W. Andrew Simpson

Methods for Evaluating Attached Bacteria and Biofilms

If you consider this text a cookbook and yourself—the investigator—the cook, how do you choose which recipe—or experimental procedure—to use? Or should you cook up something new? Like any good chef, the recipe you choose will reflect the meal you wish to prepare, the equipment in your kitchen, the supplies in your pantry, and your own past experience as a cook. But suppose you are not bound by past experience, materials, and equipment, then how do you choose an experimental approach? The answer lies in the experimental question. What hypothesis do you want to test? What meal do you wish to prepare?

Phenotypic Variation in the Pathogenesis of Experimental Endocarditis Caused by Staphylococcus epidermidis

Various colony phenotypes of Staphylococcus epidermidis were examined in an experimental endocarditis model to further explore their virulence characteristics. Our data indicate that: 1) the selection for small colony variant forms is related to the concentration of these variant forms in the respective challenge inocula and upon undetermined factors at the site of the intracardiac infections; 2) slime-producing colony phenotypes are more virulent in this animal model of foreign body-related infection; and 3) the pathogenesis of indwelling, intracardiac catheter infections may be more dependent on slime production than the pathogenesis of infection of the endocardial lesions produced by the indwelling catheters.

Hypothetical Model of Phenotypic Variation in Staphylococci

Members of the genus Staphylococcus exhibit a characteristic pleiotropic phenotypic variation. For one strain of Staphylococcus epidermidis senso stricto, colonial morphology, slime production, beta-lactam resistance, and virulence were subject to simultaneous, spontaneous, phenotypic variation at a rate of 1 ×10−5 per bacterium per generation. Based upon recent progress with Bordetella pertussis and Staphylococcus aureus we prepared a model of phenotypic variation that would explain this phenomenon.