Abstract:
The antibacterial activities of Azadirachta indica leaf extracts were tested against vancomycin and
methicillin resistant bacteria which were isolated from hospital patients in Obafemi Awolowo
University Teaching Hospital, Ile-Ife, Nigeria, Federal Medical Center, Owo, Ondo State and John
Bosco Hospital, Akure, Nigeria. The bacterial isolates originated from urine, sputum, wounds,
high vaginal swab, semen, ear swab, aspirate abscess, cerebro-spinal fluid, endocervical swab and
urethral swab. Leaves of A.indica were collected from Federal College of Agriculture, Akure Ondo
State and authenticated in the Department of Crop, Soil and Pest Management, Federal University
of Technology, Akure. The bacterial isolates from the samples are; Staphylococcus aureus,
Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Streptococcus pyogenes,
Proteus mirabilis, Streptococcus faecalis, Acinetobacter sp, and Salmonella typhi. These
organisms were subjected to vancomycin and methicillin sensitivity tests to determine their
resistance to these two antibiotics. The plasmid profile analysis of the resistant bacteria was carried
out. Methanol and n-hexane extracts of A. indica were obtained using the cold method of
extraction. Phytochemical screening of the extracts was assayed. Purification of the extracts was
carried out using column chromatographic techniques, and the fractions were obtained. The
antibacterial potency of the fractions was investigated against the antibiotic resistant bacterial
isolates. MIC value recorded for methanol extract was at 100 mg/ml for Staphylococcus faecalis
with 10.00 mm zone of inhibition, while the MIC value for other isolates was 200 mg/ml. The
MIC value for n-hexane was 50 mg/ml against all isolates with varying zone of inhibition. The
phytochemical analysis of the extract revealed the presence of tannins, flavonoids, steriods, and
terpenoids. Plasmid profile analysis and curing revealed that resistance exhibited by E. coli, P.
mirabilis, S. pyogenes, S. faecalis, Acinetobacter sp, S. typhi and K.
pneumoniae were chromosomal mediated, while the resistance exhibited by S. aureus and P. aeruginosa were
plasmid based. Infra-red spectroscopy assay showed the presence of hydroxyl group, aromatic
aldehyde and aliphatic ether as possible functional group.
