David L. Hasty

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Conventional wisdom regarding mechanisms of bacterial pathogenesis holds that pathogens arise by external acquisition of distinct virulence factors, whereas determinants shared by pathogens and commensals are considered to be functionally equivalent and have been ignored as genes that could become adapted specifically for virulence. It is shown here,(More)
Type 1 fimbriae are heteropolymeric surface organelles responsible for the D-mannose-sensitive (MS) adhesion of Escherichia coli. We recently reported that variation of receptor specificity of type 1 fimbriae can result solely from minor alterations in the structure of the gene for the FimH adhesin subunit. To further study the relationship between allelic(More)
The alarming increase in drug-resistant bacteria makes a search for novel means of fighting bacterial infections imperative. An attractive approach is the use of agents that interfere with the ability of the bacteria to adhere to tissues of the host, since such adhesion is one of the initial stages of the infectious process. The validity of this approach(More)
A key attribute of invasive Streptococcus pyogenes is their ability to resist phagocytosis and multiply in human blood. M-related protein (Mrp) is a major anti-phagocytic factor but the mechanism whereby it helps streptococci to evade phagocytosis has not been demonstrated. We investigated phagocytosis resistance in a strain of serotype M4 by inactivating(More)
Type 1 fimbriae are the most common adhesive organelles of Escherichia coli. Because of their virtual ubiquity, previous epidemiological studies have not found a correlation between the presence of type 1 fimbriae and urinary tract infections (UTIs). Recently it has become clear that type 1 fimbriae exhibit several different phenotypes, due to allelic(More)
Serum opacity factor (SOF) is a fibronectin-binding protein of group A streptococci that opacifies mammalian sera and is expressed by some strains that cause impetigo, pharyngitis and acute glomerulonephritis. Although SOF is expressed by approximately 35% of known serotypes, its role in the pathogenesis of group A streptococcal infections has not been(More)
Lipoteichoic acid and several streptococcal proteins have been reported to bind fibronectin (Fn) or fibrinogen (Fgn), which may serve as host receptors. We searched for such proteins by screening a library of genes from M type 5 group A streptococci cloned into Escherichia coli. Lysates of clones were probed with biotinylated Fn and biotinylated Fgn. One(More)
BACKGROUND Hydrophobicity is an important attribute of bacteria that contributes to adhesion and biofilm formation. Hydrophobicity of Streptococcus pyogenes is primarily due to lipoteichoic acid (LTA) on the streptococcal surface but the mechanism(s) whereby LTA is retained on the surface is poorly understood. In this study, we sought to determine whether(More)
Macrophage stimulation by lipoteichoic acid (LTA) and hemoglobin (Hb) requires Toll-like receptors 2 and 4 (TLR2 and -4). There are two distinct temporal phases of interleukin-6 (IL-6) production. The first results in a slight enhancement of IL-6 secretion in response to LTA plus Hb compared to that with LTA alone and is TLR4 independent. The second(More)