[Pasteurella] caballi infection not limited to horses - a closer look at taxon 42 of Bisgaard.

AIM: To investigate if taxon 42 of Bisgaard isolated from pigs represents genuine [Pasteurella] caballi, which was previously only isolated from horses. METHODS AND RESULTS: A total of 15 field isolates from horses and pigs from five different countries representing three continents were subjected to extended phenotypical characterization. Although minor differences were observed between taxon 42 and [P.] caballi, these differences did not allow phenotypic separation. Ribotyping based on HindIII digestion showed five profiles based on nine band positions. One [P.] caballi strain and two taxon 42 strains shared the same profile. Ribotyping using HpaII gave a higher diversity with nine profiles based on ten band positions. While no profiles were shared between the taxon 42 and [P.] caballi strains, pattern analysis showed that two of the taxon 42 isolates were most similar (91% similarity) with a [P.] caballi isolate. The 16S rRNA gene sequencing of one strain of taxon 42 and one strain of [P.] caballi was performed and compared with the published sequence for the type strain of [P.] caballi. The three strains showed nearly identical sequences with at least 99.8% similarity. DNA re-associations measured by the micro-well method were 79 and 77%, respectively between the type strain of [P.] caballi and two strains of taxon 42 representing distinct ribotypes and confirmed that taxon 42 belongs to [P.] caballi. CONCLUSION: The present investigation documents that [P.] caballi can be isolated from clinical respiratory specimens from pigs and the recognized association with respiratory infections in horses and horse bite infection in humans. Strains classified as taxon 42 are [P.] caballi isolated from pigs and for both pigs and horses, lesions mainly include the respiratory tract. SIGNIFICANCE AND IMPACT OF THE STUDY: The results will improve the diagnostics and progress studies of virulence and epidemiology of [P.] caballi.

Identification of a new biotype of Actinomyces hyovaginalis in tissues of pigs during diagnostic bacteriological examination.

Bacterial strains isolated from a large variety of necropsy samples of pigs and previously described as a phenotypical homogeneous group were shown to belong to the species Actinomyces hyovaginalis. This was unexpected because their colonial characteristics, as well as their origins, were very different from those originally reported for the vaginal strains on which the species description of A. hyovaginalis was based. Colonial morphology, as well as fermentation of cellobiose, reactions in hippurate and nitrate and production of beta-glucuronidase, allowed separation of the strains studied here from the vaginal strains. Analysis of tRNA intergenic length polymorphisms (tDNA-PCR), 16S rRNA-gene sequencing and DNA-DNA hybridizations were carried out and led to the proposal of a separate biotype within the species A. hyovaginalis. Since, the strains were isolated from different body sites, this biotype has been designated as the 'general' biotype of A. hyovaginalis, while the strains on which the original species description was based are designated as the 'vaginal' biotype.

Globicatella sulfidifaciens sp. nov., isolated from purulent infections in domestic animals.

DNA-DNA hybridization experiments and comparative 165 rDNA sequence analysis revealed that six isolates from purulent joint and lung infections in calves, from a lung lesion in a sheep, and from a joint infection of a pig represented a novel species belonging to the genus Globicatella. Whole-cell protein electrophoresis and biochemical activity testing revealed that the isolates formed a homogeneous group differing from Globicatella sanguinis, the only species of this genus described to date. These animal isolates were classified as Globicatella sulfidifaciens sp. nov. with LMG 188441 (= CCUG 44365T), isolated from the lung of a calf, as the type strain. A detailed description of its phenotypic characteristics is presented. Hydrogen sulphide production was found to be a very useful diagnostic feature.

Identification of Corynebacterium glucuronolyticum strains from the urogenital tract of humans and pigs.

Bacterial strains isolated from the genital tracts of humans (predominantly males), semen of boars, and uterine and vaginal secretions of sows were identified as Corynebacterium glucuronolyticum and were compared with the type strains of the recently proposed species Corynebacterium glucuronolyticum and Corynebacterium seminale. The two type strains as well as the clinical strains were shown by DNA-DNA hybridization and sequencing of the 16S rRNA gene to be related at the species level. All strains were classified as C. glucuronolyticum, because this name has nomenclatural priority over C. seminale.

Identification of aesculin-hydrolyzing streptococci, lactococci, aerococci and enterococci from subclinical intramammary infections in dairy cows.

Aesculin-hydrolyzing, catalase-negative, gram-positive cocci isolated from subclinical intramammary infections in dairy cows were identified to species level using growth characteristics and biochemical activity. The results indicated that the aesculin-hydrolyzing cocci associated with this type of infection are a very heterogenic group. S. uberis strains, including inulin- or beta-glucuronidase-negative isolates, accounted for only about one-third of the collection, and Enterococcus faecalis strains for one-fifth. Other species of some importance included (in descending order of isolation frequency) Aerococcus viridans, Streptococcus pluranimalium, Lactococcus garvieae, Streptococcus bovis and Streptococcus gallolyticus.

Streptococcus pluranimalium sp. nov., from cattle and other animals.

