Publications by authors named "Avelar K"

Article Synopsis
  • The research focuses on leptolysin, a metalloproteinase secreted by the bacteria Leptospira, which may aid in the bacteria's ability to cause disease by degrading host immune system components.
  • A portion of patients with mild leptospirosis showed antibodies against leptolysin, indicating its expression during infection; experiments with knockout strains demonstrated that leptolysin helps the bacteria resist serum from the host.
  • Although a mutant strain lacking leptolysin was still virulent in hamsters, it resulted in lower bacterial levels in the kidneys, suggesting the need for further investigation into the role of metalloproteinases in Leptospira pathogenicity.
View Article and Find Full Text PDF

Leptospirosis is a zoonotic disease with significant global impact and a challenging diagnosis. The utilization of adequately validated rapid tests is relevant for the opportune identification of the disease and for reduction in fatality rates. The present study analyzes the accuracy and reliability of the Dual Path Platform (DPP) assay -produced in Brazil by the Oswaldo Cruz Foundation (Fiocruz)- for diagnosing leptospirosis.

View Article and Find Full Text PDF

Leptospirosis diagnosis by MAT requires antibody levels that are typically present only after the first week of symptoms, many days after infection. To improve testing capacity and to develop a fast and reliable solution for the diagnosis of this disease in the first few days after clinical manifestations, the National Reference Laboratory for Leptospirosis/WHO Collaborating Center in Brazil implemented a duplex molecular method by qPCR for human samples for the detection of the gene L32, conserved in pathogenic spp. In this paper, we describe the overall performance of this protocol in the first 3 months as a standard routine.

View Article and Find Full Text PDF

Sphingomyelin is a major constituent of eukaryotic cell membranes, and if degraded by bacteria sphingomyelinases may contribute to the pathogenesis of infection. Among spp., there are five sphingomyelinases exclusively expressed by pathogenic leptospires, in which Sph2 is expressed during natural infections, cytotoxic, and implicated in the leptospirosis hemorrhagic complications.

View Article and Find Full Text PDF

The zoonotic disease leptospirosis is caused by pathogenic species of the genus and was recently included in the list of Neglected Diseases by the World Health Organization. Leptospirosis burden is estimated to have over a million human cases and cause 60 thousand deaths annually, in addition to its economic impact and veterinary concern. The microscopic agglutination test (MAT), recommended by the World Health Organization, exhibits reduced sensitivity at the beginning of the disease, in addition to being technically difficult.

View Article and Find Full Text PDF

Objectives: To investigate the association between the management of mandibular arch perimeter during development of the dentition and its effects on second permanent molar (M2) eruption.

Materials And Methods: Seven electronic databases were searched without restrictions up to June 2020. Assessment was performed using the Risk Of Bias In Non-randomized Studies of Interventions (ROBINS-I) tool for non-randomized clinical trials (non-RCT).

View Article and Find Full Text PDF

To systematically review the effects of functional appliances (FA) using incremental vs maximal mandibular advancement regarding cephalometric measurements in class II malocclusion individuals and to assess patient-centred-outcomes. Six electronic databases were searched without restrictions up to April 2020. We included randomized and non-randomized controlled trials using identical FA.

View Article and Find Full Text PDF

Introduction: Leptospirosis is caused by a bacterium of the genus Leptospira. This study aimed at investigating the seroprevalence of and risk factors for leptospirosis in humans in Manaus, State of Amazonas.

Methods: Interviews were performed, and 1,000 blood serum samples were examined using a microscopic agglutination test.

View Article and Find Full Text PDF

We report two cases of leptospirosis in military personnel in southeastern Brazil. The cases were hospitalized following field training exercises, and presented with acute meningoencephalitis, respiratory illnesses, and skin rash. Leptospira interrogans serovars Icterohaemorrhagiae, Hebdomadis, Patoc, and Cynopteri were identified in the cases by microscopic agglutination test and PCR.

View Article and Find Full Text PDF

Introduction: Leptospirosis is an endemic zoonosis of worldwide distribution, caused by bacteria of the genus Leptospira. This genus includes pathogenic and saprophytic species, with more than 200 different serovars, thus making it difficult to characterize. The technique of pulsed field gel electrophoresis has been used as a tool to aid in this characterization.

View Article and Find Full Text PDF

Leptospirosis is a public health problem. Infection with pathogenic Leptospira occurs by exposure to many environments and is traditionally associated with occupational risk activities. Pulsed-field gel electrophoresis was used to investigate the epidemiological relatedness among Leptospira isolates.

View Article and Find Full Text PDF

The presence of enterotoxigenic Bacteroides fragilis and nontoxigenic B. fragilis (NTBF) among 109 strains isolated from 1980-2008 in Brazil were investigated by PCR. One strain, representing 0.

