Kingella kingae

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Kingella kingae
Scientific classification
K. kingae
Binomial name
Kingella kingae
Henriksen and Bøvre 1968

Kingella kingae is a species of Gram-negative aerobic coccobacilli. First isolated in 1960 by Elizabeth O. King, it was not recognized as a significant cause of infection in young children until the 1990s, when culture techniques had improved enough for it to be recognized. It is best known as a cause of septic arthritis, osteomyelitis, spondylodiscitis, bacteraemia, and endocarditis, and less frequently lower respiratory tract infections and meningitis. [1]

Elizabeth Osborne King was an internationally known American microbiologist who discovered and described bacteria of medical importance at the United States Centers for Disease Control and Prevention from the late 1940s through the early 1960s. The genera Kingella and Elizabethkingia and the species Kingella kingae are named to honor her for her pioneering work.

Septic arthritis arthritis that involves infection by a pathogen located in joint

Septic arthritis, also known as joint infection or infectious arthritis, is the invasion of a joint by an infectious agent resulting in joint inflammation. Symptoms typically include redness, heat, and pain in a single joint associated with a decreased ability to move the joint. Onset is usually rapid. Other symptoms may include fever, weakness, and headache. Occasionally, more than one joint may be involved.

Osteomyelitis bone inflammation disease that has material basis in infection located in bone or located in bone marrow

Osteomyelitis (OM) is an infection of bone. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The long bones of the arms and legs are most commonly involved in children, while the feet, spine, and hips are most commonly involved in adults.


There are four species of Kingella: K. kingae, the most common, is part of the bacterial flora of the throat in young children and is transmitted from child to child. When it causes disease, the clinical presentation is often subtle and preceded by a recent history of stomatitis or upper respiratory infection. Other species are K. indologenes, K. denitrificans (both causing endocarditis) and K. oralis found in dental plaque.

Pharynx part of the throat that is behind the mouth and nasal cavity

The pharynx is the part of the throat behind the mouth and nasal cavity and above the oesophagus and larynx, or the tubes going down to the stomach and the lungs. It is found in vertebrates and invertebrates, though its structure varies across species.

Stomatitis inflammation of the mouth and lips

Stomatitis is inflammation of the mouth and lips. It refers to any inflammatory process affecting the mucous membranes of the mouth and lips, with or without oral ulceration.

Endocarditis endocardium disease characterized by inflammation of the endocardium of the heart chambers and valves

Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves. Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, or the surfaces of intracardiac devices. Endocarditis is characterized by lesions, known as vegetations, which is a mass of platelets, fibrin, microcolonies of microorganisms, and scant inflammatory cells. In the subacute form of infective endocarditis, the vegetation may also include a center of granulomatous tissue, which may fibrose or calcify.

One notable exception is in cases of endocarditis (heart valve infection), which can be more refractory to treatment. K. kingae is the fifth member of the HACEK group of fastidious Gram-negative bacteria that cause endocarditis. Routine laboratory tests may be normal because the organism is difficult to culture. Inoculating the fluid from infected joints directly into blood culture vials can enhance the chances of an accurate culture, but extended culture times are not helpful. [2]

The organism has also been known as Moraxella kingae.

K. kingae is oxidase-positive, catalase-negative, and beta-hemolytic.

Oxidase test microbiological and biochemical method for identification

The oxidase test is a test used in microbiology to determine if a bacterium produces certain cytochrome c oxidases. It uses disks impregnated with a reagent such as N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) or N,N-dimethyl-p-phenylenediamine (DMPD), which is also a redox indicator. The reagent is a dark-blue to maroon color when oxidized, and colorless when reduced. Oxidase-positive bacteria possess cytochrome oxidase or indophenol oxidase. These both catalyze the transport of electrons from donor compounds (NADH) to electron acceptors . The test reagent, TMPD dihydrochloride acts as an artificial electron donor for the enzyme oxidase. The oxidized reagent forms the colored compound indophenol blue. The cytochrome system is usually only present in aerobic organisms that are capable of using oxygen as the terminal electron acceptor. The end-product of this metabolism is either water or hydrogen peroxide.

Catalase protein-coding gene in the species Homo sapiens

Catalase is a common enzyme found in nearly all living organisms exposed to oxygen. It catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting the cell from oxidative damage by reactive oxygen species (ROS). Likewise, catalase has one of the highest turnover numbers of all enzymes; one catalase molecule can convert millions of hydrogen peroxide molecules to water and oxygen each second.

