Review Question - QID 101540

Methicillin-resistant Staphylococcus aureus (MRSA) is the likely causative organism in this patient's presentation. It is an increasingly common and dangerous nosocomial infection, especially in open-joint arthoplasty procedures. It is not susceptible to nafcillin/methicillin.

Given the increasing abundance of antibiotic-resistant strains of S. aureus, combined with the organism’s proclivity for asymptomatic carriage, the threat of serious nosocomial and community acquired S. aureus infection is on the rise. The external nares are the most common colonization site for Staphylococcus aureus, and 25-30% of the general population are carriers. The prevalence of methicillin-resistant strains of S. aureus (MRSA) is currently over 50% and continues to rapidly increase.


Incorrect Answers:
Answer 1: S. viridans is a common cause of endocarditis; it is not a common nosocomial infection that exhibits nasal colonization.
Answer 2: Fecal-oral transmission is common in E. coli infections.
Answer 3: S. epidermidis is found as part of the normal skin flora; it is a common cause of infection of prosthetic joint infections that occur within 3-12 months.
Answer 5: S. pyogenes (or Group A Streptococcus) is a common cause of pharyngitis; it is not as common as S. aureus in nosocomial infections.