Acute Osteomyelitis & Septic Arthritis

Clinical definition:

Acute osteomyelitis: Bone infection that usually begins in the metaphysis of long bones as a result of haematogenous deposition of organisms following transient bacteraemia. Infection may spread via the epiphysis to the joint resulting in septic arthritis. Common causative organisms vary by age: neonates – S. aureus, Group B streptococcus, Gram negative organisms including E. coli; infants & children – S. aureus, H. influenzae, Group A streptococci, S. pneumoniae. Sickle cell anaemia is associated with bone infections caused by Salmonella species & S. pneumoniae.

Septic arthritis: May occur as a result of haematogenous deposition on the synovium during transient bacteraemia or as part of generalised septicaemia and may involve more than one joint. Common causative organisms vary by age: neonates – S. aureus, Group B streptococcus, E. coli; infants / children – S. aureus, H. influenzae, Group A streptococci, and S. pneumoniae.

 

Neonate

Preferred antibiotic choice
Drug Formulation Dosage Duration
Cefotaxime (IV)  

Powder for injection: 250 or 500 mg per vial (as sodium salt)

 

o   First week of life (7 days or less): 50 mg/kg/dose 12 hourly

o   8 – 20 days: 50 mg/kg/dose 8 hourly

o   21 days & older: 50 mg/kg/dose 6 hourly

4 – 6 weeks
Alternative antibiotic choice(s)
Combination therapy with:

Cloxacillin (IV)

PLUS

Gentamicin (IV)

 

Cloxacillin- Powder for injection: 500 mg (as sodium salt) in vial.

o   First week of life (7 days or less): 50 mg/kg/dose 12 hourly

o   8-28 days: 50 mg/kg/dose 8 hourly

o   Older than 28 days: 50 mg/kg/dose 6 hourly

4 – 6 weeks
Gentamicin- Injection: 10 mg; 40 mg (as sulfate)/ mL in 2- mL vial o   4 mg/kg/dose once daily
If Cloxacillin (IV) is not available, substitute with:

Cefazolin (IV)

Combination therapy with: Cefazolin (IV)

PLUS

Gentamicin (IV)

Cefazolin- Powder for injection: 1 g (as sodium salt) in vial. o   First week of life (7 days or less): 50 mg/kg/dose 12 hourly

o   8 days of age & older: 50 mg/kg/dose 8 hourly

4 – 6 weeks
Gentamicin- Injection: 10 mg; 40 mg (as sulfate)/ mL in 2- mL vial o   4 mg/kg/dose once daily

Infant, Child & Adolescent

Preferred antibiotic choice
Drug Formulation Dosage Duration
Combination therapy with:

Ampicillin (IV)

PLUS

Cloxacillin (IV)

Ampicillin- Powder for injection: 500 mg, 1 g (as sodium salt) in vial  50 mg/kg/dose 6 hourly, maximum dose 2 g 6 hourly 4 – 6 weeks
Cloxacillin-

Powder for injection: 500 mg (as sodium salt) in vial

50 mg/kg/dose 6 hourly, maximum dose 2 g 6 hourly
If Cloxacillin (IV) is not available, treat with:

Cefazolin (IV) (alone)

Powder for injection: 1 g (as sodium salt) in vial. 50 mg/kg/dose 8 hourly, maximum dose 4 g 8 hourly 4 – 6 weeks
Alternative antibiotic choice(s)
Ceftriaxone (IV) Powder for injection: 250 mg; 1 g (as sodium salt) in vial 50 mg/kg/dose 12 hourly, maximum dose 2 g 12 hourly 4 – 6 weeks
For patients with sickle cell anemia (Empiric gram-negative cover recommended)
Ceftriaxone (IV) Powder for injection: 250 mg; 1 g (as sodium salt) in vial  

50 mg/kg/dose 12 hourly, maximum dose 2 g 12 hourly

 

4 – 6 weeks

In case of confirmed drug allergy or medical contraindication
If patient has no history of immediate hypersensitivity / anaphylaxis to penicillins, treat with:

Ceftriaxone (IV)

Powder for injection: 250 mg; 1 g (as sodium salt) in vial 50 mg/kg/dose 12 hourly, maximum dose 2 g 12 hourly 4 – 6 weeks
If patient has a history of immediate hypersensitivity / anaphylaxis to penicillins, treat with:

Clindamycin (IV/PO) PLUS

Ciprofloxacin (IV/PO)

Clindamycin- Injection: 150 mg (as phosphate)/ mL.  

6 mg/kg/dose 6 hourly, maximum dose 600 mg 8 hourly (IV) or 450 mg 6 hourly (PO)

4 – 6 weeks
Ciprofloxacin- Solution for IV infusion: 2 mg/ mL (as hyclate); Oral liquid: 250 mg/5 mL (anhydrous) ; Tablet: 250 mg (as hydrochloride) 10 mg/kg/dose 8-12 hourly, maximum dose 400 mg 8-12 hourly (IV); 15 mg/kg/dose 12 hourly, maximum dose 500 mg 12 hourly (PO)

 

Principles of Stewardship:

  • Do not give empirical antibiotics for chronic bone and joint infections. Instead, conduct bone and tissue biopsies, and treat with directed therapy.
  • Initiate IV antibiotic treatment immediately as the diagnosis is made and blood and pus specimens have been collected, if available.
  • Adjust antibiotic therapy based on culture and AST results, if available, or if clinical response to antibiotic treatment is unsatisfactory.
  • Continue with IV antibiotics until there is evidence of good clinical response and laboratory markers of infection improve, and then consider switching to oral antibiotic therapy if an appropriate oral option is available. If culture is not available consider empiric stepdown therapy to oral antimicrobials with amoxicillin/clavulanic acid, cefalexin, or flucloxacillin.

Notes:

  • Seek consultation with an orthopaedic specialist and consider surgical drainage
  • If infection is caused by S. aureus that is resistant to cloxacillin (MRSA), replace cloxacillin with vancomycin 15 mg/kg/dose 6 hourly IV.