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Stephen J. Billington - One of the best experts on this subject based on the ideXlab platform.
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Transcriptional regulation of pyolysin production in the animal pathogen, Arcanobacterium pyogenes☆
Veterinary Microbiology, 2008Co-Authors: Stefani T. Rudnick, B. Helen Jost, Stephen J. BillingtonAbstract:Arcanobacterium pyogenes is an opportunistic pathogen of a number of important livestock species, and usually infects from an endogenous, commensal source. Thus, as with other normal flora opportunistic pathogens, the regulation of A. pyogenes virulence factors is likely important during both commensal and pathogenic interactions with the host. The aim of this study was to investigate the regulation of a key A. pyogenes virulence factor, the cholesterol dependent cytolysin, pyolysin (PLO), under in vitro conditions, as a first step to understanding its regulation during the disease process. Analysis of PLO production in broth culture indicated that expression of PLO was induced during early stationary phase, and that this correlated with an increase in plo-specific mRNA. Analysis of a plo-cat transcriptional fusion indicated that transcription of plo was also induced during early stationary phase. Primer extension analysis and 5' RACE suggested that two putative promoter sequences, P1 and P2 were active. Analysis of site-directed mutants of these promoters in the plo-cat fusion indicated that P2 was the major stationary phase promoter. Deletions of the plo promoter region from the plo-cat fusion implicated three direct repeat (DR) sequences as important for plo transcription. Mutagenesis of both DR1 and DR2 resulted in reduction in plo transcription, while the presence of only DR3 in deletions of the plo promoter region repressed transcription from P2. Gel shift experiments indicated that a soluble factor from A. pyogenes binds to the plo promoter region and that the DRs may act as binding sites for a transcriptional regulator.
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Multiple Genetic Elements Carry the Tetracycline Resistance Gene tet(W) in the Animal Pathogen Arcanobacterium pyogenes
Antimicrobial agents and chemotherapy, 2006Co-Authors: Stephen J. Billington, B. Helen JostAbstract:The tet(W) gene is associated with tetracycline resistance in a wide range of bacterial species, including obligately anaerobic rumen bacteria and isolates from the human gut and oral mucosa. However, little is known about how this gene is disseminated and the types of genetic elements it is carried on. We examined tetracycline-resistant isolates of the animal commensal and opportunistic pathogen Arcanobacterium pyogenes, all of which carried tet(W), and identified three genetic elements designated ATE-1, ATE-2, and ATE-3. These elements were found in 25%, 35%, and 60% of tetracycline-resistant isolates, respectively, with some strains carrying both ATE-2 and ATE-3. ATE-1 shows characteristics of a mobilizable transposon, and the tet(W) genes from strains carrying this element can be transferred at low frequencies between A. pyogenes strains. ATE-2 has characteristics of a simple transposon, carrying only the resistance gene and a transposase, while in ATE-3, the tet(W) gene is associated with a streptomycin resistance gene that is 100% identical at the DNA level with the aadE gene from the Campylobacter jejuni plasmid pCG8245. Both ATE-2 and ATE-3 show evidence of being carried on larger genetic elements, but conjugation to other strains was not observed under the conditions tested. ATE-1 was preferentially associated with A. pyogenes strains of bovine origin, while ATE-2 and ATE-3 elements were primarily found in porcine isolates, suggesting that these elements may circulate in different environments. In addition, four alleles of the tet(W) gene, primarily associated with different elements, were detected among A. pyogenes isolates.
