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Chapter 129. Staphylococcal Infections (Part 1)

Harrison's Internal Medicine Chapter 129. Staphylococcal Infections Staphylococcal Infections: Introduction Staphylococcus aureus, the most virulent of the many staphylococcal species, has demonstrated its versatility by remaining a major cause of morbidity and mortality despite the availability of numerous effective antistaphylococcal antibiotics. S. aureus is a pluripotent pathogen, causing disease through both toxin-mediated and non-toxin-mediated mechanisms. This organism is responsible for both nosocomial and community-based infections that range from relatively minor skin and soft tissue infections to life-threatening systemic infections. . | Chapter 129. Staphylococcal Infections Part 1 Harrison s Internal Medicine Chapter 129. Staphylococcal Infections Staphylococcal Infections Introduction Staphylococcus aureus the most virulent of the many staphylococcal species has demonstrated its versatility by remaining a major cause of morbidity and mortality despite the availability of numerous effective antistaphylococcal antibiotics. S. aureus is a pluripotent pathogen causing disease through both toxin-mediated and non-toxin-mediated mechanisms. This organism is responsible for both nosocomial and community-based infections that range from relatively minor skin and soft tissue infections to life-threatening systemic infections. The other staphylococci collectively designated coagulase-negative staphylococci CoNS are considerably less virulent than S. aureus but remain important pathogens in infections associated with prosthetic devices Microbiology and Taxonomy Staphylococci gram-positive cocci in the family Micrococcaceae form grapelike clusters on Gram s stain Fig. 129-1 . These organisms are catalasepositive unlike streptococcal species nonmotile aerobic and facultatively anaerobic. They are capable of prolonged survival on environmental surfaces in varying conditions. Figure 129-1 S JF Five fS. Ktfp DL. fertunttald t. Htuia. SI. Lonpo DL. Jamatsn JL Lojcifus .1 Harriỉữnrỉ Prìnapỉas ữf ỉntaroaỉ 1.7th Edition http ttft.imtd cin .cprr- Copyright Th M0iitu-H.ll Cjmpinmi. nq. Al ri r.r- d. Gram s stain of 5. aureus in a sputum sample with polymorphonuclear leukocytes. Reprinted with permission from FD Lowy Staphylococcus aureus infections. N Engl J Med 339 520 1998. 1998 Massachusetts Medical Society. All rights reserved. More than 30 staphylococcal species are pathogenic. A simple strategy for identification of the more clinically important species is outlined in Fig. 129-2. Automated diagnostic systems kits for biochemical characterization and DNA-based assays are available for distinguishing among .