Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 22
Filtrar
Mais filtros










Base de dados
Tipo de estudo
Intervalo de ano de publicação
1.
Animals (Basel) ; 11(11)2021 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-34827779

RESUMO

Non-typeable (NT) Staphylococcus aureus strains are associated with chronic bovine mastitis. This study investigates the impact of biofilm formation by clinical NT S. aureus on cytokine production and mammary tissue damage by using a mouse mastitis model. Mice infected with two different NT S. aureus strains with strong and weak biofilm forming potential demonstrated identical clinical symptoms (moderate), minimal inflammatory infiltrates, and tissue damage (level 1 histopathological changes) in the mammary glands. However, the S. aureus load in the mammary glands of mice and the level of pro-inflammatory cytokines (IL-1ß, IL-6, IL-12, IL-17 and IFN-γ) in serum were significantly higher (p ≤ 0.05) in those infected with the strong biofilm forming NT S. aureus strain. The level of IL-6 in sera samples of these mice was extremely high (15,479.9 ± 532 Pg/mL). Furthermore, these mice died in 24h of post infection compared to 30 h in the weak biofilm forming NT S. aureus infected group. The study demonstrates no association between the strength of PIA (polysaccharide intercellular adhesion)-dependent biofilm production by clinical NT S. aureus and mammary gland pathology in a mouse mastitis model. However, the role of biofilm in the virulence of S. aureus advancing the time of mortality in mice warrants further investigation.

2.
Med Microbiol Immunol ; 207(1): 3-26, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29164393

RESUMO

Despite high vaccine coverage, whooping cough caused by Bordetella pertussis remains one of the most common vaccine-preventable diseases worldwide. Introduction of whole-cell pertussis (wP) vaccines in the 1940s and acellular pertussis (aP) vaccines in 1990s reduced the mortality due to pertussis. Despite induction of both antibody and cell-mediated immune (CMI) responses by aP and wP vaccines, there has been resurgence of pertussis in many countries in recent years. Possible reasons hypothesised for resurgence have ranged from incompliance with the recommended vaccination programmes with the currently used aP vaccine to infection with a resurged clinical isolates characterised by mutations in the virulence factors, resulting in antigenic divergence with vaccine strain, and increased production of pertussis toxin, resulting in dampening of immune responses. While use of these vaccines provide varying degrees of protection against whooping cough, protection against infection and transmission appears to be less effective, warranting continuation of efforts in the development of an improved pertussis vaccine formulations capable of achieving this objective. Major approaches currently under evaluation for the development of an improved pertussis vaccine include identification of novel biofilm-associated antigens for incorporation in current aP vaccine formulations, development of live attenuated vaccines and discovery of novel non-toxic adjuvants capable of inducing both antibody and CMI. In this review, the potential roles of different accredited virulence factors, including novel biofilm-associated antigens, of B. pertussis in the evolution, formulation and delivery of improved pertussis vaccines, with potential to block the transmission of whooping cough in the community, are discussed.


Assuntos
Antígenos de Bactérias/imunologia , Bordetella pertussis/imunologia , Transmissão de Doença Infecciosa/prevenção & controle , Vacina contra Coqueluche/imunologia , Fatores de Virulência/imunologia , Coqueluche/prevenção & controle , Bordetella pertussis/patogenicidade , Descoberta de Drogas/tendências , Humanos , Vacina contra Coqueluche/isolamento & purificação , Coqueluche/epidemiologia
3.
PLoS One ; 12(1): e0170668, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28129375

