TY - CHAP M1 - Book, Section TI - Chapter 284. Staphylococcus Infections A1 - Connelly, Beverly L. A2 - Rudolph, Colin D. A2 - Rudolph, Abraham M. A2 - Lister, George E. A2 - First, Lewis R. A2 - Gershon, Anne A. Y1 - 2011 N1 - T2 - Rudolph's Pediatrics, 22e AB - Staphylococci are ubiquitous inhabitants of the skin and mucous membranes of humans and other mammals. They exist in a commensal relationship until a breach in a cutaneous or mucosal barrier permits staphylococcal access to deeper tissues and the bloodstream or until a foreign body or medical device provides a foothold. The production of coagulase, an enzyme that clots plasma, distinguishes Staphylococcus aureus from other medically important staphylococci. Those that do not produce coagulase are grouped collectively as coagulase-negative staphylococci (CoNS) and represent the most common resident bacteria of humans.1 All staphylococci are nonmotile, nonspore-forming, facultative anaerobic bacteria. In Gram-stained specimens, they appear as gram-positive cocci in clusters, as well as in pairs and tetrads. Peptidoglycans and lipoteichoic acids form the basic cell wall structures of staphylococci and most exhibit microcapsule formation. Colony morphologies followed up with biochemical reactions allow identification of pathogenic staphylococci. Typical 24-hour S. aureus colonies are larger, yellow pigmented, and surrounded by a small zone of hemolysis. Colonies of S epidermidis are typically small, white or beige, and approximately 1 to 2 mm in diameter after overnight incubation. Small colony variants (SCV) of S aureus, important in some persistent infections, may be missed initially because of their pinpoint size. Staphylococcal colonies in general will be catalase positive, distinguishing them from streptococci.1 SN - PB - The McGraw-Hill Companies CY - New York, NY Y2 - 2024/03/28 UR - accesspediatrics.mhmedical.com/content.aspx?aid=7027979 ER -