Kingella negevensis shares multiple putative virulence factors with Kingella kingae.

Kingella negevensis is a newly described gram-negative bacterium in the Neisseriaceae family and is closely related to Kingella kingae, an important cause of pediatric osteoarticular infections and other invasive diseases. Like K. kingae, K. negevensis can be isolated from the oropharynx of young children, although at a much lower rate. Due to the potential for misidentification as K. kingae, the burden of disease due to K. negevensis is currently unknown. Similarly, there is little known about virulence factors present in K. negevensis and how they compare to virulence factors in K. kingae. Using a variety of approaches, we show that K. negevensis produces many of the same putative virulence factors that are present in K. kingae, including a polysaccharide capsule, a secreted exopolysaccharide, a Knh-like trimeric autotransporter, and type IV pili, suggesting that K. negevensis may have significant pathogenic potential.

Type-4 pili of Kingella denitrificans.

Kingella denitrificans possess type-4 pili, and the type strain, ATCC 33394, contains at least four complete copies of type-4 pilin-encoding genes. Previously reported hybridization patterns of K. denitrificans chromosomal DNA seen using a Neisseria gonorrhoeae pilin gene region probe, had been interpreted as representing possible partial, silent gene loci. This now appears to be due to cross-reaction to multiple copies of 18-bp inverted repeat structures. Data are presented on a variety of colony variants which have changed from a spreading-corroding (SC) phenotype to a nonspreading-noncorroding (N) phenotype. Interestingly, while the SC to N transition is most often associated with loss of piliation in other bacteria containing type-4 pili, many of the K. denitrificans N variants still produce pilin, and some still produce pili.