View Article and Find Full Text PDF

The Bacteroides genus, the most prevalent anaerobic bacteria of the intestinal tract, carries a plethora of the mobile elements, such as plasmids and conjugative and mobilizable transposons, which are probably responsible for the spreading of resistance genes. Production of beta-lactamases is the most important resistance mechanism including cephalosporin resistance to beta-lactam agents in species of the Bacteroides fragilis group. In our previous study, the cfxA gene was detected in B.

View Article and Find Full Text PDF

A total of 35 Brazilian isolates of Clostridium difficile from faecal stools and four isolates from hospital environments were analyzed by PCR ribotyping. A whole cell protein profile (as an alternative for serogrouping), in vitro toxin production and susceptibility to vancomycin, metronidazole and clindamycin were also investigated. All strains were typeable by both phenotypic and genotypic methods, and a total of 13 different PCR ribotypes were identified, of which seven (132, 133, 134, 135, 136, 142 and 143) were considered new types and accounted for 78.

View Article and Find Full Text PDF

Quorum sensing is a density-dependent gene regulation mechanism that has been described in many bacterial species in the last decades. Bacteria that use quorum sensing as part of their gene regulation circuits produce molecules called autoinducers that accumulate in the environment and activate target genes in a quorum-dependent way. Some specific clues led us to hypothesize that Bacteroides species can produce autoinducers and possess a quorum sensing system.

View Article and Find Full Text PDF

In this study, 197 strains of Bacteroides genus from different species and origins were evaluated with regard to their susceptibility to 5-nitroimidazoles (5-Ni)-such as tinidazole, ornidazole, and metronidazole-using the agar dilution method. The presence of nim genes was also investigated by polymerase chain reaction. It was found that 5.

View Article and Find Full Text PDF
Article Synopsis
  • Bacteroides fragilis is a common anaerobic bacterium found in clinical samples, raising questions about its genetic diversity and potential for virulence.
  • The study examined how this bacterium interacts with macrophages, revealing changes in cell morphology, actin organization, and a reduction in nitric oxide (NO) production.
  • Microscopy techniques showed that B. fragilis causes structural changes in macrophages, suggesting the bacterium has developed mechanisms to inhibit the immune response.
View Article and Find Full Text PDF

Vibrio cholerae is an important human pathogen and the cause of cholera. Since genetic variation and antibiotic resistance of strains have implications for effective treatment of the disease, we examined the genetic diversity and antibiotic resistance profile in 92 clinical strains (serogroup O1) and 56 environmental strains (O1 antigen, 42 strains; non-O1 antigen, 14 strains) isolated in Brazil between 1991 and 1999. Clinical and environmental O1 strains showed greater drug resistance compared to environmental non-O1 strains.

View Article and Find Full Text PDF

Diarrhoeic stool samples from 334 0-5-year-old children were analysed with respect to the incidence of Bacteroides fragilis as well as other enteropathogens. B. fragilis was recovered in 9.

View Article and Find Full Text PDF

Susceptibility profiles of 99 Bacteroides fragilis strains for 9 antimicrobial agents were defined by using an agar dilution method. The isolates were uniformly susceptible to imipenen and metronidazole. All isolates were resistant to ampicillin.

View Article and Find Full Text PDF

Clostridium difficile strains were detected in 14 of 210 (6.7 %) faecal samples from children in Rio de Janeiro, Brazil, by cultivating faeces on cycloserine/cefoxitin/fructose agar after alcohol-shock. Two main groups of children were studied: inpatients (n = 96) and outpatients (n = 114).

View Article and Find Full Text PDF

In this study we investigated the presence of the cfxA gene (encoding a class A beta-lactamase) in 73 strains of the Bacteroides fragilis group belonging to the species B. distasonis (34), B. vulgatus (14), B.

View Article and Find Full Text PDF

The results of this study show that there is a high frequency of resistant species in the Bacteroides fragilis group in the intestinal tract of children and adults in Brazil. B. fragilis was not studied.

View Article and Find Full Text PDF

The epidemiology of antimicrobial resistance of clinical isolates and human intestinal strains of Bacteroides fragilis has assumed great importance in the last few years since this microorganism, like other members of the B. fragilis group, can be responsible for the spread of resistance determinants. It is possible that the presence of B.

View Article and Find Full Text PDF

The ability of Bacteroides fragilis strains, isolated from various sources, to produce bacteriocin was evaluated. All strains isolated from intestinal infections were producers in high levels and less susceptible to the others. Strains from other origins were found to produce bacteriocin at a medium level and they were variably susceptible.

View Article and Find Full Text PDF