High rate of oropharyngeal Kingella kingae carriage in New Zealand children.

AIM: This study aimed to describe the burden of disease and estimated rates of oropharyngeal carriage of Kingella kingae among New Zealand children. We compared polymerase chain reaction (PCR) and culture for the detection of this microorganism with a view to further development and implementation of K. kingae PCR in Christchurch Hospital.

METHODS: Oropharyngeal swabs from children between 6 and 48 months of age were analysed by culture to estimate carriage rates of K. kingae. Samples of a subgroup of children between 12 and 24 months of age were also tested by PCR. In addition, a retrospective review was performed on all cases of invasive K. kingae disease and children with osteoarticular infections.

RESULTS: Oropharyngeal cultures were positive for K. kingae in specimens from 4 out of 176 children (2.3%). PCR was significantly more sensitive and by PCR, the carriage rate rose to 22.9% (95% CI = 9.4-33.9%) (n = 48). From 2005 to 2015, 17 children between 6 and 48 months of age were identified with invasive infections due to K. kingae. Seventy-four children were found to have an osteoarticular infection. Most of these were culture-negative with a microbiological diagnosis made in only 15 cases (20.3%), only one due to K. kingae.

CONCLUSIONS: We found a very high carriage rate of K. kingae in New Zealand children and poor performance of K. kingae culture. It is likely that many cases of invasive K. kingae infections remain undetected. We recommend the use of a K. kingae PCR in all children under 4 years of age with a possible osteoarticular infection.