Isolation of Neisseria elongata and of Capnocytophaga ochracea from vaginal specimens

Infected lung bulla caused by Neisseria elongata: A case report

Neisseria elongata is a rod-shaped, Gram-negative, aerobic bacterium that is part of the normal oral bacterial flora. Although previously considered a non- or low-pathogenic organism, the development of bacterial detection methods has resulted in increased reports of N. elongata infections such that it has recently been recognized as a causative agent of serious infections even in non-immune-compromised patients.

A 77-year-old man with rheumatoid arthritis-associated interstitial lung disease, chronic obstructive pulmonary disease, and diabetes mellitus was diagnosed with a nodule in the left lower lobe of his lung. Thoracoscopic wedge resection was performed, and pus was discharged from the specimen. Mass spectrometry of the swab culture revealed N. elongata. The patient's postoperative course was uneventful, and he was doing well without recurrence at 13 months after surgery. Since N. elongata is an oral bacterial flora, the patient consulted a local dentist, and decayed teeth were extracted.

Most of the reported cases of serious N. elongata infections have described infective endocarditis. This is the first report of infected lung bulla due to N. elongata infection, which demonstrates a new pathogenicity.

N. elongata produces type IV pili that mediate interspecies gene transfer with N. gonorrhoeae

The genus Neisseria contains at least eight commensal and two pathogenic species. According to the Neisseria phylogenetic tree, commensals are basal to the pathogens. N. elongata, which is at the opposite end of the tree from N. gonorrhoeae, has been observed to be fimbriated, and these fimbriae are correlated with genetic competence in this organism. We tested the hypothesis that the fimbriae of N. elongata are Type IV pili (Tfp), and that Tfp functions in genetic competence. We provide evidence that the N. elongata fimbriae are indeed Tfp. Tfp, as well as the DNA Uptake Sequence (DUS), greatly enhance N. elongata DNA transformation. Tfp allows N. elongata to make intimate contact with N. gonorrhoeae and to mediate the transfer of antibiotic resistance markers between these two species. We conclude that Tfp functional for genetic competence is a trait of a commensal member of the Neisseria genus. Our findings provide a mechanism for the horizontal gene transfer that has been observed among Neisseria species.

Characterization of Neisseria elongata subsp. glycolytica isolates obtained from human wound specimens and blood cultures

Four slightly yellow-pigmented, alpha-hemolytic, gram-negative coccobacilli, three from wound specimens and one from multiple blood cultures of a patient with endocarditis, were identified as Neisseria elongata subsp. glycolytica on the basis of their overall biochemical and genetic similarities to this subspecies. These strains resembled N. elongata in their guanine-plus-cytosine contents (55.6 to 57.1 mol%) and in their overall cellular fatty acid profiles, which are characterized by large amounts of 16:0, 16:1 omega 7c, and 18:1 omega 7c fatty acids. Their identities were confirmed by species-level DNA relatedness (hydroxyapatite method) to the type strains of all three N. elongata subspecies. The biochemical profiles and cultural characteristics of these strains resembled those of the type strain of N. elongata subsp. glycolytica except for the production of a weak yellow growth pigment and alpha-hemolysis on sheep blood agar. They differed from N elongata subsp. elongata by the production of catalase, by the production of alpha-hemolysis on sheep blood agar, and by acid production from D-glucose. They differed from N. elongata subsp. nitroreducens by the production of catalase and an inability to reduce nitrate. These studies suggest a pathogenic potential for N. elongata subsp. glycolytica, usually considered to be a transient colonizer in humans.

Protein profiles of Capnocytophaga species

Ninety-seven strains of Capnocytophaga isolated from the oral cavity and the type strains of C. ochracea, C. sputigena and C. gingivalis were compared by one-dimensional SDS-PAGE of whole cell proteins. The protein patterns were highly reproducible and were used as the basis for numerical taxonomic analysis. The clusters containing the type strains of C. ochracea and C. sputigena segregated at the 78% similarity level. Some of the eight clusters obtained at this level showed good correlation with grouping based on the results of biochemical testing for lactose and galactose fermentation and nitrate reduction. No consistent association was found between protein profiles and colony type, size or colour or cell length but all agar-adherent colony types segregated into a single cluster.