Researchers from Colorado have identified a new topical antibiotic that may inhibit skin infections in humans. Their findings appear in the October 2005 issue of the journal Antimicrobial Agents and Chemotherapy.
Ongoing emergence of drug-resistant bacteria continues to propel the search for new antibiotics. In the year 2000, methicillin-resistant Staphylococcus aureus (MRSA) measured an infection rate of 43.7% in U.S. hospitals, with nasal carriage as an important risk factor in transmission. Until recently, mupirocin effectively treated S. aureus and Streptococcus pyogenes skin infections, however S. aureus is now showing signs of resistance.
In the study the antibacterial activity of a novel methionyl-tRNA inhibitor, REP8839, was tested against samples of S. aureus and S. pyogenes. Researchers found all isolates of S. aureus, including strains resistant to methicillin, mupirocin, vancomycin, and linezolid, to be susceptible to REP8339 as well as all isolates of S. pyogenes.
"This study has shown that REP8839 has important coverage against both major skin pathogens: S. aureus and S. pyogenes," say the researchers. "The compound is currently in preclinical development as a topical antibiotic for the treatment of skin infections and for the eradication of nasal carriage of S. aureus."
(I.A. Critchley, C.L. Young, K.C. Stone, U.A. Ochsner, J. Guiles, T. Tarasow, N. Janjic. 2005. Antibacterial activity of REP8839, a new antibiotic for topical use. Antimicrobial Agents and Chemotherapy, 49. 10: 4247-4252.)
More Diverse Bacteria Found in Arctic Tundra than Forest Soil
The soil beneath the arctic tundra is home to a greater diversity of microorganisms than nearby boreal forests according to researchers from British Columbia. They report their findings in the October 2005 issue of the journal Applied and Environmental Microbiology.
Boreal forests (cold temperature forests found in the northern hemisphere) and arctic tundra cover 22% of the earth's terrestrial surface. These environments are very sensitive to climate change and variation in their productivity can substantially impact the global climate.
In the study soil samples were taken from three arctic tundra sites and three boreal forest locations and analyzed for bacterial diversity. Researchers found a broader range of microbial presence in undisturbed arctic tundra soil with the highest diversity identified in a sample from an extreme northern location.
"This report demonstrates that the Arctic serves as an unrecognized reservoir of microbial diversity and thus biochemical potential," say the researchers. "An appreciation of the magnitude of arctic microbial biodiversity is a critical foundation for studies of its ecological and industrial significance and an important first step toward gauging the impact of climate change on this poorly studied biome."
(J.D. Neufeld, W.W. Mohn. 2005. Unexpectedly high bacterial diversity in arctic tundra relative to boreal forest soils, revealed by serial analysis of ribosomal sequence tags. Applied and Environmental Microbiology, 71. 10: 5710-5718.)
Human Neurons Mount Innate Immune Response During Viral Attack
Human neurons may mount an innate immune response specific to the type of viral infection say researchers from France. Their findings appear in the October 2005 issue of the Journal of Virology.
In the study researches infected human neuron cell lines with rabies virus (RABV) and herpes simplex type 1 (HSV-1) and analyzed changes in gene expression. Results showed that both viruses increased the transcription of genes indicative of an innate immune response, however the genes that were turned on differed based on the virus. For example, increased gene expression following RABV infection included those responsible for the production of the cytokine beta interferon while infection with HSV-1 did not.
"Human neurons have the machinery to sense viral infection, and the nature of the innate immune response depends on the nature of the infection," say the researchers.
(C. Prehaud, F. Megret, M. Lafage, M. Lafon. 2005. Virus infection switches TLR-3-positive human neurons to become strong producers of beta interferon. Journal of Virology, 79. 20: 12893-12904.)