Clinical and Epidemiological Assessment of Children and Adolescents Hospitalized with SARS-CoV-2 in the Pre-Amazon Region.

INTRODUCTION: SARS-CoV-2 infection usually presents similarly to other respiratory viral pathogens. Children and adolescents do not present as a group that is highly affected by the disease, having low infection rates. However, limited publications are associated with the findings of pneumonia in pediatric patients with COVID-19. OBJECTIVE: To analyze the clinical and epidemiological aspects of children and adolescents hospitalized with SARS-CoV-2 in a pre-Amazon region. METHODS: A retrospective study, carried out in four public hospitals in São Luís, Brazil where medical records of children and adolescents aged from 0 to 13 years, of both sexes, with clinical diagnosis of community-acquired pneumonia were evaluated from March 2020 to March 2021. RESULTS: Almost 40.0% of children were aged between 1 year and 5 years. Of the 128 children who had SARS-CoV-2, 3 are of indigenous ethnicity. Additionally, 78.6% of the children had fever and there was no significant difference between COVID-19 patients and those of other respiratory viruses. Eighteen patients had chronic neurological disease, which is the most common comorbidity observed in patients with coronavirus infection. Ground glass opacity attenuation was observed in 24.8% of children and adolescents with COVID-19. Anemia and increased inflammatory response markers were related to SARS-CoV-2 infection. More than 90.0% of patients admitted to hospital, regardless of etiology, were treated with antibiotics. Eighteen patients died. Pediatric multisystem inflammatory syndrome (PMIS) was diagnosed in 17 patients. CONCLUSIONS: SARS-CoV-2 in children and adolescents is mild, but the condition of patients with PMIS is more serious, with an increase in inflammatory biomarkers which can lead to death. Therefore, rapid diagnosis and differentiation of agents causing respiratory diseases are necessary for better therapeutic decision making, since the results of this study make us question the excessive use of antibiotics without meeting well-defined clinical-epidemiological criteria.

Ocorrência de enteroparasitas antes e durante a pandemia da COVID-19 em Nina Rodrigues, Maranhão - Brasil / Occurrence of enteroparasites before and during the COVID-19 pandemic in Nina Rodrigues, Maranhão, Brazil

Parasitoses intestinais são infecções no trato gastrointestinal, por protozoários e/ou helmintos e representam um agravo à saúde pública, mas apesar dessa problemática, foram notificadas menos do que seria esperado devido a pandemia da COVID-19. O objetivo desse estudo foi verificar a ocorrência de enteroparasitas antes e durante a pandemia da COVID-19 em pacientes atendidos no laboratório do hospital de Nina Rodrigues, Maranhão. Foi realizado um estudo tranversal, descritivo e quantitativo, sendo analisados os exames dos anos de 2019 e 2020, coletados do banco de informações do hospital em agosto de 2021. Os dados foram inseridos no programa STATA 14.0 para análise. Em 2019 foram realizados 632 exames, e 2020 um total de 161, as mulheres e os adultos de meia idade (31-59 anos) foram os que mais realizaram exames, em relação aos laudos positivos, 18,51% e 26,09% apresentavam pelo menos um tipo de parasita em 2019 e 2020, respectivamente. O parasita mais ocorrente foi Entamoeba coli e 66,48% dos laudos tinham a presença de mais de um parasita, sendo a associação mais observada E. coli + Entamoeba histolytica. Nota-se que apesar do período pandêmico de 2020 ter sido realizado menos exames parasitológicos de fezes em comparação o período de 2019, é possível constatar que há uma ocorrência razoável de enteroparasitas na população de Nina Rodrigues, com um alto índice de indivíduos com biparasitismo. Assim, torna-se necessário a implementação de medidas que visem o diagnóstico e o tratamento dos infectados, e medidas de prevenção para minimizar a transmissão.

