Frequency of formation of small-colony variants (SCV)

Range Salmonella enterica SCV in fibroblasts 10^-3 to 10^-4 bacterial cells/host cell: Staphylococcus aureus SCV in cultured endothelial cells 10^-3 bacterial cells/host cell
Organism bacteria
Reference Cano DA, Pucciarelli MG, Martínez-Moya M, Casadesús J, García-del Portillo F. Selection of small-colony variants of Salmonella enterica serovar typhimurium in nonphagocytic eucaryotic cells. Infect Immun. 2003 Jul71(7):3690-8 p.3695 right column 2nd paragraphPubMed ID12819049
Primary Source [54] Vesga, O., M. C. Groeschel, M. F. Otten, D. W. Brar, J. M. Vann, and R. A. Proctor. 1996. Staphylococcus aureus small colony variants are induced by the endothelial cell intracellular milieu. J. Infect. Dis. 173: 739-742PubMed ID8627043
Method Primary source abstract: "To understand the process by which SCVs [small colony variants] of S. aureus appear in subjects who have not received antibiotic treatment, bovine endothelial cells were coincubated with a wild S. aureus strain for 72 h in the presence of lysostaphin. Intracellular bacteria were harvested and screened for stable SCVs."
Comments P.3695 right column 2nd paragraph: "Regardless of whether all mutants of a phenotypic class bear the same mutation, [investigators'] results demonstrate that the frequency of formation of S. enterica SCV in fibroblasts is on the order of 10^−3 to 10^−4, in close agreement with the study of Vesga et al., in which these authors estimated that the rate of formation of S. aureus SCV in cultured endothelial cells was 10^−3 (primary source). However, one difference between the two pathogens is that emergence of S. aureus SCV in endothelial cells occurs after 72 h of infection, whereas S. enterica SCV are selected in cultured fibroblasts after 6 days of infection. The reasons for this difference are not known, but factors such as the host cell type and/or bacterial type may certainly contribute to it." Primary source abstract: "Intracellular bacteria developed the SCV phenotype at a greater rate than control bacteria not exposed to endothelial cells: The intracellular induction rate was approximately 10^(-3) versus a spontaneous rate of <10^(-7)."
Entered by Uri M
ID 116905