The first report on epidemiology of oropharyngeal Kingella kingae carriage in Scandinavian children: K. kingae carriage is very common in children attending day care facilities in Western Norway

Abstract

Kingella kingae colonizes the upper airways in children and has been recognized as the most common causative agent of osteoarticular infections (OAI) in children below 4 years of age. This is the first Scandinavian study to investigate oropharyngeal K. kingae carriage in healthy children. From June 2015 to August 2016, we recruited 198 healthy children aged 11–14 months from routine consultations at health promotion centers in Hordaland County, Norway for a cross‐sectional study. After their parents had provided informed consent; demographic data were registered, and an oropharyngeal swab was collected. The oropharyngeal swab was analyzed with a real‐time PCR assay specific to K. kingae targeting the RTX toxin locus. Results showed an asymptomatic carriage rate of 12.6%. A striking and highly significant difference was observed between the children that had started attending day care facilities as compared with children still being at home (33.33% vs 8.5%; p < 0.001). K. kingae is prevalent in young children in Norway. This study emphasize that K. kingae should be considered an important etiological agent in OAI. Transmission seems to be facilitated in day care facilities. The correlation between oropharyngeal carriage and OAI needs to be further explored.

Pharyngeal Colonization by Kingella kingae, Transmission, and Pathogenesis of Invasive Infections: A Narrative Review

“…Surveillance studies have shown that daycare center attendees frequently harbor genotypically identical organisms and have also demonstrated that carried strains differ between neighboring facilities, indicating that each classroom behaves as a separate and distinct microenvironment [ 44 , 45 , 46 ]. The role of daycare center attendance in the dissemination of K. kingae has been corroborated in a Norwegian study employing NAATs [ 47 ]. While 22 of 33 (67%) attendees had detectable K. kingae DNA sequences in their oropharynx, only 14 of 165 (9%) children of comparable age not attending out-of-home childcare facilities had a positive test result ( p < 0.001 ) [ 47 ].…”

“…The role of daycare center attendance in the dissemination of K. kingae has been corroborated in a Norwegian study employing NAATs [ 47 ]. While 22 of 33 (67%) attendees had detectable K. kingae DNA sequences in their oropharynx, only 14 of 165 (9%) children of comparable age not attending out-of-home childcare facilities had a positive test result ( p < 0.001 ) [ 47 ].…”

Review highlights the latest research in Kingella kingae and stresses that molecular tests are required for diagnosis

“…Kingella kingae colonises the oropharynx and spreads through droplets of buccal secretions among young siblings and playmates 4,21,22 . Crowded conditions, such as those prevalent in day care centres, facilitate child‐to‐child transmission 4,23 . Colonisation commences after the age of 6 months, suggesting that maternally derived immunity, coupled with limited socialisation, prevents early acquisition of the bacterium 22‐25 .…”

“…Studies have shown a paediatric carriage rate of 10–12% in Israel, 22,25 9% in Switzerland, 26 13% in Western Norway, 23 23% in Christchurch, New Zealand 27 and nil in Sidney, Australia 28 and Vancouver, Canada 29 . Although this wide range of colonisation rates may reflect disparities in the true prevalence, a number of factors may also account for these discrepancies.…”

“…4,21,22 Crowded conditions, such as those prevalent in day care centres, facilitate child-to-child transmission. 4,23 Colonisation commences after the age of 6 months, suggesting that maternally derived immunity, coupled with limited socialisation, prevents early acquisition of the bacterium. [22][23][24][25] The colonisation rate gradually increases thereafter, reaching a peak of 10-12% in children aged 12-24 months.…”