Intestinal parasites are infections in the gastrointestinal tract, by protozoa and/or helminths and represent a public health problem, but despite this problem, less were reported than would be expected due to the COVID-19 pandemic. The objective of this study was to verify the occurrence of enteroparasites before and during the COVID-19 pandemic in patients treated at the laboratory of the Nina Rodrigues hospital, Maranhão. A cross-sectional, descriptive, and quantitative study was carried out, analyzing the exams from the years 2019 and 2020, collected from the hospital's information bank in August 2021. The data were entered into the STATA 14.0 program for analysis. In 2019, 632 exams were performed, and in 2020 a total of 161, women and middle-aged adults (31-59 years old) were the ones who most underwent exams, in relation to positive reports, 18.51% and 26.09% had at least one type of parasite in 2019 and 2020, respectively. The most frequent parasite was Entamoeba coli and 66.48% of the reports had the presence of more than one parasite, the most observed association being E. coli + Entamoeba histolytica. It is noted that despite the 2020 pandemic period, fewer fecal parasitological tests were performed compared to the 2019 period, it is possible to verify that there is a reasonable occurrence of enteroparasites in the population of Nina Rodrigues, with a high rate of individuals with biparasitism. Thus, it is necessary to implement measures aimed at diagnosing and treating those infected, and preventive measures to minimize transmission.

Corynebacterium diphtheriae putative tellurite-resistance protein (CDCE8392_0813) contributes to the intracellular survival in human epithelial cells and lethality of Caenorhabditis elegans

Corynebacterium diphtheriae, the aetiologic agent of diphtheria, also represents a global medical challenge because of the existence of invasive strains as causative agents of systemic infections. Although tellurite (TeO3^2-) is toxic to most microorganisms, TeO3^2--resistant bacteria, including C. diphtheriae, exist in nature. The presence of TeO3^2--resistance (Te^R) determinants in pathogenic bacteria might provide selective advantages in the natural environment. In the present study, we investigated the role of the putative Te^R determinant (CDCE8392_813gene) in the virulence attributes of diphtheria bacilli. The disruption of CDCE8392_0813 gene expression in the LDCIC-L1 mutant increased susceptibility to TeO3^2- and reactive oxygen species (hydrogen peroxide), but not to other antimicrobial agents. The LDCIC-L1 mutant also showed a decrease in both the lethality of Caenorhabditis elegansand the survival inside of human epithelial cells compared to wild-type strain. Conversely, the haemagglutinating activity and adherence to and formation of biofilms on different abiotic surfaces were not regulated through the CDCE8392_0813 gene. In conclusion, the CDCE8392_813 gene contributes to the Te^R and pathogenic potential of C. diphtheriae.

Corynebacterium diphtheriae putative tellurite-resistance protein (CDCE8392_0813) contributes to the intracellular survival in human epithelial cells and lethality of Caenorhabditis elegans.

Corynebacterium diphtheriae, the aetiologic agent of diphtheria, also represents a global medical challenge because of the existence of invasive strains as causative agents of systemic infections. Although tellurite (TeO32-) is toxic to most microorganisms, TeO32--resistant bacteria, including C. diphtheriae, exist in nature. The presence of TeO32--resistance (TeR) determinants in pathogenic bacteria might provide selective advantages in the natural environment. In the present study, we investigated the role of the putative TeR determinant (CDCE8392_813gene) in the virulence attributes of diphtheria bacilli. The disruption of CDCE8392_0813 gene expression in the LDCIC-L1 mutant increased susceptibility to TeO32- and reactive oxygen species (hydrogen peroxide), but not to other antimicrobial agents. The LDCIC-L1 mutant also showed a decrease in both the lethality of Caenorhabditis elegans and the survival inside of human epithelial cells compared to wild-type strain. Conversely, the haemagglutinating activity and adherence to and formation of biofilms on different abiotic surfaces were not regulated through the CDCE8392_0813 gene. In conclusion, the CDCE8392_813 gene contributes to the TeR and pathogenic potential of C. diphtheriae.

Biofilm formation and fibrinogen and fibronectin binding activities by Corynebacterium pseudodiphtheriticum invasive strains.

Biofilm-related infections are considered a major cause of morbidity and mortality in hospital environments. Biofilms allow microorganisms to exchange genetic material and to become persistent colonizers and/or multiresistant to antibiotics. Corynebacterium pseudodiphtheriticum (CPS), a commensal bacterium that colonizes skin and mucosal sites has become progressively multiresistant and responsible for severe nosocomial infections. However, virulence factors of this emergent pathogen remain unclear. Herein, we report the adhesive properties and biofilm formation on hydrophilic (glass) and hydrophobic (plastic) abiotic surfaces by CPS strains isolated from patients with localized (ATCC10700/Pharyngitis) and systemic (HHC1507/Bacteremia) infections. Adherence to polystyrene attributed to hydrophobic interactions between bacterial cells and this negatively charged surface indicated the involvement of cell surface hydrophobicity in the initial stage of biofilm formation. Attached microorganisms multiplied and formed microcolonies that accumulated as multilayered cell clusters, a step that involved intercellular adhesion and synthesis of extracellular matrix molecules. Further growth led to the formation of dense bacterial aggregates embedded in the exopolymeric matrix surrounded by voids, typical of mature biofilms. Data also showed CPS recognizing human fibrinogen (Fbg) and fibronectin (Fn) and involvement of these sera components in formation of "conditioning films". These findings suggested that biofilm formation may be associated with the expression of different adhesins. CPS may form biofilms in vivo possibly by an adherent biofilm mode of growth in vitro currently demonstrated on hydrophilic and hydrophobic abiotic surfaces. The affinity to Fbg and Fn and the biofilm-forming ability may contribute to the establishment and dissemination of infection caused by CPS.

