MCQs-Infections 1
– herpes simplex infections are HSV-1 and HSV-2, although varicella-zoster, cytomegalovirus, Epstein-Barr are all part of the herpes family.
– HSV-1 is typically “above the waist” – gingival stomatitis, cold sores, corneal keratitis, and skin infections of the finger in which it appears as a painful pustule on an erythematous base – “herpetic whitlow”. This is an occupational hazard of nurses, dentists, physicians, and lab technicians, usually resulting from inoculation of infected secretions through a small cut in the skin. It is frequently misdiagnosed as staph or strep infection.

– most common cause of flexor tenosynovitis is staph aureus

– HIV transmission post needle-stick is around 0.3 to 0.5%

– it seems important to be able to distinguish between strep necrosis and clostridial necrosis –

– the most common complication of neonatal osteo is growth arrest from multiple physeal involvement

– C. difficile can be treated with flagyl or oral vanco. Colitis can be caused by amp, clinda, and ceaphlosporins, and may present up to two weeks after treatment.

– ciprofloxacin inhibits DNA gyrase, and essential component of the DNA replication system; it does not work on the cell wall. Cipro has been shown in animals to cause damage to cartilage and therefore should not be used in growing children with growth plates still open. It is effective against many gram negative organisms. Its absorption is inhibited by magnesium or aluminum containing antacids, and it interacts with theophyline and coumadin.

– C. perfringens produces alpha toxin (an exotoxin) which breaks down cell membranes, including red blood cell membranes – causing hemolysis. Therefore, C. perfringens is most likely to cause a hemolytic anemia.

– know the indications for tetanus prophylaxis
– basically, if unimmunized, they need the Td regimen
– if not immunized fully and has a tetanus prone wound – get TIG and Td
– if immunized fully within the past 5 years with a tetanus prone wound – nothing
– if immunized fully but more than 5 years ago, with a tetanus prone wound – Td
– if immunized fully within the past 10 years with a clean wound – nothing

If you are unsure of tetanus status – give both .5 Td and 250 units TIG. This is the only circumstance to use TIG.

Fibronectin has a role in periprosthetic infections – fibronectin is part of the endothelial cell glycocalyx, and may be exposed when there is local damage (from putting in the joint?). Some gram-positive bacteria, including S. aureus, St. pyogenes, St mutans, and St sanguis, bind to fibronectin

Flagyl is metabolized by the liver and excreted by the kidney. The metabolism is in the liver – altered kidney function does not prolong the half life.

Eikenella corrodons infections are common with human and dog bits (pasteurella is with cat bits). Eikenella is a gram negative rod and is best treated with penicillin.

The most common organism in human bites is strep viridans.

The most common joint in septic arthritis is probably the knee.

Bacteria can exude an extracellular glyocalyx matrix which protects them from host defenses and antibiotics.

Serratia infection seems to be an opportunistic infection that is most commonly spread by hands of hospital employees and may be a cause of infection in arthroscopy.

Staph epi of the hip is treated with Vancomycin.

The most common organism in recurrent hip infection is staph aureus.

The most difficult bug to kill in hip arthroplasty is pseudomonas.

Aspiration of the hip is the best way to diagnose infection.

The most common cause of latent infection of the total hip (6 months out) is staph epi.

In puncture wounds to the foot, beware of staph and pseudomonas infections. If the nail goes through the shoe, be particularly wary of pseudomonas, which shows up with a colourless discharge rather than pus.

Listeria monocytogenes infection is typically an infection of neonates and immunocompromised.

Immune complexes are part of the pathogenesis of lyme

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