Infective endocarditis caused by USA300 methicillin-resistant Staphylococcus aureus (MRSA)

Area of Science:

• Infectious Diseases
• Cardiology
• Microbiology

Background:

• Infective endocarditis (IE) is a serious infection of the heart's inner lining.
• Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen, with the USA300 strain becoming increasingly prevalent.
• Injection drug use is a known risk factor for developing IE.

Observation:

• This study details seven cases of IE attributed to USA300 MRSA at an urban academic medical center.
• All affected patients were identified as injection drug users.
• The isolates were confirmed as USA300-type MRSA using pulsed-field gel electrophoresis.

Findings:

• Five cases involved right-sided endocarditis, and two involved left-sided endocarditis.
• Patients received prolonged antimicrobial therapy, averaging 23 days in-hospital and 55 days total.
• Complications included heart failure, requiring valve replacement in one case, and mortality in that same patient.

Implications:

• The rising prevalence of USA300 MRSA necessitates increased clinical vigilance for IE, especially in at-risk populations.
• Understanding the spectrum of illness associated with USA300 MRSA IE is crucial for effective management.
• Enhanced prevention strategies are needed to address the growing threat of this virulent MRSA strain.