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Arcanobacterium pyogenes: molecular pathogenesis of an animal opportunist
Antonie van Leeuwenhoek, 2005Co-Authors: B. Helen Jost, Stephen J. BillingtonAbstract:Arcanobacterium pyogenes is a commensal and an opportunistic pathogen of economically important livestock, causing diseases as diverse as mastitis, liver abscessation and pneumonia. This organism possesses a number of virulence factors that contribute to its pathogenic potential. A. pyogenes expresses a cholesterol-dependent cytolysin, pyolysin, which is a haemolysin and is cytolytic for immune cells, including macrophages. Expression of pyolysin is required for virulence and this molecule is the most promising vaccine candidate identified to date. A. pyogenes also possesses a number of adherence mechanisms, including two neuraminidases, the action of which are required for full adhesion to epithelial cells, and several extracellular matrix-binding proteins, including a collagen-binding protein, which may be required for adhesion to collagen-rich tissue. A. pyogenes also expresses fimbriae, which are similar to the type 2 fimbriae of Actinomyces naeslundii , and forms biofilms. However, the role of these factors in the pathogenesis of A. pyogenes infections remains to be elucidated. A. pyogenes also invades and survives within epithelial cells and can survive within J774A.1 macrophages for up to 72 h, suggesting an important role for A. pyogenes interaction with host cells during pathogenesis. The two component regulatory system, PloSR, up-regulates pyolysin expression and biofilm formation but down-regulates expression of proteases, suggesting that it may act as a global regulator of A. pyogenes virulence. A. pyogenes is a versatile pathogen, with an arsenal of virulence determinants. However, most aspects of the pathogenesis of infection caused by this important opportunistic pathogen remain poorly characterized.
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Ribosomal Mutations in Arcanobacterium pyogenes Confer a Unique Spectrum of Macrolide Resistance
Antimicrobial agents and chemotherapy, 2004Co-Authors: B. Helen Jost, J. Glenn Songer, Hien T. Trinh, Stephen J. BillingtonAbstract:Four macrolide-resistant Arcanobacterium pyogenes isolates contained A2058T, A2058G, or C2611G (Escherichia coli numbering) mutations in their 23S rRNA genes. While these mutations conferred resistance to erythromycin, oleandomycin, and spiramycin, they did not confer resistance to tylosin.
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A Second Tylosin Resistance Determinant, Erm B, in Arcanobacterium pyogenes
Antimicrobial agents and chemotherapy, 2004Co-Authors: B. Helen Jost, J. Glenn Songer, Hien T. Trinh, Stephen J. BillingtonAbstract:Arcanobacterium pyogenes, a common inhabitant of the mucosal surfaces of livestock, is also a pathogen associated with a variety of infections. In livestock, A. pyogenes is exposed to antimicrobial agents used for prophylaxis and therapy, notably tylosin, a macrolide used extensively for the prevention of liver abscessation in feedlot cattle in the United States. Many, but not all, tylosin-resistant A. pyogenes isolates carry erm(X), suggesting the presence of other determinants of tylosin resistance. Oligonucleotide primers designed for conserved regions of erm(B), erm(C), and erm(T) were used to amplify a 404-bp fragment from a tylosin-resistant A. pyogenes isolate, OX-7. DNA sequencing revealed that the PCR product was 100% identical to erm(B) genes, and the erm(B) gene region was cloned in Escherichia coli. The A. pyogenes Erm B determinant had the most DNA identity with an Erm B determinant carried by the Clostridium perfringens plasmid pIP402. However, the A. pyogenes determinant lacked direct repeat DR1 and contained a deletion in DR2. Flanking the A. pyogenes erm(B) gene were partial and entire genes similar to those found on the Enterococcus faecalis multiresistance plasmid pRE25. This novel architecture suggests that the erm(B) element may have arisen by recombination of two distinct genetic elements. Ten of 32 tylosin-resistant isolates carried erm(B), as determined by DNA hybridization, and all 10 isolates carried a similar element. Insertion of the element was site specific, as PCR and Southern blotting analysis revealed that the erm(B) element was inserted into orfY, a gene of unknown function. However, in three strains, this insertion resulted in a partial duplication of orfY.
