lastname: Rey-Ladino
authors.affiliation: College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.
authors.forename: Wael
authors.initials: W
authors.lastname: Al-Kattan
authors.affiliation: College of Medicine, Alfaisal University, Riyadh, Saudi Arabia; Department of Infection and Immunity, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia; College of Pharmacy, King Saud University, Riyadh, Sasudi Arabia.
authors.forename: Atef
authors.initials: A
authors.lastname: Shibl
authors.affiliation: College of Medicine, Alfaisal University, Riyadh, Saudi Arabia; Department of Infection and Immunity, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia. Electronic address: asenok@alfaisal.edu.
authors.forename: Abiola
authors.initials: A
authors.lastname: Senok
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008712:Methicillin / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009666:Nose / Q000382:microbiology*; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D037521:Virulence Factors; D008712:Methicillin
keywords: DNA microarray; Methicillin resistant Staphylococcus aureus; Nasal colonization; Virulence genes