Abstract: “This research’s objective is to develop methods of testing the sensitivity of bacteria to various antibiotics using quantitative assessment of DNA during log phase with UV-Vis Spectroscopy. Methods used, samples of pathogenic E. coli bacteria after cultured in broth solution containing Ciprofloxacin for 7 hours were taken for DNA extraction technique. The isolated DNA was then quantitatively calculated based on light absorbance on UV-Vis spectrophotometer, where the values of absorbance density was converted into the concentration of DNA/ml. As a control arm of this study, the equal sample of pathogenic E. coli bacteria were cultured in broth solution without antibiotic. Results: The DNA concentration from 15 samples of E. coli in broth culture solution containing antibiotic solution was 7.3 ± SD 2.28 ; whereas the DNA concentration in the control group was 10.3 ± SD 2.51 which was significant different (p. = 0. 000). This test was compared with conventional sensitivity test using disc”

Keywords: UV-Vis spectroscopy, optical density, DNA extraction, sensitivity test, pathogenic E. coli