Which of the following organisms is a fastidious, Gram-negative coccobacillus that is increasingly recognized as a leading cause of septic arthritis and osteomyelitis in children under the age of 4, often requiring inoculation of joint fluid directly into automated blood culture vials for successful isolation?

Explanation:
Kingella kingae is a normal inhabitant of the pediatric oropharynx but is a major cause of pediatric osteoarticular infections (OAI), particularly in children aged 6 months to 4 years. It is notoriously fastidious and difficult to grow on standard solid agar plates. Isolation rates are significantly improved by directly inoculating the synovial fluid or bone aspirate into automated BACTEC blood culture vials immediately at the time of aspiration. Haemophilus influenzae type b is now rare due to widespread vaccination. Reference: Tachdjian's Pediatric Orthopaedics, 6th Edition.