Staphylococcus aureus, one of the most frequently occurring community and hospital-associated pathogens, causes infectious diseases including mild skin infection to systemic infections [1].Approximately 20 -30% of the global population is persistently colonized with S. aureus in the anterior nares [2] and approximately 10 to 40% of people tested as outpatients or on admission are nasal carriers of S. aureus [3]. Nasal carriage (colonization) of S. aureus has been identified as a major risk factor for subsequent infections as carriers act as reservoirs for the pathogen assisting its spread in the community. Certain risk factors have been associated with nasal carriage of S. aureus and they include sex, occupation, age groups, ethnicity, hospitalization, nasal abnormalities, genetic makeup, immunological status, repeated needle injections, hormonal status in women, recent hospitalization, insulin dependent and non-insulin dependent diabetes mellitus, haemodialysis, HIV status, S. aureus skin infections, nose picking and administration of multiple antibiotics [4,5]. The spread of colonization occurs especially in close contact areas like schools probably by contaminated hands and surfaces [6]. An understanding of the risk factors for carriage of S. aureus is crucial to understanding the potential for invasive infections and transmission of diseases cause by this pathogen. This is of importance because the increasing resistance of S. aureus to various antibiotics has been known to complicate the treatment of diseases caused by it [7]. In addition, the emergence and spread of methicillin resistant S. aureus (MRSA) has aggravated the situation [8]. The purpose of this study was to investigate the incidence of nasal carriage of S. aureus among University students, risk factors for nasal carriage and antimicrobial susceptibility pattern of the S. aureus isolates to selected antimicrobial agents Two-hundred and seventy-seven nasal samples were obtained from male and female undergraduate students who were not showing symptoms of any infection. After informed consent was obtained, a self-administered questionnaire [9] was given to each participant to collect information pertaining to demographics, contact with or exposure to potential S. aureus carriers, medication history, intravenous drug use and involvement in sporting activities. This was followed by a single screening nose swab for each volunteer using sterile, moistened cotton swabs.
Materials and MethodsThe disk diffusion method was used to test the susceptibility of S. aureus isolates as recommended by the Clinical Laboratory Standards Institute guidelines (CLSI, 2011) to the following antibiotics: ceftazidime, cloxacillin, gentamicin, ceftriaxone, erythromycin,
Sample and Data CollectionNasal swabs were inoculated directly onto on mannitol salt agar (MSA), a selective medium for the isolation of S. aureus and the MSA plates were incubated at 37°C for 48 hours. Mannitolfermenting colonies that were yellow were selected from the MSA plates and subcultured on blood ...