RESUMO
Exposure of bacteria to low concentrations of biocides can facilitate horizontal gene transfer, which may lead to bacterial adaptive responses and resistance to antimicrobial agents. The emergence of antibacterial resistance not only poses a significant concern to the dairy industry but also adds to the complexity and cost of mastitis treatment. This study was aimed to evaluate how selective stress induced by benzalkonium chloride (BC) promotes antibiotic non-susceptibility in Staphylococcus spp. In addition, we investigated the efficacy of photodynamic inactivation (PDI) in both resistant and susceptible strains. The study determined the minimum inhibitory concentration (MIC) of BC using the broth microdilution method for different Staphylococcus strains. The experiments involved pairing strains carrying the qacA/qacC resistance genes with susceptible strains and exposing them to subinhibitory concentrations of BC for 72 h. The recovered isolates were tested for MIC BC and subjected to disc diffusion tests to assess changes in susceptibility patterns. The results demonstrated that subinhibitory concentrations of BC could select strains with reduced susceptibility and antibiotic resistance, particularly in the presence of S. pasteuri. The results of PDI mediated by toluidine blue (100 µM) followed by 60 min irradiation (total light dose of 2.5 J/cm2) were highly effective, showing complete inactivation for some bacterial strains and a reduction of up to 5 logs in others.
RESUMO
Osteomyelitis caused by Staphylococcus aureus is an important and current health care problem worldwide. Treatment of this infection frequently fails not only due to the increasing incidence of antimicrobial-resistant isolates but also because of the ability of S. aureus to evade the immune system, adapt to the bone microenvironment, and persist within this tissue for decades. We have previously demonstrated the role of staphylococcal protein A (SpA) in the induction of exacerbated osteoclastogenesis and increased bone matrix degradation during osteomyelitis. The aim of this study was to evaluate the potential of using anti-SpA antibodies as an adjunctive therapy to control inflammation and bone damage. By using an experimental in vivo model of osteomyelitis, we demonstrated that the administration of an anti-SpA antibody by the intraperitoneal route prevented excessive inflammatory responses in the bone upon challenge with S. aureus. Ex vivo assays indicated that blocking SpA reduced the priming of osteoclast precursors and their response to RANKL. Moreover, the neutralization of SpA was able to prevent the differentiation and activation of osteoclasts in vivo, leading to reduced expression levels of cathepsin K, reduced expression of markers associated with abnormal bone formation, and decreased trabecular bone loss during osteomyelitis. Taken together, these results demonstrate the feasibility of using anti-SpA antibodies as an antivirulence adjunctive therapy that may prevent the development of pathological conditions that not only damage the bone but also favor bacterial escape from antimicrobials and the immune system.
Assuntos
Osteomielite , Infecções Estafilocócicas , Humanos , Osteoclastos/metabolismo , Osteoclastos/patologia , Staphylococcus aureus , Proteína Estafilocócica A/metabolismo , Osteomielite/tratamento farmacológico , Osteomielite/microbiologia , Osteogênese , Infecções Estafilocócicas/microbiologiaRESUMO
Bovine mastitis is a disease of dairy cattle prevalent throughout the world that causes alterations in the quality and composition of milk, compromising technological performance. Staphylococcus aureus is one of the most important pathogens that produce clinical, subclinical, and chronic mastitis. Biofilms are considered a virulence factor necessary for the survival of S. aureus in the mammary gland. Its zoonotic potential is important not only for the dairy industry sector but also for public health. This study aimed to evaluate the effect of different growing culture conditions on the biofilm formation of S. aureus isolated from mastitis and to test the MALDI-TOF-MS's ability to discriminate among different biofilm formation levels. Fluids commonly found in the dairy environment were incorporated to approach the pathogen's behavior in natural surroundings. PIA production was also evaluated. All strains were able to form high biofilms in TSB, TSBg, and milk. Milk changed the behavior of some strains which formed more biofilms in this medium than in TSBg. The free iron medium CTSBg and milk whey inhibited the biofilm formation of the most strains. MALDI-TOF-MS performance was an excellent tool to discriminate between high, moderate, and low biofilm producers strains of S. aureus in each media, confirming the results of crystal violet assay. PIA production was variable among the strains and showed a media-dependent behavior. Our data highlights the importance of considering the growing conditions that mimic the natural ones to the study of biofilm formation in vitro.
