Clinical Definition of Acute Osteomyelitis
Acute osteomyelitis is a 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.
Clinical Definition of Septic Arthritis
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.