“FROM the perspective of a bacterium, higher eukaryotes are oversexed, unadventurous and reproduce in an inconvenient way.” So says Pål Johnsen and Bruce Levin in their commentary of today’s article for discussion, and nary a truer word said. Of course, one may state that inconvenient as reproduction may be, bacteria clearly have no sense of fun.
There was once an idea that we could address the problem of antibiotic resistant bacterial strains by removing the ailing antibiotic from clinical use. In the absence of selective pressure it was thought that the evolutionary traits that enable the strain to resist the antibiotic would actually put the strain at a competitive disadvantage compared with a strain that doesn’t have such antibiotic resistance. The proposed cause of this? Fitness costs – these are imposed by a resource-expensive set of mutations, or carriage of alien DNA, that make the resistant strain compete less well once its non-resistant brethren are no longer being killed off by the antibiotic.
However, some years ago now experimental evidence suggested that this is not always the case; it may in fact be often not the case. It is worth mentioning at this point that it has been shown that in some circumstances (alt) the number of infections caused by a particular antibiotic-resistant pathogenic bacterium have become fewer on reduction (or removal) of the antibiotic to which that strain is resistant, but to assume this would be the case with all strains/antibiotics is naïve.
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