RESUMO
Salicylic acid (SAL) has recently been shown to induce biofilm formation in Staphylococcus aureus and to affect the expression of virulence factors. This study was aimed to investigate the effect of SAL on the regulatory agr system and its impact on S. aureus biofilm formation. The agr quorum-sensing system, which is a central regulator in S. aureus pathogenicity, plays a pivotal role in the dispersal of S. aureus mature biofilms and contributes to the creation of new colonization sites. Here, we demonstrate that SAL impairs biofilm dispersal by interfering with agr expression. As revealed by our work, protease and surfactant molecule production is diminished, and bacterial cell autolysis is also negatively affected by SAL. Furthermore, as a consequence of SAL treatment, the S. aureus biofilm matrix revealed the lack of extracellular DNA. In silico docking and simulation of molecular dynamics provided evidence for a potential interaction of AgrA and SAL, resulting in reduced activity of the agr system. In conclusion, SAL stabilized the mature S. aureus biofilms, which may prevent bacterial cell dissemination. However, it may foster the establishment of infections locally and consequently increase bacterial persistence leading to therapeutic failure.
Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Ácido Salicílico/farmacologia , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/patogenicidade , Antibacterianos/uso terapêutico , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Farmacorresistência Bacteriana , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Humanos , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Percepção de Quorum/efeitos dos fármacos , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Transativadores/genética , Transativadores/metabolismo , Fatores de Virulência/genética , Fatores de Virulência/metabolismoRESUMO
Selection pressures exerted on Staphylococcus aureus by host factors during infection may lead to the emergence of regulatory phenotypes better adapted to the infection site. Traits convenient for persistence may be fixed by mutation thus turning these mutants into microevolution endpoints. The feasibility that stable, non-encapsulated S. aureus mutants can regain expression of key virulence factors for survival in the bloodstream was investigated. S. aureus agr mutant HU-14 (IS256 insertion in agrC) from a patient with chronic osteomyelitis was passed through the bloodstream using a bacteriemia mouse model and derivative P3.1 was obtained. Although IS256 remained inserted in agrC, P3.1 regained production of capsular polysaccharide type 5 (CP5) and staphyloxanthin. Furthermore, P3.1 expressed higher levels of asp23/SigB when compared with parental strain HU-14. Strain P3.1 displayed decreased osteoclastogenesis capacity, thus indicating decreased adaptability to bone compared with strain HU-14 and exhibited a trend to be more virulent than parental strain HU-14. Strain P3.1 exhibited the loss of one IS256 copy, which was originally located in the HU-14 noncoding region between dnaG (DNA primase) and rpoD (sigA). This loss may be associated with the observed phenotype change but the mechanism remains unknown. In conclusion, S. aureus organisms that escape the infected bone may recover the expression of key virulence factors through a rapid microevolution pathway involving SigB regulation of key virulence factors.
Assuntos
Cápsulas Bacterianas/metabolismo , Proteínas de Bactérias/genética , Staphylococcus aureus/genética , Transativadores/genética , Xantofilas/metabolismo , Adulto , Animais , Antibacterianos/farmacologia , Bacteriemia/microbiologia , Cápsulas Bacterianas/genética , Modelos Animais de Doenças , Farmacorresistência Bacteriana Múltipla/genética , Regulação Bacteriana da Expressão Gênica/genética , Humanos , Masculino , Camundongos , Osteomielite/microbiologia , Deleção de Sequência/genética , Staphylococcus aureus/isolamento & purificação , Staphylococcus aureus/patogenicidade , Virulência/genética , Fatores de Virulência/genéticaRESUMO
Selection pressures exerted on Staphylococcus aureus by host factors may lead to the emergence of mutants better adapted to the evolving conditions at the infection site. This study was aimed at identifying the changes that occur in S. aureus exposed to the host defense mechanisms during chronic osteomyelitis and evaluating whether these changes affect the virulence of the organism. Genome assessment of two S. aureus isolates collected 13 months apart (HU-85a and HU-85c) from a host with chronic osteomyelitis was made by whole genome sequencing. Agr functionality was assessed by qRT-PCR. Isolates were tested in a rat model of osteomyelitis and the bacterial load (CFU/tibia) and the morphometric osteomyelitic index (OI) were determined. The ability of the isolates to trigger the release of proinflammatory cytokines was determined on macrophages in culture. Persistence of S. aureus within the host resulted in an agrC frameshift mutation that likely led to the observed phenotype. The capacity to cause bone tissue damage and trigger proinflammatory cytokines by macrophages of the agr-deficient, unencapsulated derivative (HU-85c) was decreased when compared with those of the isogenic CP8-capsulated parental strain (HU-85a). By comparison, no significant differences were found in the bacterial load or the OI from rats challenged with isogenic Reynolds strains [CP5, CP8, and non-typeable (NT)], indicating that lack of CP expression alone was not likely responsible for the reduced capacity to cause tissue damage in HU-85c compared with HU-85a. The production of biofilm was significantly increased in the isogenic derivative HU-85c. Lack of agr-dependent factors makes S. aureus less virulent during chronic osteomyelitis and alteration of the agr functionality seems to permit better adaptation of S. aureus to the chronically infected host.
