Moellerella wisconsensis, a new genus and species of Enterobacteriaceae found in human stool specimens

Abstract

The name Moellerella wisconsensis is proposed for a group of the family Enterobacteriaceae previously called enteric group 46. The species name, wisconsensis, was coined because six of the nine strains were isolated in Wisconsin. M. wisconsensis strains were negative for indole production, Voges-Proskauer, H2S production, urea, phenylalanine deaminase, lysine and ornithine decarboxylases, arginine dihydrolase, gas production from D-glucose, acid production from trehalose, and motility; the strains were positive for methyl red, citrate (Simmons), and acid production from lactose and raffinose and resistant to colistin. DNAs from five strains of M. wisconsensis were highly related (80 to 93% in reactions assayed on hydroxyapatite at 60°C and 78 to 97% at 75°C) to 32P-labeled DNA of the proposed type strain (CDC 2896-78, ATCC 35017). Labeled DNA from this type strain was only 2 to 32% related (at 60°C) to DNA from 49 strains of named and unnamed species of Enterobacteriaceae. Eight of nine M. wisconsensis strains were isolated from human stool samples. Clinical information on one strain was available, and it was found to be associated with a case of diarrhea. On MacConkey agar, colonies of M. wisconsensis were bright red with precipitated bile around them and thus were indistinguishable from Escherichia coli colonies. Future studies should focus on the isolation of this new organism and its relationship to human disease.

Composition and properties of the family Enterobaeteriaceae

“…Thus, as noted by Brenner (1984), the current circumscription and delimitation of the Enterobacteriaceae appears to be sound on both phenotypic and genomic grounds. Whether in the future the Enterobacteriaceae will retain family status or whether, as indicated by Colwell et al (1986), the taxon will be subsumed into a 'super family', depends on further studies on the genomic relatedness of all bacteria and the effect of the results of these studies on hierarchical classifications.…”

“…The Code requires that family names be formed by adding 'aceae' to the stem of the name of the type genus. Various proposals have been made to correct this contravention of the Code (see Brenner 1984) but in the interests of nomenclatural stability the Judicial Commission of the International Committee on Systematic Bacteriology has ruled that the name Enterobacteriaceae is valid.…”

“…Many of the pathogenic forms produce toxins. Detailed descriptions of the properties of the family are given by Brenner ( , 1984, Holmes (1983) andEwing (1986).…”

“…The history and the problems associated with the early classification and nomenclature of the family are well covered by Edwards & Ewing (1972), Cowan (1974), Brenner (1984) and Ewing (1986) and will not be dealt with in detail here. Where appropriate, some reference to earlier nomenclature will be made in the treatment of the current composition of the family.…”

“…While these studies have led to the development of a more stable, scientifically based classification they have also caused problems. These mainly concern changes in nomenclature as groups have been redefined and the recognition of many more taxa (see Brenner 1984;Ewing 1986).…”