Bone, joint and MSK infections

Question 1

Bone and Joint Infections: HACEK organisms

Clx and epi clues

Answer 1

Human bite wounds (Eikenella corrodens)

Recent dental procedure or infection

Question 2

Bone and Joint Infections: Kingella kingae (K in HACEK)

Clx and epi clues

Answer 2

Co in children <4yo.

Grows poorly in routine culture (Dx by pcr)

Question 3

Bone and Joint Infections: Brucella species

Clx and epi clues

Answer 3

Unpasteurized dairy; travel to endemic areas

Sacroiliitis and spondylodiscitis

Question 4

Bone and Joint Infections: Neisseria gonorrhoeae

Clx and epi clues

Answer 4

Triad of Tenosynovitis, Dermatitis, Arthritis.

Question 5

Bone and Joint Infections: Mycoplasma species

Clx and epi clues

Answer 5

Humoral immunodeficiency (CVID, XLA)
Postpartum women.  

Difficult to grow in routine culture.

“Fried egg” morphology in culture

Question 6

Bone and Joint Infections: Non‐tuberculous mycobacteria

Clx and epi clues

Answer 6

Tenosynovitis of hands

Question 7

Bone and Joint Infections: Candida species

Clx and epi clues

Answer 7

ImmCo hosts,

IVDU

Question 8

Bone and Joint Infections: Molds

Clx and epi clues

Answer 8

Madura Foot (barefoot walking)

Environmental contamination (e.g. open fracture with soil contamination)- Farmers

ImmCo hosts (neutropenia)

Question 9

Bone and Joint Infections: Coccidio species, Blasto dermatitidis
(Histo capsulatum less frequent)

Clx and epi clues

Answer 9

Subacute to chronic monoarthritis, long bone OM, and vertebral disease.

Usually ass w/ symptomatic or asymptomatic pulm findings (esp. cocci).

ImmCo host

Question 10

Bone and Joint Infections:

Negative cultures and/or delayed culture positivity:

Answer 10

– Think Gonococcus, HACEK, Lyme, Mycoplasma, Viral, masquerading infections

Question 11

Viral arthritides

Answer 11

Rubella - not vaccinated

Parvovirus B19 - MoCo in woman

Hepatitis B Virus - Serum‐sickness like reaction; also PAN

Hepatitis C Virus - Imm complex a/w cryoglobulinemia

Alphaviruses (esp Chikungunya)

Question 12

Masquerading as joint Infection

Answer 12

– Reactive arthritis: Following infection - Salmonella, Shigella, Campylobacter, Yersinia, Chlamydia

– Crystal arthropathy (Gout, CPPD)
• May have fever, synovial WBC 10,000-100,000/mm3

– Still’s disease

– Polymyalgia rheumatica

– Many others….

Question 13

Brucella species Osteoarticular disease MoCo presentation, Dx and Tx:

Answer 13

– Sacroiliitis, septic arthritis and vertebral osteomyelitis

• Dx: serology & Cx (Laboratory biohazard )
• Treatment: doxycycline+streptomycin or doxycycline+rifampin

Question 14

Pyogenic Vertebral Osteomyelitis:

No tissue/bone Bx/Cx needed if . . .

Answer 14

– No further diagnostics if Staph aureus or Staph lugdunensis

Question 15

Brodie’s Abscess ??

Answer 15

Subacute hematogenous osteomyelitis

Question 16

Brodie’s Abscess . . .

Answer 16

• MoCo in children and young adults
• “Penumbra sign” on MRI

• Staph aureus most common
• “Penumbra sign” on MRI
– Granulation tissue lining abscess
cavity inside bone gives appearance
of double line

Question 17

“Penumbra sign” ?

Answer 17

Granulation tissue lining abscess
cavity inside bone gives appearance
of double line

Seen in Brodie’s Abscess

Question 18

Prosthetic Joint Infection:

• Early surgical site infection
• Delayed / Subacute infection
• Late acute infection

Answer 18

• Early surgical site infection (< 3months)
– Caused by virulent organisms (Staph aureus)

• Delayed / Subacute infection (3 – 24 months)
– Less virulent organisms: e.g. Coagulase-negative Staph, Cutibacterium

• Late acute infection (>2 years)
– Hematogenous seeding, virulent organisms (Staph aureus, Streptococcus)

Question 19

Dx of chronic PJI

Answer 19

• Best diagnostic test: synovial fluid cell counts and culture
– Cell counts > 3000 WBCs per μL considered suggestive

Question 20

Presence of _______ is pathognomonic of chronic infection in the bone

Answer 20

Draining sinus tract