CAN CO2 CHANGE THE MECHANISM OF ACTION OF CIPROFLOXACIN IN Escherichia coli?

VIVIANA CANO ARISTIZÁBAL; MELISA DE LOS ANGELES QUINTEROS; MARIA GABRIELA PARAJE; PAULINA L PÁEZ

San Miguel de Tucumán

Congreso; XII CONGRESO ARGENTINO DE MICROBIOLOGÍA GENERAL SAMIGE; 2017

SAMIGE

The CO2 has become in an importan poin to study due to the rapid increase in atmospheric concentrationsat the recent years. This has generated not only climate changes but also the adaptation of macro andmicroscopic living organisms. CO2 is a major by-product of cellular metabolism and it has been shownthat it can react with the hydroxyl radical (HO?) and hydrogen peroxide (H2O2 ) that increase theirtoxicity in a dose dependent manner. The oxidative action of these radical species, generatingoxidative stress, leads to oxidation of macromolecules like proteins, lipids and DNA producing the celldeath. It?s well-known that ciprofloxacin (CIP) is a bactericidal antibiotic capable of stimulatingproduction of HO? in Gram positive and Gram negative bacteria. In previous studies with CIP atdifferent concentrations (0; 0.5 y 50 µg/mL) in atmospheric conditions and CO2 controlled atmosphere(50 ppm y 5%) in E. coli ATCC 25922, we determinate that CO2 modifies the production of reactiveoxygen species (ROS) and reactive nitrogen species (RNS) mediated by CIP which affect itsantimicrobial activity in E. coli. Following to our previous results, we wanted to delve into themechanism of action of CIP and CO2 against E. coli ATCC 25922. We studied the oxidative stressmarkers, such as protein oxidation (AOPP), lipids, DNA and changes in the membrane potential. Itwas found, under atmospheric conditions, that the maximum oxidation for AOPP is given at 4h in bothCIP concentrations, while for the controlled atmospheres of CO2 the protein oxidation was favored atshorter times for CO2 50 ppm and CIP 50 µg/mL. For CO2 5% and CIP 0.5 µg/mL it was given at atime of 4h. Most malondialdehyde (MDA) formation occurs under atmospheric conditions for bothconcentrations of CIP at 4 h of reaction, while the CO2 does no bring on lipid peroxidation mediatedby CIP. Both in atmospheric conditions and in controlled atmospheres of CO2 it was evident analteration in the bacterial membrane potential generated by the highest concentration of CIP. Incontrolled atmospheres of CO2 , the oxidation of DNA was lower than in atmospheric conditions. Inconclusion, we could say that CO2 modifies the bactericidal effect of CIP against E. coli, reducing thedamage on the different macromolecules