Bacterial Skin And Joint Infections Flashcards
(15 cards)
What are the most common bacterial pathogens responsible for skin infections, and how do they typically present?
• Staphylococcus aureus: Furuncles, carbuncles, cellulitis, impetigo.
• Streptococcus pyogenes: Erysipelas, cellulitis, necrotizing fasciitis.
• Pseudomonas aeruginosa: Hot tub folliculitis, greenish wound discharge.
What are the distinguishing features of cellulitis compared to erysipelas?
• Cellulitis: Deeper infection involving dermis and subcutaneous tissue, poorly defined borders, diffuse redness.
• Erysipelas: Superficial infection, well-demarcated raised edges, bright red, often associated with S. pyogenes.
How does necrotizing fasciitis present clinically, and what are the key diagnostic features?
• Rapidly progressing, severe pain out of proportion to physical findings, crepitus, skin discoloration, and systemic signs (fever, hypotension).
• Imaging may show gas in tissues; surgical exploration confirms diagnosis.
Describe the pathogenesis of impetigo and its typical bacterial pathogens.
• Superficial epidermal infection caused by S. aureus and/or S. pyogenes.
• Presents as honey-colored crusted lesions, typically around the mouth and nose.
What is the recommended antibiotic treatment for methicillin-resistant Staphylococcus aureus (MRSA) skin infections?
• Oral options: Clindamycin, doxycycline, TMP-SMX.
• Severe cases: IV vancomycin, daptomycin, or linezolid.
How does diabetic foot infection differ in clinical presentation and treatment from other skin infections?
• Often polymicrobial, involving gram-positive cocci, gram-negative rods, and anaerobes.
• Treatment involves broad-spectrum antibiotics and aggressive debridement.
What is the pathophysiological mechanism behind septic arthritis, and which organisms are most commonly implicated?
• Pathogen enters joint space via hematogenous spread, direct inoculation, or contiguous infection.
• Common organisms: S. aureus, Streptococcus spp., Neisseria gonorrhoeae (in sexually active adults).
How is gonococcal arthritis differentiated from non-gonococcal septic arthritis?
• Gonococcal arthritis: Migratory polyarthritis, tenosynovitis, dermatitis.
• Non-gonococcal arthritis: Typically monoarticular, more destructive, purulent joint effusion.
What diagnostic tests are essential for confirming septic arthritis?
• Joint aspiration with synovial fluid analysis: Gram stain, culture, WBC count, crystal analysis.
• Blood cultures and imaging (e.g., MRI, ultrasound) for extent of infection.
Describe the clinical presentation and complications of osteomyelitis in adults.
• Localized pain, swelling, warmth, erythema, systemic signs (fever, malaise).
• Complications: Chronic infection, abscess formation, bone necrosis, sepsis.
How is Pseudomonas aeruginosa typically acquired in skin infections, and what clinical features indicate its presence?
• Acquired from contaminated water sources (e.g., hot tubs, swimming pools).
• Clinical features: Greenish-blue pus, sweet odor, resistance to common antibiotics.
What is the first-line treatment for erysipelas, and what are the primary pathogens involved?
• First-line: Penicillin or amoxicillin.
• Primary pathogen: Streptococcus pyogenes (Group A Streptococcus).
How does clostridial myonecrosis (gas gangrene) present, and what are the critical management steps?
• Rapid onset of severe pain, gas production, crepitus, foul-smelling discharge, systemic toxicity.
• Management: Surgical debridement, IV antibiotics (clindamycin, penicillin), hyperbaric oxygen therapy.
What are the key clinical features and diagnostic criteria for toxic shock syndrome (TSS)?
• High fever, hypotension, diffuse macular erythematous rash, desquamation, multi-organ involvement.
• Diagnosis: Clinical presentation plus isolation of S. aureus or S. pyogenes, or detection of toxin production.
What preventive measures are recommended for recurrent skin abscesses in patients with MRSA colonization?
• Nasal decolonization with mupirocin, chlorhexidine washes, hand hygiene, avoidance of sharing personal items, and wound care.