B. Helen Jost - One of the best experts on this subject based on the ideXlab platform.
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Transcriptional regulation of pyolysin production in the animal pathogen, Arcanobacterium pyogenes☆
Veterinary Microbiology, 2008Co-Authors: Stefani T. Rudnick, B. Helen Jost, Stephen J. BillingtonAbstract:Arcanobacterium pyogenes is an opportunistic pathogen of a number of important livestock species, and usually infects from an endogenous, commensal source. Thus, as with other normal flora opportunistic pathogens, the regulation of A. pyogenes virulence factors is likely important during both commensal and pathogenic interactions with the host. The aim of this study was to investigate the regulation of a key A. pyogenes virulence factor, the cholesterol dependent cytolysin, pyolysin (PLO), under in vitro conditions, as a first step to understanding its regulation during the disease process. Analysis of PLO production in broth culture indicated that expression of PLO was induced during early stationary phase, and that this correlated with an increase in plo-specific mRNA. Analysis of a plo-cat transcriptional fusion indicated that transcription of plo was also induced during early stationary phase. Primer extension analysis and 5' RACE suggested that two putative promoter sequences, P1 and P2 were active. Analysis of site-directed mutants of these promoters in the plo-cat fusion indicated that P2 was the major stationary phase promoter. Deletions of the plo promoter region from the plo-cat fusion implicated three direct repeat (DR) sequences as important for plo transcription. Mutagenesis of both DR1 and DR2 resulted in reduction in plo transcription, while the presence of only DR3 in deletions of the plo promoter region repressed transcription from P2. Gel shift experiments indicated that a soluble factor from A. pyogenes binds to the plo promoter region and that the DRs may act as binding sites for a transcriptional regulator.
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Functional and structural properties of CbpA, a collagen-binding protein from Arcanobacterium pyogenes
Microbiology, 2007Co-Authors: Giampiero Pietrocola, Simonetta Rindi, B. Helen Jost, Viviana Valtulina, Pietro SpezialeAbstract:Arcanobacterium pyogenes, an opportunistic pathogen of economically important food animals, is the causative agent of liver abscesses in feedlot cattle, osteomyelitis in turkeys, and pneumonia and arthritis in pigs. Previous studies identified the first A. pyogenes adhesin, CbpA, a protein located on the bacterial surface which has the ability to bind collagen and promotes adhesion to the host cells. The protein has an N-terminal ligand-binding region (region A) and a C-terminal repetitive domain (region B). In this study we found that CbpA bound to almost all the collagen types tested but not to other proteins, and it displayed a propensity to interact with several collagenous peptides derived by CNBr cleavage of type I and II collagens. The K D values of CbpA for type I and II collagens and collagen peptides determined by solid-phase binding assay and intrinsic tryptophan fluorescence were in the range of 1–15 nM. It was also found that CbpA and its A region bound fibronectin, and that collagen and fibronectin interacted with distinct subsites. Anti-CbpA antibodies were effective at inhibiting both binding of isolated CbpA and bacterial adhesion to immobilized collagen, suggesting that CbpA is a functional collagen-binding adhesin. Analysis of the immunological cross-reactivity of CbpA with antibodies against other bacterial collagen-binding proteins indicated that CbpA is immunologically related to ACE from Enterococcus faecalis but not to CNA from Staphylococcus aureus or Acm from Enterococcus faecium. Far-UV and near-UV circular dichroism spectra showed that full-length CbpA and its region A are mainly composed of β-sheet with only a minor α-helical component and that both the proteins have a well-defined tertiary structure.
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Functional and structural properties of CbpA, a collagen-binding protein from Arcanobacterium pyogenes.
Microbiology (Reading England), 2007Co-Authors: Giampiero Pietrocola, Simonetta Rindi, B. Helen Jost, Viviana Valtulina, Pietro SpezialeAbstract:Arcanobacterium pyogenes, an opportunistic pathogen of economically important food animals, is the causative agent of liver abscesses in feedlot cattle, osteomyelitis in turkeys, and pneumonia and arthritis in pigs. Previous studies identified the first A. pyogenes adhesin, CbpA, a protein located on the bacterial surface which has the ability to bind collagen and promotes adhesion to the host cells. The protein has an N-terminal ligand-binding region (region A) and a C-terminal repetitive domain (region B). In this study we found that CbpA bound to almost all the collagen types tested but not to other proteins, and it displayed a propensity to interact with several collagenous peptides derived by CNBr cleavage of type I and II collagens. The K(D) values of CbpA for type I and II collagens and collagen peptides determined by solid-phase binding assay and intrinsic tryptophan fluorescence were in the range of 1-15 nM. It was also found that CbpA and its A region bound fibronectin, and that collagen and fibronectin interacted with distinct subsites. Anti-CbpA antibodies were effective at inhibiting both binding of isolated CbpA and bacterial adhesion to immobilized collagen, suggesting that CbpA is a functional collagen-binding adhesin. Analysis of the immunological cross-reactivity of CbpA with antibodies against other bacterial collagen-binding proteins indicated that CbpA is immunologically related to ACE from Enterococcus faecalis but not to CNA from Staphylococcus aureus or Acm from Enterococcus faecium. Far-UV and near-UV circular dichroism spectra showed that full-length CbpA and its region A are mainly composed of beta-sheet with only a minor alpha-helical component and that both the proteins have a well-defined tertiary structure.
