RESUMO
Corynebacterium diphtheriae, the leading causing agent of diphtheria, has been increasingly related to invasive diseases, including sepsis, endocarditis, pneumonia, and osteomyelitis. Oxidative stress defense is required not only for successful growth and survival under environmental conditions but also in the regulation of virulence mechanisms of human pathogenic species, by promoting mucosal colonization, survival, dissemination, and defense against the innate immune system. OxyR, functioning as a negative and/or positive transcriptional regulator, has been included among the major bacterial coordinators of antioxidant response. OxyR was first reported as a repressor of catalase expression in C. diphtheriae. However, the involvement of OxyR in C. diphtheriae pathogenesis remains unclear. Accordingly, this work aimed to investigate the role of OxyR in mechanisms of host-pathogen interaction of C. diphtheriae through the disruption of the OxyR of the diphtheria toxin (DT)-producing C. diphtheriae CDC-E8392 strain. The effects of OxyR gene disruption were analyzed through interaction assays with human epithelial cell lines (HEp-2 and pneumocytes A549) and by the induction of experimental infections in Caenorhabditis elegans nematodes and Swiss Webster mice. The OxyR disruption exerted influence on NO production and mechanism accountable for the expression of the aggregative-adherence pattern (AA) expressed by CDC-E8392 strain on human epithelial HEp-2 cells. Moreover, invasive potential and intracytoplasmic survival within HEp-2 cells, as well as the arthritogenic potential in mice, were found affected by the OxyR disruption. In conclusion, data suggest that OxyR is implicated in mechanisms of host-pathogen interaction of C. diphtheriae.
Assuntos
Corynebacterium diphtheriae , Difteria , Endocardite , Animais , Corynebacterium diphtheriae/genética , Difteria/microbiologia , Endocardite/microbiologia , Interações Hospedeiro-Patógeno , Camundongos , VirulênciaRESUMO
Diphtheria by Corynebacterium ulcerans is increasingly occurring in children, adolescents and adults. In addition to diphtheria toxin (DT), phospholipase D (PLD) is considered a virulence factor of C. ulcerans. In the present study, a first case of concurrent diphtheria by a PLD-negative C. ulcerans and infectious mononucleosis (IM) was verified. Clinical and microbiological profiles and binding properties to human Fibrinogen (Fbg), Fibronectin (Fn) and type I collagen (col I) biotinylated proteins and virulence to Caenorhabditis elegans were investigated for C. ulcerans strain 2590 (clinical isolate) and two control strains, including PLD-positive BR-AD22 wild type and PLD-negative ELHA-1 PLD mutant strains. MALDI-TOF assays and a multiplex PCR of genes coding for potentially toxigenic corynebacteria identified strain 2590 as non-DT producing. Interestingly, strain 2590 did not express PLD activity in the CAMP test although the presence of the pld gene was verified. PLD-negative 2590 and a PLD-positive 210932 strains showed similar affinity to Fbg, Fn and type I collagen. C. elegans were able to escape from C. ulcerans strains, independent of PLD and DT production. Higher mortality of nematodes was verified for PLD-negative strains. Additional studies concerning multifactorial virulence potential of C. ulcerans, including environmental conditions remain necessary.
Assuntos
Infecções por Corynebacterium/microbiologia , Corynebacterium/isolamento & purificação , Difteria/microbiologia , Mononucleose Infecciosa/microbiologia , Adolescente , Animais , Antibacterianos/farmacologia , Caenorhabditis elegans , Corynebacterium/classificação , Corynebacterium/efeitos dos fármacos , Corynebacterium/genética , Humanos , Masculino , Fosfolipase D/análise , Fosfolipase D/metabolismo , Fatores de Virulência/análise , Fatores de Virulência/metabolismoRESUMO
Corynebacterium ulcerans has been increasingly isolated as an emerging zoonotic agent of diphtheria and other infections from companion animals. Since pets are able to act as symptomless carriers, it is also essential to identify virulence potential for humans of these isolates. In this work the ability of C. ulcerans to bind to fibrinogen (Fbg), fibronectin (Fn) and Type I collagen as well the genetic relationship among strains isolated from human and asymptomatic dogs in Rio de Janeiro (Brazil) were analyzed. Five pulsed-field gel electrophoresis (PFGE) profiles were demonstrated (I, II, III, IV and V). In addition, the IV and V profiles exhibiting ≥85 % similarity were expressed by the BR-AD41 and BR-AD61 strains from companion dogs living in the same neighborhood. Independent of the PFGE-types, human and dog isolates showed affinity to Fbg, Fn and collagen. Heterogeneity of PFGE profiles indicated endemicity of C. ulcerans in the Rio de Janeiro metropolitan area. Differences in the expression of adhesins to the human extracellular matrix may contribute to variations in the virulence and zoonotic potential of C. ulcerans strains.