THURSDAY, Sept. 24 (HealthDay News) -- Nitric oxide created by bacterial nitric oxide synthases (bNOS) may help protect bacteria from numerous antibiotics, according to research published in the Sept. 11 issue of Science.
Ivan Gusarov, Ph.D., of the New York University School of Medicine in New York City, and colleagues write that bNOS have been shown to protect bacteria from oxidative stress, and that antibiotics such as lactams, aminoglycosides, and quinolones work in part by creating reactive oxygen species.
The researchers found that pretreating E. coli cells with bipyridyl, which suppresses the Fenton reaction, decreased the toxicity of the antimicrobial acriflavine. Pretreatment with nitric oxide was as effective in protecting the bacteria from acriflavine, but didn't further protect cells pretreated with bipyridyl, suggesting that they work through the same pathway. They also found that pyocyanin -- a natural antimicrobial produced by Pseudomonas aeruginosa -- inhibited the growth of wild-type B. subtilis much less than the growth of a nos deletion strain. Adding exogenous nitric oxide (NOS) to the altered cells restored their growth in the presence of pyocyanin.
"Our results show that bacteria use NOS as a part of their defense system against other microorganisms. Because the pathogens, including Bacillus anthracis and Staphylococcus aureus, have NOS, which protects them against antibiotics and immune attack, the inhibition of this enzyme could serve as an effective antibacterial intervention," the authors conclude.
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