Colonial morphology of staphylococci on Memphis agar: phase variation of slime production, resistance to beta-lactam antibiotics, and virulence.

Journal Article (Journal Article)

The growth of Staphylococcus epidermidis sensu stricto and Staphylococcus saprophyticus on Memphis agar yielded up to 6 morphotypes with each strain. With S. epidermidis, one morphotype produced slime (rho) but became non-slime-producing (epsilon) at a high frequency. The slime-producing rho variants were methicillin-resistant and more virulent than methicillin-susceptible epsilon variants in an endocarditis model. With S. saprophyticus, phase variation was of higher frequency. Nitrosoguanidine mutagenesis produced a stable blue epsilon form that was more virulent than the parent in a mouse model of urinary tract infection. Mutants with the blue epsilon phenotype differed from gold epsilon parents in a variety of phenotypic properties, including increased resistance to oxacillin. These staphylococcal species have a high frequency of phase variation: Phase variants differ in antibiotic resistance and virulence, which is only partially correlated with suggested virulence factors such as slime production.

Full Text

Duke Authors

Cited Authors

  • Christensen, GD; Baddour, LM; Madison, BM; Parisi, JT; Abraham, SN; Hasty, DL; Lowrance, JH; Josephs, JA; Simpson, WA

Published Date

  • June 1990

Published In

Volume / Issue

  • 161 / 6

Start / End Page

  • 1153 - 1169

PubMed ID

  • 2345296

International Standard Serial Number (ISSN)

  • 0022-1899

Digital Object Identifier (DOI)

  • 10.1093/infdis/161.6.1153


  • eng

Conference Location

  • United States