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Esther Chua | Bench E | 31 Aug 2016 ^[1]

Classification

Higher order taxa

Bacteria - Proteobacteria - Betaproteobacteria - Neisseriales - Neisseriaceae - Kingella - Kingella oralis

Species

Kingella oralis

Type strain: strain UB-38 = ATCC 51147= CCUG 30450 = CIP 103803

Description and significance

Kingella oralis was originally described by Chen et al.(1990) as Eikenella corrodens -like isolates. In the original 1993 classification paper, this species was named K. orale¹, but the spelling was changed to "oralis" in 1994². K. oralis is a gram-negative facultative (aerobic and anaerobic growth) organism thats grows in mesophillic environments. K. oralis is normally found in small numbers in the oral cavity in dental plaque, however periodontitis and gingivitis may correlate with increases in numbers of this species in the gingiva. They also produce corroding colonies. K. oralis is rather prevalent in dental plaque and has shown to constitute more than 5% of the total microbiota in peridontitis sites. ³

Genome structure

Kingella Oralis strain ATCC 51147 does not encode for chromosomes and plasmids. It has a total length of about 2.41mb, encodes for 2,315 proteins and has a GC content of 54.3%. Sequencing results show that ATCC51147 consists of 5 scaffolds (Scfld 0-4) with no gaps between, an assembly gap length of 700, and 12 contigs. It has 3,165 coding genes and 52 non-coding genes. However the functions of these genes are not yet known.

This strain has contains specialty genes that are of particular interest, such as antibiotic resistance genes, drug targets, virulence factors, and human homologs.

Select a strain for which genome information (e.g. size, plasmids, distinct genes, etc.) is available.

Cell structure and metabolism

Cell wall, biofilm formation, motility, metabolic functions.

Kingella oralis are gram negative rods or cocobacilli that can form pairs or chains. It has a cell wall that consists of an outer membrane containing lipopolysaccharides, a periplasmic space with a peptidoglycan layer, and an inner, cytoplasmic membrane. Cells are nonmotile by flagella, but have monopolar fimbriae and form spreading colonies which suggests twitching motility¹. Cells can be aerobic or facultatively anaerobic.

They are oxidase positive, catalase negative and are able to ferment glucose.

Ecology

K. oralis is an aerobic or facultatively anaerobic organism that is often cultured for on blood agar. The main habitat of K. oralis is in human dental plaque, however, it can also be found in smaller quantities in salival and mucosal sites. In periodontally healthy patients, K. Oralis is relatively evenly distributed in subgingival and supragingival plaque, but it has a higher distribution in the supragingival plaque of those with periodontalis¹³.

The Kingella species are known to exchange antibiotic resistance plasmids with Neisseria gononhoeae and Neisseria meningitidis, resulting in a possibility of K. oralis as a plasmid reservoir. ¹⁴

Pathology

K. oralis is an organism that contributes to gum diseases such as gingivitis and periodontitis that affects both adults and juveniles¹³.

Gingivitis is caused by gum inflammation due to K. oralis and other bacteria accumulating as plaque or tartar on teeth. In gingivitis, the gums become red, swollen, and bleeds easily. With regular cleaning of teeth, gingivitis can usually be reversed. However, when gingivitis is not treated, there is a possibility of periodontitis (inflammation around the tooth) occurring. This causes gums to pull away from the teeth to form pockets that become infected. Bacterial toxins produced and the body's immune response to the infection causes the breakdown of bone and connective tissue that hold the teeth in place. When left untreated, the teeth may eventually become loose and would have to be removed. However, by maintaining good oral hygiene and practices, gum diseases such as these can be controlled.¹²