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Gonorrhea Laboratory Information
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 Thus, with a rare exception (one known, unpublished report of a lactose-negative strain), this species should not be misidentified.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 colonies
Pigmentation pigmentation
Oxidase Test oxidase
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

acid

acid

Enzyme Substrate Test Beta-galactosidase (ONPG)-positive
Nitrate Reduction Test Nitrate -ve
Polysaccharide from Sucrose polysaccharide
Polysaccharide -ve
Production of
Deoxyribonuclease (DNase)
DNase
DNase -ve
Superoxol Test
(Reaction with 30% hydrogen peroxide)
superoxol
Weak (1+) to Strong (3+) Reactions
Catalase Test
(Reaction with 3% hydrogen peroxide)
catalase
Catalase-positive
Colistin Resistance colistin
Colistin-resistant

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 Thus, with a rare exception (one known, unpublished report of a lactose-negative strain), this species should not be misidentified.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.

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.

 

 
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