Aggregative adherent strains of Corynebacterium pseudodiphtheriticum enter and survive within HEp-2 epithelial cells.

Corynebacterium pseudodiphtheriticum is a well-known human pathogen that mainly causes respiratory disease and is associated with high mortality in compromised hosts. Little is known about the virulence factors and pathogenesis of C. pseudodiphtheriticum. In this study, cultured human epithelial (HEp-2) cells were used to analyse the adherence pattern, internalisation and intracellular survival of the ATCC 10700 type strain and two additional clinical isolates. These microorganisms exhibited an aggregative adherence-like pattern to HEp-2 cells characterised by clumps of bacteria with a "stacked-brick" appearance. The differences in the ability of these microorganisms to invade and survive within HEp-2 cells and replicate in the extracellular environment up to 24 h post infection were evaluated. The fluorescent actin staining test demonstrated that actin polymerisation is involved in the internalisation of the C. pseudodiphtheriticum strains. The depolymerisation of microfilaments by cytochalasin E significantly reduced the internalisation of C. pseudodiphtheriticum by HEp-2 cells. Bacterial internalisation and cytoskeletal rearrangement seemed to be partially triggered by the activation of tyrosine kinase activity. Although C. pseudodiphtheriticum strains did not demonstrate an ability to replicate intracellularly, HEp-2 cells were unable to fully clear the pathogen within 24 h. These characteristics may explain how some C. pseudodiphtheriticum strains cause severe infection in human patients.

Aggregative adherent strains of Corynebacterium pseudodiphtheriticum enter and survive within HEp-2 epithelial cells

Corynebacterium pseudodiphtheriticum is a well-known human pathogen that mainly causes respiratory disease and is associated with high mortality in compromised hosts. Little is known about the virulence factors and pathogenesis of C. pseudodiphtheriticum. In this study, cultured human epithelial (HEp-2) cells were used to analyse the adherence pattern, internalisation and intracellular survival of the ATCC 10700 type strain and two additional clinical isolates. These microorganisms exhibited an aggregative adherence-like pattern to HEp-2 cells characterised by clumps of bacteria with a "stacked-brick" appearance. The differences in the ability of these microorganisms to invade and survive within HEp-2 cells and replicate in the extracellular environment up to 24 h post infection were evaluated. The fluorescent actin staining test demonstrated that actin polymerisation is involved in the internalisation of the C. pseudodiphtheriticum strains. The depolymerisation of microfilaments by cytochalasin E significantly reduced the internalisation of C. pseudodiphtheriticum by HEp-2 cells. Bacterial internalisation and cytoskeletal rearrangement seemed to be partially triggered by the activation of tyrosine kinase activity. Although C. pseudodiphtheriticum strains did not demonstrate an ability to replicate intracellularly, HEp-2 cells were unable to fully clear the pathogen within 24 h. These characteristics may explain how some C. pseudodiphtheriticum strains cause severe infection in human patients.

Pangenomic study of Corynebacterium diphtheriae that provides insights into the genomic diversity of pathogenic isolates from cases of classical diphtheria, endocarditis, and pneumonia.

