Microbiology
A 68-year-old male presents with painful left total knee arthroplasty 3 years post-operatively. Aspiration yields turbid fluid with WBC 45,000 cells/µL (90% neutrophils). Synovial fluid cultures grow coagulase-negative Staphylococcus (CoNS) in 3 of 5 bottles at 4 days. The surgical team debates whether this represents true infection or contamination. You explain that CoNS, particularly *Staphylococcus epidermidis*, is a common cause of chronic periprosthetic joint infection (PJI), accounting for 30-40% of cases. Understanding common orthopaedic pathogens, their virulence mechanisms (biofilm formation), and antimicrobial resistance patterns is essential for diagnosis and treatment. Regarding common pathogens in orthopaedic infections:
Mark each as TRUE or FALSE
Staphylococcus aureus is the most common pathogen in acute orthopaedic infections including acute os...
Biofilm formation is a critical virulence mechanism in chronic orthopaedic infections, where bacteri...
Methicillin-resistant Staphylococcus aureus (MRSA) accounts for 30-50% of S. aureus orthopaedic infe...
Polymicrobial infections account for 10-30% of orthopaedic infections, particularly in open fracture...
Culture-negative orthopaedic infections are rare (less than 5%), and when they occur, they are usual...
Answer the questions to see explanations
Click T (True) or F (False) for each option