RESUMO
Mannheimia haemolytica leukotoxin (LKT) is a known cause of bovine respiratory disease (BRD) which results in severe economic losses in the cattle industry (up to USD 1 billion per year in the USA). Vaccines based on LKT offer the most promising measure to contain BRD outbreaks and are already commercially available. However, insufficient LKT yields, predominantly reflecting a lack of knowledge about the LKT expression process, remain a significant engineering problem and further bioprocess optimization is required to increase process efficiency. Most previous investigations have focused on LKT activity and cell growth, but neither of these parameters defines reliable criteria for the improvement of LKT yields. In this article, we review the most important process conditions and operational parameters (temperature, pH, substrate concentration, dissolved oxygen level, medium composition and the presence of metabolites) from a bioprocess engineering perspective, in order to maximize LKT yields.
Assuntos
Animais , Bovinos , Toxinas Bacterianas/biossíntese , Mannheimia haemolytica/metabolismo , Complexo Respiratório Bovino/microbiologia , Exotoxinas/biossíntese , Temperatura , Oligoelementos , Carbono/metabolismo , Mannheimia haemolytica/patogenicidade , Aminoácidos/metabolismo , Concentração de Íons de Hidrogênio , CinetinaRESUMO
Staphylococcus aureus es uno de los principales agentes etiológicos de infecciones en niños provenientes de la comunidad y del ámbito hospitalario. La gravedad de estos cuadros se asocia a factores de virulencia, entre los que se encuentra la leucocidina de Panton-Valentine. Tanto Staphylococcus aureus resistente como sensible a la meticilina producen esta leucocidina, aunque con frecuencia variable. Presentamos a dos niños con infección grave por Staphylococcus aureus sensible a la meticilina productor de leucocidina de Panton-Valentine con complicaciones osteoarticulares y endovasculares. Es fundamental la sospecha diagnóstica, el tratamiento antibiótico adecuado y el manejo quirúrgico precoz para mejorar el abordaje de estas infecciones. Se debe mantener la vigilancia epidemiológica para detectar la frecuencia de las infecciones causadas por estas bacterias.
Staphylococcus aureus is a major etiologic agent of infections in children from the community and the hospital setting. The severity of these conditions is associated with virulence factors, including the Panton-Valentine leukocidin. Both methicillin resistant and sensitive Staphylococcus aureus produce this leukocidin although with varying frequency. We present two children with severe infection by sensitive Staphylococcus aureus producer of Panton-Valentine leukocidin with musculoskeletal and endovascular complications. It is essential the suspected diagnosis, appropriate antibiotic treatment and early surgical management to improve the approach of these infections. Epidemiological surveillance should be mantained to detect the frequency of infections caused by these bacteria.
Assuntos
Humanos , Masculino , Feminino , Criança , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/terapia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/metabolismo , Toxinas Bacterianas/biossíntese , Exotoxinas/biossíntese , Leucocidinas/biossíntese , Meticilina/farmacologia , Antibacterianos/farmacologia , Índice de Gravidade de Doença , Testes de Sensibilidade MicrobianaRESUMO
Staphylococcus aureus is a major etiologic agent of infections in children from the community and the hospital setting. The severity of these conditions is associated with virulence factors, including the Panton-Valentine leukocidin. Both methicillin resistant and sensitive Staphylococcus aureus produce this leukocidin although with varying frequency. We present two children with severe infection by sensitive Staphylococcus aureus producer of Panton-Valentine leukocidin with musculoskeletal and endovascular complications. It is essential the suspected diagnosis, appropriate antibiotic treatment and early surgical management to improve the approach of these infections. Epidemiological surveillance should be mantained to detect the frequency of infections caused by these bacteria.
