Isolation of potential bacterial pathogens from the phylloplane of some selected medicinal plants

Microorganisms are ubiquitous and their impact could be appreciated directly or indirectly. This study was aimed at determining the occurrence of pathogenic bacteria on the phylloplane of some medicinal plants commonly used to treat diseases by oral administration. Leaves samples were collected aseptically from Cassia fistula (Cassia) Mangifera indica (Mango) and Psidium guajavum (Guava) and their bacterial contents were assessed. Higher bacterial counts were observed in raw samples followed by those washed with sterile water. Samples washed with sterile warm water (blanched) were shown to have lower counts although without statistical significance (p ≤ 0.05). Guava leaves had higher counts (3.4×106 cfu/g) in the raw samples and cassia in blanched (6.4×105 cfu/g). However, mango leaves had the lowest (8.4×105 cfu/g and 2.0×105 cfu/g) in both the treatments respectively. Twenty bacterial species were isolated comprising Gram negative and Gram positive species. Bacterial identification revealed that Proteus mirabilis (35%), Proteus vulgaris (15%), Escherichia coli (15%), Klebsiella pneumoniae (5%), Morganella morganii (5%), Salmonella typhi (10%), Enterobacter sp. (5%), Staphylococcus aureus (5%) and Vibrio cholarae (5%) were the prevalent species. These organisms could be potential pathogens and proper washing with hot water may serve a better means of reducing the microbial contents and thus, it is recommended.