ABSTRACT
The emergence of pathogenic bacteria that are resistant to several antibiotics has recently presented a significant challenge to the healthcare system. Therefore, an alternative source of antimicrobial agents is needed. The study aimed to compare the antibacterial activities of aqueous and ethanol extracts of ripe and unripe fruits of red and yellow varieties of Anacardium occidentale against Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa and Staphylococcus aureus. Cold maceration method of extraction was used using water and ethanol. Antibacterial activities of the extracts against the isolates were evaluated by agar diffusion method while minimum inhibitory concentration (MIC) was determined using broth dilution method. In the determination of the antibacterial activities of all the extracts, the highest zones of inhibition were shown by ethanolic extracts of both ripe red cashew (25 mm) and yellow cashew (26 mm) against Escherichia coli. Both the aqueous and ethanolic extracts of unripe red and yellow cashew had no antibacterial effect against Klebsiella pneumoniae and Pseudomonas aeruginosa. As well, both aqueous and ethanol extracts of ripe red and yellow cashew and ethanolic extract of ripe yellow cashew inhibited all the test organisms. Minimum inhibitory concentration ranged from 50 to 150 mg/ml. At 100 mg/ml, both ethanolic extracts of ripe red and yellow cashew were bactericidal to Escherichia coli while aqueous extract of ripe red cashew was bactericidal to Escherichia coli at 150 mg/ml. The antibacterial activities of A. occidentale apple (fruit) extracts underscore the credence to the efficacy of their use as traditional remedy against some human ailments.