Assuntos
Adaptação Biológica/genética , Proteínas de Bactérias/genética , Interações Hospedeiro-Patógeno , Mutação , Osteomielite/microbiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/fisiologia , Transativadores/genética , Animais , Carga Bacteriana , Biofilmes , Doença Crônica , Citocinas/metabolismo , Modelos Animais de Doenças , Suscetibilidade a Doenças , Humanos , Macrófagos/imunologia , Macrófagos/metabolismo , Masculino , Ratos , Adulto JovemRESUMO
Community-acquired methicillin resistant Staphylococcus aureus emerged as a worldwide health problem in the last few years. In Argentina, it is found in 70% of skin and skin structure infections in previously healthy adult patients and causes severe invasive diseases. The ST30-SCCmecIVc-spat019 clone is predominant in adult infections and has displaced the previously prevalent ST5-SCCmecIVa-spat311 clone in community settings. In the present work we compared the virulence of both clones in order to explain the displacement, and found that ST30-IVc is associated with invasive infections in adult patients from Argentina and possesses a different virulence-associated genes profile compared to ST5-IVa. A representative strain of ST30 lineage has a more aggressive behavior in animal models of infection and expresses higher level of Fibronectin binding protein A coding gene, which could enhance the bacterial invasion capacity.
Assuntos
Proteínas de Bactérias/genética , Staphylococcus aureus Resistente à Meticilina/genética , Fatores de Virulência/genética , Adesinas Bacterianas/genética , Adesinas Bacterianas/metabolismo , Animais , Argentina , Proteínas de Bactérias/metabolismo , Contagem de Colônia Microbiana , Infecção Hospitalar/microbiologia , Modelos Animais de Doenças , Feminino , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Camundongos , Camundongos Endogâmicos BALB C , Estudos Multicêntricos como Assunto , Ratos , Ratos Wistar , Infecções Respiratórias/microbiologia , Infecções Cutâneas Estafilocócicas/microbiologiaRESUMO
Aspirin has provided clear benefits to human health. But salicylic acid (SAL) -the main aspirin biometabolite- exerts several effects on eukaryote and prokaryote cells. SAL can affect, for instance, the expression of Staphylococcus aureus virulence factors. SAL can also form complexes with iron cations and it has been shown that different iron chelating molecules diminished the formation of S. aureus biofilm. The aim of this study was to elucidate whether the iron content limitation caused by SAL can modify the S. aureus metabolism and/or metabolic regulators thus changing the expression of the main polysaccharides involved in biofilm formation. The exposure of biofilm to 2 mM SAL induced a 27% reduction in the intracellular free Fe2+ concentration compared with the controls. In addition, SAL depleted 23% of the available free Fe2+ cation in culture media. These moderate iron-limited conditions promoted an intensification of biofilms formed by strain Newman and by S. aureus clinical isolates related to the USA300 and USA100 clones. The slight decrease in iron bioavailability generated by SAL was enough to induce the increase of PIA expression in biofilms formed by methicillin-resistant as well as methicillin-sensitive S. aureus strains. S. aureus did not produce capsular polysaccharide (CP) when it was forming biofilms under any of the experimental conditions tested. Furthermore, SAL diminished aconitase activity and stimulated the lactic fermentation pathway in bacteria forming biofilms. The polysaccharide composition of S. aureus biofilms was examined and FTIR spectroscopic analysis revealed a clear impact of SAL in a codY-dependent manner. Moreover, SAL negatively affected codY transcription in mature biofilms thus relieving the CodY repression of the ica operon. Treatment of mice with SAL induced a significant increase of S aureus colonization. It is suggested that the elevated PIA expression induced by SAL might be responsible for the high nasal colonization observed in mice. SAL-induced biofilms may contribute to S. aureus infection persistence in vegetarian individuals as well as in patients that frequently consume aspirin.