RESUMO

BACKGROUND: Biofilm formation by Staphylococcus aureus is an important virulence attribute because of its potential to induce persistent antibiotic resistance, retard phagocytosis and either attenuate or promote inflammation, depending upon the disease syndrome, in vivo. This study was undertaken to evaluate the potential significance of strength of biofilm formation by clinical bovine mastitis-associated S. aureus in mammary tissue damage by using a mouse mastitis model. METHODS: Two S. aureus strains of the same capsular phenotype with different biofilm forming strengths were used to non-invasively infect mammary glands of lactating mice. Biofilm forming potential of these strains were determined by tissue culture plate method, ica typing and virulence gene profile per detection by PCR. Delivery of the infectious dose of S. aureus was directly through the teat lactiferous duct without invasive scraping of the teat surface. Both bacteriological and histological methods were used for analysis of mammary gland pathology of mice post-infection. RESULTS: Histopathological analysis of the infected mammary glands revealed that mice inoculated with the strong biofilm forming S. aureus strain produced marked acute mastitic lesions, showing profuse infiltration predominantly with neutrophils, with evidence of necrosis in the affected mammary glands. In contrast, the damage was significantly less severe in mammary glands of mice infected with the weak biofilm-forming S. aureus strain. Although both IL-1ß and TNF-α inflammatory biomarkers were produced in infected mice, level of TNF-α produced was significantly higher (p<0.05) in mice inoculated with strong biofilm forming S. aureus than the weak biofilm forming strain. CONCLUSION: This finding suggests an important role of TNF-α in mammary gland pathology post-infection with strong biofilm-forming S. aureus in the acute mouse mastitis model, and offers an opportunity for the development of novel strategies for reduction of mammary tissue damage, with or without use of antimicrobials and/or anti-inflammatory compounds for the treatment of bovine mastitis.


Assuntos
Biofilmes/crescimento & desenvolvimento , Mastite Bovina/microbiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/crescimento & desenvolvimento , Animais , Bovinos , Modelos Animais de Doenças , Feminino , Interleucina-1beta/metabolismo , Glândulas Mamárias Animais/metabolismo , Glândulas Mamárias Animais/microbiologia , Glândulas Mamárias Animais/patologia , Mastite Bovina/metabolismo , Mastite Bovina/patologia , Camundongos , Projetos Piloto , Infecções Estafilocócicas/patologia , Staphylococcus aureus/metabolismo , Staphylococcus aureus/patogenicidade , Fator de Necrose Tumoral alfa/metabolismo
4.
Microb Drug Resist ; 23(3): 384-390, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27754780

RESUMO

Staphylococcus aureus in biofilms is highly resistant to the treatment with antibiotics, to which the planktonic cells are susceptible. This is likely to be due to the biofilm creating a protective barrier that prevents antibiotics from accessing the live pathogens buried in the biofilm. S. aureus biofilms consist of an extracellular matrix comprising, but not limited to, extracellular bacterial DNA (eDNA) and poly-ß-1, 6-N-acetyl-d-glucosamine (PNAG). Our study revealed that despite inferiority of dispersin B (an enzyme that degrades PNAG) to DNase I that cleaves eDNA, in dispersing the biofilm of S. aureus, both enzymes were equally efficient in enhancing the antibacterial efficiency of tobramycin, a relatively narrow-spectrum antibiotic against infections caused by gram-positive and gram-negative pathogens, including S. aureus, used in this investigation. However, a combination of these two biofilm-degrading enzymes was found to be significantly less effective in enhancing the antimicrobial efficacy of tobramycin than the individual application of the enzymes. These findings indicate that combinations of different biofilm-degrading enzymes may compromise the antimicrobial efficacy of antibiotics and need to be carefully assessed in vitro before being used for treating medical devices or in pharmaceutical formulations for use in the treatment of chronic ear or respiratory infections.


Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/metabolismo , Biofilmes/efeitos dos fármacos , Desoxirribonuclease I/metabolismo , Staphylococcus aureus/efeitos dos fármacos , Tobramicina/farmacologia , DNA Bacteriano/genética , Testes de Sensibilidade Microbiana/métodos , Staphylococcus aureus/metabolismo
5.
Biofouling ; 32(9): 1141-1152, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27669900

RESUMO

Whooping cough caused by Bordetella pertussis is increasing in several countries despite high vaccine coverage. One potential reason for the resurgence is the emergence of genetic variants of the bacterium. Biofilm formation has recently been associated with the pathogenesis of B. pertussis. Biofilm formation of 21 Western Australian B. pertussis clinical isolates was investigated. All isolates formed thicker biofilms than the reference vaccine strain Tohama I while retaining susceptibility to ampicillin, erythromycin, azithromycin and streptomycin. When two biofilm-forming clinical isolates were compared with Tohama I, minimum bactericidal concentrations of antimicrobial agents increased. Isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic analysis revealed significant differences in protein expression in B. pertussis biofilms, providing an opportunity for identification of novel biofilm-associated antigens for incorporation in current pertussis vaccines to improve their protective efficacy. The study also highlights the importance of determining antibiograms for biofilms to formulate improved antimicrobial therapeutic regimens.