Mechanism of infection

Kingella kingae is thought to begin infection by colonizing the pharynx, crossing the epithelium by using an RTX toxin, and entering the circulation and reaching deeper tissues, such as bones and joints.

The RTX toxin superfamily is a group of cytolysins and cytotoxins produced by bacteria. There are over 1000 known members with a variety of functions. The RTX family is defined by two common features: characteristic repeats in the toxin protein sequences, and extracellular secretion by the type I secretion systems (T1SS). The name RTX refers to the glycine and aspartate-rich repeats located at the C-terminus of the toxin proteins, which facilitate export by a dedicated T1SS encoded within the rtx operon.

K. kingae expresses type IV pili, which allow for enhanced adhesion to respiratory epithelial and synovial cells and thus increased likelihood of colonization. These pili have also been shown to be reduced in number as pathogenesis progresses. σ54 regulates the transcription of pilA1, a major pilus subunit. PilS and PilR, regulatory transcription factors best known from the Pseudomonas aeruginosa pilus system, also may regulate pilA expression. High levels of type IV pili on K.kingae are associated with spreading/corroding colony types, while low levels of type IV pili are associated with nonspreading/noncorroding colony types of K. kingae. [3] The three different types of populations are: spreading/corroding (with high-density pilation), nonspreading/noncorroding colonies (low density pilation), and domed colonies (no pilation, and thus no adherence to epithelium). Generally, respiratory and nonendocarditis infections tend to be highly piliated, while joint fluid, bone, and endocarditis blood isolates are less piliated, if at all. [4]


A pilus is a hair-like appendage found on the surface of many bacteria. The terms pilus and fimbria can be used interchangeably, although some researchers reserve the term pilus for the appendage required for bacterial conjugation. All pili in the latter sense are primarily composed of pilin proteins, which are oligomeric.

Synovial membrane

The synovial membrane is a specialized connective tissue that lines the inner surface of capsules of synovial joints and tendon sheath. It makes direct contact with the fibrous membrane on the outside surface and with the synovial fluid lubricant on the inside surface. In contact with the synovial fluid at the tissue surface are many rounded macrophage-like synovial cells and also type B cells. Type A cells maintain the synovial fluid by removing wear-and-tear debris. As for type B cells, they produce hyaluronan, as well as other extracellular components in the synovial fluid.

<i>Pseudomonas aeruginosa</i> common bacterium

Pseudomonas aeruginosa is a common encapsulated, Gram-negative, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, P. aeruginosa is a multidrug resistant pathogen recognized for its ubiquity, its intrinsically advanced antibiotic resistance mechanisms, and its association with serious illnesses – hospital-acquired infections such as ventilator-associated pneumonia and various sepsis syndromes.


Children under three years of age may become infected with K.kingae and develop spondylodiscitis. Typical symptoms include back pain, abdominal pain, and damage to the bones and joints. It generally targets the lumbar region of the spinal cord, and the only true way of diagnosing it is through biopsy or needle aspiration, as blood plate growth gives many false negatives. [5]


Osteomyelitis occurs in previously healthy children. The infection rate is poorly documented, thus the illness tends to go underdiagnosed. K. kingae can be transmitted person to person in rare cases. Diagnostic tools include low-grade fever, elevated inflammatory markers (ESR and CRP), but white blood cell counts are generally unreliable since they vary among infected patients. K. kingae infections are generally comcomitant with upper respiratory diseases or stomatitis, since disrupted respiratory or buccal mucosa is likely to facilitate bacterial invasion and hematogenous dissemination.

The cause of osteoarticular infections is frequently not identified. Less than 15% of K. kingae-positive clinical specimens reveal organisms on Gram stain. [6] Infections due to K. kingae are treatable with a wide variety of antibiotics, such as beta-lactams, tetracyclines, erythromycin, and fluoroquinolones. [2] Minimum inhibitory concentrations of penicillins, rifampicin, and azithromycin are easily achieved. Multiple studies have shown that inoculating synovial fluid or bone samples directly into blood culture bottles substantially increases the detection of K. kingae compared with direct plating of specimens on solid media.