Corynebacterium diphtheriae is one of the most prominent human pathogens and the causative agent of the communicable disease diphtheria. The genomes of 12 strains isolated from patients with classical diphtheria, endocarditis, and pneumonia were completely sequenced and annotated. Including the genome of C. diphtheriae NCTC 13129, we herewith present a comprehensive comparative analysis of 13 strains and the first characterization of the pangenome of the species C. diphtheriae. Comparative genomics showed extensive synteny and revealed a core genome consisting of 1,632 conserved genes. The pangenome currently comprises 4,786 protein-coding regions and increases at an average of 65 unique genes per newly sequenced strain. Analysis of prophages carrying the diphtheria toxin gene tox revealed that the toxoid vaccine producer C. diphtheriae Park-Williams no. 8 has been lysogenized by two copies of the ω(tox)(+) phage, whereas C. diphtheriae 31A harbors a hitherto-unknown tox(+) corynephage. DNA binding sites of the tox-controlling regulator DtxR were detected by genome-wide motif searches. Comparative content analysis showed that the DtxR regulons exhibit marked differences due to gene gain, gene loss, partial gene deletion, and DtxR binding site depletion. Most predicted pathogenicity islands of C. diphtheriae revealed characteristics of horizontal gene transfer. The majority of these islands encode subunits of adhesive pili, which can play important roles in adhesion of C. diphtheriae to different host tissues. All sequenced isolates contain at least two pilus gene clusters. It appears that variation in the distributed genome is a common strategy of C. diphtheriae to establish differences in host-pathogen interactions.

Corynebacterium diphtheriae 67-72p hemagglutinin, characterized as the protein DIP0733, contributes to invasion and induction of apoptosis in HEp-2 cells.

Although Corynebacterium diphtheriae has been classically described as an exclusively extracellular pathogen, there is growing evidence that it may be internalized by epithelial cells. The aim of the present report was to investigate the nature and involvement of the surface-exposed non-fimbrial 67-72 kDa proteins (67-72p), previously characterized as adhesin/hemagglutinin, in C. diphtheriae internalization by HEp-2 cells. Transmission electron microscopy and bacterial internalization inhibition assays indicated the role of 67-72p as invasin for strains of varied sources. Cytoskeletal changes with accumulation of polymerized actin in HEp-2 cells beneath adherent 67-72p-adsorbed microspheres were observed by the Fluorescent actin staining test. Trypan blue staining method and Methylthiazole tetrazolium reduction assay showed a significant decrease in viability of HEp-2 cells treated with 67-72p. Morphological changes in HEp-2 cells observed after treatment with 67-72p included vacuolization, nuclear fragmentation and the formation of apoptotic bodies. Flow cytometry revealed an apoptotic volume decrease in HEp-2 cells treated with 67-72p. Moreover, a double-staining assay using Propidium Iodide/Annexin V gave information about the numbers of vital vs. early apoptotic cells and late apoptotic or secondary necrotic cells. The comparative analysis of MALDI-TOF MS experiments with the probes provided for 67-72p CDC-E8392 with an in silico proteome deduced from the complete genome sequence of C. diphtheriae identified with significant scores 67-72p as the protein DIP0733. In conclusion, DIP0733 (67-72p) may be directly implicated in bacterial invasion and apoptosis of epithelial cells in the early stages of diphtheria and C. diphtheriae invasive infection.

Difteria pelo Corynebacterium ulcerans: uma zoonose emergente no Brasil e no mundo / Corynebacterium ulcerans diphtheria: an emerging zoonosis in Brazil and worldwide / Difteria por Corynebacterium ulcerans: una zoonosis emergente en Brasil y en el mundo

O artigo revisa a literatura sobre a emergência de infecções humanas causadas por Corynebacterium ulcerans em diversos países, incluindo o Brasil. Foi realizada análise de artigos publicados entre 1926 e 2011 nas bases Medline/PubMed e SciELO, bem como artigos e informes do Ministério da Saúde. Apresenta-se um esquema de triagem, rápido, econômico e de fácil execução, capaz de permitir a realização do diagnóstico presuntivo de C. ulcerans e C. diphtheriae na maioria dos laboratórios brasileiros públicos e privados. A circulação de C. ulcerans em vários países, aliada aos recentes casos de isolamento do patógeno no Rio de Janeiro, é um alerta a clínicos, veterinários e microbiologistas sobre a ocorrência de difteria zoonótica e a circulação do C. ulcerans em regiões urbanas e rurais do território nacional e/ou da América Latina.

The article is a literature review on the emergence of human infections caused by Corynebacterium ulcerans in many countries including Brazil. Articles in Medline/PubMed and SciELO databases published between 1926 and 2011 were reviewed, as well as articles and reports of the Brazilian Ministry of Health. It is presented a fast, cost-effective and easy to perform screening test for the presumptive diagnosis of C. ulcerans and C. diphtheriae infections in most Brazilian public and private laboratories. C. ulcerans spread in many countries and recent isolation of this pathogen in Rio de Janeiro, southeastern Brazil, is a warning to clinicians, veterinarians, and microbiologists on the occurrence of zoonotic diphtheria and C. ulcerans dissemination in urban and rural areas of Brazil and/or Latin America.