6.
Biomed Res Int ; 2016: 8651918, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27247944

RESUMO

An extensive array of virulence factors associated with S. aureus has contributed significantly to its success as a major nosocomial pathogen in hospitals and community causing variety of infections in affected patients. Virulence factors include immune evading capsular polysaccharides, poly-N-acetyl glucosamine, and teichoic acid in addition to damaging toxins including hemolytic toxins, enterotoxins, cytotoxins, exfoliative toxin, and microbial surface components recognizing adhesive matrix molecules (MSCRAMM). In this investigation, 31 West Australian S. aureus isolates of human origin and 6 controls were analyzed for relative distribution of virulence-associated genes using PCR and/or an immunoassay kit and MSCRAMM by PCR-based typing. Genes encoding MSCRAMM, namely, Spa, ClfA, ClfB, SdrE, SdrD, IsdA, and IsdB, were detected in >90% of isolates. Gene encoding α-toxin was detected in >90% of isolates whereas genes encoding ß-toxin and SEG were detectable in 50-60% of isolates. Genes encoding toxin proteins, namely, SEA, SEB, SEC, SED, SEE, SEH, SEI, SEJ, TSST, PVL, ETA, and ETB, were detectable in >50% of isolates. Use of RAPD-PCR for determining the virulence factor-based genetic relatedness among the isolates revealed five cluster groups confirming genetic diversity among the MSSA isolates, with the greatest majority of the clinical S. aureus (84%) isolates clustering in group IIIa.


Assuntos
Meticilina/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética , Fatores de Virulência/genética , Adesinas Bacterianas/genética , Austrália , Toxinas Bacterianas/genética , DNA Bacteriano/genética , Variação Genética/genética , Proteínas Hemolisinas/genética , Humanos , Esfingomielina Fosfodiesterase/genética
7.
Folia Microbiol (Praha) ; 61(6): 473-478, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27106696

RESUMO

Attachment of bacterial pathogens to the niche tissue in the host is the first step in biofilm formation leading to colonization and establishment of infection in the host. While the most common method used for determining the potential role of a bacterial antigen in biofilm formation has been demonstration of loss of this property using specific knockout mutants, it is an expensive and a laborious procedure. This study describes an alternative immunological assay for identification of attachment antigens of Staphylococcus aureus, potentially important in the development of an effective vaccine against infections caused by this pathogen. The method is based upon the concept of inhibition of attachment of S. aureus to PEGs coated with virulence antigen-specific antibodies. Antibodies used for validation of this assay were specific for ClfA, FnBPA, SdrD, PNAG and α-toxin, accredited biofilm-associated antigens of S. aureus.


Assuntos
Antígenos de Bactérias/análise , Biofilmes/crescimento & desenvolvimento , Imunoensaio/métodos , Staphylococcus aureus/química , Staphylococcus aureus/fisiologia , Adesinas Bacterianas/análise , Anticorpos Antibacterianos/metabolismo , Aderência Bacteriana , Poliestirenos
8.
PLoS One ; 11(2): e0148383, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26862761

RESUMO

Protein A, encoded by the spa gene, is one of the major immune evading MSCRAMM of S. aureus, demonstrated to be prevalent in a significant percentage of clinical bovine mastitis isolates in Australia. Given its' reported significance in biofilm formation and the superior performance of S. aureus biofilm versus planktonic vaccine in the mouse mastitis model, it was of interest to determine the immunogenicity and protective potential of Protein A as a potential vaccine candidate against bovine mastitis using the mouse mastitis model. Pregnant Balb/c mice were immunised with Protein A emulsified in an alum-based adjuvant by subcutaneous (s/c) or intramammary (i/mam) routes. While humoral immune response of mice post-immunization were determined using indirect ELISA, cell-mediated immune response was assessed by estimation of interferon-gamma (IFN-γ) produced by protein A-stimulated splenocyte supernatants. Protective potential of Protein A against experimental mastitis was determined by challenge of immunized versus sham-vaccinated mice by i/mam route, based upon manifestation of clinical symptoms, total bacterial load and histopathological damage to mammary glands. Significantly (p<0.05) higher levels of IgG1 isotype were produced in mice immunized by the s/c route. In contrast, significantly higher levels of the antibody isotype IgG2a were produced in mice immunized by the i/mam route (p<0.05). There was significant reduction (p<0.05) in bacterial loads of the mammary glands of mice immunized by Protein A regardless of the route of immunization, with medium level of clinical symptoms observed up to day 3 post-challenge. However, Protein A vaccine failed to protect immunized mice post-challenge with biofilm producing encapsulated S. aureus via i/mam route, regardless of the route of immunization, as measured by the level of mammary tissue damage. It was concluded that, Protein A in its' native state was apparently not a suitable candidate for inclusion in a cell-free vaccine formulation against mastitis.


