Epidemiology of Nasal Carriage of Staphylococcus Aureus among hospitalised children at Agogo Presbyterian Hospital, Ghana

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Staphylococcus aureus is an important human pathogen. Nasal carriage of S. aureus is a major risk factor for subsequent invasive S. aureus infections and transmission in the environment. However, little is known about the prevalence, virulence and diversity of S. aureus among children admitted to hospitals in Ghana. This study aimed to describe the epidemiology of nasal carriage of S. aureus among hospitalised Children at the Agogo Presbyterian hospital. Nasal swabs were collected from hospitalised children. S. aureus and MRSA were identified and characterized by phenotypic and genotypic methods. S. aureus was confirmed by nucA PCR and MRSA was by mecA and mecC PCR. Antimicrobial susceptibility test was performed by the Kirby-Bauer disk diffusion method. PCR was used to amplify genes encodng for Panton-Valentine Leukocidin (PVL) toxin. Typing of the isolates was done by the staphylococcal protein A (spa) typing. Out of the 545 nasal swabs, 22.0% (n=120) S. aureus were isolated. High level of resistance against penicillin (96.7%) and tetracycline (52.5%) was observed. Gentamycin, trimethoprim/sulfamethoxazole, clindamycin and erythromycin recorded 99.2%, 97.5%, 94.2% and 86.7% sensitivity respectively. All the isolates were sensitive to linezolid and teicoplanin. Of all the S. aureus isolates, 1.7% (n=2) were MRSA. The MRSA strains were resistant to penicillins, cefoxitin and tetracycline. High prevalence of PVL (57.5%) was noted among the S. aureus. Thirty-five spa types were identified; predominant spa types were t355 (20%), t084 (14.9%) and t939 (10.7%). The spa types for the MRSA were t1096 and t4454. Two novel spa types (t15727 and t15728) were identified and submitted to the spa database. This study has shown that a substantial number of the hospitalized children were nasal carriers of S. aureus with low prevalence of MRSA and high prevalence of PVL. The high prevalence of S. aureus and high rate of resistance to penicillin and tetracycline coupled with high prevalence of PVL is a major threat to public health in Ghana. This study has therefore provided data on the nature of nasal carriage of S. aureus during hospital admission and could guide policy on infectious diseases prevention and the monitoring of the evolution of S. aureus strains in Ghana and globally over time.
A thesis submitted to the Department of Clinical Microbiology in partial fulfillment of the requirements for the award of master of philosophy (mphil.) degree in Clinical Microbiology in the department of Clinical Microbiology, School of Medical Sciences, College of Health Sciences, KNUST, Ghana.