Nasal Carriage of Methicillin Resistant Staphylococcus aureus Strains Among Inpatients of Jimma Hospital, South Western Ethiopia

Abstract

BACKGROUND: Staphylococcus aureus is one of the major causes of community and hospital acquired infections. The emergence of methicillin resistant strains of Staphylococcus aureus in the hospitals and the community is a serious health problem. The aim of this study was to determine the nasal carriage and antimicrobial resistance patterns of Staphylococcus aureus isolates in Jimma Hospital inpatients. METHOD: This cross sectional study was conducted from January 22 to February 18, 2002. Nasal swabs from 152 inpatients were taken using simple systematic sampling method. Specimens were cultured on mannitol-salt and blood agars. Antimicrobial tested included ampicillin, Oxacillin, Erythromycin, trimethoprim-sulphamethoxazole, chloramphenicol, gentamycin, kanamycin, and clindamycin. Susceptibility tests were carried out on Muller Hinton agar using modified Kirby-Bauer agar diffusion method. Questionnaire was employed to collect data on risk factors for nasal colonization of methicillin resistant Staphylococcus aureus. RESULTS: Out of the total 152 inpatients enrolled in the study, 79(52%) were males and 73(48%) females with a sex ratio of 1:08. One hundred forty-four swabs cultured on mannitol salt agar grew Staphylococcus species out of which 85(59%) were coagulase positive and 59 (41%) were coagulase negative. Antibiotic sensitivities of 85 Staphylococcus aureus isolates to ampicillin, chloramphenicol, trimethoprimsulphamethoxazole, oxacillin, erythromycin, kanamycin, gentamycin and clidamycin showed resistance pattern of 87.1%, 70.6%, 68.2%, 51.8%, 42.4%, 16.5, 15.3% and 12.9% respectively. 51.8% of the isolates were methicillin resistant Staphylococcus
aureus and 72.9% were multi resistant. There was an association between known underlying conditions, previous hospitalization and previous antibiotic use with carriage state of Staphylococcus aureus; P< 0.05. CONCLUSION: This study showed a high rate of nasal carriage of methicillin resistant Staphylococcus aureus among inpatients. Most methicillin resistant Staphylococcus aureus strains are resistant to other beta-lactam antibiotics. Hence, antimicrobial susceptibility tests should be conducted before prescribing antibiotics in order reduce the transmission route and control the problem. [Ethiop J Health Sci 2003; 13(2): 107-116].