Staphylococcus aureus es uno de los principales agentes etiológicos de infecciones en niños provenientes de la comunidad y del ámbito hospitalario. La gravedad de estos cuadros se asocia a factores de virulencia, entre los que se encuentra la leucocidina de Panton-Valentine. Tanto Staphylococcus aureus resistente como sensible a la meticilina producen esta leucocidina, aunque con frecuencia variable. Presentamos a dos niños con infección grave por Staphylococcus aureus sensible a la meticilina productor de leucocidina de Panton-Valentine con complicaciones osteoarticulares y endovasculares. Es fundamental la sospecha diagnóstica, el tratamiento antibiótico adecuado y el manejo quirúrgico precoz para mejorar el abordaje de estas infecciones. Se debe mantener la vigilancia epidemiológica para detectar la frecuencia de las infecciones causadas por estas bacterias.
Assuntos
Antibacterianos/farmacologia , Toxinas Bacterianas/biossíntese , Exotoxinas/biossíntese , Leucocidinas/biossíntese , Meticilina/farmacologia , Infecções Estafilocócicas , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/metabolismo , Criança , Feminino , Humanos , Masculino , Testes de Sensibilidade Microbiana , Índice de Gravidade de Doença , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/terapiaRESUMO
The use of invasive techniques, such as intravascular catheter insertion, and the formation of biofilms in several devices by methicillin-resistant Staphylococcus aureus (MRSA) have contributed to the increased number of septic patients, morbidity and mortality. This study aimed to evaluate the virulence of strains through catheter colonization and identification of microbial biofilm, as well as pathological changes on the colonized skin. An experimental biofilm formation model utilized catheter fragments implanted subcutaneously in 25 Swiss mice. The technique consisted of inoculating a catheter fragment on the back of each animal, followed by intradermal inoculation of 50 µl of bacterial suspension at 1.0 × 107 colony forming units/ml. After 96 h, catheters were removed for macroscopic analysis and evaluated through culture. Local skin fragments were also extracted for histopathology analysis. Staphylococcus aureus can adhere to catheters, colonize and form biofilms. The high amount of viable bacterial cells colonizing catheters and virulence factors can lead to severe infections of skin and adjacent tissues. [Int Microbiol 19(4): 199-207 (2016)].
Assuntos
Toxinas Bacterianas/biossíntese , Biofilmes/crescimento & desenvolvimento , Infecções Relacionadas a Cateter/microbiologia , Exotoxinas/biossíntese , Leucocidinas/biossíntese , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/crescimento & desenvolvimento , Animais , Humanos , Masculino , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Camundongos , Staphylococcus aureus/patogenicidadeRESUMO
We describe three cases of community-acquired necrotizing pneumonia which were caused by Panton-Valentine leucocidin-producing strains of Staphylococcus aureus (one of them methicillin sensitive). All cases were successfully treated without any sequelae for the patients due to the prompt initiation of adequate antimicrobial therapy. High suspicion toward this fatal pathogen was the key to the successful outcome of the patients.
Assuntos
Adolescente , Adulto , Feminino , Humanos , Masculino , Toxinas Bacterianas/biossíntese , Exotoxinas/biossíntese , Leucocidinas/biossíntese , Pneumonia Estafilocócica/diagnóstico , Staphylococcus aureus/metabolismo , Infecções Comunitárias Adquiridas/diagnóstico , Infecções Comunitárias Adquiridas/microbiologia , Infecções Comunitárias Adquiridas/patologia , Necrose/microbiologia , Necrose/patologia , Pneumonia Estafilocócica/microbiologia , Pneumonia Estafilocócica/patologia , Índice de Gravidade de DoençaRESUMO
We describe three cases of community-acquired necrotizing pneumonia which were caused by Panton-Valentine leucocidin-producing strains of Staphylococcus aureus (one of them methicillin sensitive). All cases were successfully treated without any sequelae for the patients due to the prompt initiation of adequate antimicrobial therapy. High suspicion toward this fatal pathogen was the key to the successful outcome of the patients.