El articulo revisa la literatura sobre la emergencia de infecciones humanas causadas por Corynebacterium ulcerans en diversos países, incluyendo Brasil. Se realizó análisis de artículos publicados entre 1926 y 2011 en las bases Medline/Pubmed y SciELO, así como artículos e informes del Ministerio Brasileño de la Salud. Se presenta un esquema de selección, rápido, económico y de fácil ejecución, capaz de permitir la realización del diagnóstico presuntivo de C. ulcerans y C. diphtheriae en la mayoría de los laboratorios brasileños públicos y privados. La circulación de C. ulcerans en varios países, aliada a los recientes casos de aislamiento del patógeno en Rio de Janeiro (Sureste de Brasil), es un alerta a clínicos, veterinarios y microbiólogos sobre la ocurrencia de difteria zoológica y la circulación de C. ulcerans en regiones urbanas y rurales del territorio nacional y/o de América Latina.

Corynebacterium ulcerans diphtheria: an emerging zoonosis in Brazil and worldwide.

The article is a literature review on the emergence of human infections caused by Corynebacterium ulcerans in many countries including Brazil. Articles in Medline/PubMed and SciELO databases published between 1926 and 2011 were reviewed, as well as articles and reports of the Brazilian Ministry of Health. It is presented a fast, cost-effective and easy to perform screening test for the presumptive diagnosis of C. ulcerans and C. diphtheriae infections in most Brazilian public and private laboratories. C. ulcerans spread in many countries and recent isolation of this pathogen in Rio de Janeiro, southeastern Brazil, is a warning to clinicians, veterinarians, and microbiologists on the occurrence of zoonotic diphtheria and C. ulcerans dissemination in urban and rural areas of Brazil and/or Latin America.

Comparative analysis of two complete Corynebacterium ulcerans genomes and detection of candidate virulence factors.

BACKGROUND: Corynebacterium ulcerans has been detected as a commensal in domestic and wild animals that may serve as reservoirs for zoonotic infections. During the last decade, the frequency and severity of human infections associated with C. ulcerans appear to be increasing in various countries. As the knowledge of genes contributing to the virulence of this bacterium was very limited, the complete genome sequences of two C. ulcerans strains detected in the metropolitan area of Rio de Janeiro were determined and characterized by comparative genomics: C. ulcerans 809 was initially isolated from an elderly woman with fatal pulmonary infection and C. ulcerans BR-AD22 was recovered from a nasal sample of an asymptomatic dog. RESULTS: The circular chromosome of C. ulcerans 809 has a total size of 2,502,095 bp and encodes 2,182 predicted proteins, whereas the genome of C. ulcerans BR-AD22 is 104,279 bp larger and comprises 2,338 protein-coding regions. The minor difference in size of the two genomes is mainly caused by additional prophage-like elements in the C. ulcerans BR-AD22 chromosome. Both genomes show a highly similar order of orthologous coding regions; and both strains share a common set of 2,076 genes, demonstrating their very close relationship. A screening for prominent virulence factors revealed the presence of phospholipase D (Pld), neuraminidase H (NanH), endoglycosidase E (EndoE), and subunits of adhesive pili of the SpaDEF type that are encoded in both C. ulcerans genomes. The rbp gene coding for a putative ribosome-binding protein with striking structural similarity to Shiga-like toxins was additionally detected in the genome of the human isolate C. ulcerans 809. CONCLUSIONS: The molecular data deduced from the complete genome sequences provides considerable knowledge of virulence factors in C. ulcerans that is increasingly recognized as an emerging pathogen. This bacterium is apparently equipped with a broad and varying set of virulence factors, including a novel type of a ribosome-binding protein. Whether the respective protein contributes to the severity of human infections (and a fatal outcome) remains to be elucidated by genetic experiments with defined bacterial mutants and host model systems.

