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Diplococcus mucosus

N. mucosa (Diplococcus mucosus) was described in 1906 but was not recognized again until 1959, when it was re-described by Veron et al. The failure to identify strains of N. mucosa occurred because nitrate reduction was not used as differential test until the 1960s. Strains of N. mucosa are distinguished from those of N. subflava biovar perflava and N. sicca by their ability to reduce nitrate.

Table 1. Characteristics of N. mucosa

Characteristic	Illustration
Gram stain Cell Morphology	Gram-negative diplococcus
Colony Morphology
Pigmentation
Oxidase Test
Acid Production
Enzyme Substrate Test	Prolyl aminopeptidase +ve
Nitrate Reduction Test	Nitrate -ve
Polysaccharide from Sucrose
Production of Deoxyribonuclease (DNase)
Superoxol Test (Reaction with 30% hydrogen peroxide)
Catalase Test
Colistin Resistance

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Species which may be misidentified as N. mucosa in acid detection tests

Three Neisseria species, N. mucosa, N. sicca, and N. subflava biovar perflava, produce acid from glucose, maltose, fructose, and sucrose. N. mucosa may be identified by it's ability to reduce nitrate.

Table 2. Characteristics of N. mucosa and other Neisseria spp. that produce acid from glucose, maltose, fructose, and sucrose

Species	Acid from					Nitrate Reduction	Poly- saccharide from Sucrose	Pigment	Colistin Resistance*
	G	M	S	F	L
N. mucosa	+	+	+	+	-	+	+	-	S
N. subflava Biovar perflava	+	+	+	+	-	-	+	d	(R)
N. sicca	+	+	+	+	-	-	+	d	S

Abbreviations: G, glucose; M, maltose, S, sucrose; F, fructose; L, lactose; +, 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.

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. mucosa produces prolyl aminopeptidase 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 prolyl aminopeptidase in enzyme substrate tests

Species that Produce PAP	Cellular Elongation*	Acid from					Nitrate Reduction	Polysaccharide from Sucrose	Superoxol	Colistin Resistance
		G	M	S	F	L
N. flavescens	Diplococci	-	-	-	-	-	-	+	Weak (2+) positive	S
N. cinerea	Diplococci	(-)	-	-	-	-	-	-	Weak (2+) positive	(R)
N. gonorrhoeae	Diplococci	+	-	-	-	-	-	-	Strong (4+) positive	R
N. gonorrhoeae subspecies kochii	Diplococci	(-)	-	-	-	-	-	-	Strong (4+) positive	R
K. denitrificans	Rod filaments	+	-	-	-	-	+	-	-	R
N. subflava biovar subflava	Diplococci	+	+	-	-	-	-	-	Weak (2+) positive	S
N. subflava biovar flava	Diplococci	+	+	-	+	-	-	-	Weak (2+) positive	S
N. subflava biovar perflava	Diplococci	+	+	+	+	-	-	+	Weak (2+) positive	(R)
N. sicca	Diplococci	+	+	+	+	-	-	+	Weak (2+) positive	S
N. mucosa	Diplococci	+	+	+	+	-	+	+	Weak (2+) positive	S
N. elongata	Rod filaments	-	-	-	-	-	-	-	-	S

Abbreviations: G, glucose; M, maltose, S, sucrose; F, fructose; L, lactose; +, most strains positive; -, most strains negative; (+), strains may give weak positive reactions; 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 known to be resistant; S, all strains believed to be susceptible, no strains known to be resistant.

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References

Bovre K. Family VIII. Neisseriaceae Prevot, In N. R. Krieg (ed.). Manual of Systematic Bacteriology, vol. 1. The Williams & Wilkins co., Baltimore. 1984. p. 288-309.

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. Genus I. Neisseria Trevisan 1885, 105AL, In NR Krieg (ed.). Bergey's Manual of Systematic Bacteriology, vol. 1. The Williams & Wilkins Co., Baltimore. 1984. p. 290-296.

von Lingelsheim W. Die bakteriologisch Arbeiten der Kgl. hygienischen Station zu Beuthen O.-Sch. wahrend der Genickstarreepidemie in Oberschlesien Im Winter 1904/05. Klin Jahrb 1906;15:373-489.

Veron M, Thibault P, Second L. Neisseria mucosa (Diplococcus mucosus Lingelsheim). I. Description bacteriologique et etude du pouvoir pathogene. Ann Inst Pasteur (Paris) 1959;100:497-500.