Assuntos
Toxinas Bacterianas/biossíntese , Exotoxinas/biossíntese , Leucocidinas/biossíntese , Pneumonia Estafilocócica/diagnóstico , Staphylococcus aureus/metabolismo , Adolescente , Adulto , Infecções Comunitárias Adquiridas/diagnóstico , Infecções Comunitárias Adquiridas/microbiologia , Infecções Comunitárias Adquiridas/patologia , Feminino , Humanos , Masculino , Necrose/microbiologia , Necrose/patologia , Pneumonia Estafilocócica/microbiologia , Pneumonia Estafilocócica/patologia , Índice de Gravidade de DoençaRESUMO
INTRODUCTION: Very little is known of the diversity and expression of virulence factors of serotypes of Aggregatibacter actinomycetemcomitans. Toxic activity on Chinese hamster ovary (CHO) cells and cdt and ltx genotyping were evaluated in A. actinomycetemcomitans serotypes. METHODS: Forty-one A. actinomycetemcomitans isolates were analysed for CHO cell growth inhibition. Genotyping was performed by polymerase chain reactions specific to the ltx promoter region, serotype-specific and cdt region and by sequencing of cdtB. RESULTS: cdtABC was detected in 40 strains. Analysis of the cdtA upstream region revealed 10 cdt genotypes. Toxicity to CHO cells was detected for 92.7% of the isolates; however, no correlation between the toxic activity and the cdt genotype was detected. Serotype c was more prevalent among Brazilian samples (68.0%). Four serotype b isolates from subjects with aggressive periodontitis were associated with high leukotoxin production and exhibited moderate to strong toxic activity in CHO cells, but were classified in different cdt genotypes. High levels of toxicity in CHO cells were not associated with a particular serotype; 57.1% of serotype a isolates presented low toxicity to CHO cells whereas the highly toxic strains belonged to serotypes b and c. Sequencing of cdtB revealed a single nucleotide polymorphism of amino acid 281 but this was not related to the toxic activity in CHO cells. CONCLUSION: Differences in prevalence of the low and highly cytotoxic strains among serotypes reinforce the hypothesis that serotype b and c isolates of A. actinomycetemcomitans are more virulent than serotype a strains.
Assuntos
Aggregatibacter actinomycetemcomitans/genética , Aggregatibacter actinomycetemcomitans/fisiologia , Periodontite Agressiva/microbiologia , Toxinas Bacterianas/genética , Citotoxinas/genética , Animais , Toxinas Bacterianas/toxicidade , Células CHO/efeitos dos fármacos , Cricetinae , Cricetulus , Exotoxinas/biossíntese , Exotoxinas/genética , Variação Genética , Humanos , Polimorfismo de Nucleotídeo Único , Sorotipagem , Especificidade da Espécie , Virulência/genéticaRESUMO
We evaluated clinical outcomes and molecular epidemiology of methicillin-resistant Staphylococcus aureus carrying SCCmecIV recovered from patients who attended at a teaching hospital from Porto Alegre, Brazil. All Panton-Valentine leukocidin (PVL)-producer isolates belonged to clonal complex (CC) 30 (11 isolates, related to Oceania Southwest Pacific clone [OSPC]), and the PVL-negative isolates were typed as CC5 (2 isolates, related to the pediatric clone). Five patients had health care-associated infections (HCAIs) with hospital-onset, 5 HCAIs with community-onset, and 3 community-acquired infections without risks. A high overall mortality (30.8%) was found. This study show that OSPC isolates are not only causing community-associated infections but are also involved in HCAI in our country.
