M86.1
DESCRIPTION
Most cases result from haematogenous deposition of organisms in the bone marrow after a transient bacteraemic episode. Osteomyelitis most commonly begins in the metaphyses of long bones which are highly vascular. The spread of infection through the epiphysis can result in septic arthritis.
The organisms involved vary:
- Neonates: S. aureus , Group B Streptococci, Gram negative (E. coli).
- Infants/children: S. aureus , H. influenzae , Group A Streptococci, S. pneumoniae .
- Traumatic direct infection: P. aeruginosa (penetrating foot wounds).
- Co-existing medical conditions e.g. diabetes, HIV, leucopaenia: M. tuberculosis , fungi.
- Sickle cell disease: Salmonella, pneumococcus.
DIAGNOSTIC CRITERIA
Clinical
- Local pain and tenderness, loss of function, general toxicity and fever.
- If lower extremities are involved (development of a limp or refusal to bear weight).
- In neonates, early signs may be subtle or non-specific, e.g. irritability, feeding problems and pseudoparalysis.
- Investigate for multi-organ disease, e.g. endocarditis, pericarditis and pneumonia.
Investigations
Diagnostic
- Aspiration of pus for microscopy, Gram stain, culture and sensitivity.
- Blood culture and full blood count.
- Raised white cell count, CRP.
The following may be helpful:
- X-ray after 2 weeks.
- Bone scan (Tc99).
- MRI.
GENERAL AND SUPPORTIVE MEASURES
- Immobilise affected limb in position of function.
- Supportive and symptomatic care.
MEDICINE TREATMENT
Antibiotic therapy
Minimum duration of therapy: 4–6 weeks.
IV antibiotics
Initiate IV antibiotic treatment immediately as diagnosis is made and blood and pus specimens have been collected.
Adjust antibiotic therapy based on culture results or if response to antibiotic treatment is unsatisfactory.
Where a single agent has been found to be sensitive, continue treatment on that single agent.
Continue with IV antibiotics until there is evidence of good clinical response and laboratory markers of infection improve. Once clinical improvement and inflammatory markers are normalising, patients can be switched to oral antibiotic therapy.
Ongoing fever suggests an undrained focus of pus.
Neonates:
- Cloxacillin, IV, 50 mg/kg/dose.
- If 1ˢᵗ week of life: 12 hourly.
- If 2ⁿᵈ –4ᵗʰ week of life: 8 hourly.
- If >4 weeks old: 6 hourly.
PLUS
- Cefotaxime, IV, 50 mg/kg/dose.
- Preterm: 12 hourly.
- If 1ˢᵗ week of life: 8 hourly.
- If >2 weeks old: 6 hourly.
Infants and children:
- Cloxacillin, IV, 50 mg/kg/dose 6 hourly.
PLUS - Ceftriaxone, IV, 50 mg/kg/dose 12 hourly.
Special Circumstances
If MRSA, replace cloxacillin with vancomycin.
- Vancomycin IV, 15mg/kg/dose administered over 1 hour given 6 hourly.
Where available, vancomycin doses should be adjusted on the basis of therapeutic drug levels.- Trough levels (taken immediately prior to next dose), target plasma level 15-20mcg/mL.
Penetrating foot bone injuries: replace cefotaxime with ceftazidime plus an aminoglycoside:
- Ceftazidime, IV, 50 mg/kg/dose 6 hourly.
PLUS - Gentamicin, IV, 6 mg/kg once daily.
Where available, gentamicin doses should be adjusted on the basis of therapeutic drug levels.- Trough levels (taken immediately prior to next dose), target plasma level < 1 mg/L.
- Peak levels (measured 1 hour after commencement of IV infusion or IM/IV bolus dose), target plasma level > 8 mg/L.
Oral antibiotics
- Can transition to oral therapy once there is sustained clinical improvement, resolution of fever and CRP < 30mg/L.
- 4-6 weeks of treatment.
ANTIBIOTICS ACCORDING TO SENSITIVITIES:
- Clindamycin, oral, 6 mg/kg/dose 6 hourly.
OR
For children able to swallow a capsule:
- Flucloxacillin, oral, 25 mg/kg/dose, 6 hourly.
For pain and inflammation:
Refer to Pain control .
REFERRAL
- Refer to specialist for confirmation of diagnosis, and consideration of surgical drainage.
- Multi-organ involvement.
- Failure to achieve progressive improvement on treatment.