Assuntos
Carga Bacteriana , Vacinas Bacterianas/imunologia , Glândulas Mamárias Animais/imunologia , Glândulas Mamárias Animais/microbiologia , Mastite/imunologia , Proteína Estafilocócica A/imunologia , Animais , Biofilmes , Concanavalina A/química , Ensaio de Imunoadsorção Enzimática , Feminino , Imunização , Imunoglobulina G/imunologia , Injeções Subcutâneas , Interferon gama/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Gravidez , Baço/citologia
9.
PLoS One ; 10(11): e0142717, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26588070

RESUMO

Buffaloes are the second largest source of milk. Mastitis is a major impediment for milk production, but not much information is available about bubaline mastitis, especially subclinical mastitis. The aim of this study was to (a) investigate the application of various tests for the diagnosis of bubaline subclinical mastitis, (b) identify the major bacteria associated with it, and (c) evaluate the antibiotic resistance pattern of the bacteria. To this end, 190 quarter milk samples were collected from 57 domesticated dairy buffaloes from organized (64 samples) and unorganized (126 samples) sectors. Of these, 48.4%, 40.0%, 45.8%, 61.1%, and 61.6% were positive for subclinical mastitis by somatic cell count, electrical conductivity, California mastitis test, bromothymol blue test, and N-acetyl glucosaminidase test, respectively. As compared to the gold standard of somatic cell count, California mastitis test performed the best. However, a combination of the two methods was found to be the best option. Microbiological evaluation, both by biochemical methods as well as by monoplex and multiplex polymerase chain reaction, revealed that coagulase-negative staphylococci were the most predominant (64.8%) bacteria, followed by streptococci (18.1%), Escherichia coli (9.8%) and Staphylococcus aureus (7.3%). Most of the pathogens were resistant to multiple antibiotics, especially to ß-lactam antibiotics. We propose that California mastitis test be combined with somatic cell count for diagnosis of subclinical mastitis in domestic dairy buffaloes. Further, our results reveal high resistance of the associated bacteria to the ß-lactam class of antibiotics, and a possible major role of coagulase-negative staphylococci in causing the disease in India.


Assuntos
Búfalos/microbiologia , Mastite Bovina/microbiologia , Leite/microbiologia , Staphylococcus/isolamento & purificação , Streptococcus/isolamento & purificação , Animais , Anti-Infecciosos/uso terapêutico , Bovinos , Escherichia coli/isolamento & purificação , Escherichia coli/patogenicidade , Feminino , Humanos , Índia , Mastite Bovina/tratamento farmacológico , Mastite Bovina/genética , Staphylococcus/patogenicidade , Streptococcus/patogenicidade , Resistência beta-Lactâmica
10.
Biofouling ; 31(7): 543-54, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26293793

RESUMO

This study was undertaken to compare the immunogenicity and protective potential of biofilm vs planktonic Staphylococcus aureus vaccine for the prevention of mastitis using the mouse as a model system. Mice immunized with formalin-killed whole cell vaccine of S. aureus residing in a biofilm when delivered via an intramammary route produced a cell mediated immune response. Mice immunized with this biofilm vaccine showed significant reductions in colonization by S. aureus in mammary glands, severity of clinical symptoms and tissue damage in mammary glands in comparison with the mice immunized with formalin-killed whole cells of planktonic S. aureus. The planktonic vaccine administered by a subcutaneous route produced a significantly higher humoral immune response (IgG1 and IgG) than the biofilm vaccine. However, considering the host response, tissue damage, the clinical severity and colonization of S. aureus in mammary glands, the biofilm vaccine performed better in immunogenicity and protective potential when administered by the intramammary route.


