The
            <i>rtxA</i>
            Toxin Gene of Kingella kingae: a Pertinent Target for Molecular Diagnosis of Osteoarticular Infections

Lehours, Philippe; Freydière, Anne-Marie; Richer, Olivier; Burucoa, Christophe; Boisset, Sandrine; Lanotte, Philippe; Prère, Marie Françoise; Ferroni, Agnès; Lafuente, Christine; Vandenesch, François; Mégraud, Françis; Ménard, Armelle

doi:10.1128/jcm.01657-10

Cited by 66 publications

(76 citation statements)

References 24 publications

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“…All K. kingae clinical strains possess the rtxA toxin gene, making this gene a relevant target to diagnose K. kingae infection by PCR. However, there is a polymorphism of the rtxA gene, which encodes the RTX toxin [48], and a few studies have demonstrated that the most virulent strains of the species harbored a 33-bp duplication or triplication in their rtxA sequence, suggesting that this genetic trait could represent a genetic determinant of virulence [48,49]. Finally, Bendaoud et al reported that K. kingae forms biofilms in a microtiter plate assay [50].…”

Section: Rtx Toxin Productionmentioning

confidence: 99%

30 Years of Study of Kingella Kingae : Post Tenebras , Lux

et al. 2013

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Kingella kingae is a Gram-negative bacterium that is today recognized as the major cause of joint and bone infections in young children. This microorganism is a member of the normal flora of the oropharynx, and the carriage rate among children under 4 years of age is approximately 10%. K. kingae is transmitted from child to child through close personal contact. Key virulence factors of K. kingae include expression of type IV pili, Knh-mediated adhesive activity and production of a potent RTX toxin. The clinical presentation of K. kingae invasive infection is often subtle and may be associated to mild-to-moderate biologic inflammatory responses, highlighting the importance a high index of suspicion. Molecular diagnosis of K. kingae infections by nucleic acid amplification techniques enables identification of this fastidious microorganism. Invasive infections typically respond favorably to medical treatment, with the exception of cases of endocarditis, which may require urgent valve replacement

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Section: Rtx Toxin Productionmentioning

confidence: 99%

30 Years of Study of Kingella Kingae : Post Tenebras , Lux

et al. 2013

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“…It is possible that prolonged carriage induces strain-specific immunity that facilitates elimination of the carried organism but does not prevent acquisition of an antigenically different strain. This possibility is supported by the demonstration of strain-to-strain variability of K. kingae outer-membrane proteins [37], the PilA1 gene encoding the major pilus subunit [17], and the RTX toxin [10,13], suggesting that immunogenic surface-exposed bacterial components involved in pharyngeal colonization, undergo antigenic variation to evade the host's immune response.…”

Section: Colonization Dynamics and Turnover Of Strainsmentioning

confidence: 63%

“…The nucleic acid amplification assays developed to amplify conserved segments of the RTX toxin endoding genes rtxA and/or rtxB are able to detect 30 colony forming units (c.f.u.) of the organism, exhibiting a higher sensitivity than that of broad range 16S rRNA [12,14] or the cpn60 gene PCR tests [13], are highly specific, can be applied to a variety of clinical specimens, and enable detection of strains exhibiting RTX locus polymorphisms [10][11][12][13][14].…”

Section: Nucleic Acid Amplificationmentioning

confidence: 99%

“…It was natural that this sensitive approach was consequently adopted to study the colonization of the respiratory tract by K. kingae and its connection to invasive disease. The RTX toxin, a putative virulence factor, is produced by all K. kingae strains examined so far and, therefore, the encoding RTX locus genes appear as pertinent targets for molecular diagnosis of invasive infections and mucosal colonization by the organism [10][11][12][13]. The nucleic acid amplification assays developed to amplify conserved segments of the RTX toxin endoding genes rtxA and/or rtxB are able to detect 30 colony forming units (c.f.u.)…”

Section: Nucleic Acid Amplificationmentioning

confidence: 99%

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Respiratory Colonization by Kingella kingae, Person-to-Person Transmission, and Pathogenesis of Invasive Infection

Yagupsky¹

2013

TOIDJ

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Increasing recognition of Kingella kingae as an important pathogen of early childhood in recent years has elicited interest in the study of the asymptomatic carriage of the organism, its dissemination in the human population, and the role played by colonization of the upper respiratory tract in the pathogenesis of K. kingae invasion of the skeletal system and the endocardium.Research has revealed that K. kingae is a frequent component of the normal oropharyngeal microbiota, disclosed the subtle molecular mechanisms responsible for adherence of the bacterium to the pharyngeal mucosa, and revealed the presence of a potent RTX toxin, probably implicated in breaching the epithelial barrier, survival of the organism in the bloodstream, and damage to bone and joint tissues. Epidemiological studies have shown that carriage of K. kingae peaks in 6-30 month-old children, coinciding with the age of increased susceptibility to invasive disease, and daycare-center attendance represent a significant risk factor for pharyngeal colonization. The organism is transmitted from person-toperson by close contact between family members, playmaytes, and day-care center attendees. Carriage is characterized by frequent turnover of colonizing strains, similar to what has been described in other pathogens of respiratory origin.

