Forbes, and postdoctoral research associate Joe Latimer then grew the small colony variant, as well as the unexposed strain of S. aureus, in the wax moth larvae model, Galleria mellonella, "and found that our small colony variants were indeed less pathogenic in this test system than the unexposed strain," says McBain. Even after it was grown another ten times in triclosan-free media, the small colony variant failed to fully regain its virulence, as well as its normal ability to form biofilms and to produce the enzyme, DNase.
"The work suggests that at least for small colony variants, long-term exposure can select for reduced susceptibility, but that the resulting organisms may also be reduced in their pathogenic capability, or fitness," says McBain. He adds that "even though our small colony variants were less susceptible, their resistance levels remained markedly lower than commonly used concentrations so they were still probably effectively treatable."
(J. Latimer, S. Forbes, and A.J. McBain, 2012. Attenuated virulence and biofilm formation in Staphylococcus aureus following sublethal exposure to triclosan. Antim. Agents Chemother. 56:3092-3100.)
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Changing Pigs' Diets Alters the Gut Microbiota
Including chicory in cereal-based diets of pigs results in profound changes in gut micro-environment, morphology, and microbial population of pigs, according to a study in the June 2012 Applied and Environmental Microbiology. Some of these changes were health-promoting, says principal investigator Jan Erik Lindberg of the Swedish University
|Contact: Jim Sliwa|
American Society for Microbiology