Assuntos
Biofilmes/efeitos dos fármacos , Mastite Bovina , Plâncton/microbiologia , Infecções Estafilocócicas , Vacinas Antiestafilocócicas/farmacologia , Staphylococcus aureus/imunologia , Animais , Bovinos , Feminino , Humanos , Imunoglobulina G/análise , Mastite Bovina/imunologia , Mastite Bovina/microbiologia , Mastite Bovina/prevenção & controle , Camundongos , Modelos Animais , Infecções Estafilocócicas/imunologia , Infecções Estafilocócicas/prevenção & controle
12.
Drug Des Devel Ther ; 8: 1003-12, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25114507

RESUMO

Gliclazide (G) is an antidiabetic drug commonly used in type 2 diabetes. It has extrapancreatic hypoglycemic effects, which makes it a good candidate in type 1 diabetes (T1D). In previous studies, we have shown that a gliclazide-bile acid mixture exerted a hypoglycemic effect in a rat model of T1D. We have also shown that a gliclazide-deoxycholic acid (G-DCA) mixture resulted in better G permeation in vivo, but did not produce a hypoglycemic effect. In this study, we aimed to develop a novel microencapsulated formulation of G-DCA with uniform structure, which has the potential to enhance G pharmacokinetic and pharmacodynamic effects in our rat model of T1D. We also aimed to examine the effect that DCA will have when formulated with our new G microcapsules, in terms of morphology, structure, and excipients' compatibility. Microencapsulation was carried out using the Büchi-based microencapsulating system developed in our laboratory. Using sodium alginate (SA) polymer, both formulations were prepared: G-SA (control) at a ratio of 1:30, and G-DCA-SA (test) at a ratio of 1:3:30. Complete characterization of microcapsules was carried out. The new G-DCA-SA formulation was further optimized by the addition of DCA, exhibiting pseudoplastic-thixotropic rheological characteristics. The size of microcapsules remained similar after DCA addition, and these microcapsules showed no chemical interactions between the excipients. This was supported further by the spectral and microscopy studies, suggesting microcapsule stability. The new microencapsulated formulation has good structural properties and may be useful for the oral delivery of G in T1D.


Assuntos
Células Artificiais/química , Ácido Desoxicólico/química , Diabetes Mellitus Experimental/tratamento farmacológico , Gliclazida/administração & dosagem , Alginatos/química , Animais , Cápsulas , Química Farmacêutica , Diabetes Mellitus Tipo 1/tratamento farmacológico , Excipientes/química , Gliclazida/química , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Hipoglicemiantes/administração & dosagem , Hipoglicemiantes/química , Tamanho da Partícula , Ratos , Reologia
13.
J Med Microbiol ; 63(Pt 11): 1427-1431, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25142964

RESUMO

The aim of this study was to compare the performance of serological versus molecular typing methods to detect capsular polysaccharide (CP) and surface-associated polysaccharide antigen 336 phenotypes of Staphylococcus aureus isolates. Molecular typing of CP types 1, 5 and 8 was carried out using PCR, whereas serological typing of CP1, 2, 5, 8 and antigen 336 was carried out by slide agglutination using specific antisera. By genotyping, 14/31 strains were CP8 positive, 12/31 strains were CP5 and the remaining 6/31 isolates were non-typable (NT). One isolate was positive for both CP5 and CP8 by PCR, but was confirmed as CP8 type serologically. Detection of CP2 and type 336 by PCR was not possible because specific primers were either not available or non-specific. Using serotyping, 14/31 strains were CP8 positive, 11/31 CP5 positive and 2/31 positive for antigen 336. The remaining four S. aureus isolates were serologically NT. However, three of four NT and two 336-positive S. aureus isolates were encapsulated as determined by light microscopy after capsular staining. This discovery was surprising and warrants further investigations on the identification and characterization of additional capsular phenotypes prevalent among S. aureus clinical isolates. It was concluded that serological typing was a better method than molecular typing for use in epidemiological investigations based upon the distribution of surface-associated polysaccharide antigens-based phenotypes.