As an oropharyngeal colonizer, K. kingae is transmitted by respiratory secretions, saliva, and potentially oral contact with contaminated objects. Recent studies suggest K. kingae strains may demonstrate varying degrees of pathogenicity, which could support the person-to-person transfer of pathogenic K. kingae. Infection has been shown to have high prevalence in the autumn and winter months. [6]

Infections in adults

K.kingae infections are rare in adults, but they occur in immunocompromised patients. Poor oral hygiene, pharyngitis, and mucosal ulceration are also predisposing factors for infection. The infection can occur in the respiratory or urinary tracts, as it is a part of the normal flora in those two areas, and will develop into septicemia or septic arthritis. [7] Most K. kingae are sensitive to beta-lactam antibiotics, but reports describe strains producing beta-lactamases. [8] Options include aminoglycosides, macrolides and fluoroquinolones. K.Kingae can also cause infectious endocarditis, in children as well as in adults. [9]

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The HACEK organisms are a group of fastidious gram-negative bacteria that are an unusual cause of infective endocarditis, which is an inflammation of the heart due to bacterial infection. HACEK is an abbreviation of the initials of the genera of this group of bacteria: Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella. The HACEK organisms are a normal part of the human microbiota, living in the oral-pharyngeal region.

Infective endocarditis endocarditis that is characterized by inflammation of the endocardium caused by infectious agents.

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  1. Yagupsky P (2004). "Kingella kingae: from medical rarity to an emerging paediatric pathogen". Lancet Infect Dis. 4 (6): 358–67. doi:10.1016/S1473-3099(04)01046-1. PMID   15172344.
  2. 1 2 Petti CA, Bhally HS, Weinstein MP, Joho K, Wakefield T, Reller LB, Carroll KC (2006). "Utility of extended blood culture incubation for isolation of Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella organisms: a retrospective multicenter evaluation". J. Clin. Microbiol. 44 (1): 257–9. doi:10.1128/JCM.44.1.257-259.2006. PMC   1351967 . PMID   16390985.
  3. Kehl-Fie TE, Porsch EA, Miller SE, St Geme JW (2009). "Expression of Kingella kingae type IV pili is regulated by sigma54, PilS, and PilR". J. Bacteriol. 191 (15): 4976–86. doi:10.1128/JB.00123-09. PMC   2715724 . PMID   19465661.
  4. Kehl-Fie TE, Porsch EA, Yagupsky P, Grass EA, Obert C, Benjamin DK, St Geme JW (2010). "Examination of type IV pilus expression and pilus-associated phenotypes in Kingella kingae clinical isolates". Infect. Immun. 78 (4): 1692–9. doi:10.1128/IAI.00908-09. PMC   2849430 . PMID   20145101.
  5. Ceroni D, Cherkaoui A, Kaelin A, Schrenzel J (2010). "Kingella kingae spondylodiscitis in young children: toward a new approach for bacteriological investigations? A preliminary report". J Child Orthop. 4 (2): 173–5. doi:10.1007/s11832-009-0233-2. PMC   2839857 . PMID   21455474.
  6. 1 2 Kiang KM, Ogunmodede F, Juni BA, Boxrud DJ, Glennen A, Bartkus JM, Cebelinski EA, Harriman K, Koop S, Faville R, Danila R, Lynfield R (2005). "Outbreak of osteomyelitis/septic arthritis caused by Kingella kingae among child care center attendees". Pediatrics. 116 (2): e206–13. doi:10.1542/peds.2004-2051. PMID   16024681.
  7. Ramana K, Mohanty S (2009). "An adult case of urinary tract infection with Kingella kingae: a case report". J Med Case Rep. 3: 7236. doi:10.1186/1752-1947-3-7236. PMC   2726550 . PMID   19830146.
  8. Banerjee A, Kaplan JB, Soherwardy A, Nudell Y, Mackenzie GA, Johnson S, Balashova NV (2013). "Characterization of TEM-1 β-lactamase producing Kingella kingae clinical isolates". Antimicrob. Agents Chemother. 57 (9): 4300–4306. doi:10.1128/AAC.00318-13. PMC   3754283 . PMID   23796935.
  9. Debora Pierce, Bethany C. Calkins, Kirsten Thornton, Infectious Endocarditis: Diagnosis and Treatment, Am Fam Physician, 2012, 15;85(10):981-986