bone infections

Question 1

bone infection aka osteomyelitis : categories

Answer 1

Hematogenous: resulting from seeding of bone related to a previous bacteremia

Direct implantation: resulting from a penetrating injury

Contiguous: resulting from direct spread of bacteria from an overlying wound or pressure ulcer (like diabetes)

Infection of prosthesis: resulting from infection of prosthetic material implanted in bone with spread of organisms into the adjacent bone

Hematogenous osteomyelitis (more common in kids usually monomicrobial) Contiguous osteomyelitis (more common in adults is polymicrobial)

Question 2

osteomyelitis pathogens

Answer 2

Hematogenous: Staph aures, Strep bacteria,, gram negatives, Mycobacterium TB, salmonella sp in SCA patients)

Direct implantation: pseudomonas aeruginosa (in nail injuries with sneakers

Contiguous: S aureus, gram negatives, Strep, Candida

Prosthesis: Coagulase negatives staph, S aureus, gram negatives, Strep sp, probionibacterium

Stap a. 70-70% of hematogenous, 
Gram negatives (ecoli, klebsiella, enterobacter, more common in UTIs

From 1-3% of patients with TB will have bone infections

P acnes in shoulder prosthesis

Question 3

General characteristics of osteomyelitis

Answer 3

Chronic infections difficult to eradicate
Fever in acute but rare in chronic
Damage to the periosteum may result in pieces of dead bone (sequestrum), or new external bone formation (involucrum), or localized abscesses may also occur (Brodies abcess)
X ray may be negative in early infections and not very sensitive to osteomyelitis, Bone scans, the bacteria sometimes can be cultured

Cultures of open ulcers unreliable

Question 4

Biofilms

Answer 4

Biofilms are aggregates of microorganisms adherent to a surface, particularly a hard surface
Adherent microorganisms are frequently embedded in a matrix that they produce–called slime, extracellular polymeric polymeric substances of glycocalyx

biofilm organisms more resistant to antibiotics than suspended/planktonic bacteria

Question 5

Osteomyelitis treatment

Answer 5

long course of Antibiotics, 6 weeks of IV therapy, oral antibiotics

Surgery to remove

Antibiotic rifampin appears to be useful in treating biofilm (staphylococcs)

Abx only useful for bone covered by tissue