RESUMO
Interleukin 1 (IL-1) ß is a critical cytokine that orchestrates host defenses against Staphylococcus aureus and is crucial for the eradication of bacteria. The production and action of IL-1ß are regulated by multiple control pathways. Among them, IL-1RII (the type II IL-1 receptor) acts as a decoy receptor and has been shown to regulate the biological effects of IL-1ß. High levels of soluble IL-1RII are present in septic patients; however, the stimuli that regulate the expression and release of IL-1RII in pathological conditions are incompletely elucidated. In the present study, we demonstrated the ability of S. aureus and protein A to induce IL-1RII shedding in myeloid cells. The positive modulation of IL-1RII expression and cleavage was associated with the failure to detect IL-1ß in response to S. aureus both in vitro and in vivo, suggesting that the soluble form of the receptor could be masking the availability of IL-1ß. The absence of detectable IL-1ß was associated with low levels of inflammatory cytokines and chemokines known to be regulated by IL-1ß and with increased bacterial persistence. Modulation of decoy receptors during systemic S. aureus infection is proposed as a new strategy used by this bacterium to evade the immune response.
Assuntos
Interleucina-1beta/imunologia , Monócitos/imunologia , Neutrófilos/imunologia , Receptores Tipo II de Interleucina-1/metabolismo , Sepse/imunologia , Infecções Estafilocócicas/imunologia , Staphylococcus aureus/imunologia , Animais , Linhagem Celular , Regulação da Expressão Gênica , Humanos , Evasão da Resposta Imune , Mediadores da Inflamação/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Monócitos/microbiologia , Neutrófilos/microbiologia , Proteólise , Receptores Tipo II de Interleucina-1/genética , Proteína Estafilocócica A/imunologiaRESUMO
Staphylococcus aureus is an invasive bacterial pathogen, and antibiotic resistance has impeded adequate control of infections caused by this microbe. Moreover, efforts to prevent human infections with single-component S. aureus vaccines have failed. In this study, we evaluated the protective efficacy in rats of vaccines containing both S. aureus capsular polysaccharides (CPs) and proteins. The serotypes 5 CP (CP5) and 8 CP (CP8) were conjugated to tetanus toxoid and administered to rats alone or together with domain A of clumping factor A (ClfA) or genetically detoxified alpha-toxin (dHla). The vaccines were delivered according to a preventive or a therapeutic regimen, and their protective efficacy was evaluated in a rat model of osteomyelitis. Addition of dHla (but not ClfA) to the CP5 or CP8 vaccine induced reductions in bacterial load and bone morphological changes compared with immunization with either conjugate vaccine alone. Both the prophylactic and therapeutic regimens were protective. Immunization with dHla together with a pneumococcal conjugate vaccine used as a control did not reduce staphylococcal osteomyelitis. The emergence of unencapsulated or small-colony variants during infection was negligible and similar for all of the vaccine groups. In conclusion, addition of dHla to a CP5 or CP8 conjugate vaccine enhanced its efficacy against S. aureus osteomyelitis, indicating that the inclusion of multiple antigens will likely enhance the efficacy of vaccines against both chronic and acute forms of staphylococcal disease.
