NEW YORK (Reuters Health)—Oropharyngeal carriage of Kingella kingae is strongly associated with osteoarticular infection in young children, a case-control study done from Canada and Switzerland shows.
“Most of the kids who have osteoarticular infection with Kingella kingae will also have it in their throat, so if we do a throat swab, we can identify it in many kids,” Dr. Jocelyn Gravel of the Universite de Montreal in Quebec, the study’s first author, told Reuters Health by telephone. Osteoarticular infections with K. kingae had been considered a European concern, Dr. Gravel noted, but the new findings confirm that “it’s probably more of a universal problem. It’s just that we’ve never looked for it in North America.”
Children with osteoarticular infection typically present with fever, limping, and joint pain, Dr. Gravel said. About 20% or 30% have Staphylococcus aureus or Streptococcus infection, he added, but the germ responsible for infection remains unidentified in most cases. K. kingae is difficult to culture, so it is rarely identified using traditional methods.
Investigators in Israel, reporting their findings in 2009, followed by others in Europe and Canada, developed specialized polymerase chain reaction tests to detect K. kingae in young children with osteoarticular infection. Laboratories must develop their own version of the tests, Dr. Gravel noted, so they are not widely available. While research has found that K. kingae infection is on the rise, he added, the more-effective detection methods are likely responsible for the increase.
In the new investigation, Dr. Gravel and his colleagues prospectively studied 77 children 6 to 48 months old admitted to two hospitals (one in Canada, one in Switzerland) for suspected osteoarticular infection. Each child was age-matched with four controls presenting to the same emergency department for trauma.
Sixty-five confirmed cases of osteoarticular infection (35 in Geneva, 30 in Montreal) were compared to 286 controls in the final analysis. Among the cases, 71% had K. kingae in the throat, while just 6% of controls did (odds ratio, 38.3). K. kingae infection was confirmed in 49% of the Geneva and 57% of the Montreal cases.
Of the 62 patients with available blood cultures, 34 had K. kingae infection confirmed by joint or bone aspirate. Eight carried other bacteria in the blood, joints, or both, including S. aureus in four patients, Streptococcus pyogenes in two patients, and one case each of Salmonella typhi and Escherichia coli.
Patients with K. kingae infection are typically not as sick as those infected with these other bacteria, Dr. Gravel noted. While patients with osteoarticular infection are typically treated empirically with intravenous antibiotics for six weeks, the researcher added, patients with K. kingae may respond to shorter courses of treatment. But more research is needed to establish the natural history of K. kingae infection and to determine the optimal length of treatment, he said.
Invasive K. kingae infections are thought to enter the body through the oropharnyx, Dr. Romain Basmaci of Hopital Louis-Mourier in Colombes, France, and Dr. Stephane Bonacorsi of Sorbonne Paris Cite in Paris write in a commentary published with the study online September 5 in CMAJ.
But because up to 10% of healthy children in some parts of the world carry K. kingae in their oropharynx, “relying on oropharyngeal detection as a proxy for diagnosis in the case of a joint infection would result in a high false-positive diagnosis,” they add. “Additional data, such as genotyping, capsule typing or specific viral detection, would improve the performance of oropharyngeal screening.”
Gravel J, Ceroni D, Lacroix L, et al. Association between oropharyngeal carriage of Kingella kingae and osteoarticular infection in young children: a case-control study. Canadian Medical Association Journal. 2017 Sep 5;189(35):E1107-E1111.