Assuntos
Tipagem Molecular/métodos , Polissacarídeos Bacterianos/metabolismo , Testes Sorológicos/métodos , Staphylococcus aureus/metabolismo , Genótipo , Humanos , Evasão da Resposta Imune/fisiologia , Polissacarídeos Bacterianos/genética , Polissacarídeos Bacterianos/imunologia , Staphylococcus aureus/genética , Staphylococcus aureus/imunologia , Austrália Ocidental
14.
J Basic Microbiol ; 54(7): 721-8, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23686411

RESUMO

The development of persistent antibiotic resistance by human methicillin-sensitive Staphylococcus aureus (MSSA) strains and substantial association with poly-N-acetyl glucosamine (PNAG) in biofilms is reported in this investigation. Sixteen of 31 MSSA strains under study were found to have developed resistance to one or more antibiotics, with four strains, two of which did not produce biofilms, showing resistance to cefoxitin, undetectable by mecA amplification. Antibiotic resistance displayed by 13/14 biofilm-forming S. aureus isolates remained persistent for 4 weeks prior to reverting back to the original antibiotic susceptibility, prompting a suggestion of determining antibiograms for clinical S. aureus isolates subcultured from biofilms developed in vitro as well as planktonic subcultures prepared from the site of infection. While there was correlation of antibiotic resistance with biofilm formation confirming previous reports, this is the first time that persistence of the biofilm-associated antibiotic resistance by S. aureus as planktonic cells is reported. Among the two methods used for assessment of biofilm formation, the tissue culture plate (TCP) method revealed that almost all strains were strong or moderate biofilm producers whereas only 19/31 strains were biofilm producers using the Congo Red agar (CRA) method indicating the superiority of the TCP method in detecting biofilm producers. We also observed no association between biofilm formation and major capsule types. However, substantial, although not absolute, association of biofilm formation with PNAG was observed, warranting continued identification of additional surface-associated polysaccharide and/or protein antigens associated with biofilm formation for development of an effective vaccine against S. aureus infections regardless of capsular phenotype.


Assuntos
Acetilglucosamina/biossíntese , Antibacterianos/farmacologia , Biofilmes/crescimento & desenvolvimento , Cefoxitina/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Aderência Bacteriana/efeitos dos fármacos , Cápsulas Bacterianas/química , Cápsulas Bacterianas/efeitos dos fármacos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biofilmes/efeitos dos fármacos , Farmacorresistência Bacteriana , Expressão Gênica , Humanos , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Testes de Sensibilidade Microbiana , Proteínas de Ligação às Penicilinas , Plâncton/efeitos dos fármacos , Infecções Estafilocócicas/microbiologia
15.
Folia Microbiol (Praha) ; 58(6): 469-74, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23446489

RESUMO

The aim of this investigation was to determine the persistence of biofilm-associated antibiotic resistance developed by methicillin-sensitive Staphylococcus aureus (MSSA), of different capsular types, during biofilm formation. Because of superiority of the tissue culture plate (TCP) over the Congo Red Agar (CRA) method for measuring biofilm formation, it was used to determine the persistence of the antibiotic resistance developed by the isolates in biofilms. The antibiotic resistance was found to persist for 3-4 wk post-propagation as planktonic subcultures. Interestingly, some strains even developed resistance to vancomycin and/or teicoplanin. However, no association of either biofilm formation or persistent antibiotic resistance with the major capsular phenotype was observed. These observations highlight the potential significance of (a) determining the antibiograms of S. aureus subcultured from biofilms developed in vitro using the TCP method as well as from planktonic cultures for formulation of an optimal therapeutic strategy, and (b) continuing to identify predominant non-capsular antigens contributing to biofilm formation, regardless of the capsular phenotype for the development of an effective potentially broad-spectrum vaccine for prevention of bovine mastitis caused by S. aureus.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Farmacorresistência Bacteriana , Mastite Bovina/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/fisiologia , Animais , Austrália , Cápsulas Bacterianas/genética , Proteínas de Bactérias , Bovinos , Genótipo , Testes de Sensibilidade Microbiana , Reação em Cadeia da Polimerase , Staphylococcus aureus/isolamento & purificação
16.
J Microencapsul ; 30(3): 283-94, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-22994538

RESUMO

This study describes the development of a biodegradable nanoparticulate system for the intranasal delivery of multiple proteins. Chitosan (CS)-dextran sulphate (DS) nanoparticles were developed and optimised for the incorporation of pertussis toxin (PTX) and a potential targeting ligand (immunoglobulin-A, IgA). In vitro characterization and in vivo uptake studies were performed for the evaluation of developed nanoparticles. The ratio of CS to DS, the order of mixing and pH of nanoparticle suspension were identified as important formulation factors governing the size and zeta potential of nanoparticles. An optimised CS-DS nanoparticle formulation prepared with the CS to DS weight ratio of 3 : 1 was used to load PTX and/or IgA. Entrapment efficiency of >90% was obtained for both. The in vivo uptake of IgA-loaded CS-DS nanoparticles in mice showed a preferential uptake of nanoparticles probably by nasal membranous or microfold cells following intranasal administration. The results of this study indicate the potential application of IgA-loaded CS-DS nanoparticles as a nasal vaccine delivery system.