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“…Al romperse la barrera epitelial el proceso es potencialmente mediado por una toxina extracelular de tipo RTX, con capacidad de lisar células epiteliales, sinoviales y macrófagos, que permite la diseminación a través del torrente sanguíneo a sitios distales, como huesos y articulaciones. 7,8 La fase de bacteriemia transitoria es corta y asintomática, lo que explica la frecuente negatividad de los hemocultivos.…”

Section: Comentariounclassified

Artritis séptica pediátrica causada por Kingella kingae

et al. 2012

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Presentación de casos clínicos RESUMENKingella kingae es un microorganismo que coloniza el tracto respiratorio superior. A pesar de su baja patogenicidad en esta localización, los procesos patológicos respiratorios previos pueden favorecer su diseminación sistémica y producir infecciones osteoarticulares, principalmente en menores de cinco años. En pacientes pediátricos, se considera un patógeno emergente en la infección osteoarticular. Presentamos el caso de una niña de dos años de edad con cuadro clínico de dolor de caderas, limitación de la abducción y extensión, y fiebre. La radiografía y la ecografía eran compatibles con sinovitis transitoria y la gammagrafía con patología osteoarticular inflamatoria de la cadera derecha. Se realizó punción articular y los parámetros bioquímicos arrojaron resultados alterados. Se procesó microbiológicamente y se aisló K. kingae sensible a antibióticos betalactámicos, azitromicina y trimetoprima-sulfametoxazol. Los hemocultivos fueron negativos. Se trató empíricamente con cloxacilina y cefotaxima IV y se continuó oralmente con amoxicilina-clavulánico, con mejoría osteoarticular. Palabras clave: Kingella kingae, artritis, infancia. SUMMARYKingella kingae is a bacterium that colonizes the upper respiratory tract. Despite its low pathogenicity in this location, previous respiratory pathological processes may favor its systemic spread causing bone and joint infections, mainly in children under five years. It can be considered an emerging pathogen in osteoarticular infection in pediatric patients. We report the case of a two-year-old girl with hips pain and limitation of both abduction and extension, and fever. Radiography and ultrasonography were compatible with transitory synovitis; showed scintigraphy inflammatory pathology of the right hip. Articular puncture was performed. The material showed altered biochemical parameters. Microbiological culture yielded isolation of a strain of K. kingae susceptible to beta-lactam antibiotics, azithromycin and trimethoprim-sulfamethoxazole. Blood cultures were negative. The patient was treated empirically with cloxacillin and cefotaxime iv. and continued with amoxicillinclavulanate orally with osteoarticular improvement. INTRODUCCIÓNLa artritis séptica de la cadera infantil es un proceso poco frecuente, caracterizado por la invasión del espacio articular por diversos microorganismos. Su relevancia radica en la asociación de un manejo difícil, desde el punto de vista mé-dico-quirúrgico, con numerosas complicaciones. Por esta razón se plantean importantes retos diagnósticos que deben ser abordados de forma multidisciplinar. La tinción de Gram y el cultivo son los métodos convencionales más frecuentemente empleados para detectar el agente etiológico de una forma rápida y precisa, de modo de abordar un correcto tratamiento en forma precoz.Kingella kingae pertenece a la familia Neisseriaceae. Coloniza el tracto respiratorio superior a nivel amigdalino, condición que favorece su transmisión persona-persona, especialmente entre niños de corta ed...

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The rtxA Toxin Gene of Kingella kingae: a Pertinent Target for Molecular Diagnosis of Osteoarticular Infections

Cited by 66 publications

References 24 publications

30 Years of Study of Kingella Kingae : Post Tenebras , Lux

30 Years of Study of Kingella Kingae : Post Tenebras , Lux

Respiratory Colonization by Kingella kingae, Person-to-Person Transmission, and Pathogenesis of Invasive Infection

Artritis séptica pediátrica causada por Kingella kingae

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