H. Ülbegi-Mohyla

Phenotypic and Genotypic Characterization of Arcanobacterium haemolyticum Isolates from Infections of Horses

ABSTRACT 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.

Molecular identification and further characterization of Arcanobacterium pyogenes isolated from bovine mastitis and from various other origins

The present study was designed to identify phenotypically and genotypically 61 Arcanobacterium pyogenes isolated from bovine mastitis and from various other origins. The A. pyogenes isolates showed the typical cultural and biochemical properties of this species and displayed CAMP-like synergistic hemolytic activities with various indicator strains. The species identity could be confirmed genotypically by amplification and sequencing of the superoxide dismutase A encoding gene sodA of reference strains representing 8 species of genus Arcanobacterium and subsequent design of A. pyogenes sodA gene-specific oligonucleotide primer. The A. pyogenes sodA gene-specific oligonucleotide primer allowed, together with previously described A. pyogenes 16S-23S rDNA intergenic spacer region-specific oligonucleotide primer, a reliable molecular identification of all 61 A. pyogenes of various origins. The additionally performed PCR-mediated amplification of 5 known and putative virulence factor encoding genes revealed that 100, 20, 87, 75, and 98% of the A. pyogenes carried the genes plo, cbpA, nanH, nanP, and fimA, which allowed an individual strain characterization. This might help to elucidate the role the putative virulence factors play in bovine mastitis and in various other infections caused by this bacterial pathogen.

Identification of Arcanobacterium pyogenes isolated by post mortem examinations of a bearded dragon and a gecko by phenotypic and genotypic properties

The present study was designed to identify phenotypically and genotypically two Arcanobacterium (A.) pyogenes strains isolated by post mortem examinations of a bearded dragon and a gecko. The A. pyogenes strains showed the typical biochemical properties and displayed CAMP-like synergistic hemolytic activities with various indicator strains. The species identity could be confirmed genotypically by amplification and sequencing of the 16S rDNA gene and, as novel target gene, by sequencing of the beta subunit of RNA polymerase encoding gene rpoB, of both strains and of reference strains representing nine species of the genus Arcanobacterium. The species identity of the two A. pyogenes strains could additionally be confirmed by PCR mediated amplification of species specific parts of the 16S-23S rDNA intergenic spacer region, the pyolysin encoding gene plo and by amplification of the collagen-binding protein encoding gene cbpA. All these molecular targets might help to improve the future identification and further characterization of A. pyogenes which, as demonstrated in the present study, could also be isolated from reptile specimens.

Genetic relatedness of methicillin-resistant Staphylococcus pseudintermedius (MRSP) isolated from a dog and the dog owner.

In the present study four methicillin-resistant Staphylococcus pseudintermedius (MRSP) strains isolated from a dog (n=3) and the anterior nares of the dog owner (n=1) were investigated by conventional and molecular methods. The species identity of the four S. pseudintermedius strains was confirmed by conventional methods, by PCR mediated amplification of S. intermedius/S. pseudintermedius specific segments of thermonuclease encoding gene nuc and by restriction fragment length polymorphism analysis of phosphoacetyltransferase encoding gene pta. Investigation of the four S. pseudintermedius for toxinogenic potential revealed that all four strains were positive for the exfoliative toxin encoding gene siet and the leukotoxin encoding genes lukS, lukF. The oxacillin and penicillin resistance of the four S. pseudintermedius strains could be determined by cultivation of the strains on oxacillin resistant screening agar base, ChromID MRSA Agar and Brilliance MRSA Agar and by multiplex PCR detecting the resistance genes mecA and blaZ. The genetic relatedness of the strains was studied by macrorestriction analysis of their chromosomal DNA using pulsed field gel electrophoresis (PFGE). According to PFGE all four S. pseudintermedius strains represent an identical bacterial clone indicating a cross transmission between the dog and the dog owner.

Synergistic and antagonistic hemolytic activities of bacteria of genus Arcanobacterium and CAMP-like hemolysis of Arcanobacterium phocae and Arcanobacterium haemolyticum with Psychrobacter phenylpyruvicus

A total of 57 bacteria representing eight species of genus Arcanobacterium (A.) were investigated for hemolytic properties on blood agar containing sheep and rabbit blood and for CAMP-like reactions. An enhanced hemolysis on blood agar containing rabbit blood compared to sheep blood could be observed for A. haemolyticum, less pronounced for A. hippocoleae and A. pluranimalium. A synergistic hemolytic reaction with staphylococcal beta-hemolysin appeared to be constantly visible for A. hippocoleae, A. pluranimalium and A. pyogenes, with Streptococcus agalactiae for A. phocae and A. haemolyticum, with Rhodococcus equi for A. phocae, A. haemolyticum, A. pluranimalium and A. pyogenes and with A. haemolyticum for A. hippocoleae, A. pluranimalium and A. pyogenes, respectively. A reverse CAMP-reaction in the zone of staphylococcal beta-hemolysin could be observed for A.phocae and A.haemolyticum. In addition, a novel CAMP-like reaction could be noted between Psychrobacter phenylpyruvicus, identified by 16S rDNA sequencing, and A. phocae and A. haemolyticum. These synergistic or antagonistic hemolytic properties could possibly be used as additional criteria for identification of bacteria of genus Arcanobacterium.

