Show Summary Details
Page of



Kyle J. Popovich

, Robert A. Weinstein

, and Bala Hota

Page of

PRINTED FROM OXFORD MEDICINE ONLINE ( © Oxford University Press, 2021. All Rights Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford Medicine Online for personal use (for details see Privacy Policy and Legal Notice).

date: 28 February 2021

This chapter looks at staphylococci, which are Gram-positive cocci that form clusters, but can occur singly, in pairs, chains, or tetrads. They are classically distinguished from other Gram-positive cocci by presence of catalase, an enzyme that degrades hydrogen peroxide (H2O2). S. aureus is distinguished from other coagulase-negative staphylococci, which are generally less virulent, by the presence of coagulase, an enzyme that coagulates plasma. Many toxins and regulatory elements enhance virulence in staphylococci. Staphylococci are skin commensals. About 20% of adults are persistently colonized by S. aureus, 60% are intermittently colonized, and 20% are never colonized. High-risk groups for S. aureus colonization include infants, insulin-dependent diabetics, intravenous drug users, HIV-infected patients, and renal dialysis patients. Methicillin-resistant Staphylococcus aureus (MRSA) was once predominantly seen in hospitals. However, over the past twenty years the epidemiology of MRSA has significantly changed, with MRSA infections now being observed in community settings.

Access to the complete content on Oxford Medicine Online requires a subscription or purchase. Public users are able to search the site and view the abstracts for each book and chapter without a subscription.

Please subscribe or login to access full text content.

If you have purchased a print title that contains an access token, please see the token for information about how to register your code.

For questions on access or troubleshooting, please check our FAQs, and if you can't find the answer there, please contact us.