Regulation of virulence and antibiotic resistance in Gram-positive microbes in response to cell wall-active antibiotics.

Purpose Of Review: Antibiotic stress can evoke considerable genotypic and phenotypic changes in Gram-positive bacteria. Here, we review recent studies describing altered virulence expression in response to cell wall-acting antibiotics and discuss mechanisms that coordinate regulation of the antibiotic response.

Recent Findings: Pleiotropic effects induced by antibiotic exposure include alterations to bacterial metabolism, cell wall structure and antibiotic resistance.

Factors affecting use of ballistics gelatin in laboratory studies of bacterial contamination in projectile wounds.

Background: Ballistics gelatin is a common tissue surrogate used in bacterial contamination models for projectile wounds. Although these studies have demonstrated that bacteria are transferred from the surface of the gelatin to the wound track by a projectile, quantifiable results have been inconsistent and not repeatable in successive tests.

Methods: In this study, five areas of a typical contamination model in which bacterial recovery or survival are affected were identified for optimization.

Divergent Roles of RPA Homologs of the Model Archaeon in Survival of DNA Damage.

The haloarchaea are unusual in possessing genes for multiple homologs to the ubiquitous single-stranded DNA binding protein (SSB or replication protein A, RPA) found in all three domains of life. contains five homologs: two are eukaryotic in organization, two are prokaryotic and are encoded on the minichromosomes, and one is uniquely euryarchaeal. Radiation-resistant mutants previously isolated show upregulation of one of the eukaryotic-type RPA genes.