Abstract
CDC group M-6 is the vernacular name given to a gram-negative, oxidase-positive, aerobic, nonmotile, rod-shaped bacterium. This organism is biochemically similar to Kingella denitrificans and displays a cellular fatty acid profile consistent with CDC groups M-5 and EF-4 and with Neisseria elongata. Of the 95 M-6 strains referred to the Centers for Disease Control (CDC) for identification, 32 (64%) of the first 50 were from the throat or sputum and only 3 (6%) were from blood; only 5 (11%) of the next 45 isolates were from the upper respiratory tract and 23 (51%) were from blood, with many of these (15 or 65%) being associated with endocarditis. The major characteristics of CDC group M-6 include reduction of nitrate and nitrite with no gas formation; positive reaction for oxidase; negative reactions for catalase, urease, indole, and motility; and no acid production from carbohydrates. Guanine-plus-cytosine content determined spectrophotometrically by thermal denaturation was 55 to 58 mol % for six M-6 strains tested: 56 mol % for the N. elongata subsp. elongata type strain and for the N. elongata subsp. glycolytica type strain. By the hydroxyapatite method, DNAs from 24 M-6 strains showed an average of 78% relatedness to M-6 reference strain B1019 in reactions at 60 degrees C and 73% relatedness in reactions at 75 degrees C. M-6 strain B1019 was 79% related to the N. elongata type strain at 60 degrees C and 71% related at 75 degrees C; it was 75% related to the type strain N. elongata subsp. glycolytica at 60 degrees C and was 66% related at 75 degrees C. DNAs from CDC group EF-4, K. denitrificans, and CDC group M-5 were all less than 14% related to CDC group M-6 at 75 degrees C. The DNA relatedness data showed conclusively that all the M-6 strains belong in the species N. elongata. M-6 is different from N. elongata subsp. elongata in that M-6 reduces nitrate and sometimes weakly acidifies D-glucose, and it is different from N. elongata subsp. glycolytica in that it reduces nitrate and is negative for glucose and catalase. Because of the apparent clinical significance of M-6 compared with the clinical significance of N. elongata subsp. elongata and N. elongata subsp. glycolytica and the ease in distinguishing it biochemically, we propose M-6 as a third subspecies of N.elongata, N. elongata subsp. nitroreducens subsp. nov.
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- Bovre K., Holten E. Neisseria elongata sp.nov., a rod-shaped member of the genus Neisseria. Re-evaluation of cell shape as a criterion in classification. J Gen Microbiol. 1970 Jan;60(1):67–75. doi: 10.1099/00221287-60-1-67. [DOI] [PubMed] [Google Scholar]
- Brenner D. J., McWhorter A. C., Knutson J. K., Steigerwalt A. G. Escherichia vulneris: a new species of Enterobacteriaceae associated with human wounds. J Clin Microbiol. 1982 Jun;15(6):1133–1140. doi: 10.1128/jcm.15.6.1133-1140.1982. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Garner J., Briant R. H. Osteomyelitis caused by a bacterium known as M6. J Infect. 1986 Nov;13(3):298–300. doi: 10.1016/s0163-4453(86)91487-8. [DOI] [PubMed] [Google Scholar]
- MARMUR J., DOTY P. Determination of the base composition of deoxyribonucleic acid from its thermal denaturation temperature. J Mol Biol. 1962 Jul;5:109–118. doi: 10.1016/s0022-2836(62)80066-7. [DOI] [PubMed] [Google Scholar]
- Moss C. W., Wallace P. L., Hollis D. G., Weaver R. E. Cultural and chemical characterization of CDC groups EO-2, M-5, and M-6, Moraxella (Moraxella) species, Oligella urethralis, Acinetobacter species, and Psychrobacter immobilis. J Clin Microbiol. 1988 Mar;26(3):484–492. doi: 10.1128/jcm.26.3.484-492.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Perez R. E. Endocarditis with Moraxella-like M-6 after cardiac catheterization. J Clin Microbiol. 1986 Sep;24(3):501–502. doi: 10.1128/jcm.24.3.501-502.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Simor A. E., Salit I. E. Endocarditis caused by M6. J Clin Microbiol. 1983 May;17(5):931–933. doi: 10.1128/jcm.17.5.931-933.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]