What is the recommended empiric antibiotic treatment for a child with a Kingella kingae‑susceptible osteo‑articular infection, including options for penicillin allergies?

Empiric Antibiotic Treatment for Kingella kingae Osteoarticular Infections in Children

For children with suspected or confirmed Kingella kingae osteoarticular infection, initiate empiric treatment with a third-generation cephalosporin (ceftriaxone or cefotaxime) until penicillin susceptibility is confirmed, then narrow to amoxicillin or penicillin for susceptible strains. 1

First-Line Empiric Therapy

• Start with ceftriaxone (50 mg/kg/day IV) or cefotaxime as empiric therapy for suspected K. kingae osteoarticular infections in children aged 6-36 months 1
• This approach accounts for the variable prevalence of β-lactamase-producing strains, which can reach 25% in certain geographic regions (Minnesota, Iceland) 2
• Third-generation cephalosporins provide reliable coverage regardless of β-lactamase production status 1

De-escalation Strategy After Susceptibility Results

• Once penicillin susceptibility is confirmed, switch to amoxicillin or penicillin for the remainder of treatment 3, 1
• The majority of K. kingae isolates remain susceptible to β-lactam antibiotics 3, 4
• Amoxicillin-clavulanate can be used for oral step-down therapy and provides coverage even if β-lactamase production is present 4

Treatment Duration and Monitoring

• Continue IV antibiotics initially, then transition to oral therapy once clinical improvement is documented 4
• Total treatment duration should be guided by clinical response, typically several weeks for osteoarticular infections 4
• K. kingae infections usually show mild symptoms and run a benign clinical course when adequately and promptly treated 3

Options for Penicillin-Allergic Patients

Non-Type I (Delayed) Penicillin Allergy

• Use cefdinir, cefuroxime, or cefpodoxime for patients with non-severe, delayed-type penicillin reactions that occurred >1 year ago 5
• These second- and third-generation cephalosporins have only 0.1% cross-reactivity with penicillin due to different side chain structures 5
• Cefdinir is preferred based on patient acceptance 6

Type I (Immediate/Anaphylactic) Penicillin Allergy

• Avoid all cephalosporins in patients with immediate-type hypersensitivity reactions due to up to 10% cross-reactivity risk 5
• Consider azithromycin as an alternative, though K. kingae susceptibility data for macrolides is limited 4
• Trimethoprim-sulfamethoxazole has documented activity against K. kingae and can be considered 4

Critical Clinical Pitfalls

Geographic Resistance Patterns

• β-lactamase production in K. kingae is clonal and geographically variable 3, 2
• The TEM-1 β-lactamase-producing strains likely originated from a single plasmid-bearing isolate that spread between Europe and North America 2
• Always obtain susceptibility testing, as local resistance patterns may differ significantly 2

Flucloxacillin Failure

• Do not use flucloxacillin (or other penicillinase-resistant penicillins like nafcillin/oxacillin) for K. kingae infections 7
• A documented case of treatment failure occurred with high-dose IV flucloxacillin despite the isolate not producing β-lactamase, suggesting an unknown resistance mechanism 7
• This contrasts with staphylococcal infections where these agents are first-line 6

Diagnostic Challenges

• K. kingae isolation on routine solid media is suboptimal 3
• Inoculate joint fluid or other specimens into blood culture bottles to significantly improve detection rates 3
• Consider PCR-based assays when K. kingae is suspected but cultures remain negative 3

Clinical Context

• K. kingae is the leading cause of osteoarticular infections in children aged 6-36 months 3
• The organism colonizes the oropharynx asymptomatically and disseminates via close interpersonal contact 3
• Children often present with only mild symptoms and signs, requiring high clinical suspicion 3
• Previous respiratory infections may facilitate systemic spread 4