Arcanobacterium phocisimile sp. nov., isolated from harbour seals.

A polyphasic taxonomic study was performed on two previously unidentified Arcanobacterium-like Gram-positive strains isolated from harbour seals. Comparative 16S rRNA gene sequencing showed that both bacteria belonged to the genus Arcanobacterium and were most closely related to Arcanobacterium haemolyticum CIP 103370(T) (98.4% 16S rRNA gene sequence similarity), A. canis P6775(T) (97.4%), A. phocae DSM 10002(T) (97.4%), A. pluranimalium M430/94/2(T) (95.7%) and A. hippocoleae CCUG 44697(T) (95.5%). The presence of the major menaquinone MK-9(H4) supported the affiliation of the isolates with the genus Arcanobacterium. The polar lipid profile consisted of major amounts of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, an unidentified phospholipid and two unidentified glycolipids. The major fatty acids were C16:0, C18:0, C18:1ω9c and summed feature 5 (comprising C18:2ω6,9c and/or anteiso-C18:0). Physiological and biochemical tests clearly distinguished the isolates from other members of the genus Arcanobacterium. Based on the common origin and various physiological properties comparable to those of A. phocae, it is proposed that the isolates are classified as members of a novel species with the name Arcanobacterium phocisimile sp. nov. The type strain is 2698(T) (=LMG 27073(T) =CCM 8430(T)).

Arcanobacterium pinnipediorum sp. nov., isolated from a harbour seal.

A polyphasic taxonomic study was performed on an unidentified Arcanobacterium-like, Gram-stain-positive bacterium, strain 2710T, isolated from a harbour seal. Comparative 16S rRNA gene sequence analysis showed that this bacterial strain belonged to the genus Arcanobacterium and was related most closely to the type strains of Arcanobacterium phocae (98.4 % similarity) and Arcanobacterium phocisimile (97.5 %). 16S rRNA gene sequence similarities to the type strains of other Arcanobacterium species were between 95.3 and 96.9 %. DNA-DNA hybridization values between strain 2710T and A. phocae DSM 10002T and A. phocisimile LMG 27073T were 4.7 % (reciprocal 56 %) and 23 % (reciprocal 7.7 %), respectively. The presence of the major menaquinone MK-9(H4) and a polar lipid profile with the major compounds diphosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside supported the affiliation of strain 2710T to the genus Arcanobacterium. The major fatty acids were C16:0, C18:1ω9c, C18:0 and C18:2ω6,9c/anteiso-C18:0. The peptidoglycan structure was of cross-linkage type A5α (l-Lys-l-Lys-d-Glu). Physiological and biochemical tests clearly distinguished the isolate from other members of the genus Arcanobacterium. Based on these tests, it is proposed that this unknown bacterium should be classified as a novel species of the genus Arcanobacterium, with the name Arcanobacterium pinnipediorum sp. nov. The type strain is 2710T ( = DSM 28752T = LMG 28298T).

Identification of Arcanobacterium haemolyticum isolated from postcastrational complications of a horse

An Arcanobacterium haemolyticum strain isolated from a postcastrational lesion of a horse was identified phenotypically and genotypically. The latter was performed by sequencing the 16S–23S rDNA intergenic spacer region (ISR), by amplification of the gene encoding A. haemolyticum phospholipase D, by amplification of A. haemolyticum specific parts of ISR-23S rDNA and by amplification of the newly described CAMP factor family protein encoding gene of A. haemolyticum. This indicates (as described previously for seven additional A. haemolyticum strains; Hassan et al. 2009) that A. haemolyticum seems to occur also in infections of horses.

Characterization of Arcanobacterium abortisuis by phenotypic properties and by sequencing the 16S–23S rDNA intergenic spacer region

The present study was designed to characterize phenotypically and genotypically nine Arcanobacterium abortisuis strains collected from specimen of pigs in a period of nine years. All nine A. abortisuis strains and A. abortisuis reference strain DSM 19515 displayed a synergistic hemolytic reaction with Staphylococcus aureus β-hemolysin, Rhodococcus equi, and Arcanobacterium haemolyticum indicator strains and showed the typical biochemical properties of this species. The species identity could be confirmed by identification and sequencing of the 16S-23S rDNA intergenic spacer region (ISR), which appeared to be a useful target for genotypic characterization of this bacterial species. The A. abortisuis strains of the present study were isolated from specimen of pigs together with various other bacterial species indicating that the pathogenic importance of this newly described species remains to be elucidated.