Assuntos
Staphylococcus aureus Resistente à Meticilina/classificação , Staphylococcus aureus Resistente à Meticilina/genética , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/microbiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/farmacologia , Toxinas Bacterianas/biossíntese , Brasil/epidemiologia , Criança , Pré-Escolar , Cromossomos Bacterianos/genética , Análise por Conglomerados , Infecções Comunitárias Adquiridas/epidemiologia , Infecções Comunitárias Adquiridas/microbiologia , Infecções Comunitárias Adquiridas/mortalidade , Infecção Hospitalar/epidemiologia , Infecção Hospitalar/microbiologia , Infecção Hospitalar/mortalidade , Impressões Digitais de DNA , DNA Bacteriano/genética , Eletroforese em Gel de Campo Pulsado , Exotoxinas/biossíntese , Feminino , Genótipo , Hospitais Universitários , Humanos , Leucocidinas/biossíntese , Masculino , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Epidemiologia Molecular , Infecções Estafilocócicas/mortalidade , Adulto JovemAssuntos
Toxinas Bacterianas/biossíntese , Técnicas de Tipagem Bacteriana , Infecções Comunitárias Adquiridas/diagnóstico , Exotoxinas/biossíntese , Leucocidinas/biossíntese , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Infecções Estafilocócicas/diagnóstico , Fatores de Virulência/biossíntese , Adolescente , Antibacterianos/farmacologia , Toxinas Bacterianas/genética , Análise por Conglomerados , Colômbia , Infecções Comunitárias Adquiridas/microbiologia , Impressões Digitais de DNA , Eletroforese em Gel de Campo Pulsado , Exotoxinas/genética , Genótipo , Humanos , Lactente , Leucocidinas/genética , Masculino , Testes de Sensibilidade Microbiana , Epidemiologia Molecular , Infecções Estafilocócicas/microbiologia , Fatores de Virulência/genéticaRESUMO
Epidemiological surveillance for community-associated methicillin-resistant Staphylococcus aureus revealed prevalences of 33% and 13% in pediatric and adult patients, respectively, in Cordoba, Argentina, in 2005. This study describes for the first time the emergence and dissemination of the sequence type 5 (ST5) lineage as the most prevalent clone (89%) (pulsed-field gel electrophoresis type I-ST5-staphylococcal cassette chromosome type IVa-spa type 311) harboring the Panton-Valentine leukocidin and enterotoxin A genes.
Assuntos
Toxinas Bacterianas/biossíntese , Infecções Comunitárias Adquiridas/microbiologia , Exotoxinas/biossíntese , Leucocidinas/biossíntese , Resistência a Meticilina , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/genética , Staphylococcus aureus/isolamento & purificação , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Argentina/epidemiologia , Técnicas de Tipagem Bacteriana , Criança , Pré-Escolar , Análise por Conglomerados , Infecções Comunitárias Adquiridas/epidemiologia , Infecção Hospitalar/microbiologia , Impressões Digitais de DNA , DNA Bacteriano/genética , Eletroforese em Gel de Campo Pulsado , Feminino , Genótipo , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Infecções Estafilocócicas/epidemiologia , Staphylococcus aureus/classificaçãoRESUMO
Panton-Valentine leukocidin-producing Staphylococcus aureus is an emerging pathogen world-wide, causing necrotizing lung infections in otherwise healthy individuals. We describe 2 episodes of patient-to-patient transmission of Panton-Valentine leukocidin-producing S. aureus, resulting in acute, life-threatening pulmonary complications in patients with cystic fibrosis. Appropriate infection control measures may be warranted to prevent similar episodes.