Assuntos
Antígenos/administração & dosagem , Sulfato de Dextrana/administração & dosagem , Imunoglobulina A/administração & dosagem , Nanopartículas , Administração Intranasal , Animais , Ensaio de Imunoadsorção Enzimática , Feminino , Concentração de Íons de Hidrogênio , Camundongos , Camundongos Endogâmicos BALB C , Microscopia Eletrônica de Varredura
17.
Mol Med Rep ; 6(1): 9-15, 2012 07.
Artigo em Inglês | MEDLINE | ID: mdl-22576734

RESUMO

RNA interference (RNAi) is a sequence-specific, post-transcriptional gene silencing mechanism in animals and plants, which is mediated by double-stranded RNA (dsRNA). There has recently been an increasing interest in harnessing the gene silencing activity of dsRNA to develop novel drugs for the treatment of various diseases, such as cancer, neurological disorders, age-related macular degeneration and viral infections. Small interfering RNA (siRNA)-based drugs have distinct advantages over conventional small molecule or protein-based drugs, including high specificity, higher potency and reduced toxicity. However, there are several technical obstacles to overcome before siRNA-based drugs reach the clinic. Delivery of siRNA to the target tissues and stability in the serum remain a major challenge and are the main focus of current research and development efforts. This review focused primarily on the progress made in developing RNAi as therapeutics for cancer and the challenges associated with its clinical development. Use of ligands recognizing cell-specific receptors to achieve tumor-specific delivery of siRNA, methods for enhanced siRNA delivery, improving the bioavailability and pharmacokinetic properties of siRNA and reducing the off-target effects and non-specific gene silencing are discussed in the light of current evidence.


Assuntos
Neoplasias/terapia , Interferência de RNA , RNA Interferente Pequeno/uso terapêutico , Animais , Ensaios Clínicos como Assunto , Humanos , Neoplasias/genética , RNA Interferente Pequeno/efeitos adversos , RNA Interferente Pequeno/farmacocinética
18.
J Microbiol Biotechnol ; 22(6): 856-65, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22573165

RESUMO

We describe the construction and immunobiological properties of a novel whooping cough vaccine candidate, in which the aroQ gene, encoding 3-dehydroquinase, was deleted by insertional inactivation using the kanamycin resistance gene cassette and allelic exchange using a Bordetella suicide vector. The aroQ B. pertussis mutant required supplementation of media to grow but failed to grow on an unsupplemented medium. The aroQ B. pertussis mutant was undetectable in the trachea and lungs of mice at days 6 and 12 post-infection, respectively. Antigen-specific antibody isotypes IgG1 and IgG2a, were produced, and cell-mediated immunity [CMI], using interleukin-2 and interferon-gamma as indirect indicators, was induced in mice vaccinated with the aroQ B. pertussis vaccine candidate, which were substantially enhanced upon second exposure to virulent B. pertussis. Interleukin- 12 was also produced in the aroQ B. pertussis-vaccinated mice. On the other hand, neither IgG2a nor CMI-indicator cytokines were produced in DTaP-vaccinated mice, although the CMI-indicator cytokines became detectable post-challenge with virulent B. pertussis. Intranasal immunization with one dose of the aroQ B. pertussis mutant protected vaccinated mice against an intranasal challenge infection, with no pathogen being detected in the lungs of immunized mice by day 7 post-challenge. B. pertussis aroQ thus constitutes a safe, non-reverting, metabolite-deficient vaccine candidate that induces both humoral and cellmediated immune responses with potential for use as a single-dose vaccine in adolescents and adults, in the first instance, with a view to disrupting the transmission cycle of whooping cough to infants and the community.


