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Kingella kingae is a species of Gram-negative aerobic coccobacilli. First isolated in 1960, 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]

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.

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.

Mechanism of infectionEdit

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.

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]

SpondylodiscitisEdit

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]

OsteomyelitisEdit

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] Fortunately, K. kingae is readily treatable with a wide variety of antibiotics, such as beta-lactams, tetracyclines, erythromycin, and fluoroquinolones.^[2] It shows low minimum inhibitory concentrations for penicillins, rifampicin, and azithromycin. 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]

Adult infectionsEdit

K.kingae infections are quite rare in adults, but they do 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.

ReferencesEdit

^ 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.
^ ^a ^b 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.
^ 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.
^ 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.
^ 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.
^ ^a ^b 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.
^ 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.
^ 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. doi:10.1128/AAC.00318-13. PMC 3754283. PMID 23796935.

External LinksEdit

"Kingella kingae". NCBI Taxonomy Browser. 504.

UpToDate Contents

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1. 細菌性関節炎：幼児および小児における疫学、病因、および微生物学 bacterial arthritis epidemiology pathogenesis and microbiology in infants and children
2. 小児における血行性骨髄炎：疫学、病因、および微生物学 hematogenous osteomyelitis in children epidemiology pathogenesis and microbiology
3. 小児における血行性骨髄炎：マネージメント hematogenous osteomyelitis in children management
4. 細菌性関節炎：幼児および小児の治療および転帰 bacterial arthritis treatment and outcome in infants and children
5. 細菌性関節炎：幼児および小児における臨床的特徴および診断 bacterial arthritis clinical features and diagnosis in infants and children

English Journal

Impact of Periodontal Therapy on the Subgingival Microbiota of Severe Periodontitis: Comparison between Good Responders and "Refractory" Subjects by the Human Oral Microbe Identification Microarray (HOMIM).

Colombo AP, Bennet S, Cotton SL, Goodson JM, Kent R, Haffajee AD, Socransky SS, Hasturk H, Van Dyke TE, Dewhirst FE, Paster BJ.SourceAssociate Professor, Department of Medical Microbiology, Institute of Microbiology of Federal University of Rio de Janeiro, Brazil;
Journal of periodontology.J Periodontol.2012 Feb 10. [Epub ahead of print]
Aim: This study compared the changes on the subgingival microbiota of subjects with "refractory" periodontitis (RP) or treatable periodontitis (GR) before and after periodontal therapy by using the Human Oral Microbe Identification Microarray (HOMIM). Methods: Individuals with chronic periodontitis
PMID 22324467

High frequency of Tropheryma whipplei in culture-negative endocarditis.

Geissdörfer W, Moos V, Moter A, Loddenkemper C, Jansen A, Tandler R, Morguet AJ, Fenollar F, Raoult D, Bogdan C, Schneider T.SourceMikrobiologisches Institut-Klinische Mikrobiologie, Immunologie und Hygiene, Friedrich Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.
Journal of clinical microbiology.J Clin Microbiol.2012 Feb;50(2):216-22. Epub 2011 Nov 30.
"Classical" Whipple's disease (cWD) is caused by Tropheryma whipplei and is characterized by arthropathy, weight loss, and diarrhea. T. whipplei infectious endocarditis (TWIE) is rarely reported, either in the context of cWD or as isolated TWIE without signs of systemic infection. The frequency of T
PMID 22135251