SEPTIC ARTHRITIS (SA) & OSTEOMYELITIS (OM) 

>3 months to 5 years old

Cloxacillin 200mg/kg/day IV in 4-6 divided doses (max. 2g/dose)

MAY ADD

Cefuroxime 100-200mg/kg/day IV in 3 divided doses (max. 1.5g/dose) (monotherapy) 

OR

Cefotaxime 200mg/kg/day IV in 4 divided doses (max. 2g/dose)

Older than 5 years old

Cloxacillin 200 mg/kg/day IV in 4-6 divided doses (max. 2g/dose)

0 - 3 months old

Cefazolin is alternative anti-staphylococcal agent for infants age 1-3 months if no CNS involvement

>3 months

Cefazolin 100-150mg/kg/day IV in 3 divided doses (max. 1g/dose)

(Can be used in children with suspected S. aureus or S. pyogenes. Less hypersensitivity reaction compared to cloxacillin & more convenient dosing)

Kingella kingae: uncommon organism causing infection in <5 years old; indolent onset; preceding oral ulcers; may affect nontubular bones; sensitive to β-lactam antibiotics e.g., cefuroxime or amoxicillin/clavulanate

Empiric antibiotics should be started based on clinical diagnosis of SA or OM.

CBC, blood cultures and CRP +/- ESR should be taken prior to antibiotic therapy.

Optimise antimicrobial treatment based on C&S.

Surgical debridement often not required in OM.

Urgent wash out & drainage is needed in SA in hip and other joints to reduce pressure on growth plate.

Synovial fluid and bone culture/analysis is part of diagnostic work up if child is subjected to drainage or debridement.

Duration of antibiotics:

SA: total of 3-4 weeks (*4-6 weeks if hip is involved)

OM: 4-6 weeks

For both SA and OM, transition to oral antibiotic is based on clinical and laboratory improvement if compliance and follow up is assured.

Shorter duration of 3-4 weeks antibiotics for uncomplicated MSSA or culture negative OM responded to initial therapy for children > 3 months old.

Neonatal OM: Similar duration for other age group but at least 4 weeks of IV antibiotics.

Choice of oral regimen is based on culture and susceptibility results.  If cultures are negative, oral therapy is directed toward the most likely pathogen with similar spectrum of activity as parenteral therapy.  Higher doses are generally given to ensure adequate bone penetration.

Uncomplicated OM is defined as single bone involvement, rapid resolution of bacteremia, rapid clinical response to medical and surgical treatment, rapid fall of CRP with no identified acute or late sequalae of infection.

Complex OM (multifocal, significant bone destruction, immunocompromised host & resistant/unusual pathogens), prolonged IV antibiotics are needed & duration might exceed 6 weeks.