Strains from subclinical mastitis, from the genital tract and tonsils of cattle, from tonsils of a goat and a cat and from the crop and the respiratory tract of canaries were found to constitute a new streptococcal species, for which the name Streptococcus pluranimalium sp. nov. is proposed. Sequencing of 16S rRNA showed that Streptococcus thoraltensis and Streptococcus hyovaginalis were its closest known phylogenetic relatives. The new species showed some phenotypic resemblance to the poorly described species Streptococcus acidominimus, but whole-cell protein analysis and 16S rRNA sequencing revealed that the new species was only distantly related to the type strain of S. acidominimus. Identification of these bacteria, which showed heterogeneous biochemical reaction patterns, was most reliably made by whole-cell protein analysis. Nevertheless, a number of biochemical reactions can be used to differentiate S. pluranimalium from other animal streptococci. Strain LMG 14177T, isolated from mastitic milk of a dairy cow, was designated as the type strain of S. pluranimalium sp. nov.

Identification of nonlipophilic corynebacteria isolated from dairy cows with mastitis.

Nonlipophilic corynebacteria associated with clinical and subclinical mastitis in dairy cows were found to belong to four species: Corynebacterium amycolatum, Corynebacterium ulcerans, Corynebacterium pseudotuberculosis, and Corynebacterium minutissimum. These species may easily be confused. However, clear-cut differences between C. ulcerans and C. pseudotuberculosis were found in their acid production from maltotriose and ethylene glycol, susceptibility to vibriostatic agent O129, and alkaline phosphatase. Absence of growth at 20 degrees C and lack of alpha-glucosidase and 4MU-alpha-D-glycoside hydrolysis activity differentiated C. amycolatum from C. pseudotuberculosis and C. ulcerans. The mastitis C. pseudotuberculosis strains differed from the biovar equi and ovis reference strains and from caprine field strains in their colony morphologies and in their reduced inhibitory activity on staphylococcal beta-hemolysin. C. amycolatum was the most frequently isolated nonlipophilic corynebacterium.

Pelistega europaea gen. nov., sp. nov., a bacterium associated with respiratory disease in pigeons: taxonomic structure and phylogenetic allocation.

Twenty-four strains isolated mainly from infected respiratory tracts of pigeons were characterized by an integrated genotypic and phenotypic approach. An extensive biochemical examination using conventional tests and several API microtest systems indicated that all isolates formed a phenotypically homogeneous taxon with a DNA G + C content between 42 and 43 mol%. Whole-cell protein and fatty acid analysis revealed an unexpected heterogeneity which was confirmed by DNA-DNA hybridizations. Four main genotypic sub-groups (genomovars) were delineated. 16S rDNA sequence analysis of a representative strain indicated that this taxon belongs to the beta-subclass of the Proteobacteria with Taylorella equigenitalis as its closest neighbour (about 94.8% similarity). A comparison of phenotypic and genotypic characteristics of both taxa suggested that the pigeon isolates represented a novel genus for which the name Pelistega is proposed. In the absence of differential phenotypic characteristics between the genomovars, it was preferred to include all of the isolates into a single species, Pelistega europaea, and strain LMG 10982 was selected as the type strain. The latter strain belongs to fatty acid cluster I and protein electrophoretic sub-group 1, which comprise 13 and 5 isolates, respectively. It is not unlikely that the name P. europaea will be restricted in the future to organisms belonging to fatty acid cluster I, or even to protein electrophoretic sub-group 1, upon discovery of differential diagnostic features.

Identification of porcine Serpulina strains in routine diagnostic bacteriology.

Serpulina strains from pigs were identified using simple tests. The large size of S. hyodysenteriae in stainings from colonic contents and faeces was found useful for the presumptive differentiation of this major pathogenic species from the other Serpulinae. However, this morphological characteristic gets lost upon cultivation. The 'ring phenomenon' aided to confirm the strong haemolysis typical for S. hyodysenteriae. The weakly haemolytic species S. innocens, S. pilosicoli, S. intermedia and S. hyodysenteriae could be differentiated with the help of the indole spot test and two or four other simple enzymatic tests. Nearly half of the S. hyodysenteriae strains isolated in Belgium were indole-negative. Such strains have only rarely been reported earlier, and were absent among the strains from other European countries examined.

Streptococcus hyovaginalis sp. nov. and Streptococcus thoraltensis sp. nov., from the genital tract of sows.

Two groups of strains isolated from sows were shown to belong to new sublines in the genus Streptococcus. Based on phenotypic and phylogenetic analyses, we propose that these bacteria should be classified as two new species, Streptococcus hyovaginalis sp. nov. and Streptococcus thoraltensis sp. nov. These two species are found in the genital tract, but the capnophilic species S. thoraltensis may also occur in the intestinal tract of pigs. The type strain of S. hyovaginalis is SHV515 (= LMG 14710), and S69 (= LMG 13593) is the type strain of S. thoraltensis.

An atypical Staphylococcus aureus intramammary infection in a dairy herd.

