The root, stem and leaves of Vitellaria paradoxa, belonging to the Sapotaceae family and which have some ethnomedicinal applications were studied. Phytochemical screening of the plant parts reveals the presence of carbohydrates (free reducing sugars, ketoses, pentoses and starch), saponins, steroids, tannins and alkaloids. The antimicrobial screening of the crude methanol extract carried out in vitro on the following clinical isolates; Bacillus cereus, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pnuemoniae and Salmonella typhi showed that the crude methanol extracts had wider range of activity on these organisms than the petroleum ether extracts. The crude stem extracts inhibited the growth of P. aeruginosa, K. pneumoniae, B. cereus and S. typhi at concentration of 50 mg/ml while the leaf had a minimal inhibition concentration (MIC) of 70 mg/ml on S. aureus, E. coli and S. typhi. The root had an MIC of 60 mg/ml on S. aureus, E. coli, P. aeruginosa, K. pneumoniae and S. typhi. The MBC in all the cases were slightly higher than the MIC and was lowest in the stem extracts which indicates that the stem bark may contain the most active components.
Antimicrobial activity of aqueous, methanol and chloroform leaf extracts of Cissus multistriata were investigated against 8 bacterial and 2 fungal test organisms, using the tube dilution and agar ditch diffusion methods. Aqueous leaf extract had no activity against both the bacterial and fungal test organisms. Both the methanol and chloroform leaf extracts inhibited all the test organisms with chloroform leaf extract showing the highest zone of inhibition against Escherichia coli (diameter 25 mm) and least against Staphylococcus aureus (diameter 13 mm). The methanol leaf extract was least inhibitory against Salmonella typhi (diameter 8 mm) and most inhibitory against S. aureus (diameter 15 mm). The methanol leaf extract of C. multistriata show more antifungal activity compared with chloroform leaf extract, with Candida albicans being more susceptible than Aspergillus niger to both methanol and chloroform leaf extracts. The minimum inhibitory concentration (MIC) of methanol leaf extract show least activity against Yersinia enterocolitica and Pseudomonas aeruginosa (MIC = 100 mg/ml) and higher activity of MIC at 50 mg/ml against the other bacterial test organisms. The chloroform leaf extract MIC of 100 mg/ml had least activity against Proteus mirabilis and P. aeruginosa and MIC of 20 mg/ml most inhibitory against E. coli, Klebsiella pneumonia and S. typhi. The antimicrobial activity of the heated extracts persisted after exposure to various temperatures between 30 o C to 121 o C for 15 to 30 min. However, the extract activity decreased as the temperature increased. The killing rate of the MBC of chloroform extract on E. coli was 1 cfu/3 min while on S. typhi was 1 cfu/3.8 min.
Staphylococcus species, Acinetobacter species and Stenotrophomonas maltophilia are of particular importance as they sometimes reside as flora on the intact skin and nasal passages of man and farm animals. Studies around the globe have shown them as "friends and foes" especially in immunocompromised individuals as they occur as commensals but sometimes as pathogens that infect, causing morbidity and consequently higher therapeutic cost. The occurrence of antibiotic resistance gene(s) in their genomes and their phenotypic display of resistance make them difficult to control and places a high demand on the assessment of such genes in the bacteria. In doing this, the less considered (commensals) have been described more recently as a reservoir for antibiotic resistance genes. The transfer of heavy metal and antibiotic resistance genes from Staphylococcus spp., a Gram positive bacterium to S. maltophilia and Acinetobacter species, Gram negative bacteria confer the resilience to control measures that is peculiar with the former on the latter. This attribute in Acinetobacter spp. and S. maltophilia have encouraged their inclusion in drug screening research. Intermittent assessment of resistance genes in the ecosystem should be embraced to foster appropriate measures against their spread.
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