Assuntos
Toxinas Bacterianas/biossíntese , Fibrose Cística/complicações , Transmissão de Doença Infecciosa , Exotoxinas/biossíntese , Leucocidinas/biossíntese , Pneumonia Bacteriana/microbiologia , Pneumonia Bacteriana/transmissão , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/transmissão , Antibacterianos/uso terapêutico , Pré-Escolar , Busca de Comunicante , Fibrose Cística/diagnóstico , Feminino , Seguimentos , Humanos , Lactente , Masculino , Resistência a Meticilina , Medição de Risco , Índice de Gravidade de Doença , Irmãos , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/isolamento & purificação , Resultado do TratamentoRESUMO
Pseudomonas syringae pv. phaseolicola synthesizes a non-host-specific toxin, phaseolotoxin, and also synthesizes a phaseolotoxin-resistant ornithine carbamoyltransferase (ROCT) to protect itself from its own toxin. ROCT is encoded by argK, which is expressed coordinately with phaseolotoxin synthesis at 18 degrees C. To investigate the regulatory mechanisms of this system, null mutants were constructed for argK, argF (encoding the phaseolotoxin-sensitive OCTase [SOCT]), and amtA (encoding an amidinotransferase involved in phaseolotoxin synthesis). The argF mutant did not exhibit arginine auxotrophy when grown in M9 medium at 28 degrees C, because under this condition SOCT was replaced by ROCT. This loss of thermoregulation of argK was apparently caused by accumulation of carbamoylphosphate, one of the substrates of SOCT. Carbamoylphosphate, which has a structure similar to that of the inorganic moiety of phaseolotoxin, was used in induction assays with wild-type P. syringae pv. phaseolicola and was shown to be able to induce argK expression in M9 medium at 28 degrees C. These results indicate that argK expression is independent of temperature and is regulated directly by a compound resembling the inorganic moiety of phaseolotoxin.
Assuntos
Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica , Ornitina Carbamoiltransferase/metabolismo , Precursores de Proteínas/metabolismo , Temperatura , Proteínas de Bactérias/metabolismo , Carbamoil-Fosfato/metabolismo , Meios de Cultura , Exotoxinas/biossíntese , Exotoxinas/farmacologia , Mutação , Ornitina/análogos & derivados , Ornitina Carbamoiltransferase/genética , Pseudomonas syringae/efeitos dos fármacos , Pseudomonas syringae/genética , Pseudomonas syringae/crescimento & desenvolvimento , Pseudomonas syringae/metabolismoRESUMO
Pseudomonas syringae pv. phaseolicola is the causal agent of the "halo blight" disease of beans. A key component in the development of the disease is a nonhost-specific toxin, Ndelta-(N'-sulphodiaminophosphinyl)-ornithyl-alanyl-homoarginine, known as phaseolotoxin. The homoarginine residue in this molecule has been suggested to be the product of L-arginine:lysine amidinotransferase activity, previously detected in extracts of P. syringae pv. phaseolicola grown under conditions of phaseolotoxin production. We report the isolation and characterization of an amidinotransferase gene (amtA) from P. syringae pv. phaseolicola coding for a polypeptide of 362 residues (41.36 kDa) and showing approximately 40% sequence similarity to L-arginine:inosamine-phosphate amidinotransferase from three species of Streptomyces spp. and 50.4% with an L-arginine:glycine amidinotransferase from human mitochondria. The cysteine, histidine, and aspartic acid residues involved in substrate binding are conserved. Furthermore, expression of the amtA and argK genes and phaseolotoxin production occurs at 18 degrees C but not at 28 degrees C. An amidinotransferase insertion mutant was obtained that lost the capacity to synthesize homoarginine and phaseolotoxin. These results show that the amtA gene isolated is responsible for the amidinotransferase activity detected previously and that phaseolotoxin production depends upon the activity of this gene.
Assuntos
Amidinotransferases/genética , Exotoxinas/biossíntese , Pseudomonas/metabolismo , Sequência de Aminoácidos , Sequência de Bases , Primers do DNA , Dados de Sequência Molecular , Ornitina/análogos & derivados , Reação em Cadeia da Polimerase , Pseudomonas/enzimologia , Pseudomonas/genéticaRESUMO
Sete amostras de Moraxella bovis foram investigadas quanto a produçäo de exotoxina. os resultados observados em quatro delas (57,14%) mostraram que M. bovis é capaz de induzir no modelo do camundongo recém-nascido um efeito semelhante ao observado para a toxina termoestável secretada por Escherichia coli