Prevalence and risk factors of nasal carriage of methicillin-resistant staphylococcus aureus (MRSA) among Hospitalized patients at the Komfo Anokye Teaching Hospital, Kumasi, Ghana.

Abstract

Methicillin-Resistant Staphylococcus aureus (MRSA) is implicated in several nosocomial infections, some of which are life threatening. It is carried asymptomatically in the nasal cavity and other parts of the human body. This asymptomatic carriage serves as an important source of transmission of the organism to other patients, especially within a confined place such as the hospital wards. There is limited data on the prevalence of Methicillin-Resistant S. aureus (MRSA) among hospitalized patients in Komfo Anokye Teaching Hospital (KATH). This study aimed to establish the prevalence and risk factors of MRSA nasal carriage among hospitalized patients at KATH in Kumasi, Ghana. Informed consent was obtained from the patients and their nasal swabs were collected and cultured overnight on mannitol salt agar (MSA) at 37oC under aerobic conditions. Questionnaires were administered to patients to assess risk factors of MRSA nasal carriage. The risk factors assessed included procedures the patients had undertaken (surgery, urinary caterization etc), conditions of patients (chronic skin infection, chronic long disease etc.) and history of previous hospitalization. Catalase and coagulase tests were performed on yellow colonies from the overnight culture on MSA. Coagulase positive isolates were confirmed as S. aureus by nucA PCR. The Kirby-Bauer disk diffusion method was used to test the antibiotic susceptibility profile of the S. aureus isolates. Isolates that were resistant to cefoxitin were confirmed as MRSA by PCR identification of the mecA gene. Out of 224 in-patients samples, 31 (13.84%) were identified as S. aurueus. Of the 31 S. aureus isolates, 14 were confirmed as MRSA, resulting in MRSA carriage of 6.25%. The MRSA isolates showed high resistance against most of the antibiotics tested in this study, including 86% against both erythromycin and amoxicillin/clavulanic acid. Resistance proportions of the S. aureus isolates in general were 100% against penicillin and 97.06% against ampicillin. The most effective antibiotic against the MRSA and the overall S. aureus isolates was gentamicin, to which 79% of the MRSA isolates and 87% of the S. aureus isolates were susceptible. Among the risk factors assessed, the highest nasal carriage prevalence of MRSA i.e 50% was observed among patients with chronic hepatic disease, followed by patients with burns who recorded 16.6% MRSA nasal carriage prevalence. This study revealed that there is high prevalence of MRSA among the patients. This high prevalence of MRSA poses a challenge to healthcare delivery at KATH as it constitutes a transmission risk to other patients. It is recommended that healthworkers in KATH adhere strictly to infection prevention and control measures to avoid passing on MRSA to other patients. Further studies on genotyping are needed to ascertain if these nasal carriage MRSA strains are the same strains circulating and causing infections among patients on admission in the hospital.