Pseudomonas aeruginosa deficient in 8-oxodeoxyguanine repair system shows a high frequency of resistance to ciprofloxacin

• Published in: FEMS microbiology letters Vol. 290; no. 2; pp. 217 - 226
• Main Authors: Morero, Natalia R, Argaraña, Carlos E
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 2009; Blackwell Publishing Ltd; Wiley-Blackwell; Oxford University Press
• Subjects: Amino Acid Sequence; Anti-Bacterial Agents - pharmacology; Antibiotics; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Cell viability; Ciprofloxacin; Ciprofloxacin - pharmacology; ciprofloxacin resistance; Cloning; Deactivation; Deoxyguanosine - analogs & derivatives; Deoxyguanosine - metabolism; Deoxyribonucleic acid; DNA; DNA damage; DNA Repair; DNA topoisomerase IV; Drug Resistance, Bacterial; Eukaryotes; Fundamental and applied biological sciences. Psychology; Gene frequency; Genes; Genetics; High frequencies; Hydrogen peroxide; Inactivation; Metabolism. Enzymes; Microbial Sensitivity Tests; Microbial Viability - drug effects; Microbiology; Mismatch repair; Molecular Sequence Data; Mutation; mutM; mutT; mutY; nfxB; Oxidation resistance; Oxidative stress; Paraquat; Prevention; Prokaryotes; Pseudomonas aeruginosa; Pseudomonas aeruginosa - chemistry; Pseudomonas aeruginosa - drug effects; Pseudomonas aeruginosa - genetics; Pseudomonas aeruginosa - metabolism; Repair; Resistant mutant; Sequence Alignment; ciprofloxacin resistance; Pseudomonadales; Hydrogen peroxide; Rifampicin; muté mutY; mutM; nfxB; ciprofloxacin résistance; Antibiotic resistance; Bacteria; Pseudomonadaceae; Paraquat; Pseudomonas aeruginosa; Ciprofloxacin; Pseudomonas seruginosa
• ISSN: 0378-1097; 1574-6968
• DOI: 10.1111/j.1574-6968.2008.01411.x

The 8-oxodeoxyguanine (8-oxodG) repair system participates in the prevention and correction of mutations generated by oxidative DNA damage in prokaryotes and eukaryotes. In this study, we report that Pseudomonas aeruginosa strains deficient in this repair mechanism by inactivation of the mutT, mutM and mutY genes generate a high frequency of cells resistant to the antibiotic ciprofloxacin. In the mutT strain, the increase in ciprofloxacin resistance achieved at threefold minimal inhibitory concentration was about 1600-fold over the wild-type (WT) level, similar to the frequency achieved by the mismatch repair-deficient mutS strain. Molecular analysis of WT, mutT and mutY clones resistant to ciprofloxacin indicated that the nfxB gene was mutated in the majority of the cases, while mutS-derived resistant clones were mainly mutated in gyrA and parC genes. Cell viability analysis after treatment with paraquat or hydrogen peroxide indicated that 8-oxodG repair-deficient strains were considerably more susceptible to oxidative stress than the parental strain. Finally, it is shown that the ciprofloxacin resistance frequency of WT and repair-deficient strains increased significantly after cell exposure to paraquat. Thus, oxidative stress is strongly implicated in the emergence of ciprofloxacin-resistant mutants in P. aeruginosa, and the 8-oxodG repair pathway plays an important role in the prevention of these mutations.