Bone and Joint Infections Flashcards Preview

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Flashcards in Bone and Joint Infections Deck (32)


Inflammation of bone and marrow due to infection


What are the different causes of osteomyelitis?

- Hematogenous
- Contiguous


What population is most likely to have hematogenous spread of osteomyelitis?

Children due to growing bone taking up more of the blood supply


What is the pathogenesis of acute osteomyelitis?

Infection at a focal point in the bone can lead to blockage of arteries leading to decalcification while proteolytic enzymes destroy bacteria leading to increased intramedullary pressure


What is the pathogenesis of chronic osteomyelitis?

Inadequate treatment of acute osteomyelitis leads to the continuation of the inflammatory process and eventual bone necrosis followed by new bone formation (involucrum) and possible sinus formation in the involucrum.


What is the cause of contiguous osteomyelitis?

Extension from proximal infection - examples are ulcers from diabetes or infection from trauma/surgery


Where does osteomyelitis spread in children?

Infection often spreads out to the skin


Where does osteomyelitis spread older patients?

Infection tends to stay in the bone


What are the typical pathogens of osteomyelitis?

- Staph
- Strep
- Enterococcus and Gram Negative Rods (more rare)


What is the the MOST common pathogen for osteomyelitis?

S. aureus


What is the most likely pathogen for osteomyelitis due to a puncture wound?



What is the most likely pathogen for osteomyelitis in those with sickle cell anemia?



What is the most useful lab test for diagnosis of osteomyelitis?

Bone biopsy with a culture


What is the best imaging to use for osteomyelitis?



A 60 yr old man with type 1 DM has a chronic ulcer over R sole of foot. It has been draining pus for weeks. No fevers, pain. On PE, he is AF. There is a draining sinus tract on R sole of foot. Culture from the pus grow E.coli and enterococcus faecalis. Placement of a steel probe through the sinus tract goes to bone. Which of the following should be done next?
• A.ObtainX‐ray
B. Obtain MRI
C. Start Vancomycin and Zosyn
D. Start oral clindamycin and levofloxacin
E. Schedule bone biopsy

E. Schedule bone biopsy


What is the probe bone test?

Probing to the bone in an ulcer requires no further testing to classify as osteomyelitis


What can 2 vertebrae back to back affected by osteomyelitis indicate?

Tuberculosis Osteomyelitis


Septic Arthritis

Rapid joint destruction, irreversible loss of function - often due to bacterial infection


How serious is septic arthritis?

EMERGENCY - 50% with permanent loss of function


What are some risk factors for septic arthritis?

- Age greater than 80
- Recent joint surgery
- IV drug use
- Endocarditis
- Joint diseases (RA/OA/Gout)


A 65 yr old woman with RA has a 1d hx of pain and swelling of the 3rd R PIP joint. Current Meds are: Prednisone, Methotrexate. On PE: T39.2, rest wnl. The joint is warm, erythematous, tender and has decreased range of motion (ROM). What do you do?:
A. Prescribe colchicine
B. Treat her for a RA flare
C. Perform diagnostic tap
D. Prescribe ampicillin

C. Perform diagnostic tap


What is the main diagnostic test for septic arthritis?

Diagnostic Tap


Does a negative Gram stain rule out septic arthritis?



What are the main causes of septic arthritis?

- S. aureus
- Strep

Much less common:
- E. coli
- Neisseria
- Pseudomonas


What WBC levels increase risk for septic arthritis?

Higher WBC levels increase the risk fro septic arthritis


A 65 yr old woman with RA has a 1d hx of pain and swelling of the 3rd R PIP joint. Current Meds are: Prednisone, Methotrexate. On PE: T39.2, rest wnl. The joint is warm, erythematous, tender and has decreased ROM. Examination of purulent fluid aspirate from the joint is negative for crystals. Which of the following organisms is the most likely cause?

A.Strep pyrogenes
B.Strep agalactiae
C.Staph aureus
D.Pseudo aeruginosa
E. Salmonella Enteritidis

C.Staph aureus


What is the population for gonococcal arthritis?

Most common in sexually active individuals less than 30 yrs of age


What gender gets gonococcal arthritis more?



What is the presentation triad of disseminated gonococcal infection?

- Dermatitis
- Tenosynovitis
- Migratory polyarthralgia or arthritis


25 yr old man from Hawaii had a 2d hx of severe R wrist pain. The pt is sexually active with multiple partners and infrequently uses condoms. On PE, his T38.9, HR: 100, BP: 100/70. Exam reveals erythema and swelling and decreased ROM of R wrist. His serum WBC in 18,000. What is the most likely causative micro‐organism?
A. Staph aureus
B. Strep agalactiae
C. Neisseria gonorrhea
D. Ebstein Barr Virus
E. Borrelia burgdorferi

C. Neisseria gonorrhea


What are symptoms of lyme arthritis?

Polyarticular, intermittent and relapsing arthritis - can be migratory


What is the most common site for lyme arthritis?


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