Bacterial Pathogen

Bacterial Pathogen: Kingella kingae

Kingella kingae species is a fastidious gram-negative beta-hemolytic cocco-baccilli. This species was first isolated in 1960, it was considered a rare cause of human disease. In the late 1980’s inoculation of synovial fluid and bone exudates into blood culture vials helped to improve the detection of the organism. This increased the recognition of K. kingae as an invasive pathogen. In 1968 K. kingae is previously known as Moraxella kingie due to similar appearance to the Moraxella species. Further studies showed that M. kingae was catalase negative. The analysis of M. kingae showed that the fatty acid composition was most related to members of the Neisseriaceae. After more extensive analysis Bovre and Henriksen renamed the species Kingella kingae and placed it in the family Neisseriaceae, containing the genus Neisseria (Powell, Mortensen, 2013).

K. Kingae is a cocco-baccillus , catalase negative, and produces a cytotoxic RTX (repeat toxin). It is hypothesized that the RTX allows K. kingae to disrupt the laryngeal epithelim and enter the blood stream. This may help explain how K. kingae causes septic arthritis. It also produces a type IV pilus allowing adherence of K. Kingae to the respiratory epithelium, promoting colonization. Assays have shown the pilus expression is required for K. kingae to adhere to the laryngeal cells, suggesting the involvement of both in colonization of the oropharynx and infection of joint synovia in osteoarthritis infections (Powell et al.,2013).

This invasive pathogen presents itself usually in young children age six months to three years, and adults in rare cases. K. kingae is transmitted by droplet transmission from colonized children. Between the ages of 12-24 months, 9-12% of children are colonized at an average rate of 12 cases per 100,000 people per year (Powell et al.,2013). Children who attend day care have a higher rate of colonization. K. kingae are Gram-negative bacilli with flat ends in...