Assuntos
Antígenos de Bactérias/imunologia , Cápsulas Bacterianas/imunologia , Osteomielite/prevenção & controle , Infecções Estafilocócicas/prevenção & controle , Vacinas Antiestafilocócicas/imunologia , Staphylococcus aureus/imunologia , Animais , Anticorpos Antibacterianos/imunologia , Antígenos de Bactérias/administração & dosagem , Proteínas de Bactérias/administração & dosagem , Proteínas de Bactérias/imunologia , Modelos Animais de Doenças , Osteomielite/imunologia , Osteomielite/microbiologia , Ratos , Ratos Wistar , Infecções Estafilocócicas/imunologia , Infecções Estafilocócicas/microbiologia , Vacinas Antiestafilocócicas/administração & dosagem , Vacinas Conjugadas/administração & dosagem , Vacinas Conjugadas/imunologiaRESUMO
Staphylococcus aureus infections are an important public health concern due to their increasing incidence and high rates of mortality. The success of S. aureus as a pathogen is highly related to its enormous capacity to evade the host immune response. The critical role of tumor necrosis factor alpha (TNF-α) in the initial host defense against systemic staphylococcal infection has been demonstrated in experimental models and may partially explain the lack of significant benefits observed in clinical trials attempting to neutralize this cytokine in septic patients. S. aureus protein A plays a key role in regulating inflammation through its ability to bind and signal through the TNF-α receptor 1 (TNFR1). In this study, we demonstrate that S. aureus, via protein A-mediated signaling, induces early shedding of TNFR1, which precedes the secretion of TNF-α in vitro and in vivo. The results obtained using a protein A-deficient mutant and tnfr1(-/-) mice strongly suggest that the increased levels of soluble TNFR1 present during experimental S. aureus infection may neutralize circulating TNF-α and impair the host inflammatory response. Early shedding of TNFR1 induced by protein A may constitute a novel mechanism by which S. aureus subverts the host immune response.
Assuntos
Receptores Tipo I de Fatores de Necrose Tumoral/metabolismo , Sepse/imunologia , Infecções Estafilocócicas/imunologia , Proteína Estafilocócica A/metabolismo , Staphylococcus aureus/imunologia , Fator de Necrose Tumoral alfa/imunologia , Fatores de Virulência/metabolismo , Animais , Linhagem Celular , Humanos , Evasão da Resposta Imune , Macrófagos/imunologia , Macrófagos/microbiologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Sepse/microbiologia , Staphylococcus aureus/patogenicidadeRESUMO
Staphylococcus aureus nasal carriage is a risk factor for individuals suffering from trauma, surgical procedures, invasive devices, and/or decreased immunity. Recently, we demonstrated that artificial nasal colonization with an attenuated S. aureus mutant reduced by bacterial interference with the colonization of pathogenic strains of S. aureus. This could be an optional tool to diminish the rate of S. aureus infections in hospitalized patients. The aim of this study was to construct a safe ΔaroA mutant of S. aureus and to discriminate it from nasal colonizing and osteomyelitis S. aureus isolates by SmaI pulsed-field gel electrophoresis (PFGE) typing. The ΔaroA mutant, named RD17, exhibited an LD(50) (3.2 × 10(6) colony-forming unit (CFU)) significantly higher than that of the parental strain (2.2 × 10(3) CFU). The colony number of the RD17 mutants recovered from nares of leukopenic mice was similar to that observed in the animals of the control group. Therefore, the ΔaroA mutant was demonstrated to be safe due to maintaining low growth levels in the nares regardless of immune status of the animals. PFGE typing allowed the unequivocal identification of the S. aureus and differentiation of aroA mutants in nasal colonizing and osteomyelitis isolates. This information could be important to discriminate endogenous infections from laboratory strains of S. aureus.
RESUMO
Staphylococcus aureus protein A (SpA) plays a critical role in the induction of inflammation. This study was aimed to determine whether the number of short sequence repeats (SSRs) present in the polymorphic region modulates the inflammatory response induced by SpA. We demonstrated that there is a dose-response effect in the activation of interferon (IFN)-ß signaling in airway epithelial and immune cells, depending on the number of SSRs, which leads to differences in neutrophil recruitment. We also determined that a significant proportion of isolates from patients with chronic infections such as osteomyelitis and cystic fibrosis carry fewer SSRs than do isolates from patients with acute infections or healthy carriers and that there was an inverse correlation between the number of SSRs and the length of disease course. Given the importance of IFN signaling in eradication of S. aureus, loss of SSRs may represent an advantageous mechanism to adapt to and persist in the host.
