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      The Type a and Type b Polysaccharide Capsules Predominate in an International Collection of Invasive Kingella kingae Isolates

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          Abstract

          Kingella kingae has emerged as a significant cause of septic arthritis, osteomyelitis, and bacteremia in young children. A recent study examining a diverse collection of K. kingae isolates from Israel revealed four different polysaccharide capsule types in this species, designated types a to d. To determine the global distribution of K. kingae capsule types, we assembled and capsule typed an international collection of K. kingae isolates. The findings reported here show that the type a and type b capsules represent >95% of the invasive isolates, similar to the Israeli isolate collection, suggesting that a polysaccharide-based vaccine targeting these two capsules could be an attractive approach to prevent K. kingae disease.

          ABSTRACT

          Kingella kingae is an encapsulated Gram-negative bacterium and an important etiology of osteoarticular infections in young children. A recent study examining a diverse collection of carrier and invasive K. kingae isolates from Israel revealed four distinct polysaccharide capsule types. In this study, to obtain a global view of K. kingae capsule type diversity, we examined an international collection of isolates using a multiplex PCR approach. The collection contained all four previously identified capsule types and no new capsule types. Over 95% of invasive isolates in the collection were type a or type b, similar to the findings in Israel. These results suggest that the type a and type b polysaccharide capsules may have enhanced pathogenic properties or may mark clonal groups of strains with specific virulence genes. In addition, they raise the possibility that a vaccine containing the type a and type b capsules might be an effective approach to preventing K. kingae disease.

          IMPORTANCE Kingella kingae has emerged as a significant cause of septic arthritis, osteomyelitis, and bacteremia in young children. A recent study examining a diverse collection of K. kingae isolates from Israel revealed four different polysaccharide capsule types in this species, designated types a to d. To determine the global distribution of K. kingae capsule types, we assembled and capsule typed an international collection of K. kingae isolates. The findings reported here show that the type a and type b capsules represent >95% of the invasive isolates, similar to the Israeli isolate collection, suggesting that a polysaccharide-based vaccine targeting these two capsules could be an attractive approach to prevent K. kingae disease.

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          Most cited references 13

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          The pathogenicity of Haemophilus influenzae.

           D Turk (1984)
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            Specific real-time polymerase chain reaction places Kingella kingae as the most common cause of osteoarticular infections in young children.

            The use of universal 16S rDNA polymerase chain reaction (PCR) has recently shown that the place of Kingella kingae in osteoarticular infections (OAI) in young children has been underestimated, but this technique is not the most sensitive or the most rapid method for molecular diagnosis. We developed a specific real-time PCR method to detect K. kingae DNA and applied it to the etiologic diagnosis of OAI. All children admitted to a pediatric unit for OAI between January 2004 and December 2005 were enrolled in this prospective study. Culture-negative osteoarticular specimens were tested by 16S rDNA PCR and by K. kingae-specific real-time PCR when sufficient sample remained. By culture alone, a pathogen was identified in 45% of the 131 specimens tested (Staphylococcus aureus, n = 25; K. kingae, n = 17; others, n = 18). 16S rDNA PCR and K. kingae-specific PCR were both applied to 61 of the culture-negative samples. The combination of culture and 16S rDNA PCR identified a pathogen in 61% of cases (K. kingae DNA, n = 16; DNA of other microorganisms, n = 5). Specific real-time PCR identified a further 6 cases caused by K. kingae and confirmed all 16 universal PCR-positive cases, bringing the overall documentation rate to 66%. K. kingae was the leading cause of OAI in this pediatric series (n = 39, 45%), followed by S. aureus (n = 25, 29%) The K. kingae-specific real-time PCR places K. kingae as the leading cause of OAI in children at our hospital.
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              Broad-spectrum biofilm inhibition by Kingella kingae exopolysaccharide.

              Cell-free extracts prepared from Kingella kingae colony biofilms were found to inhibit biofilm formation by Aggregatibacter actinomycetemcomitans, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis, Candida albicans, and K. kingae. The extracts evidently inhibited biofilm formation by modifying the physicochemical properties of the cell surface, the biofilm matrix, and the substrate. Chemical and biochemical analyses indicated that the biofilm inhibition activity in the K. kingae extract was due to polysaccharide. Structural analyses showed that the extract contained two major polysaccharides. One was a linear polysaccharide with the structure →6)-α-d-GlcNAcp-(1→5)-β-d-OclAp-(2→, which was identical to a capsular polysaccharide produced by Actinobacillus pleuropneumoniae serotype 5. The second was a novel linear polysaccharide, designated PAM galactan, with the structure →3)-β-d-Galf-(1→6)-β-d-Galf-(1→. Purified PAM galactan exhibited broad-spectrum biofilm inhibition activity. A cluster of three K. kingae genes encoding UDP-galactopyranose mutase (ugm) and two putative galactofuranosyl transferases was sufficient for the synthesis of PAM galactan in Escherichia coli. PAM galactan is one of a growing number of bacterial polysaccharides that exhibit antibiofilm activity. The biological roles and potential technological applications of these molecules remain unknown.
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                Author and article information

                Contributors
                Role: Editor
                Journal
                mSphere
                mSphere
                msph
                msph
                mSphere
                mSphere
                American Society for Microbiology (1752 N St., N.W., Washington, DC )
                2379-5042
                15 March 2017
                Mar-Apr 2017
                : 2
                : 2
                Affiliations
                [a ]Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
                [b ]Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
                [c ]Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, USA
                [d ]Soroka University Medical Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel
                [e ]University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
                University of Kentucky
                Author notes
                Address correspondence to Joseph W. St. Geme III, stgemeiiij@ 123456email.chop.edu .

                Citation Porsch EA, Starr KF, Yagupsky P, St Geme JW, III. 2017. The type a and type b polysaccharide capsules predominate in an international collection of invasive Kingella kingae isolates. mSphere 2:e00060-17. https://doi.org/10.1128/mSphere.00060-17.

                Article
                mSphere00060-17
                10.1128/mSphere.00060-17
                5352833
                Copyright © 2017 Porsch et al.

                This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.

                Counts
                Figures: 2, Tables: 2, Equations: 0, References: 15, Pages: 8, Words: 4694
                Product
                Funding
                Funded by: HHS | NIH | National Institute of Allergy and Infectious Diseases (NIAID) https://doi.org/10.13039/100000060
                Award ID: R56AI103125
                Award Recipient : Joseph W. St. Geme III
                Funded by: HHS | NIH | National Institute of Allergy and Infectious Diseases (NIAID) https://doi.org/10.13039/100000060
                Award ID: 1R01AI121015
                Award Recipient : Joseph W. St. Geme III
                Categories
                Observation
                Host-Microbe Biology
                Custom metadata
                March/April 2017

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