IN-VITRO DETERMINATION OF THE ANTIBACTERIAL PROPERTIES OF 4 GUAVA GENOTYPES

摘要

The efficacy of leaf decoctions from four guava genotypes against Staphylococcus aureus, Streptococcus pyogenes and Escherichia coli was evaluated. The guava genotypes, namely guapple, red guava, native guava and oblong guava were identified based ontheir leaf and fruit characteristics. The antibacterial activity of the decoctions were tested and compared with a control antibiotic, Amoxicillin, using disc diffusion method Significant differences in the inhibition zones were observed among the four guava cultivars and Amoxicillin depending on type of bacteria. Among the leaf decoctions, the highest zone of inhibition was exhibited in guapple and red guava against S. pyogenes; red guava and medium-sized guava against S. aureus; and native guava against E. coli. Using the performance standards for antimicrobial disk susceptibility test for Amoxicillin as reference, S. pyogenes is rated susceptible to guapple, red guava and native guava but moderately susceptible to oblong guava. S. aureus is susceptible to red guava and oblong guava but resistant to guapple and native guava. E. coli has intermediate susceptibility to native guava and resistant to the other cultivars. These results imply that genotype affects the antimicrobial property of guava The red guava is best used in ailments where S. aureus and S. pyogenes are the etiological causes. Thus, the red guava leaf decoction is more promising as a cheaper substitute for Amoxicillin, and doubly so since Amoxicillin has been recommended by WHO, UNAIDS and UNICEF as prophylactic treatment for children with HIV. The native guava may be used in cases where E. coli is implicated.