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Multiple Genetic Elements Carry the Tetracycline Resistance Gene tet(W) in the Animal Pathogen Arcanobacterium pyogenes
Antimicrobial agents and chemotherapy, 2006Co-Authors: Stephen J. Billington, B. Helen JostAbstract:The tet(W) gene is associated with tetracycline resistance in a wide range of bacterial species, including obligately anaerobic rumen bacteria and isolates from the human gut and oral mucosa. However, little is known about how this gene is disseminated and the types of genetic elements it is carried on. We examined tetracycline-resistant isolates of the animal commensal and opportunistic pathogen Arcanobacterium pyogenes, all of which carried tet(W), and identified three genetic elements designated ATE-1, ATE-2, and ATE-3. These elements were found in 25%, 35%, and 60% of tetracycline-resistant isolates, respectively, with some strains carrying both ATE-2 and ATE-3. ATE-1 shows characteristics of a mobilizable transposon, and the tet(W) genes from strains carrying this element can be transferred at low frequencies between A. pyogenes strains. ATE-2 has characteristics of a simple transposon, carrying only the resistance gene and a transposase, while in ATE-3, the tet(W) gene is associated with a streptomycin resistance gene that is 100% identical at the DNA level with the aadE gene from the Campylobacter jejuni plasmid pCG8245. Both ATE-2 and ATE-3 show evidence of being carried on larger genetic elements, but conjugation to other strains was not observed under the conditions tested. ATE-1 was preferentially associated with A. pyogenes strains of bovine origin, while ATE-2 and ATE-3 elements were primarily found in porcine isolates, suggesting that these elements may circulate in different environments. In addition, four alleles of the tet(W) gene, primarily associated with different elements, were detected among A. pyogenes isolates.
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Arcanobacterium pyogenes: molecular pathogenesis of an animal opportunist
Antonie van Leeuwenhoek, 2005Co-Authors: B. Helen Jost, Stephen J. BillingtonAbstract:Arcanobacterium pyogenes is a commensal and an opportunistic pathogen of economically important livestock, causing diseases as diverse as mastitis, liver abscessation and pneumonia. This organism possesses a number of virulence factors that contribute to its pathogenic potential. A. pyogenes expresses a cholesterol-dependent cytolysin, pyolysin, which is a haemolysin and is cytolytic for immune cells, including macrophages. Expression of pyolysin is required for virulence and this molecule is the most promising vaccine candidate identified to date. A. pyogenes also possesses a number of adherence mechanisms, including two neuraminidases, the action of which are required for full adhesion to epithelial cells, and several extracellular matrix-binding proteins, including a collagen-binding protein, which may be required for adhesion to collagen-rich tissue. A. pyogenes also expresses fimbriae, which are similar to the type 2 fimbriae of Actinomyces naeslundii , and forms biofilms. However, the role of these factors in the pathogenesis of A. pyogenes infections remains to be elucidated. A. pyogenes also invades and survives within epithelial cells and can survive within J774A.1 macrophages for up to 72 h, suggesting an important role for A. pyogenes interaction with host cells during pathogenesis. The two component regulatory system, PloSR, up-regulates pyolysin expression and biofilm formation but down-regulates expression of proteases, suggesting that it may act as a global regulator of A. pyogenes virulence. A. pyogenes is a versatile pathogen, with an arsenal of virulence determinants. However, most aspects of the pathogenesis of infection caused by this important opportunistic pathogen remain poorly characterized.