Aspectos fenotípicos e do potencial patogênico de amostra de Corynebacterium diphtheriae isolada de processo de osteomielite em paciente com neoplasia / Phenotypic aspects and pathogenic potential of Corynebacterium diphtheriae strains isolated from cancer patient with osteomyelitis

Além da difteria permanecer endêmica em diversos países, os clínicos e microbiologistas também devem permanecer atentos ao fato de amostras atoxinogênicas de Corynebacterium diphtheriae causarem infecções invasivas, inclusive em pacientesimunocomprometidos e/ou hospitalizados. Um grupo de microrganismos, incluindo C. diphtheriae, tem sido relacionado com quadros de osteomielite. Em casos de câncer, pode ser favorecido o aparecimento de quadros de osteomielite em decorrência de contaminação por via hematogênica, foco infeccioso ou lesão contígua ao osso. Entretanto, ainda são poucas as investigações relativas ao potencial patogênico de cepas atoxinogênicas de C. diphtheriae. No presente estudo, foi descrito o primeiro caso de isolamento de C.diphtheriae subsp. mitis atoxinogênico e do biotipo não fermentador de sacarose (BR5015) de osteomielite em paciente com câncer.O microrganismo foi capaz de expressar os seguintes fatores de virulência: expressão de perfil de aderência misto dos tipos agregativo e difuso (AA-AD) e elevada (11,13%) capacidade de sobrevivência intracitoplasmática em células epiteliais humanas (HEp-2) além da produção de porfirina e de enzimas catalase, nitrato redutase e DNAse. C. diphtheriae atoxinogênico não deve serconsiderado como mero contaminante, uma vez que pode estar direta ou indiretamente relacionado com o estabelecimento e/ou manutenção de processos infecciosos de origens diversas, incluindo osteomielite.

As well diphtheria remaining endemic in several countries, clinicians and microbiologists must also remain alert to the fact that nontoxigenic samples of Corynebacterium diphtheriae are capable of causing invasive infections, especially in hospitalized and/or immunocompromised patients. Patients with cancer are more susceptible to the appearance of cases of osteomyelitisobtained by hematogenic contamination, an infectious focus or by lesions adjacent to bone. Many microorganisms may be related to cases of osteomyelitis, including C. diphtheriae. However, there are still only a low number of investigations into the pathogenic potential of nontoxigenic strains of C. diphtheriae. The present study is the first documented case of isolation of a nontoxigenic C.diphtheriae subsp. mitis of the non sucrose-fermenting biotype (BR5015 strain) from osteomyelitis in the frontal bone of a patient with adenoid cystic carcinoma. The virulence factors tests were as follows: expression of a mixed adherence patterns of aggregativediffuse(AA-DA) types; high (11.13%) ability to survive within HEp-2 cells; DNase, catalase, nitrate-reductase activities. Therefore, nontoxigenic C. diphtheriae should not be merely regarded as a contaminant, since it can be directly or indirectly related to the establishment and/or maintenance of infectious processes, including osteomyelitis.

Fibrinogen binds to nontoxigenic and toxigenic Corynebacterium diphtheriae strains.

The production of fibrinous exudates may play an important role in determining the outcome of bacterial infection. Although pseudomembrane formation is a characteristic feature of diphtheria, little is known about the fibrinogen (Fbn)-binding properties of Corynebacterium diphtheriae strains and the influence of the gene that codes for diphtheria toxin (tox gene) in this process. In this study we demonstrated the ability of C. diphtheriae strains to bind to Fbn and to convert Fbn to fibrin. Bacterial interaction with rabbit plasma was evaluated by both slide and tube tests. Interaction of microorganisms with human Fbn was evaluated by both enzyme linked immunosorbent assay (ELISA) and fluorescein isothiocyanate-conjugated (FITC) Fbn binding assays. Nontoxigenic and toxigenic strains formed bacterial aggregates in the presence of plasma in the slide tests. The ability to convert Fbn to a loose web of fibrin in the plasma solution in the tube tests appeared to be a common characteristic of the species, including strains that do not carry the tox gene. Fbn binding to C. diphtheriae strains occurred at varying intensities, as demonstrated by the FITC-Fbn and ELISA binding assays. Our data suggest that the capacity to bind to Fbn and to convert Fbn to fibrin may play a role in pseudomembrane formation and act as virulence determinants of both nontoxigenic and toxigenic strains.

