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Sexually Transmitted Diseases > Gonorrhea > Laboratory Information > Related
Species > Kingella denitrificans Kingella denitrificans IntroductionK. denitrificans is one of several species which are colistin-resistant and may be routinely isolated on selective medium for N. gonorrhoeae. Colonies of K. denitrificans are usually glistening and smooth in consistency. Although cells of K. denitrificans are coccobacilli, the cell morphology of some isolates may appear to be diplococci and very similar in appearance to N. gonorrhoeae. In contrast to Neisseria spp., K. denitrificans isolates are catalase- and superoxol-negative. N. gonorrhoeae and K. denitrificans may, however, be confused because isolates of both species produce acid from glucose in acid production tests and hydroxylprolylaminopeptidase in enzyme substrate tests. Crossreactions also have been noted with isolates of K. denitrificans in coagglutination serologic tests for the identification of N. gonorrhoeae. Thus, additional tests must be performed to differentiate between these species. The nitrate test permits differentiation between N. gonorrhoeae (nitrate-negative) and K. denitrificans (nitrate-positive). Characteristics of K. denitrificans Table 1. Characteristics of K. denitrificans
Species which may be misidentified as K. denitrificans in acid detection testsDepending on the identification test used, several strains of Neisseria may be misidentified as K. denitrificans; the biochemical characteristics of these species are shown in Table 2. Table 2. Supplemental tests which permit differentiation among gram-negative diplococci that produce acid only from glucose.
Abbreviations. GND, Gram-negative diplococcus; GNR, Gram-negative rod;
+, most strains positive; -, most strains negative; R, strains grow well
on selective medium for N. gonorrhoeae and/or show no inhibition
around a colistin disk (10 micrograms); (R), most strains susceptible,
some strains resistant. Although enzyme substrate tests are intended to be used only for the identification of Neisseria spp. isolated on selective media for N. gonorrhoeae, isolates of K. denitrificans give the same reaction (hydroxylaminopeptidase-positive) in this test as do isolates of N. gonorrhoeae. Thus additional tests must be performed to differentiate between these species. Table 3. Supplemental tests which permit differentiation among Neisseria and related species that produce hydroxyprolylaminopeptidase.
Abbreviations: +, most strains positive; -, most strains negative; (+), some strains give weak positive reactions which are not representative of the species; R, strains grow well on selective medium for N. gonorrhoeae and/or show no inhibition around a colistin disk (10 micrograms); (R), most strains susceptible, some strains resistant. ReferencesBovre K. 1984. Family VIII. Neisseriaceae Prevot, p. 288-309. In N. R. Krieg (ed.). Manual of Systematic Bacteriology, vol. 1. The Williams & Wilkins co., Baltimore. Knapp JS. Historical perspectives and identification of Neisseria and related species. Clin Microbiol Rev 1988;1:415-431. Knapp JS, Rice RJ. Neisseria and Branhamella. In. Murray PR, Baron EJ, Pfaller MA, Tenover FC, Yolken RH. (ed.). Manual of Clinical Microbiology. 6th ed. American Society for Microbiology, Washington D. C, 1995. Vedros NA. 1984. Genus I. Neisseria Trevisan 1885, 105AL, p. 290-296. In NR Krieg (ed.). Bergey's Manual of Systematic Bacteriology, vol. 1. The Williams & Wilkins Co., Baltimore. Page last modified: October 17, 2008 Page last reviewed: October 24, 2008 Content Source: Division of STD Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention |
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