Assuntos
Inflamação/genética , Infecções Estafilocócicas/microbiologia , Proteína Estafilocócica A/metabolismo , Adolescente , Adulto , Animais , Linhagem Celular , Criança , Pré-Escolar , Doença Crônica , Fibrose Cística/genética , Fibrose Cística/imunologia , Fibrose Cística/metabolismo , Fibrose Cística/microbiologia , Relação Dose-Resposta Imunológica , Humanos , Lactente , Inflamação/imunologia , Inflamação/metabolismo , Inflamação/microbiologia , Interferon beta/imunologia , Interferon beta/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Repetições de Microssatélites , Infiltração de Neutrófilos/genética , Infiltração de Neutrófilos/imunologia , Osteomielite/genética , Osteomielite/imunologia , Osteomielite/metabolismo , Osteomielite/microbiologia , Polimorfismo Genético , Mucosa Respiratória/imunologia , Mucosa Respiratória/microbiologia , Infecções Estafilocócicas/genética , Infecções Estafilocócicas/imunologia , Infecções Estafilocócicas/metabolismo , Proteína Estafilocócica A/genética , Proteína Estafilocócica A/imunologia , Staphylococcus aureus/genética , Staphylococcus aureus/metabolismo , Adulto JovemRESUMO
The aim of this study was to analyze the prevalence of Staphylococcus aureus and Candida species in samples of nasal mucosa from 100 immunocompetent subjects of both sexes, aged 18-70 years, during stomatological clinical examination. Samples were taken from the mucosa of both nasal fossae using sterile swabs. Samples were observed fresh, stained with Gram and Giemsa, and cultured on selective differential media at 37 degrees C to isolate and identify the selected microorganisms; conventional biochemical tests and commercial equipment and molecular studies using PCR were performed. A digital thermometer-hygrometer was used to measure room temperature at the time of sampling, which was on average 25 +/- 2 degrees C, with relative ambient humidity 66 +/- 11%. S. aureus was isolated from 38% of the samples; 4% of the samples were methicillin-resistant (MRSA) strains, with 2% identified genetically as community-acquired (CA-MRSA) and 2% as hospital-acquired (HA-MRSA). Candida was identified in 23% of the samples, with prevalence of C. albicans (19%) followed by C. dubliniensis (3%) and C. krusei (1%). There was significant association between Candida and S. aureus (Chi-squared = 27.75; df = 1; (p < 0.001). The nasal cavity is a reservoir and the identification of genus and species contributes to adequate epidemiological surveillance.
Assuntos
Candida/isolamento & purificação , Portador Sadio , Imunocompetência , Nariz/microbiologia , Staphylococcus aureus/isolamento & purificação , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
El propósito de este trabajo fue analizar la prevalencia de Staphylococcus aureus y especies de Candida en muestras demucosa nasal de 100 individuos inmunocompetentes de ambos sexos con edades entre 18-70 años, durante el examen clínico estomatológico. Las muestras fueron obtenidas con hisoposestériles sobre la mucosa de ambas fosas nasales. Se realizó observación en fresco, tinción de Gram, Giemsa y cultivos en medios selectivos y diferenciales a 37ºC para el aislamiento e identificación de los microorganismos seleccionados, pruebas bioquímicas convencionales y equipos comerciales y estudios moleculares mediante la prueba de PCR. Con un termo higrómetro digital se midió la temperatura ambiente cuyo promedio en el momento de la toma en el consultoriofue de 25±2 oC y la humedad relativa ambiente fue del 66±11 por ciento.S aureus se aisló en el 38 por ciento de las muestras y dentro del mismo, 4 por ciento fueron meticilino resistentes (MRSA) siendo genéticamente 2 por ciento de la Comunidad (MRSA-CA) y 2 por ciento Hospitalarios (MRSA-HA).En el 23 por ciento de las muestras fue identificada Candida siendo la especie prevalente C. albicans: 19 por ciento y en menor proporción C. dubliniensis: 3 opr ciento , C. krusei: 1 por ciento. Se registró una asociación significativa entre Candida y S. aureus (Chi-cuadrado=27,75; gl=1; (p<0,001). La cavidad nasal constituye un reservorio yla identificación de género y especie contribuye a la adecuada vigilancia epidemiológica.