P Oudeacoumar - One of the best experts on this subject based on the ideXlab platform.
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three cases of Arcanobacterium pyogenes associated soft tissue infection
Journal of Medical Microbiology, 2010Co-Authors: Kannaiyan Kavitha, Rangan Latha, C Udayashankar, Kamala Jayanthi, P OudeacoumarAbstract:Arcanobacterium pyogenes is an established but often unrecognized human pathogen. A. pyogenes may also be misidentified as Arcanobacterium haemolyticum, which gives remarkably similar results in conventional biochemical tests. In this study, we have reported three cases of wound infections associated with A. pyogenes and also on the bacteriological characteristics which are relevant for identification of these isolates. The negative reverse CAMP test, the ability to produce acid from xylose and to hydrolyse gelatin and the positive β-glucuronidase test clearly differentiated A. pyogenes from other closely related species. All three isolates were uniformly susceptible to penicillin, ampicillin, amoxicillin–clavulanic acid, ceftriaxone and gentamicin, variably susceptible to tetracycline and erythromycin and uniformly resistant to cotrimoxazole. Only a few confirmed cases have been reported throughout the world and therefore the diagnostic evaluation of this organism is emphasized.
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Three cases of Arcanobacterium pyogenes-associated soft tissue infection.
Journal of medical microbiology, 2010Co-Authors: Kannaiyan Kavitha, Rangan Latha, C Udayashankar, Kamala Jayanthi, P OudeacoumarAbstract:Arcanobacterium pyogenes is an established but often unrecognized human pathogen. A. pyogenes may also be misidentified as Arcanobacterium haemolyticum, which gives remarkably similar results in conventional biochemical tests. In this study, we have reported three cases of wound infections associated with A. pyogenes and also on the bacteriological characteristics which are relevant for identification of these isolates. The negative reverse CAMP test, the ability to produce acid from xylose and to hydrolyse gelatin and the positive beta-glucuronidase test clearly differentiated A. pyogenes from other closely related species. All three isolates were uniformly susceptible to penicillin, ampicillin, amoxicillin-clavulanic acid, ceftriaxone and gentamicin, variably susceptible to tetracycline and erythromycin and uniformly resistant to cotrimoxazole. Only a few confirmed cases have been reported throughout the world and therefore the diagnostic evaluation of this organism is emphasized.
J. Glenn Songer - One of the best experts on this subject based on the ideXlab platform.
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Ribosomal Mutations in Arcanobacterium pyogenes Confer a Unique Spectrum of Macrolide Resistance
Antimicrobial agents and chemotherapy, 2004Co-Authors: B. Helen Jost, J. Glenn Songer, Hien T. Trinh, Stephen J. BillingtonAbstract:Four macrolide-resistant Arcanobacterium pyogenes isolates contained A2058T, A2058G, or C2611G (Escherichia coli numbering) mutations in their 23S rRNA genes. While these mutations conferred resistance to erythromycin, oleandomycin, and spiramycin, they did not confer resistance to tylosin.
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A Second Tylosin Resistance Determinant, Erm B, in Arcanobacterium pyogenes
Antimicrobial agents and chemotherapy, 2004Co-Authors: B. Helen Jost, J. Glenn Songer, Hien T. Trinh, Stephen J. BillingtonAbstract:Arcanobacterium pyogenes, a common inhabitant of the mucosal surfaces of livestock, is also a pathogen associated with a variety of infections. In livestock, A. pyogenes is exposed to antimicrobial agents used for prophylaxis and therapy, notably tylosin, a macrolide used extensively for the prevention of liver abscessation in feedlot cattle in the United States. Many, but not all, tylosin-resistant A. pyogenes isolates carry erm(X), suggesting the presence of other determinants of tylosin resistance. Oligonucleotide primers designed for conserved regions of erm(B), erm(C), and erm(T) were used to amplify a 404-bp fragment from a tylosin-resistant A. pyogenes isolate, OX-7. DNA sequencing revealed that the PCR product was 100% identical to erm(B) genes, and the erm(B) gene region was cloned in Escherichia coli. The A. pyogenes Erm B determinant had the most DNA identity with an Erm B determinant carried by the Clostridium perfringens plasmid pIP402. However, the A. pyogenes determinant lacked direct repeat DR1 and contained a deletion in DR2. Flanking the A. pyogenes erm(B) gene were partial and entire genes similar to those found on the Enterococcus faecalis multiresistance plasmid pRE25. This novel architecture suggests that the erm(B) element may have arisen by recombination of two distinct genetic elements. Ten of 32 tylosin-resistant isolates carried erm(B), as determined by DNA hybridization, and all 10 isolates carried a similar element. Insertion of the element was site specific, as PCR and Southern blotting analysis revealed that the erm(B) element was inserted into orfY, a gene of unknown function. However, in three strains, this insertion resulted in a partial duplication of orfY.
