Synopsis
Distinguish meticillin-resistant Staphylococcus aureus carriage from infection, secure cultures and source control, select site- and susceptibility-directed therapy, clear bloodstream infection rigorously, and apply proportionate decolonisation and infection prevention.
- MRSA carries mecA or mecC-mediated altered penicillin-binding protein, making standard anti-staphylococcal beta-lactams ineffective despite otherwise typical S. aureus virulence.
- Colonisation means MRSA is present on nose, throat, perineum, skin or a wound without attributable inflammation or systemic disease; systemic antibiotics are not used to sterilise carriage.
- Culture blood and the true infection focus before antimicrobials when safe, then request full susceptibility because MRSA resistance beyond beta-lactams is variable.
Key red flags
Persistent positive blood cultures beyond 48 to 72 hours on active therapy suggests uncontrolled source, endocarditis, infected thrombosis, prosthetic material or inadequate drug exposure.
Fever, rigors, hypotension or an otherwise unexplained inflammatory syndrome with MRSA in blood is always clinically significant.
Investigation priorities
Confirm MRSA at the infection focus and identify active oral and intravenous options.
Management branches
MRSA is detected from screening or a clinical specimen.
- Identify the exact specimen and examine for pain, erythema, purulence, systemic illness or organ dysfunction; do not infer disease from the organism name.
- Before antibiotics, obtain blood cultures when systemically unwell and a deep or sterile-site specimen from the focus when sampling is safe.
Key medicines
VancomycinUse an intravenous weight-based loading and maintenance regimen from the local AUC or concentration protocol, commonly beginning around 15 to 20 mg/kg every eight to twelve hours with renal adjustment.
TeicoplaninFor severe infection, a common regimen is 12 mg/kg intravenously every 12 hours for three to five loading doses, then 12 mg/kg once daily with level-guided renal adjustment.