Fibrinogen binds to nontoxigenic and toxigenic Corynebacterium diphtheriae strains

The production of fibrinous exudates may play an important role in determining the outcome of bacterial infection. Although pseudomembrane formation is a characteristic feature of diphtheria, little is known about the fibrinogen (Fbn)-binding properties of Corynebacterium diphtheriae strains and the influence of the gene that codes for diphtheria toxin (tox gene) in this process. In this study we demonstrated the ability of C. diphtheriae strains to bind to Fbn and to convert Fbn to fibrin. Bacterial interaction with rabbit plasma was evaluated by both slide and tube tests. Interaction of microorganisms with human Fbn was evaluated by both enzyme linked immunosorbent assay (ELISA) and fluorescein isothiocyanate-conjugated (FITC) Fbn binding assays. Nontoxigenic and toxigenic strains formed bacterial aggregates in the presence of plasma in the slide tests. The ability to convert Fbn to a loose web of fibrin in the plasma solution in the tube tests appeared to be a common characteristic of the species, including strains that do not carry the tox gene. Fbn binding to C. diphtheriae strains occurred at varying intensities, as demonstrated by the FITC-Fbn and ELISA binding assays. Our data suggest that the capacity to bind to Fbn and to convert Fbn to fibrin may play a role in pseudomembrane formation and act as virulence determinants of both nontoxigenic and toxigenic strains.

Non-opsonic phagocytosis of homologous non-toxigenic and toxigenic Corynebacterium diphtheriae strains by human U-937 macrophages.

As interactions between bacteria and macrophages dictate the outcome of most infectious diseases, analyses of molecular mechanisms of non-opsonic phagocytosis should lead to new approaches for the prevention of diphtheria and systemic Corynebacterium diphtheriae infections. The present study aimed to evaluate human macrophage-bacteria interactions in the absence of opsonin antibodies and the influence of the tox gene on this process. Homologous C. diphtheriae tox+ and tox- strains were evaluated for adhesion, entering and survival within U-937 human macrophages at different incubation periods. Higher numbers of viable bacteria associated with and internalized by macrophages were demonstrated for the tox+ strain. However, viable intracellular bacteria were detected at T-24 hr only for the tox- strain. Cytoskeletal inhibitors, cytochalasin E, genistein and colchicine, inhibited intracellular viability of both strains at different levels. Bacterial replication was evidenced at T-24 hr in supernatants of monolayers infected with the tox- strain. Host cell death and nuclear alterations were evidenced by the Trypan blue exclusion assay and DAPI fluorescence microscopy. ELISA of histone-associated DNA fragments allowed detection of apoptosis and necrosis induced by tox+ and tox- strains at T-1 hr and T-3 hr. In conclusion, human macrophages in the absence of opsonins may not be promptly effective at killing diphtheria bacilli. The presence of the tox gene influences the susceptibility of C. diphtheriae to human macrophages and the outcome of non-opsonic phagocytosis. C. diphtheriae strains exhibit strategies to survive within macrophages and to exert apoptosis and necrosis in human phagocytic cells, independent of the tox gene.

Papel das hemaglutininas 67-72p de Corynebacterium diphtheriae na ligação a proteínas plasmáticas, superfícies celulares, invasão e indução de apoptose / Role of haemagglutinins 67-72p de Corynebacterium diphtheriae in binding to plasma proteins, cell surfaces, invasion and induction of apoptosis

Corynebacterium diphtheriae pode ser isolado tanto de quadros de difteria clássica, quanto de infecções sistêmicas, como endocardite. O fibrinogênio (Fbn) e a fibronectina (Fn) são glicoproteínas presentes na matriz extracelular de tecidos conjuntivos. A influência destas proteínas na patogênese das infecções locais e invasivas causadas por C. diphtheriae é objeto de estudo devido ao fato do bacilo diftérico poder ser encontrado em lesões nas quais o Fbn e a Fn são predominantes, incluindo a pseudomembrana diftérica e vegetações cardíacas presentes na endocardite infecciosa. São crescentes as evidências de que o C. diphtheriae pode, além de aderir, ser internalizado por células em cultura. No presente estudo, investigou-se a participação de C. diphtheriae e das proteínas de superfície 67-72p na aderência à Fn e ao Fbn de plasma humano e a eritrócitos. A aderência às células HEp-2 e internalização também foram analisadas. A participação de 67-72p nos mecanismos de morte celular foi avaliada através das colorações por Azul de Tripan e 4'6-diamidino-2-fenil indol (DAPI), pelo ensaio de redução utilizando dimetil-tiazol-difenil tetrazólio (MTT) e por citometria de fluxo. As 67-72p foram extraídas da superfície da amostra toxigênica C. diphtheriae subsp. mitis CDC-E8392 através de processos mecânicos e precipitação com sulfato de amônio saturado. Análises por SDS-PAGE e immunoblotting detectaram a presença das bandas protéicas de 67 e 72kDa nas amostras toxinogênicas e atoxinogênicas analisadas, as quais pertenciam aos biotipos fermentador e não fermentador de sacarose. C. diphtheriae foi capaz não só de formar agregados na presença de plasma de coelho, mas também de converter Fbn em fibrina independentemente da presença do gene tox. No entanto, a amostra atoxinogênica ATCC 27010 (tox-) foi menos aderente ao Fbn do que a homóloga ATCC 27012 (tox+). A interação bacteriana com eritrócitos foi inibida somente pela Fn. Ligações entre Fn e/ou Fbn com 67-72p foram ...

