Guido Mora | PubMed Health

PubMed2003

Prophage contribution to bacterial population dynamics.

Cocultures of Salmonella strains carrying or lacking specific prophages undergo swift composition changes as a result of phage-mediated killing of sensitive bacteria and lysogenic conversion of survivors. Thus, spontaneous prophage induction in a few lysogenic cells enhances the competitive fitness of the lysogen population as a whole, setting a selection regime that forces maintenance and spread of viral DNA. This is likely to account for the profusion of prophage sequences in bacterial genomes and may contribute to the evolutionary success of certain phylogenetic lineages.

Biological Evolution↗

PubMed2002

[Molecular characterization of resistance mechanisms to chloramphenicol in Shigella flexneri strains isolated from Chilean children with acute diarrhea].

BACKGROUND: Chloramphenicol is one of the therapeutic options for shigellosis, but resistance to this antimicrobial is increasing. AIM: To characterize molecular mechanisms conferring resistance to chloramphenicol (Cm) in Shigella flexneri strains isolated from Chilean children with acute diarrhea. MATERIAL AND METHODS: Thirty one Shigella filexneri strains, including 22 with the Cm phenotype were analyzed. Strains were tested for antimicrobial susceptibility by plate dilution and for the presence of an internal fragment of the cat gene encoding for chloramphenicol o-acetyl-transferase, by polymerase chain reaction and Southern blot analysis. RESULTS: All Cm strains had a minimal inhibitory concentration over 64 micrograms/ml and amplified the internal fragment of the cat gene. Southern blot analyses indicated that this gene was located in the bacterial chromosome. CONCLUSIONS: Resistance to chloramphenicol in this group of Shigella flexneri strains was mediated by a chromosomally located cat gene.

Acute Disease↗