Evaluation of the in vitro antibacterial activity of neem (Azadirachta indica Juss.) bark alcohol extracts against pathogenic bacteria in Philippine native chicken

Abstract

The study was conducted from February 8 to 20, 2019 at the College of Medical Technology Laboratory, Central Philippine University, Jaro, Iloilo City to evaluate the in vitro antibacterial activity of neem bark alcohol extracts against different pathogenic bacteria. The experimental treatments were laid out in a factorial completely randomized design with three replications. The treatments consisted of neem tree stem bark (NTSB) acetone, ethanol, and methanol extracts, NTSB pure extract, and alcohol extraction solvents, AES, (acetone, ethanol, and methanol). Tetracycline antibiotic was used as a positive control and distilled water as the negative. The potency of the NTSB alcoholic extracts was analyzed through zones of inhibition (ZOI) 24 hours after the application of the controlling treatments. Results of the study revealed that responses of test organisms to NTSB alcoholic extracts varied indicating that E. coli and S. typhimurium are best controlled by NTSB methanolic extracts, while S. aureus by NTSB ethanolic extract. Pure extract of neem had anti S. typhimuhum but is not significantly different from distilled water and AES in controlling E. coli and S. aureus. AES and distilled water have the same antibacterial abilities. These ZOI are statistically narrower than that in tetracycline. Based on the interpretative criteria using disc diffusion susceptibility testing, all treatments against all pathogenic bacteria except for tetracycline and NTSB ethanolic extract against S. aureus showed resistance.