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Neisseria lactamica

Introduction

N. lactamica was described by Hollis et al. in 1969 and as N. meningococcoides by Berger in 1970.

Strains of N. lactamica had not been described in studies previous to 1969 because acid production from lactose was not used as a differential test for the identification of Neisseria spp. Prior to the description of this species, strains of N. lactamica would have been identified as N. meningitidis.

N. lactamica strains are colistin-resistant, grow on gonococcal selective medium, and are characterized by their ability to produce acid from glucose, maltose, and lactose, and by their ability to produce beta-galactosidase. Among the Neisseria species, N. lactamica is the probably the easiest species to identify; it is the only species that produces acid from lactose and produces beta-galactosidase. Thus, with a rare exception (one known, unpublished report of a lactose-negative strain), this species should not be misidentified.

N. lactamica is isolated frequently from children but infrequently from from adults.

Table 1. Characteristics of N. lactamica

Characteristic	Illustration
Gram stain Cell Morphology	Gram-negative diplococcus
Colony Morphology
Pigmentation
Oxidase Test
Acid Production Most strains of N. lactamica produce acid from lactose. One strain is known to be lactose-negative; this strain, however, produced beta-galactosidase in an enzyme substrate test
Enzyme Substrate Test	Beta-galactosidase (ONPG)-positive
Nitrate Reduction Test	Nitrate -ve
Polysaccharide from Sucrose	Polysaccharide -ve
Production of Deoxyribonuclease (DNase)	DNase -ve
Superoxol Test (Reaction with 30% hydrogen peroxide)	Weak (1+) to Strong (3+) Reactions
Catalase Test (Reaction with 3% hydrogen peroxide)	Catalase-positive
Colistin Resistance	Colistin-resistant

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Neisseria species which may be misidentified as N. lactamica

Among the Neisseria species, N. lactamica is the probably the easiest species to identify. N. lactamica is the only species that produces acid from lactose and beta-galactosidase. Thus, with a rare exception (one known, unpublished report of a lactose-negative strain), this species should not be misidentified. An identification of N. lactamica may be confirmed by detection of beta-galactosidase in an enzyme substrate test.

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References

Bovre 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, J. S. 1988. Historical perspectives and identification of Neisseria and related species. Clin. Microbiol. Rev. 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 N. R. Krieg (ed.). Bergey's Manual of Systematic Bacteriology, vol. 1. The Williams & Wilkins Co., Baltimore.