Neem (Azadirachta indicaA. Juss) Oil to Tackle EnteropathogenicEscherichia coli
Neem (Azadirachta indicaA. Juss) oil (NO) was assayed against forty-eight isolates ofEscherichia coliby standardised disc diffusion test and microdilution test. By molecular biology characterization, fourteen isolates resulted in diarrheagenicE. coliwith sixteen primer pairs that specifically amplify unique sequences of virulence genes and of 16S rRNA. The NO showed biological activity against all isolates. The bacterial growth inhibition zone by disc diffusion method (100 µL NO) ranged between 9.50 ± 0.70 and 30.00 ± 1.00 mm. The antibacterial activity was furthermore determined at lower NO concentrations (1 : 10–1 : 10,000). The percent of growth reduction ranged between 23.71 ± 1.00 and 99.70 ± 1.53. The highest bacterial growth reduction was 1 : 10 NO concentration with 50 µL of bacterial suspension (ca. 1 × 106 CFU/mL). There is significant difference between the antibacterial activities against pathogenic and nonpathogenicE. coli, as well as NO and ciprofloxacin activities. Viable cells after the different NO concentration treatments were checked by molecular biology assay using PMA dye. On the basis of the obtained results, NO counteractsE. coliand also influences the virulence ofE. coliviable cells after NO treatment. The NO metabolomic composition was obtained using fingerprint HPTLC.