Turbidimeter investigations of behavior of antimicrobial agents on bacterial cells

Author: Giorgi Lobzhanidze
Keywords: Turbidimetry, Spectrophotometry, bacteria E.coli, Ampiox, Gentamycin, MIC, resistance.
Annotation:

The experiments held by us concerns the dependence of bacteria E. coli proliferation on the miscellaneous external conditions. The roles of these conditions were played by various antibiotics, particularly by Ampiox and Gentamycin. We used to conduct our experiments on E.coli C bacteria gained from Giorgi Eliava Institute of Bacteriophages, Microbiology and Virology. The effect of these antibiotics’ action was determined according to bacterial proliferation. It was found out that bacterial proliferation depends on the amount of antibiotics, more precisely the bacterial proliferation is ceased at certain ratio between bacterial cells and antibiotics’ molecules, and this ratio in microbiology has got a special term- minimum inhibitory concentration, MIC. It was used the turbidimeter in our experiments that enabled us to observe the variability in amount of bacteria by means of measuring the turbidity of the solution real-time mode and exactly this method enabled us to define the MIC for these both antibiotics. In addition, by means of using the turbidimeter we observed a very important case of interaction between bacteria and antibiotic such as acquired resistance when adding the same antibiotic the second times to bacteria could not affect the bacterial proliferation any more. Moreover, this methods enabled us ascertain that the autocrine signaling is responsible for this acquired resistance. It is interesting that turbidimeter also showed that heating the solution by 20 degrees forced this resistance to vanish.