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The phylogenetic position of the causative agent of septicemia anserum exsudativa, now most often referred to as [Moraxella] anatipestifer (brackets indicate a generically misnamed taxon) or "[Pasteurella] anatipestifer," was established by performing rRNA cistron similarity studies.[Moraxella] anatipestifer belongs to rRNA superfamily V, together with the genera Flavobacterium, Cytophuga, Fkxibacter, Weeksella, Capnocytophaga, and Sphingobacterium. The detailed structure of rRNA superfamily V, which now contains five major rRNA homology groups, is described. An analysis of various phenotypic parameters, including new data (cellular proteins and fatty acids) and previously published data (respiratory quinones, enzyme activities, and classical phenotypic features), revealed that [Moraxella] anatipestifer differs in many aspects from its closest relatives, Flavobacterium indologenes, Flavobacterium gleum, Flavobacterium indoltheticum, Flavobacterium balustinum , Flavobacterium meningosepticum, and Weekseh zoohelcum. The combined genotypic and phenotypic data indicate that this organism should be placed in a separate genus; the name Riemerella anatipestifer gen. nov., comb. nov. is proposed for this bacterium. The specific epithet anatipestifer is kept in order to avoid nomenclatural confusion. However, it should be emphasized that the illness caused by this organism is a septicemic disease which is not restricted to ducks.The epizootic infectious disease of domestic birds known as septicemia anserum exsudativa was first described ,by Riemer in 1904 (30). The taxonomic status of few other bacteria has been changed as often as the taxonomic status of the organism causing this disease. The phylogenetic position of this organism remained unsettled (it was classified in various genera with several specific epithets) from 1904 until 1986, when Piechulla and coworkers described for the first time its correct affiliation with the FlavobacteriumCytophaga group (29). An overview of this nomenclatural odyssey was given by Floren et al. (14). At present, the organism is most often referred to as [Moraxella] anatipestifer (brackets indicate a generically misnamed taxon) or " [Pasteurella] anatipestifer," and it is considered a species incertae sedis in Be%ey s Manual of Systematic Bacteriology (5,24). The numerous similarities between this organism and members of the Flavobacterium-Cytophaga group (lack of flagellation, low DNA base ratio, presence of menaquinones as the sole respiratory quinones, presence of branchedchain fatty acids in high percentages, absence of carbohydrate fermentation, and similar hydrolytic enzyme patterns) were significant parameters used to determine genomic relatedness, as shown by Rossau and coworkers (31). Rossau et al. also showed by performing a DNA-rRNA hybridization analysis that [Moraxella] anatipestifer indeed is not a close relative of the Muraxella or Pasteurella rRNA homology clusters but belongs to the Flavobacten'urn-Cytophaga rRNA homology cluster (31).The phylogenetic relationships...

The phylogenetic position and various genotypic, chemotaxonomic, and classical phenotypic characteristics of 21 gram-negative avian isolates were studied. These strains constitute a genotypically homogeneous taxon in rRNA superfamily V, as shown by DNA-rRNA hybridization data. Determination of the 16s rRNA sequence of this taxon revealed its detailed position within the "flavobacter" subgroup of the "flavobacter-bacteroides" phylum as described by Gherna and Woese (R. Gherna and C. R. Woese, Syst. Apple Microbiol. 15513-521, 1992). This new taxon is only distantly related to other members of the "flavobacter-bacteroides" phylum and is therefore given separate generic status. The DNA-DNA binding values for members of this taxon, for which we propose the name Ornithobacterium rhinotracheale, confirmed that all of the strains are highly interrelated (DNA-DNA binding values greater than 90% were measured). The G+C contents of members of this taxon are between 37 and 39 mol%, An analysis of the cellular proteins and fatty acids and classical phenotypic characteristics allowed us to distinguish 0. rhinotracheafe from phenotypically similar taxa, such as Riemrelliz anatipestiyer and Capnocytophaga species. The respiratory quinone content (menaquinone 7) and carbohydrate pattern of 0 . rhinotracheale conform with the respiratory quinone contents and carbohydrate patterns of other members of rRNA superfamily V.In the past decade, we determined the protein and fatty acid profiles of a large number of avian isolates which could not be classified after primary identification tests were performed in veterinary laboratories. A total of 21 of these isolates had very similar profiles and differed clearly from all of the other strains investigated, including reference strains of well-known fowl pathogens. These 21 strains were isolated from the respiratory tracts of turkeys (10 strains), chickens (7 strains), rooks, (3 strains), and a partridge (1 strain). Clinical data were not available for all of these strains. However, most of the strains were associated with various respiratory tract infections, including tracheitis, pericarditis, sinusitis, airsacculitis, and pneumonia. Preliminary data on some of the chemotaxonomic characteristics of four strains have been described previously (36).We studied a wide range of taxonomic parameters, including genotypic, chemotaxonomic, and classical phenotypic parameters, in order to establish the phylogenetic affiliation and to comprehensively describe the new taxon, for which we propose the name Omithobacterium rhinotracheale. Special emphasis was given to the differentiation of 0. rhinotracheale, Riemerella anatipestifer, and Capnocytophaga species as these taxa share a number of phenotypic characteristics. * Corresponding author. Mailing address: Laboratorium voorMicrobiologie, Universiteit Gent, K. L. Ledeganckstraat 35, B-9000 Gent, Belgium. Phone: 32-9-2645114. Fax: 32-9-2645346. MATERIALS AND METHODSIsolation of 0. rhinotracheale strains. Samples were inoculated onto media routinel...

The Pasteurella-like organism of porcine necrotizing pleuropneumonia described by Bertschinger and Seifert in 1978 was shown to be phenotypically similar to the V factor-requiring strains hitherto classified as Haemophilus pleuropneumoniae (Matthews and Pattison 1961) Shope 1964. Deoxyribonucleic acid-deoxyribonucleic acid hybridization experiments in which the optical method was used yielded 91% binding of the genomes of the type and reference strains of these two taxa, thus indicating that they belong to the same species. The levels of deoxyribonucleic acid binding between these strains and the type strain of Haemophilus influenzae indicated no measurable relatedness. Therefore, these organisms do not belong to the genus Haemophilus sensu stricto. On the other hand, they are closely related to Actinobacillus lignieresii, as determined by both phenotypic characteristics and deoxyribonucleic acid base sequence relatedness (72 to 75% binding). To take into account the different host ranges of these organisms, we propose to classify them as a species distinct from, but closely related to, A. lignieresii, under the new combination Actinobacillus pleuropneumoniae. The emended species A. pleuropneumoniae is composed of V factorrequiring and V factor-independent biovars. The type strain (strain Shope 4047 [= CCM 5869 = ATCC 270881) requires V factor; the V factor-independent biovar is represented by strain Bertschinger 2008/76 (= Frederiksen P 597 = HIM 677-3/4). granules or actinomycotic granules. Such granules were never observed in porcine infections with the new organism. Furthermore, the organism isolated by Bertschinger and Seifert (designated the BS organism) resembled Haemophilus pleuropneumoniae in many physiological properties; an exception was the V factor requirement (10). In this paper we describe the genetic relationships among the organisms mentioned above, as revealed by deoxyribonucleic acid (DNA)-DNA hybridization, and propose a classification of these organisms. MATERIALS AND METHODSon the basis Of Phenotypic charac-studied are listed in Table 1. They were kept lyophi-

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