7. Infectious Arthritis Flashcards
Septic arthritis is always associated with what? More likely to appear in what joints with what quality?
Inflammation or true arthritis (not just arthralgia, which is pain in and around the joint) More likely to appear in a joint previously afflicted with another form of arthritis.
Septic Arthritis: what are the culprits for ACUTE presentation?
Bacterial (usually gram neg) or viral. Anaerobes are uncommon
Septic Arthritis: what are the culprits for CHRONIC presentation?
Lyme, Mycobacterial, fungal, filarial, bacterial (gonococcal, meningiococcal)
What organism is the most common agent?
Staph Aureus because it expresses receptors found in joints, and it is part of normal skin flora. Opportunities to spread from minor wounds
What is the pathophysiology of Septic (infectious) arthritis? In otherwords, how does this hapepn?
Synovial tissue is vascularized, susceptible to being seeded by bacteria –> bacterial toxins induce leukocytes and chondrocytes to produce proteases, which are destructive to cartilage
clinical presentation: how many joints? feels better in resting position or with movement? systemic sx?
- abrupt onset
- usually MONOarticular, may be pauci (2-3 joints)
- discomfort in Resting position**
- May have low fever, rigors
which joints are typically affected?
- weight bearing joints like KNEE, hip, ankle
- for bedridden patients, still weight-bearing joints, but that may mean sternoclavicular, collarbone, shoulder
findings on physical exam?
- redness, swelling, warmth
- bulge sign, floating patella (“ballottement”)
- decr ROM
- tender proximal lymph nodes
- source of infection (but may not be present)
best method for diagnosis?
Arthrocentesis is crucial
The following findings on Arthrocentesis indicate what?
- PMNs
- blood
- crystals
- protein
- low glucose
- PMNs -> infection
- blood -> trauma
- crystals -> gout, pseudogout
- high protein -> infection
- low glucose -> infection
Beyond arthrocentesis, other methods of dx?
-Technetium bone scan (cellulitis v septic arthritis v osteomyelitis) -peripheral blood leukocytes -ESR -culture Arthrocentesis is best!
You suspect septic arthritis: what do you do first?
aspirate that joint FAST: outcome depends on early dx and treatment!
Synovial fluid analysis of Normal joint: what is cell count? appearance of fluid? amount of protein? glucose?
0-200
translucent
protein < 3
glucose 80-100
Synovial fluid analysis of OA or trauma joint: what is cell count? appearance of fluid? amount of protein? glucose?
200-2000
translucent
protein < 3
glucose 80-100
Synovial fluid analysis of RLA, SLE, gout joint: what is cell count? appearance of fluid? amount of protein? glucose?
2000-30000 opaque protein > 3 glucose < 60
Synovial fluid analysis of septic joint: what is cell count? appearance of fluid? amount of protein? glucose?
This is disgusting fluid
75,000 + 90% PMNs
opaque + pus
protein > 3
glucose < 60
Epidemiology for septic arthritis?
peak incidence is bimodal: childhood and old age, predominantly males
what factors predispose the elderly to septic arthritis?
chronic arthritis, systemic disease, immune deficiency, prosthetic joints, underlying RA
what factors predispose younger pts to septic arthritis?
trauma, IVDU
what is the major cause of septic arthritis in sexually active pts under 30? what pattern does it follow?
Neisseria gonorrhoeae –> migrating polyarthritis, inflammation that follows tendon sheaths. may not have GU symptoms. May also settle into one or two joints. That sucks. We had a conference case on this…
If we are unsure if a pt has septic arthritis secondary to Neisseria gonorrhea, what is diagnostic?
response to ceftriaxone via IV for 48 h.
Prosthetic joint infection: what is a symptom that 95% of these pts have?
constant joint pain - even painful at rest
prosthetic joint infection: when/how is the infectious agent introduced? how does it progress?
in half of cases, the infection is introduced at time of surgery. may take months to years to become apparent.
Therapy for septic arthritic joints?
-drainage, debridement -antibiotics -physical therapy (initially non weight bearing)
Prosthetic joint infection: should we try to debride the joint and retain it, or remove it entirely?