Assuntos
Bordetella pertussis/imunologia , Vacina contra Coqueluche/imunologia , Coqueluche/prevenção & controle , Administração Intranasal , Animais , Anticorpos Antibacterianos/sangue , Bordetella pertussis/enzimologia , Bordetella pertussis/genética , Bordetella pertussis/patogenicidade , Meios de Cultura/química , Citocinas/metabolismo , Modelos Animais de Doenças , Hidroliases/genética , Hidroliases/metabolismo , Imunoglobulina G/sangue , Leucócitos Mononucleares/imunologia , Pulmão/microbiologia , Camundongos , Mutação , Vacina contra Coqueluche/administração & dosagem , Traqueia/microbiologia , Vacinação/métodos , Vacinas Atenuadas/administração & dosagem , Vacinas Atenuadas/imunologia , Fatores de Virulência/genética , Fatores de Virulência/metabolismo , Coqueluche/imunologia
19.
J Pharm Sci ; 101(1): 233-44, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21953499

RESUMO

The objective of the present study was to evaluate immunological activities of chitosan-dextran sulfate (CS-DS) nanoparticle formulation of pertussis toxoid (PTXd) and its combination with a potential immunological adjuvant, immunoglobulin A (IgA). CS-DS nanoparticles were prepared using a complex coacervation (polyelectrolyte complexation) technique. CS-DS nanoparticle formulations with size and zeta potential in a range of 300-350 nm and +40-+55 mV, respectively, were obtained. An entrapment efficiency of more than 90% was obtained for pertussis toxin and IgA in CS-DS nanoparticles. All loaded nanoparticle formulations showed less than 20% of release within 24 h in in vitro release studies. The immunological evaluation of developed formulations in female Balb/c mice groups showed that the CS-DS nanoparticles formulations induced significantly higher serum IgG and IgG1 titers (p < 0.05) as compared with conventional alum-adjuvanted PTXd formulation administered by subcutaneous route. This study indicated the potential of CS-DS nanoparticles to be a simple and effective particulate delivery system with in-built immunological adjuvant property for acellular protein antigens. The study also revealed the potential important role of IgA-loaded CS-DS nanoparticles as a novel immunological adjuvant for vaccine delivery.


Assuntos
Quitosana/administração & dosagem , Sulfato de Dextrana/administração & dosagem , Imunoglobulina A/administração & dosagem , Imunoglobulina A/imunologia , Nanopartículas/administração & dosagem , Toxoides/imunologia , Adjuvantes Imunológicos/administração & dosagem , Adjuvantes Imunológicos/química , Compostos de Alúmen/administração & dosagem , Compostos de Alúmen/química , Animais , Química Farmacêutica/métodos , Quitosana/química , Quitosana/imunologia , Sulfato de Dextrana/química , Sulfato de Dextrana/imunologia , Portadores de Fármacos/administração & dosagem , Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos/métodos , Feminino , Imunoglobulina A/química , Imunoglobulina G/sangue , Camundongos , Camundongos Endogâmicos BALB C , Nanopartículas/química , Toxoides/antagonistas & inibidores
20.
Hum Vaccin ; 6(7): 543-53, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20448470

RESUMO

Prior to the introduction of killed whole cell pertussis vaccine [wP] in the 1940s, whooping cough was a major cause of infant death worldwide. Widespread vaccination of children with this vaccine caused a significant reduction in mortality. However in the 1990s and now more recently, there has been a resurgence of pertussis in several countries even in populations previously vaccinated with an acellular pertussis vaccine [aP]. In this review, we describe the epidemiology of whooping cough, the vast array of virulence factors produced by this pathogen potentially contributing to the resurgence of pertussis even in previously vaccinated populations of infants and children, history of whooping cough prophylaxis, possible mechanisms of immunity, lack of availability of a suitable non-toxic adjuvant capable of inducing both arms of the immune response, and the current status of development of improved vaccines with potential to induce longer-lasting protection, than is currently possible with the wP or aP vaccines, against whooping cough.


Assuntos
Doenças Transmissíveis Emergentes/epidemiologia , Doenças Transmissíveis Emergentes/prevenção & controle , Vacina contra Coqueluche/efeitos adversos , Vacina contra Coqueluche/imunologia , Coqueluche/epidemiologia , Coqueluche/prevenção & controle , Adjuvantes Imunológicos , Pesquisa Biomédica/tendências , Bordetella pertussis/imunologia , Bordetella pertussis/patogenicidade , Doenças Transmissíveis Emergentes/imunologia , Humanos , Fatores de Virulência/imunologia , Fatores de Virulência/metabolismo , Coqueluche/imunologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...