Causative Agents of Actinomycosis

The principal agents of human actinomycosis are Actinomyces israelii, Actinomyces gerencseriae, and the morphologically similar Propionibacterium propionicum. The cells of these species are filamentous, beaded, and branching gram-positive rods. The organisms in vivo form characteristic microcolonies with radiating filaments and clubbed ends composed of both bacterial and host materials and surrounded by neutrophils and foamy macrophages. In wound exudates, microcolonies may be visible to the naked eye as hard white or yellowish grains, commonly called ''sulphur granules.'' Actinomyces spp. are highly suscep tible in vitro to a wide range of antimicrobial agents. However, within microcolonies, the organisms are protected from the actions of these and of host defenses, and this is thought to be a major pathogenicity factor. In the laboratory, the above-named species may require up to 10 days of anaerobic incubation on a serum-containing medium before characteristic white or beige ''breadcrumb'' or ''molar tooth'' colonies are visible. Colonies may be very gritty, pitting, and adherent to the agar. These growth characteristics and the almost universal presence of concomitant organisms, commonly members of the oral flora, can result in difficulties in laboratory isolation, identification, and susceptibility testing.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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