METHODS: Antibacterial activity of B. kockiana flower was evaluated qualitatively and quantitatively using disc diffusion assay and microbroth dilution method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of extracts were examined. Phytochemical analysis was performed to determine the classes of phytochemicals in the extracts. Bioactivity guided isolation was employed to purify the antibacterial agents and identified via various spectroscopy methods. Scanning electron microscopy (SEM) technique was used to evaluate the antibacterial mechanism of extract and compounds isolated.
RESULTS: B. kockiana flower was found to exhibit fairly strong antibacterial activity towards both strains of MRSA bacteria used, MIC varies from 62.5-250 μg/mL. Tannins and flavonoids have been detected in the phytochemical analysis. Gallic acid and its ester derivatives purified from ethyl acetate extract could inhibit MRSA at 250-500 μg/mL. SEM revealed that the cells have undergone plasmolysis upon treatment with the extract and compounds.
CONCLUSION: Tannins and polyphenols are the antibacterial components towards MRSA in B. kockiana. Massive leakage of the cell content observed in treated cells showed that the phytochemicals have changed the properties of the cell membranes. Amphiphilic nature of the compounds exhibited the antibacterial activity towards MRSA via three stages: (1) cell membrane attachment; (2) cell membrane fluidity modification; and (3) cell membrane structure disruption.
METHOD: Electronic search (PubMed, Scopus and Google scholar) was conducted using the following search terms: "MRSA OR Methicillin Resistant Staphylococcus aureus AND Nigeria." Reference list of selected studies was scanned to identify more studies. Studies published between 2007 and 2017 that tested at least 30 non-duplicate S. aureus isolates were selected. An independent reviewer extracted data from the studies using a standardized form.
RESULTS: Twelve studies were included in this review. Overall, prevalence of MRSA infection increased from 18.3% (2009) to 42.3% (2013). The prevalence of MRSA infection was less than 50% in all the regions during the period under review. There was a decline in the prevalence of MRSA infection in the North-East (from 12.5% to 8.0%) between 2007 and 2012, and an increase in the South-West (from 20.2% to 47.4%) between 2006 and 2010. Wound, blood and urine specimens had the highest proportion of MRSA isolates. Non-susceptibility of MRSA strains to cotrimoxazole and tetracycline was greater than 85%.
CONCLUSION: Prevalence of MRSA infection in Nigeria is rising, albeit regional variations. Non-susceptibility to commonly prescribed, orally available and inexpensive antibiotics was high. Antimicrobial resistance surveillance system, infection control, and antimicrobial stewardship interventions are recommended.