The Stealth and Potentially Fatal Nature of Kingella kingae Outbreaks in Daycare Facilities

Although Kingella kingae infections are usually sporadic, outbreaks of K. kingae disease have been reported. Outbreaks of invasive K. kingae infections in daycare centers were searched through the Pubmed database. Twenty-seven outbreaks have been detected in North America, Western Europe, and Israel. The median age of the 72 affected attendees was 14 months, and the attack rate was 18%. Osteoarthritis was diagnosed in 66 (92%) attendees, and endocarditis in 3 (4%), 2 of whom died. A high prevalence of the invasive strains was found among asymptomatic classmates. Genomic analysis of the available strains identified the highly invasive sequence-type complexes 23/25, 14, or 6 in 12 of 13 (92%) outbreaks. Kingella kingae strains causing daycare outbreaks exhibit enhanced colonization, transmissibility, and virulence. Increased awareness of this emerging public health problem and the use of molecular diagnostic methods are recommended for early identification of outbreaks and prevention of fatal outcomes.