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The gene encoding pyolysin, the pore-forming toxin of Arcanobacterium pyogenes, resides within a genomic islet flanked by essential genes
FEMS microbiology letters, 2003Co-Authors: Stefani T. Rudnick, B. Helen Jost, J. Glenn Songer, Stephen J. BillingtonAbstract:The plo gene, encoding the Arcanobacterium pyogenes cholesterol-dependent cytolysin, pyolysin (PLO), was localized to a 2.7-kb genomic islet of reduced %G+C content and alternate codon usage frequency. This islet, conserved among isolates from diverse hosts and geographical locations, separated the housekeeping genes smc and ftsY, which are found adjacent in many prokaryotes. The ftsY and ffh genes, located downstream of the plo islet, encode components of the signal recognition particle. Mutational analysis suggested that these genes were essential for viability in A. pyogenes. The A. pyogenes ffh gene was unable to complement a conditional ffh mutant of Escherichia coli and its overexpression was toxic in E. coli. Mutagenesis of the islet-encoded orf121 did not affect plo expression, indicating that it may not be involved directly in the regulation of plo expression. Regardless, the presence of the plo gene as part of a genomic islet inserted between genes essential for normal growth may provide selective pressure for the retention of this important virulence factor.
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The Arcanobacterium pyogenes Collagen-Binding Protein, CbpA, Promotes Adhesion to Host Cells
Infection and immunity, 2003Co-Authors: Paula A. Esmay, Stephen J. Billington, Malen A. Link, J. Glenn Songer, B. Helen JostAbstract:Arcanobacterium pyogenes is an opportunistic pathogen associated with suppurative diseases in economically important food animals such as cattle, pigs, and turkeys. A. pyogenes adheres to host epithelial cells, and adhesion is promoted by the action of neuraminidase, which is expressed by this organism. However, a neuraminidase-deficient mutant of A. pyogenes only had a reduced ability to adhere to host epithelial cells, indicating that other factors are involved in adhesion. Far Western blotting revealed the presence of an approximately 120-kDa A. pyogenes cell wall protein that binds collagen type I. The 3.5-kb gene that encodes the 124.7-kDa CbpA protein was cloned, and sequence analysis indicated that CbpA contains a typical MSCRAMM protein domain structure. Recombinant, six-His-tagged CbpA (HIS-CbpA) was capable of binding collagen types I, II, and IV but not fibronectin. In addition, CbpA was involved in the ability of A. pyogenes to adhere to HeLa and 3T6 cells, as a cbpA knockout strain had 38.2 and 57.0% of wild-type adhesion, respectively. This defect could be complemented by providing cbpA on a multicopy plasmid. Furthermore, HIS-CbpA blocked A. pyogenes adhesion to HeLa or 3T6 cells in a dose-dependent manner. cbpA was only present in 48% of the A. pyogenes strains tested (n = 75), and introduction of plasmid-encoded cbpA into a naturally cbpA-deficient strain increased the ability of this strain to bind to HeLa and 3T6 cells 2.9- and 5.7-fold, respectively. These data indicate that CbpA, a collagen-binding protein of A. pyogenes, plays a role in the adhesion of this organism to host cells.