An atypical Staphylococcus aureus (S. aureus) strain, isolated in a dairy herd over an 8 month period, was examined. The S. aureus strain was clumping factor negative, weakly heat-resistant deoxyribonuclease positive and produced narrow zones of double haemolysis. In total, 57 quarter infections were observed. Prevalence data per month, calculated as the percentage of quarters infected with this atypical S. aureus strain varied from 7.5% to 17.7% and the new infection rate varied from 0.14 to 0.55. In routine bacteriology, the large number of quarters infected with the atypical S. aureus could easily be misclassified as quarters infected with non-aureus staphylococci.

Presence of vancomycin-resistant enterococci in farm and pet animals.

Enterococcus faecium strains with vanA-mediated glycopeptide resistance were isolated by enrichment culture from the intestines and feces of several animal species, mainly horses and dogs (8% positive), chickens (7% positive), and pigs (6% positive). Other vanA-positive enterococcal strains were identified as E. durans in gallinaceous birds, E. faecalis in a horse, and E. gallinarum in a pheasant. Samples from pigeons, cage birds, and ruminants were negative. It was concluded that vancomycin resistance is widespread among isolates from farm and pet animals.

Bordetella hinzii sp. nov., isolated from poultry and humans.

A polyphasic taxonomic study that included DNA-rRNA hybridizations, DNA-DNA hybridizations, DNA base ratio determinations, whole-cell protein and fatty acid analyses, and an examination of classical phenotypic characteristics was performed in order to classify human and veterinary isolates that resemble Bordetella avium. Twelve poultry isolates and two human isolates were assigned to a new species, for which we propose the name Bordetella hinzii. The position of this organism in the family Alcaligenaceae and various genotypic, phenotypic, and chemotaxonomic characteristics are described.

Flavobacterium meningosepticum, a pathogen in birds.

Five bacterial isolates were recovered from various diseased birds (chickens, a pigeon, and a zebra finch) and were identified as Flavobacterium meningosepticum. Four of them were isolated in pure or nearly pure culture of samples from internal organs, and one strain was isolated in mixed culture of a tarsal joint fluid sample. Except for the last case, there was no evidence of other disease agents. By using phenotypic, chemotaxonomic, and genomic methods, the strains were taxonomically characterized and could not be differentiated from the human clinical reference strains of the species. Two avian strains were different in their phenotypic behaviors and constituted another genotypic subgroup. In general, all F. meningosepticum strains constituted a single species which was easily differentiated from biochemically similar species and phylogenetically closely related taxa.

Characterization and identification of Vagococcus fluvialis strains isolated from domestic animals.

Strains of Vagococcus fluvialis, a species of Gram-positive catalase-negative cocci, related to the genera Enterococcus and Carnobacterium, were isolated from various lesions of pigs, from lesions and tonsils of cattle and cats and from tonsils of a horse. Most lesion strains were isolated in mixed culture from animals with disease conditions unrelated to coccal infection. Certain differences with the species description of Vagococcus fluvialis were found: only a proportion of the strains was motile; many strains gave positive reactions to Voges-Proskauer, alkaline phosphatase and leucine arylamidase tests or produced acid from galactose and D-tagatose. SDS-PAGE of whole-cell protein patterns, however, confirmed the phenotypic identification. Guidelines for identification of Vagococcus fluvialis are given and an emended description of the species is proposed.

A simple identification scheme for coagulase negative staphylococci from bovine mastitis.

Coagulase-negative staphylococci from cases of bovine mastitis were identified to species level by using an identification scheme based on a three-plate test system which tested for DNase on DNA agar, for protease on calcium caseinate agar, and for the organism's sensitivity to novobiocin, desferrioxaminine (deferoxamine) and fosfomycin by agar diffusion tests. Testing for the inhibition of Staphylococcus delta haemolysin (Skalka 1991) can replace the protease tests.

Identification and composition of the streptococcal and enterococcal flora of tonsils, intestines and faeces of pigs.

Streptococcus suis was the most frequent Streptococcus spp. in pig tonsils, followed by the beta-haemolytic porcine 'equisimilis' ecovar of Strep. dysgalactiae. The intestinal streptococcal flora was composed of Strep. bovis, Strep. hyointestinalis and Strep. suis. Many of these intestinal Strep. suis belonged to a beta-glucuronidase-negative biotype which is infrequent in lesions. Nearly half of the strains presumptively identified as Strep. alactolyticus produced acid from lactose. This species was not found in tonsils and intestines but was about equally prevalent as Strep. hyointestinalis in pig faeces and rectal swabs. Other streptococci were rare in this material. Enterococci were much less frequently identified than streptococci in tonsils and faeces. In intestinal samples Enterococcus faecalis, Ent. faecium, Ent. hirae and Ent. cecorum were most frequently found. In faeces Ent. faecium was the most prevalent enterococcus. The characteristics of the less well known species Strep. alactolyticus and Strep. hyointestinalis are described in detail, and guidelines for their differentiation from Strep. bovis and Strep. suis given.