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Sexually Transmitted Diseases > Gonorrhea > Laboratory Information > Related
Species > Neisseria cinerea Neisseria cinerea IntroductionN. cinerea was first described as Micrococcus cinereus by von Lingelsheim in 1906. Isolates of N. cinerea (N. cinereus) were identified as M. catarrhalis (Neisseria catarrhalis); sometimes N. cinerea isolates were recognized as belonging to a colonial morphologic subtype of M. catarrhalis (Neisseria catarrhalis). In 1934, Huntoon described N. pseudocatarrhalis, whose description was consistent with that of N. cinerea. N. cinerea was not recognized and correctly identified again until 1962 in Germany and in 1984 in the United States. By DNA hybridization studies, N. cinerea exhibits approximately 50% relatedness to N. gonorrhoeae. N. cinerea has been isolated from endocervical and rectal infections, from conjunctivitis in neonates, and from lymphadenitis, and has been misidentified repeatedly as N. gonorrhoeae. Strains of N. cinerea have been isolated from the conjunctiva of newborns treated prophylactically with erythromycin and misidentified as N. gonorrhoeae. Thus, a gram-negative, oxidase-positive diplococcus isolated on nonslective media should be identified by definitive methods. N. cinerea has been isolated on gonococcal selective media for the identification of N. gonorrhoeae. Some strains of N. cinerea may grow when subcultured on selective media. Colonies of N. cinerea are similar in size, appearance, and consistency with those of N. gonorrhoeae. Similar to N. gonorrhoeae, N. cinerea may also give rise to different colony forms that vary in diameter, degree of convexity, and opacity. N. cinerea has been misidentified as N. gonorrhoeae not only because of similarities in colonial morphology but also because of similarities in biochemical activities. Although N. cinerea is considered to be glucose-negative, strains may produce weak acid reactions from glucose in some acid detection tests. N. cinerea produces acid from glucose but rapidly overoxidizes the acid to carbon dioxide with the result that acid does not accumulate in the reaction tube although the carbohydrate has been used. Thus, depending on the buffering capacity of the medium, N. cinerea strains may be identified as weakly glucose-positive or glucose-negative. N. cinerea may be misidentified as N. gonorrhoeae if tested only with an enzyme substrate test because both species produce are hydroxyprolylaminopeptidase-positive. Some N. cinerea isolates may be misidentified as gonococcal strains because they have reacted in coagglutination serologic tests performed in accordance with the manufacturer's directions. Table 1. Characteristics of N. cinerea
Species which may be misidentified as N. cinerea in acid detection tests Based on acid production patterns, N. cinerea may be misidentified as M. catarrhalis, N. flavescens, or as a glucose-negative strain of N. gonorrhoeae. Supplemental tests that may aid in differentiating between species that produce no detectable acid from carbohydrates are shown in Table 2. Table 2. Supplemental tests which permit differentiation among gram-negative diplococci that produce no detectable acid from carbohydrates.
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, these tests do provide additional information that may aid in accurately identifying an isolate. However, N. cinerea produces hydroxyaminopeptidase in enzyme substrate test and may be misidentified as N. gonorrhoeae if additional tests are not performed. Table 3. Supplemental tests which permit differentiation among Neisseria and related species that produce hydroxyprolylaminopeptidase in enzyme substrate tests.
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Content provided by the Division of STD Prevention |
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