Antibacterial Effects of Guava ( Psidium guajava L.) Extracts Against Food Borne Pathogens

Abstract

Guava is commonly used as a medicine against gastroenteritis and child diarrhea by those who cannot afford or do not have access to antibiotics. The present study was conducted to clarify the possible effects of antimicrobial activities of guava extracts. Its antimicrobial activities was determined against five food-borne pathogens: Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Bacillus cereus (BTCC 19), Shigella sonnei (BTCC) and Salmonella typhi (BTCC 197) using disc diffusion method at four different concentrations: 10%, 50%, 75% and 100%. Its antibacterial activity was also determined at three different temperatures: 50°C, 75°C and 100°C. The test organisms differed in their reaction to these different extracts, but as a whole inhibition of bacterial growth increased with the increased concentration. All the samples showed antibacterial activity after heat treatment at 50°C, 75°C and 100°C suggesting that the temperature does not affect the activity. Guava extracts showed higher antibacterial activity against gram positive bacteria compared to gram negative bacteria. None of the extracts (10%) showed antibacterial activity against these pathogens. The results of the present study assume that guava extracts possess compounds containing antibacterial properties that can potentially be useful to control food borne pathogens especially diarrhea causing organisms.