Staph aureus Flashcards
What is the first-line imaging modality used to detect infection in the lower limb?
X-ray is the initial imaging modality, but MRI is more sensitive for detecting early infections.
Which bone is commonly affected in lower limb infections, especially in hematogenous osteomyelitis?
The tibia is commonly involved in lower limb infections.
What are the classical clinical signs of septic arthritis in the lower limb?
Redness, swelling, heat, and pain over the affected joint with reduced range of motion.
Name two common risk factors for lower limb infections.
Diabetes mellitus and peripheral vascular disease.
What is the most common pathogen responsible for osteomyelitis in the lower limb?
Staphylococcus aureus.
what to give for MSSA and MRSA
MSSA –> clindamycin
MRSA –> Linezolid
What is Panton-Valentine Leukocidin (PVL) and its significance in infections?
PVL is a toxin produced by some strains of Staphylococcus aureus, associated with severe skin and soft tissue infections, including necrotizing fasciitis.
How does PVL-positive Staphylococcus aureus typically present in patients?
PVL-positive Staphylococcus aureus causes aggressive skin infections, such as abscesses, boils, and occasionally, more severe necrotizing infections like necrotizing pneumonia.
What is the USA300 strain, and why is it clinically significant?
USA300 is a strain of methicillin-resistant Staphylococcus aureus (MRSA) prevalent in community-acquired infections. It often carries the PVL gene and is associated with skin and soft tissue infections.
Why is the USA300 strain of MRSA particularly concerning in the clinical setting?
USA300 is resistant to multiple antibiotics, including methicillin, making treatment of infections more difficult and requiring the use of more potent agents like vancomycin or linezolid.
What is a severe systemic complication of PVL-positive S. aureus?
PVL-positive S. aureus can cause necrotizing pneumonia, particularly in young, healthy individuals, leading to severe lung damage and high mortality rates.
How is the USA300 strain of MRSA typically transmitted?
USA300 is often spread through direct contact with infected wounds or contaminated surfaces, commonly seen in community settings such as gyms, schools, and prisons.
What laboratory test is used to confirm the presence of the PVL toxin in Staphylococcus aureus?
Polymerase chain reaction (PCR) is used to detect the PVL gene in clinical isolates of Staphylococcus aureus.
What distinguishes CA-MRSA infections like those caused by the USA300 strain from hospital-acquired MRSA?
CA-MRSA, including the USA300 strain, tends to affect healthy individuals outside of healthcare settings and is commonly associated with skin and soft tissue infections, while hospital-acquired MRSA typically affects immunocompromised or hospitalized patients.
What is the first-line treatment for severe infections caused by PVL-positive MRSA, such as USA300?
Severe infections are typically treated with IV antibiotics like vancomycin, daptomycin, or linezolid, often in combination with surgical drainage if necessary.