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Tylosin Resistance in Arcanobacterium pyogenes Is Encoded by an Erm X Determinant
Antimicrobial agents and chemotherapy, 2003Co-Authors: B. Helen Jost, J. Glenn Songer, Hien T. Trinh, Adam C. Field, Stephen J. BillingtonAbstract:Arcanobacterium pyogenes , a commensal on the mucous membranes of many economically important animal species, is also a pathogen, causing abscesses of the skin, joints, and visceral organs as well as mastitis and abortion. In food animals, A. pyogenes is exposed to antimicrobial agents used for growth promotion, prophylaxis, and therapy, notably tylosin, a macrolide antibiotic used extensively for the prevention of liver abscessation in feedlot cattle in the United States. Of 48 A. pyogenes isolates, 11 (22.9%) exhibited inducible or constitutive resistance to tylosin (MIC of ≥128 μg/ml). These isolates also exhibited resistance to other macrolide and lincosamide antibiotics, suggesting a macrolide-lincosamide resistance phenotype. Of the 11 resistant isolates, genomic DNA from nine hybridized to an erm (X)-specific probe. Cloning and nucleotide sequencing of the A. pyogenes erm (X) gene indicated that it was >95% similar to erm (X) genes from Corynebacterium and Propionibacterium spp. Eight of the erm (X)-containing A. pyogenes isolates exhibited inducible tylosin resistance, which was consistent with the presence of a putative leader peptide upstream of the erm (X) open reading frame. For at least one A. pyogenes isolate, 98-4277-2, erm (X) was present on a plasmid, pAP2, and was associated with the insertion sequence IS 6100 . pAP2 also carried genes encoding the repressor-regulated tetracycline efflux system determinant Tet 33. The repA gene from pAP2 was nonfunctional in Escherichia coli and at least one A. pyogenes isolate, suggesting that there may be host-encoded factors required for replication of this plasmid.
Kannaiyan Kavitha - One of the best experts on this subject based on the ideXlab platform.
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three cases of Arcanobacterium pyogenes associated soft tissue infection
Journal of Medical Microbiology, 2010Co-Authors: Kannaiyan Kavitha, Rangan Latha, C Udayashankar, Kamala Jayanthi, P OudeacoumarAbstract:Arcanobacterium pyogenes is an established but often unrecognized human pathogen. A. pyogenes may also be misidentified as Arcanobacterium haemolyticum, which gives remarkably similar results in conventional biochemical tests. In this study, we have reported three cases of wound infections associated with A. pyogenes and also on the bacteriological characteristics which are relevant for identification of these isolates. The negative reverse CAMP test, the ability to produce acid from xylose and to hydrolyse gelatin and the positive β-glucuronidase test clearly differentiated A. pyogenes from other closely related species. All three isolates were uniformly susceptible to penicillin, ampicillin, amoxicillin–clavulanic acid, ceftriaxone and gentamicin, variably susceptible to tetracycline and erythromycin and uniformly resistant to cotrimoxazole. Only a few confirmed cases have been reported throughout the world and therefore the diagnostic evaluation of this organism is emphasized.
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Three cases of Arcanobacterium pyogenes-associated soft tissue infection.
Journal of medical microbiology, 2010Co-Authors: Kannaiyan Kavitha, Rangan Latha, C Udayashankar, Kamala Jayanthi, P OudeacoumarAbstract:Arcanobacterium pyogenes is an established but often unrecognized human pathogen. A. pyogenes may also be misidentified as Arcanobacterium haemolyticum, which gives remarkably similar results in conventional biochemical tests. In this study, we have reported three cases of wound infections associated with A. pyogenes and also on the bacteriological characteristics which are relevant for identification of these isolates. The negative reverse CAMP test, the ability to produce acid from xylose and to hydrolyse gelatin and the positive beta-glucuronidase test clearly differentiated A. pyogenes from other closely related species. All three isolates were uniformly susceptible to penicillin, ampicillin, amoxicillin-clavulanic acid, ceftriaxone and gentamicin, variably susceptible to tetracycline and erythromycin and uniformly resistant to cotrimoxazole. Only a few confirmed cases have been reported throughout the world and therefore the diagnostic evaluation of this organism is emphasized.