In the latest issue of Science researchers in the UK and Finland studied genetic recombination in Streptococcus pneumonia, the bacteria that causes pneumonia and bacterial meningitis.
They analyzed the genetic sequences of recombination loci of 2,024 different pneumococcus genotypes from the MLST database, a database that gives recombination locus sequence data for seven housekeeping genes found in pneumococcal bacteria. Housekeeping genes, according to a quick google search, are simply those genes that are involved in basic cell function are are thus always turned on. Using a Bayesian analysis program, the researchers grouped the genotypes into six clusters based on allele frequencies. They found that half of these clusters matched non-pneumococcal bacteria and the other half matched pneumococcal sub-populations. Most importantly, when they looked at cluster 4, one of the non-pneumococcal clusters, they found that it contained almost all of the non-pneumococcal alleles. Upon further investigation, they found cluster 4 bacteria were associated with higher antibiotic resistance to enicillin, erythromycin, tetracycline, chloramphenicol, and cefotaxime. "In contrast, cluster 1, which almost exclusively contained alleles from one cluster, negatively associated with resistance" (3).
This suggests that those strains of bacteria that exhibit the hyper-recombination, a higher tendency to accept genes from other species, are important in the evolution and spread of antibiotic resistance.
This seems consistent with what we've been learning about viruses--the higher the rate of mutation or recombination, the higher the likelihood a strain will develop drug resistance. What I am not clear on is whether their is a recombination mechanism for pox-viruses as there are for most bacteria? Bacteria, especially when they are of the same species, routinely undergo homologous recombination, "in which short tracts of DNA in the recipient are replaced by the corresponding tract from a donor strain, resulting in a mosaic of DNA from different ancestors" (2). How rare are recombination events for pox-viruses and viruses in general? I know Kaitlyn mentioned theories that vaccinia was a recombination of various strains of pox-viruses...
(1) Science summary
(2) Science article
(3) News summary