The present study was designed to characterize phenotypically and genotypically seven Arcanobacterium haemolyticum strains obtained from infections of six horses. All seven strains showed the cultural and biochemical properties typical of A. haemolyticum and were susceptible to most of the antibiotics tested. The species identification could be confirmed by amplification and sequencing of the 16S rRNA gene and the 16S-23S rRNA intergenic spacer region and by PCR amplification of species-specific parts of the gene encoding phospholipase D in A. haemolyticum. Use of the latter could possibly improve future identification of this generally human pathogenic bacterial species which, according to the present results, seems to occur also in infections of horses.Arcanobacterium haemolyticum, originally known as Corynebacterium haemolyticum, was first described in 1946 and reported to be the cause of exudative pharyngitis and skin infections in humans (23). This bacterial species, formerly considered to be a mutant form of Actinomyces (Corynebacterium) pyogenes (1), has been reclassified as a single species in the newly proposed genus Arcanobacterium (8). In the following years, the mainly animal pathogenic species Actinomyces pyogenes and human pathogenic Actinomyces bernardiae were renamed Arcanobacterium pyogenes and Arcanobacterium bernardiae, respectively, and five new species, namely, Arcanobacterium bialowiezense, Arcanobacterium bonasi, Arcanobacterium hippocoleae, Arcanobacterium phocae, and Arcanobacterium pluranimalium, were assigned to this genus (14,19,20,28). A. haemolyticum, known as a pathogen causing nonstreptococcal pharyngitis (6, 22), could also be isolated from systemic and deep-seated infections of humans. The latter was reviewed by Skov et al. (31) and Tan et al. (33). However, the isolation of A. haemolyticum from animals appears to be rare. Tyrrell et al. (34) discussed the etiological role of a single A. haemolyticum strain isolated from a periodontal infection of a rabbit.The aim of the present study was to characterize phenotypically and genotypically seven A. haemolyticum strains isolated from infections of six horses over a period of 10 years. MATERIALS AND METHODSBacterial cultures. A total of 21 bacterial cultures were used in this study. The cultures included the reference strains A. haemolyticum DSM 20595, A. bernardiae DSM 9152, A. bialowiezense DSM 17162, A. bonasi DSM 17163, A. hippocoleae DSM 15539, A. phocae DSM 10002, A. pluranimalium DSM 13483, A. pyogenes DSM 20630, Corynebacterium pseudotuberculosis biovar equi DSM 7177, and C. pseudotuberculosis biovar ovis DSM 7179 and seven bacterial cultures isolated from infections of six horses which were presumptively identified as A. haemolyticum. Further data about the origins of the seven strains are summarized in Table 1.Phenotypic properties. Hemolytic properties of the bacteria were examined on blood agar containing 5% sheep or rabbit blood after incubation of the bacteria for 24 to 48 h in a candle jar. The rabbit blood was ob...

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Phenotypic properties and species-specific PCR tests based on the nuc gene of Staphylococcus intermedius and S. aureus, and a conserved region of 16S rDNA were used to identify 45 S. intermedius and four S. aureus isolated from samples of dogs during routine diagnostics. Four S. pseudintermedius strains used for control purposes reacted positively with the S. intermedius nuc PCR showing the close relationship between both species. Investigating the 45 S. intermedius and four S. pseudintermedius strains for the prevalence of the exfoliative toxin SIET encoding gene yielded the presence of the gene for 21 of the S. intermedius and two of the S. pseudintermedius strains. Partial sequencing of the toxin gene of a single S. intermedius strain and comparing this sequence with that obtained from GenBank revealed an almost complete identity. The presence of the exfoliative toxin gene could mainly be found among S. intermedius isolated from skin and wound infections and from otitis externa possibly indicating a role of this toxin for the clinical symptoms.

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