Assuntos
Humanos , Masculino , Adolescente , Adulto , Feminino , Pessoa de Meia-Idade , Candida/crescimento & desenvolvimento , Cavidade Nasal/microbiologia , Hospedeiro Imunocomprometido , Staphylococcus aureus/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Meios de Cultura , Reação em Cadeia da Polimerase/métodos , Interpretação Estatística de DadosRESUMO
El propósito de este trabajo fue analizar la prevalencia de Staphylococcus aureus y especies de Candida en muestras demucosa nasal de 100 individuos inmunocompetentes de ambos sexos con edades entre 18-70 años, durante el examen clínico estomatológico. Las muestras fueron obtenidas con hisoposestériles sobre la mucosa de ambas fosas nasales. Se realizó observación en fresco, tinción de Gram, Giemsa y cultivos en medios selectivos y diferenciales a 37ºC para el aislamiento e identificación de los microorganismos seleccionados, pruebas bioquímicas convencionales y equipos comerciales y estudios moleculares mediante la prueba de PCR. Con un termo higrómetro digital se midió la temperatura ambiente cuyo promedio en el momento de la toma en el consultoriofue de 25±2 oC y la humedad relativa ambiente fue del 66±11 por ciento.S aureus se aisló en el 38 por ciento de las muestras y dentro del mismo, 4 por ciento fueron meticilino resistentes (MRSA) siendo genéticamente 2 por ciento de la Comunidad (MRSA-CA) y 2 por ciento Hospitalarios (MRSA-HA).En el 23 por ciento de las muestras fue identificada Candida siendo la especie prevalente C. albicans: 19 por ciento y en menor proporción C. dubliniensis: 3 opr ciento , C. krusei: 1 por ciento. Se registró una asociación significativa entre Candida y S. aureus (Chi-cuadrado=27,75; gl=1; (p<0,001). La cavidad nasal constituye un reservorio yla identificación de género y especie contribuye a la adecuada vigilancia epidemiológica.(AU)
Assuntos
Humanos , Masculino , Adolescente , Adulto , Feminino , Pessoa de Meia-Idade , Idoso , Candida/crescimento & desenvolvimento , Cavidade Nasal/microbiologia , Staphylococcus aureus/crescimento & desenvolvimento , Hospedeiro Imunocomprometido , Meios de Cultura , Reação em Cadeia da Polimerase/métodos , Interpretação Estatística de Dados , Contagem de Colônia MicrobianaRESUMO
One of the virulence factors required by Staphylococcus aureus at the early stages of infection is Eap, a secreted adhesin that binds many host proteins and is upregulated by the two-component regulatory system saeRS. The S. aureus Newman strain harbors a mutation in saeS that is thought to be responsible for the high level of Eap expression in this strain. This study was designed to ascertain whether salicylic acid (SAL) affects the expression of Eap and the internalization of S. aureus into epithelial cells. The strain Newman treated with SAL exhibited increased levels of eap transcription and protein expression. Furthermore, SAL treatment increased the eap promoter activity. SAL treatment enhanced Eap expression in the Newman and in other S. aureus strains that do not carry the mutation in saeS. Internalization of S. aureus eap and sae mutants into the MAC-T epithelial cells was significantly decreased compared with the wild-type counterparts. In conclusion, we demonstrated that a low concentration of SAL increased S. aureus Eap expression possibly due to enhancement of sae. SAL may create the conditions for S. aureus persistence in the host, not only by decreasing the capsular polysaccharide expression as shown before, but also by enhancing Eap expression.
Assuntos
Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Proteínas de Ligação a RNA/metabolismo , Ácido Salicílico/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/fisiologia , Animais , Proteínas de Bactérias/genética , Bovinos , Linhagem Celular , Células Epiteliais/microbiologia , Feminino , Mutação , Regiões Promotoras Genéticas/genética , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , RNA Bacteriano/genética , RNA Mensageiro/genética , Proteínas de Ligação a RNA/genética , Análise de Sequência de DNA , Especificidade da Espécie , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Staphylococcus aureus/genética , Fatores de Transcrição , Fatores de Virulência/genética , Fatores de Virulência/metabolismoRESUMO
Staphylococcus aureus nasal carriage is a risk factor for infection in humans, particularly in the hospital setting. Bacterial interference was used as an alternative strategy for the prevention of upper respiratory, urogenital and gastrointestinal tract infections. This study was designed to assess if the administration of a live-attenuated aroA mutant of S. aureus is useful as a potential approach to prevent transient staphylococcal nasal carriage by virulent strains. We constructed an aroA mutant of S. aureus Newman strain by homologous recombination. The auxotrophic NK41 mutant was attenuated as determined by the increase of the LD(50) after intraperitoneal challenge. In mice, previous nasal colonization with the NK41 mutant significantly reduced the number of CFU of S. aureus (HU-71 and Hde288) clinical isolates and the parental Newman strain. The NK41 mutant was unable to induce a pro-inflammatory response and to damage the invaded human respiratory epithelial cells. Moreover, the cells previously or simultaneously infected with the NK41 mutant were invaded by virulent strains in a significantly lower degree than those of the control group. In conclusion, the attenuated NK41 mutant interfered with the colonization and establishment of pathogenic strains of S. aureus, which produce severe infections.
