The pathogenic potential of commensal species ofNeisseria

Abstract

SUMMARY Although Neisseria species other than N gonorrhoeae and N meningitidis normally comprise part of the commensal bacterial flora of the oropharynx, they may occasionally act as opportunistic pathogens. Infections in which these organisms have been implicated include cases of endocarditis, meningitis, septicaemia, otitis, bronchopneumonia and possibly genital tract disease. In this paper, the clinical and pathological features of such infections are described, together with a discusssion of factors that may contribute to their development.In most textbooks of medical microbiology, the genus Neisseria is considered to contain only two pathogenic species, namely, N gonorrhoeae and N meningitidis. The other members of the genus are generally regarded as harmless inhabitants of the oropharynx. There is ample evidence in the literature, however, that these normally non-pathogenic species are capable of producing infection in a variety of anatomical sites including the heart, nervous system, bloodstream, respiratory tract and possibly the genital tract. Although the pathogenesis of gonococcal and meningococcal infections has been investigated extensively and is well documented,' 2 there is little collated information concerning infections produced by other Neisseria spp. This article is an attempt to remedy this deficiency. Classification of the genus NeisseriaAny review of Neisseria infections is complicated by the fact that the classification of the organisms comprising the genus has undergone a number of changes over the years. A detailed discussion of the evolution of the taxonomy of the genus is beyond the scope of this article, but a brief ojitline, which conveys some idea of the degree of change is presented below. In the early part of this century,

Identification of Epitopes Recognized by Monoclonal Antibodies SM1 and SM2 Which React with All Pili of Neisseria gonorrhoeae but Which Differentiate between Two Structural Classes of Pili Expressed by Neisseria meningitidis and the Distribution of Their Encoding Sequences in the Genomes of Neisseria spp.

“…The presence of class IpiI DNA sequences in N . lactamica, which is commonly regarded as a commensal, is consistent with a number of reports that members of this species can occasionally cause infections at different sites in humans (Johnson, 1983;Brown et al, 1987). In addition, N .…”

A numerical phenotypic taxonomic study of the genus Neisseria

“…flavescens should be regarded as different species. The type strains of both occur in this phenon, but we are reluctant to reduce them to synonymy (N. szlbflava has priority) because N.flavescens is classically associated with meningitis, and N. subflava is only rarely (see however Johnson, 1983). Furthermore, the latter is reported to ferment glucose and maltose unlike N .…”

“…The rarity of N. flavescens has been noted (Knapp, 1988) and, given the unpredictability of carbohydrate metabolism suggested for both N. flavescens and N. subflava together with their high phenetic similarity as indicated in the present study, it is possible that it occurs more frequently than has been realised. Cowan believed that N. flavescens had not with certainty been isolated since the Chicago outbreak, but recent isolations supported by serology have been discussed by Johnson (1983) and Berger (1984).…”

Bacteriemia por Neisseria subflava en un recién nacido

“…Estudios realizados en lactantes demuestran una colonización en las primeras semanas de vida, la que aumenta con la edad 9 . En ocasiones pueden actuar como patógenos oportunistas, especialmente en hospederos inmunocomprometidos o a consecuencia de mordeduras de animales 10 . Neisseria subflava, presenta tres biovariedades (bv): N. subflava bv flava, bv.…”