Light effect and reactive oxygen species in the action of ciprofloxacin on Staphylococcus aureus.
Oxygen consumption by Staphylococcus aureus ATCC 29213 sensitive to ciprofloxacin was determined with an oxygen selective electrode. Increase in the O(2) consumption was observed with 0.45 micromL(-1) ciprofloxacin while higher concentrations gave rise to a reduction of O(2) consumption. Resistant S. aureus strain did not show increase of O(2) consumption in presence of ciprofloxacin. Nitro Blue Tetrazolium assay showed that production of reactive oxygen species (ROS) increased intracellularly in sensitive bacteria incubated with this antibiotic. The exposition to UV light (360 nm) augmented the intracellular oxidative stress of S. aureus and provoked increment of ROS in extracellular media. Generation of singlet oxygen O(2) ((1)Delta(g)) in S. aureus was measured by means of oxidation of methionine. The absorbance of methionine was monitored at 215 nm and a clear decrease was detected when sensitive S. aureus was stressed with ciprofloxacin. Sodium azide and 2,5-dimethylfuran were used to reinforce the evidence of O(2) ((1)Delta(g)) generation during oxidative stress. Assays with methionine and 2,5-dimethylfuran demonstrated that resistant S. aureus did not increase the production of O(2) ((1)Delta(g)) in the presence of antibiotic. DNA oxidation was investigated in presence of O(2) ((1)Delta(g)) generated by laser excitation of perinaphthenone and subsequent energy transfer. Deactivation of O(2) ((1)Delta(g)) by reaction with DNA of sensitive and resistant bacteria was observed. According to the results obtained, the effect of ciprofloxacin in S. aureus led to an increment of O(2) ((1)Delta(g)) generating oxidative stress in the bacteria.
Departamento de Farmacia, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, pabellón Argentina, Ala 1, 2do Piso, Suc. 16., Haya de la Torre y Medina Allende, Ciudad Universitaria, C.C. 61, 5000 Córdoba, Argentina.
María Cecilia
MC
Becerra
Martín
M
Sarmiento
Paulina Laura
PL
Páez
Gustavo
G
Argüello
Inés
I
Albesa
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002939:Ciprofloxacin / Q000494:pharmacology*; D004249:DNA Damage / Q000528:radiation effects; D024881:Drug Resistance, Bacterial; D004566:Electrodes; D004735:Energy Transfer; D005663:Furans / Q000378:metabolism; D008027:Light; D008715:Methionine / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D043803:Phenalenes / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013194:Staining and Labeling; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D013997:Time Factors; D014466:Ultraviolet Rays
D000900:Anti-Bacterial Agents; D005663:Furans; D043803:Phenalenes; D017382:Reactive Oxygen Species; C038036:phenalen-1-one; D002939:Ciprofloxacin; D008715:Methionine; C037555:2,5-dimethylfuran