Assuntos
Antibiose/fisiologia , Células Epiteliais/microbiologia , Mucosa Nasal/microbiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/fisiologia , Aminoácidos Aromáticos/biossíntese , Aminoácidos Aromáticos/genética , Animais , Linhagem Celular , Células Cultivadas , Ciclo-Oxigenase 2/metabolismo , Citocinas/genética , Teste de Complementação Genética , Humanos , Dose Letal Mediana , Masculino , Camundongos , Mutação , Recombinação Genética , Staphylococcus aureus/genética , Staphylococcus aureus/patogenicidade , VirulênciaRESUMO
Capsular polysaccharides (CP) of serotypes 5 (CP5) and 8 (CP8) are major Staphylococcus aureus virulence factors. Previous studies have shown that salicylic acid (SAL), the main aspirin metabolite, affects the expression of certain bacterial virulence factors. In the present study, we found that S. aureus strain Reynolds (CP5) cultured with SAL was internalized by MAC-T cells in larger numbers than strain Reynolds organisms not exposed to SAL. Furthermore, the internalization of the isogenic nonencapsulated Reynolds strain into MAC-T cells was not significantly affected by preexposure to SAL. Pretreatment of S. aureus strain Newman with SAL also enhanced internalization into MAC-T cells compared with that of untreated control strains. Using strain Newman organisms, we evaluated the activity of the major cap5 promoter, which was significantly decreased upon preexposure to SAL. Diminished transcription of mgrA and upregulation of the saeRS transcript, both global regulators of CP expression, were found in S. aureus cultured in the presence of SAL, as ascertained by real-time PCR analysis. In addition, CP5 production by S. aureus Newman was also decreased by treatment with SAL. Collectively, our data demonstrate that exposure of encapsulated S. aureus strains to low concentrations of SAL reduced CP production, thus unmasking surface adhesins and leading to an increased capacity of staphylococci to invade epithelial cells. The high capacity of internalization of the encapsulated S. aureus strains induced by SAL pretreatment may contribute to the persistence of bacteria in certain hosts.
Assuntos
Cápsulas Bacterianas/metabolismo , Inibidores Enzimáticos/farmacologia , Ácido Salicílico/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Fatores de Virulência/antagonistas & inibidores , Proteínas de Bactérias/biossíntese , Linhagem Celular , Células Epiteliais/microbiologia , Perfilação da Expressão Gênica , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Humanos , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
We analyzed 90 nonduplicates community-associated methicillin-resistant S. aureus (CA-MRSA) strains isolated from skin and soft-tissue infections. All strains were mecA positive. Twenty-four of the 90 strains showed inducible macrolide-lincosamide-streptogramin B resistance. All strains produced alpha-toxin; 96% and 100% of them displayed positive results for lukS-F and cna genes, respectively. Eigthy-five strains expressed capsular polysaccharide serotype 8. Six different pulsotypes were discriminated by pulsed-field gel electrophoresis (PFGE) and three predominant groups of CA-MRSA strains (1, 2, and 4) were identified, in agreement with phenotypic and genotypic characteristics. Strains of group 1 (pulsotype A, CP8+, and Panton-Valentine leukocidin (PVL)+) were the most frequently recovered and exhibited a PFGE band pattern identical to other CA-MRSA strains previously isolated in Uruguay and Brazil. Three years after the first local CA-MRSA report, these strains are still producing skin and soft-tissue infections demonstrating the stability over time of this community-associated emerging pathogen.