Osteomyelitis Treatment
Principles of Therapy
Factors to consider when choosing an antibiotic for empiric therapy
- Suspected pathogens & their antimicrobial susceptibility pattern
- Empiric antibiotic coverage for S aureus is indicated
- Age of patient esp children
- Severity of infection
- History of recent antibiotic intake
- Current Gram stain results
- Underlying co-morbid conditions
- Antibiotic safety & efficacy
Pharmacotherapy
Antibiotics for Empiric Therapy
- Antibiotic treatment should be started after specimens for cultures are sent
- However, treatment in an acutely ill patient should not be delayed to wait for bone debridement
- Empirical therapy of acute hematogenous osteomyelitis in both children & adults should include coverage against S aureus
- IV antibiotics are given at the start of therapy; step-down to per orem treatment later may be possible based on clinical response
Antibacterial Combinations
- Eg Co-trimoxazole [Sulfamethoxazole (SMZ) & Trimethoprim (TM)]
- Effective against many Methicillin-resistant S aureus isolates but studies regarding effectiveness in osteomyelitis are limited
- TMP-SMZ is also active against streptococci & enterobacteriaceae
Beta-lactam Antibiotics
- Eg penicillins, cephalosporins, carbapenems
- Achieve therapeutic concentrations in bone
- 1st generation cephalosporins (eg Cefazolin) & Oxacillin are good initial choices for osteomyelitis suspected to be caused by methicillin-sensitive Staphylococcus aureus
- Cefalexin & Cloxacillin are per orem agents that may be used to complete treatment
- Benzylpenicillin is the drug of choice for treating osteomyelitis caused by group A streptococcus, susceptible S pneumoniae & enterococci
- Amoxicillin or Phenoxymethylpenicillin are per orem agents recommended for completing treatment
- Antipseudomonal penicillin, or Cefepime, or Ceftazidime &/or an aminoglycoside is an effective combination for osteomyelitis caused by Pseudomonas
- Ampicillin is effective against Salmonella
- Cefotaxime or Ceftriaxone may be used for resistant isolates
- Most beta-lactam antibiotics are active against K kingae
Clindamycin
- Achieves good bone penetration
- May be used for empirical therapy of osteomyelitis suspected to be due to methicillin-sensitive Staphylococcus aureus & anaerobes
- However, S aureus isolates susceptible to Clindamycin but resistant to Erythromycin should be tested for inducible macrolide-lincosamide-streptogramin B resistance through the D test
- Treatment failure is more likely in the presence of inducible resistance
- Active against most isolates of S pyogenes & S pneumoniae
Linezolid
- May be as effective as Vancomycin in treating infections caused by Methicillin-resistant S aureus
- Active against streptococci & Vancomycin-resistant enterococci
- Alternative to prolonged IV therapy because of excellent oral bioavailability
Quinolones
- Eg Ciprofloxacin & Ofloxacin
- May be used for PO treatment of osteomyelitis in adults because of good penetration into the bone & excellent oral absorption
- Not routinely recommended for use in young children
- May be used to treat osteomyelitis caused by gram-negative organisms including enterobacteriaceae
- Quinolones have variable coverage against S aureus & S epidermidis; no coverage against Enterococcus spp; newer quinolones have better action against Streptococcus spp & some anaerobes
- Should be combined w/ another antibiotic to achieve adequate coverage against S aureus during empiric therapy
Rifampicin
- May be used in combination w/ cell-wall antibiotics for synergistic action against S aureus
- Should never be used as monotherapy because resistance develops rapidly
Tetracyclines
- Effective against many Methicillin-resistant S aureus isolates but studies regarding effectiveness in osteomyelitis are limited
- Tetracycline use in young children may result in stunted bone & tooth growth; should only be considered in >8 yr of age
- Should be avoided in pregnant patients
Vancomycin
- Drug of choice for empiric therapy in areas where community acquired-Methicillin-resistant S aureus resistance to Methicillin & Clindamycin exceeds 10-15%
- Active against most isolates of S pyogenes, S pneumoniae & Ampicillin-resistant enterococci
- Antibiotic-impregnated (usually w/ aminoglycosides or Vancomycin) acrylic beads may be placed to sterilize a dead space while waiting for definitive management
- Limited studies are available to adequately support the superiority of local therapy over systemic antibiotic therapy, though local therapy is associated w/ markedly fewer adverse events
Suppressive Antibiotic Therapy
- Considered for patients in whom surgical treatment is needed but is not feasible
- Choose antibiotics that achieve adequate penetration into bone, have good bioavailability & low toxicity & are active against etiologic agents as based on sensitivity testing results
- Choices include Fusidic acid, quinolones, TMP-SMZ, Rifampicin (combined w/ other antibiotics)
- Treatment duration is usually 6 mth
Duration of Antibiotic Therapy
- Based on extent of infection, etiologic agent & clinical course
- Range is usually between 3-6 wk