Corynbacterium diphtheriae have been isolated from classical diphtheria and systemic infections such as endocarditis. Fibrinogen (Fbn) and fibronectin (Fn) are high molecular-weight glycoproteins that may be found in extracellular matrix of connective tissues. Their influence in the pathogenesis of local and in invasive C. diphtheriae infection is object of interest due to the fact that diphtheria bacilli is recovered from lesions where such proteins are predominant, including pharyngeal pseudomembrane and valve heart vegetations in infectious endocarditis. There is growing evidence that C. diphtheriae may adhere to and be internalized by cells in culture. The present study investigated the participation of C. diphtheriae strains and 67-72p, a surface protein, in adherence to human plasma Fn, Fbn, erityrocytes, adherence to and internalization by HEp-2 cells. The participation of 67-72p in promoting cell death was evaluated by the Trypan blue, DAPI staining methods, methylthiazole tetrazolium (MTT) reduction assay and flow cytometry. The 67-72p was extracted from C. diphtheriae subsp. mitis CDC-E8392 toxigenic strain, by mechanical process and ammonium sulfate fractionation. SDS-PAGE and immunoblotting analysis detected the polypeptide bands of 67 and 72 kDa in all toxigenic and nontoxigenic strains from both sucrose-fermenting and non-fermanting biotypes. Diphtheria bacilli were capable to both form bacterial aggregates in rabbit plasma and to convert Fbn to fibrin independently to the presence of tox gene, albeit the ATCC 27010 (tox-) strain was less adherent to Fbn than the paental strain ATCC 27012 (tox+). Bacteria-erythrocytes interaction was inhibited only ...

Corynebacterium diphtheriae as an emerging pathogen in nephrostomy catheter-related infection: evaluation of traits associated with bacterial virulence.

Corynebacterium diphtheriae still represents a global medical challenge, particularly due to the significant number of individuals susceptible to diphtheria and the emergence of non-toxigenic strains as the causative agents of invasive infections. In this study, we characterized the clinical and microbiological features of what we believe to be the first case of C. diphtheriae infection of a percutaneous nephrostomy catheter insertion site in an elderly patient with a fatal bladder cancer. Moreover, we demonstrated the potential role of adherence, biofilm formation and fibrin deposition traits in C. diphtheriae from the catheter-related infection. Non-toxigenic C. diphtheriae isolated from the purulent discharge (named strain BR-CAT5003748) was identified by the API Coryne system (code 1 010 324) and a multiplex PCR for detection of dtxR and tox genes. Strain BR-CAT5003748 showed resistance to oxacillin, ceftazidime and ciprofloxacin. In experiments performed in vitro, the catheter isolate was classified as moderately hydrophobic and as moderately adherent to polystyrene surfaces. Glass provided a more effective surface for biofilm formation than polystyrene. Micro-organisms adhered to (>1.5 x 10(6) c.f.u.) and multiplied on surfaces of polyurethane catheters. Microcolony formation (a hallmark of biofilm formation) and amorphous accretions were observed by scanning electron microscopy on both external and luminal catheter surfaces. Micro-organisms yielded simultaneous expression of localized adherence-like and aggregative-like (LAL/AAL) adherence patterns to HEp-2 cells. Interestingly, the coagulase tube test resulted in the formation of a thin layer of fibrin embedded in rabbit plasma by the non-toxigenic BR-CAT5003748 strain. In conclusion, C. diphtheriae should be recognized as a potential cause of catheter-related infections in at-risk populations such as elderly and cancer patients. LAL/AAL strains may be associated with virulence traits that enable C. diphtheriae to effectively produce biofilms on catheter surfaces. Biofilm formation and fibrin deposition could have contributed to the persistence of C. diphtheriae at the infected insertion site and the obstruction of the nephrostomy catheter.