Oropharyngeal Kingella kingae carriage in children: characteristics and correlation with osteoarticular infections

Background: The aim of this study was to investigate changes in oropharyngeal K. kingae carriage during the first 4 y of life, including seasonal variation and comparison of asymptomatic carriage with cases of invasive osteoarticular infections (OAI). Methods: Oropharyngeal bacterial K. kingae carriage was screened in 744 healthy children aged 7–48 mo between January 2009 and December 2012. Oropharyngeal swabs were analyzed by rt-PCR targeting the DNA of K. kingae RTX toxin, epidemiological characteristics of asymptomatic carriers and OAI case patients were recorded. Results: The carriage prevalence showed no significant difference between age groups or seasons. Compared with asymptomatic carriers, OAI cases were more likely to be aged from 7 to 12 mo (OR = 2.5; 95% CI (1.2–5.0)) and 13–24 mo (OR = 2.2; 95% CI (1.2–3.9)), and less likely over 36 mo (OR = 0.2; 95% CI (0.1–0.7)). Fewer OAI cases were identified in spring compared to asymptomatic carriers (OR = 0.3; 95% CI (0.1–0.7)), while more were detected in autumn (OR = 2.5; 95% CI (1.4–4.4)). Conclusion: Although oropharyngeal K. kingae colonization is a prerequisite for further invasive infection, this epidemiological study emphasizes that the carriage rate variations do not correlate with the variations of OAI incidence by gender, season, or age group.