-custom now is to try to retain it, esp if EARLY infection and sensitive organism (Strep); lecturer thinks that is crazy and we should remove them
Early Septic Prosthetic Arthritis: definition?
infection within the first year of prosthesis
what is indication that the agent causing prosthetic joint sepsis is staph or gram neg?
it becomes apparent more than 30 d post op, or has sx of infection lasting greater than 3 weeks.
with prosthetic joints that become infected, what is the difference between the one-stage procedure and the two-stage procedure?
- one-stage procedure: only a few months post-op, less than 3 weeks of infectious symptoms. removal of infected prosthesis and re-implantation at same time. 70% success
- two stage: when infection appears much later (maybe 1 yr post op). removal of prosthesis and re-implantation are separated by 6 weeks of antibiotics. 80-90% success.
infected prosthesis: outcomes with debridement and retention? (rather than one-stage or two-stage procedures)?
worse outcomes: depending on organism, rate of ultimately retaining the prosthesis is 22-82%
infected prosthesis: debridement and retention is most successful under what circumstances?
-removal is not possible -early infection, no osteomyelitis -organism responds to antibiotic -prosthesis is not loose or painful
Dental prophylaxis (with penicillin) for people with prosthetic joints: good idea or not?
-given the amount of bacteria we come across in daily life vs the tiny amount we are exposed to with dental work, prob not worth it. ALSO, some people are allergic to penicillin and the extra exposure is not worth it.
what presentation of neisseria meningitidis can lead to arthritis and dermatitis syndrome?
chronic meningococcemia
child with low fever, sort throat, achy joints, and slapped-cheek appearance, with lacy reticular rash. what organism is the culprit?
Parvovirus B-19
with Parvovirus B-19, what would you worry about in kids with chronic hemolytic anemia?
aplastic crisis due to the virus infecting erythroblasts in marrow
what does Parvo B-19 cause in adults?
persistent arthritis
what virus can mimic rheumatoid arthritis? what is its overall presentation?
Rubella virus “3 day measles” fever, malaise, posterior cervical and postauricular LN swelling, rash and arthritis
what are 2 emerging infectious diseases that are able to cause arthralgia/arthritis? why are they re-emerging?
Dengue fever (flavivirus) Chikungunya fever (alphavirus) Both spread by mosquitos. re-emerging due to cessation of mosquito control programs
med student with swollen, tender knee. arthritis waxes and wanes over a few weeks. worse with exercise. arthritis eventually affects a few other joints. he develops anorexia, fatigue, wt loss. what is the likely dx?
Hep B. He has history of a needle stick.
What is occuring in this picture? (generally)
Loss of joint space due to septic arthritis
What is this a pic of?
Bacterial arthritis of the 3rd PIP
Redness, swelling, effusion.
What is demonstrated in this pic?
at the greater trochanter and distal to that, extensive bone loss due to infected prosthetic joint. This particular joint has undergone multiple revisions (5) without hardware removal: due to lack of functional bone, the only option now is amputation.
this was from a joint aspiration. what bug is this?
Septic arthritis. Gram pos cocci, in chains and (a few) clusters. Staph.
what is depicted?
Gout with soft tissue tophus, cystic erosion, diaphyseal erosion, kissing lesions
He didn’t talk about all those things, but just in case……
What’s this???
Gonorrhea. Awesome.
Gram neg and intracellular.
Describe this rash: what is it characteristic of?
Faint, lacy, reticular rash of the proximal lower extremities.
Parvovirus B-19
What happened to this kid? This is characteristic of what? what other sx will accompany it?
“slapped cheek” appearance due to Parvo B19.
usually co-occurs with fever, chills, maculopapular eruption on trunk, buttocks, extremeties.
What is this? Due to what?
Pustular nodule on an erythematous base. May occur with migratory arthritis.
Most common cause = rheumatic fever. Lyme disease can also do it.
what kind of arthritis?
Rheumatoid arthritis with marginal errosions, cockup deformities, subluxations
What kind of arthritis?
Septic arthritis of 2nd MTP and osteomyelitis
What is this - what disease is it seen in?
Urticarial rash often seen with chronic active hepatitis
