Apple, Guava and Pineapple Fruit Extracts as Antimicrobial Agents against Pathogenic Bacteria

This investigation was conducted to compare the antimicrobial properties of alcohol fruit extracts from Apple (Malus pumila), Guava (Psidium guajava), and Pineapple (Ananas comosus) against eight bacteria: Staphylococcus aureus, Enteroaggregative E.coli (EAEC), Enterotoxigenic E.coli (ETEC), Enterobacter cloacae, Shigella flexineri, Enterococcus faecalis, Klebsiella, and Pseudomonas aeruginosa. All the fruits were bought fresh from the market, cut into small cubes, and sun dried to a crisp over 4-5 days. After being blended to a fine powder, 75g of each powder was passed through a Soxhlet apparatus containing 250 ml of 99% ethanol to obtain a crude extract. This process was repeated with 250 ml of methanol to obtain a methanolic crude extract. The antimicrobial properties of the extracts were tested using agar well diffusion, Norfloxacin used as positive control and water as negative control. The inhibition zones from each extract were measured and an activity index was calculated from the mean zone sizes. All fruits showed some degree of antimicrobial properties with the highest activity index (2.6) being from Pineapple ethanolic and methanolic extracts against EAEC. Both Apple ethanolic and methanolic extracts showed activity only against Staph. aureus and EAEC. Guava extracts were effective against all the strains except for ETEC. Pineapple extracts were strongly active against all the bacteria. The methanolic extracts of Apple and Guava showed slightly larger zones compared to their ethanolic extracts. For Pineapple, inhibition zones from the ethanolic extracts were slightly larger. The results of this investigation show great promise for potential antimicrobial drugs.