Background: Kingella kingae is a gram-negative coccobacillus, increasingly recognized as an invasive pediatric pathogen. To date, only few small series of invasive K. kingae infections have been published, mostly from single medical centers. A nationwide multicenter study was performed to investigate the epidemiologic, clinical, and laboratory features of children with culture-proven K. kingae infections.
Methods: Clinical microbiology laboratories serving all 22 medical centers in Israel were contacted in a search for children aged 0 to 18 years from whom K. kingae was isolated from a normally sterile site, dating from as far back as possible until December 31, 2007. Medical records of identified patients were reviewed using uniform case definitions.
Results: A total of 322 episodes of infection were identified in 321 children, of which 96% occurred before the age of 36 months. The annual incidence in children aged <4 years was 9.4 per 100,000. Infections showed a seasonal nadir between February and April. Skeletal system infections occurred in 169 (52.6%) children and included septic arthritis, osteomyelitis, and tenosynovitis. Occult bacteremia occurred in 140 children (43.6%), endocarditis in 8 (2.5%), and pneumonia in 4 (1.2%). With the exception of endocarditis cases, patients usually appeared only mildly ill. About one-quarter of children had a body temperature <38°C, 57.1% had a blood white blood cell count <15,000/mm3, 22.0% had normal C-reactive protein values, and 31.8% had nonelevated erythrocyte sedimentation rate.
Conclusions: K. kingae infections usually occur in otherwise healthy children aged 6 to 36 months, mainly causing skeletal system infections and bacteremia, and occasionally endocarditis and pneumonia. Clinical presentation is usually mild, except for endocarditis, necessitating a high index of suspicion.
From the *Edmond and Lily Safra Children's Hospital, Chaim Sheba Medical Center, Tel-Hashomer, Israel; †Pediatric Infectious Disease Unit, Carmel Medical Center, Haifa, Israel; ‡Department of Pediatrics B, Schneider Children's Medical Center of Israel, Petah Tiqwa, Israel; §Infectious Disease Unit, Shaare-Zedek Medical Center, Jerusalem, Israel; ¶Tel Aviv Souraski Medical Center, Tel Aviv, Israel; ∥Infectious Diseases Service, Meyer Children Hospital, Rambam Medical Center, Haifa, Israel; **Clinical Microbiology Laboratory, Edith Wolfson Medical Center, Holon, Israel; and ††Clinical Microbiology Laboratory, Soroka University Medical Center, Beer-Sheva, Israel.
Accepted for publication January 21, 2010.
Address for correspondence: Gal Dubnov-Raz, MD, MSc, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Israel. E-mail: firstname.lastname@example.org.
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