Kingella spp

Published 18.7.21

• Fastidious gram-negative coccobacilli that appear in pairs or short chains.

• Commensal of the mouth and upper respiratory tract.

• The genus Kingela have species like – K. kingae, K. denitrificans, Kingella negevensis, K. oralis etc.

It appears as pairs/short chains of plump bacilli (or coccobacilli) with tapered ends.
Capnophilic and facultatively anaerobic, nonmotile, non-spore-forming.
Beta-haemolytic colonies on blood agar, often producing marked pitting of the agar surface.
It is catalase, urease, and indole tests negative. It is oxidase positive.

Kingella kingae produces 4 different types of colonies-

• A spreading-corroding type – a small central colony encircled by a wide fringe,

• A non-spreading/noncorroding type – a flat colony surrounded by a narrow fringe,

• A dome-shaped colony with no noticeable fringe

• Small-colony variants – pinpoint colonies on blood agar plates and no growth on Thayer-Martin medium

Identification could be made using – API NH, Vitek 2, MALDI-TOF, 16S rRNA gene sequencing. Remel RapID NH kit is not reliable.

• Pilli – adherence and colonisation.

• Capsule – protection from phagocytosis and complement-mediated killing.

• Biofilm formation.

• RTX (repeat-in-toxin) toxin – broad-spectrum cytotoxicity, adherence to mucosa and persistence in body.

• Outer Membrane Vesicles.

Varicella infection,
stomatitis, failure to thrive, congenital heart disease, prolonged corticosteroid therapy, primary immunodeficiency, haematological malignancies, liver cirrhosis, end-stage renal disease, sickle cell anaemia, diabetes mellitus, cardiac valve pathology, systemic lupus erythematosus, rheumatoid arthritis, renal transplants, solid tumours, or AIDS.

• Kingella infection is mild unless associated with a deep infection – Fever, rhinorrhea, pharyngitis, stomatitis, diarrhoea, transient bacteraemia.

• Deep infections:
  Endocarditis – it is a part of the HACEK group of organism. It could be associated with the embolic phenomenon.
  Septic arthritis and osteomyelitis – the commonest cause of septic arthritis in 6m to 3 years olds, usually involves large weight-bearing joints. Association – varicella, stomatitis.
  Spondylodiscitis.
  Lower respiratory tract pleural empyema.
  Pediatric vaginitis.
  Chorioamnionitis, and
  Granulomatous disease in AIDS patients

• Penicillin or cephalosporin group of drugs are usually used for treatment – The drug of choice is usually a third-generation cephalosporin- cefotaxime or ceftriaxone.

• Other antibiotics to which Kingella is susceptible in vitro: aminoglycosides, trimethoprim-sulfamethoxazole, tetracycline, erythromycin, and fluoroquinolones.

• Duration of treatment: The deep infection needs 4-12 weeks of treatment depending on the condition.