Rita Cordeiro

Disease association with two Helicobacter pylori duplicate outer membrane protein genes, homB and homA

BackgroundhomB encodes a Helicobacter pylori outer membrane protein. This gene was previously associated with peptic ulcer disease (PUD) and was shown to induce activation of interleukin-8 secretion in vitro, as well as contributing to bacterial adherence. Its 90%-similar gene, homA, was previously correlated with gastritis. The present study aimed to evaluate the gastric disease association with homB and homA, as well as with the H. pylori virulence factors cagA, babA and vacA, in 415 H. pylori strains isolated from patients from East Asian and Western countries. The correlation among these genotypes was also evaluated.ResultsBoth homB and homA genes were heterogeneously distributed worldwide, with a marked difference between East Asian and Western strains. In Western strains (n = 234, 124 PUD and 110 non-ulcer dyspepsia (NUD), homB, cagA and vacA s1 were all significantly associated with PUD (p = 0.025, p = 0.014, p = 0.039, respectively), and homA was closely correlated with NUD (p = 0.072). In East Asian strains (n = 138, 73 PUD and 65 NUD), homB was found more frequently than homA, and none of these genes was associated with the clinical outcome.Overall, homB was associated with the presence of cagA (p = 0.043) and vacA s1 (p < 0.001), whereas homA was found more frequently in cagA-negative (p = 0.062) and vacA s2 (p < 0.001) strains.Polymorphisms in homB and homA copy number were observed, with a clear geographical specificity, suggesting an involvement of these genes in host adaptation. A correlation between the homB two-copy genotype and PUD was also observed, emphasizing the role of homB in the virulence of the strain.ConclusionThe global results suggest that homB and homA contribute to the determination of clinical outcome.

Clinical Relevance and Diversity of Two Homologous Genes Encoding Glycosyltransferases in Helicobacter pylori

ABSTRACT Helicobacter pylori is known to be a major cause of peptic ulceration. The jhp0562 gene, encoding a glycosyltransferase involved in the synthesis of the lipopolysaccharide, was associated with peptic ulcer disease (PUD) in children. The β-(1,3)-galactosyltransferase [β-(1,3)GalT] gene (jhp0563), involved in Lewis (Le) antigen expression, is highly similar to jhp0562. The clinical significance and diversity of both genes were examined by PCR and sequencing of clinical strains (n = 117) isolated from children with PUD (n = 57) and nonulcer dyspepsia (NUD; n = 60). The prevalence of the jhp0562 gene was significantly higher in strains with a more-virulent profile (strains positive for the cag pathogenicity island [PAI], vacA sl allele, babA, homB, phase-variable gene oipA “on” [i.e., functional], and hopQ I allele). The distribution of genotypes according to clinical outcome showed that the presence of jhp0562 represented one of the greatest risks for the development of PUD. Moreover, the triple-positive genotype for the cag PAI, jhp0562, and homB provided the best discriminatory model for distinguishing PUD and NUD outcomes in children. Sequence and in vitro expression analyses of jhp0562 showed the presence of a complete open reading frame, while the β-(1,3)GalT gene was shown to be a phase-variable gene. The regular presence of jhp0562 in strains with a truncated β-(1,3)GalT gene suggests that jhp0562 may also be implicated in the regulation of Le antigen expression. Overall, the results of this study suggest that the jhp0562 gene is of great clinical relevance, being a useful comarker for severe H. pylori-related disease and contributing to host adaptation.

Allelic diversity and phylogeny of homB, a novel co-virulence marker of Helicobacter pylori

BackgroundThe homB gene is a Helicobacter pylori disease-marker candidate, strongly associated with peptic ulcer disease, while homA, its paralogue gene with 90% sequence identity, is correlated with non-ulcer dyspepsia. The HomB encoded outer membrane protein was shown to contribute to the proinflammatory properties of H. pylori and also to be involved in bacterial adherence.This study investigated the distribution of homB and homA genes in 455 H. pylori strains from East Asian and Western countries, and carried out sequence comparison and phylogenetic analyses.ResultsBoth homB and homA genes were heterogeneously distributed worldwide, with a marked difference between East Asian and Western strains.Analysis of homB and homA sequences revealed diversity regarding the number of copies and their genomic localization, with East Asian and Western strains presenting different genotypes. Moreover, homB and homA sequence analysis suggests regulation by phase variation. It also indicates possible recombination events, leading to gene duplication or homB/homA conversion which may as well be implicated in the regulation of these genes. Phylogenetic reconstruction of homB and homA revealed clustering according to the geographic origin of strains. Allelic diversity in the middle region of the genes was observed for both homB and homA, although there was no correlation between any allele and disease. For each gene, a dominant worldwide allele was detected, suggesting that homB/homA allelic variants were independent of the geographical origin of the strain. Moreover, all alleles were demonstrated to be expressed in vivo.ConclusionOverall, these results suggest that homB and homA genes are good candidates to be part of the pool of H. pylori OMPs implicated in host-bacteria interface and also contributing to the generation of antigenic variability, and thus involved in H. pylori persistence.

Role of 13C-Urea Breath Test in Experimental Model of Helicobacter pylori Infection in Mice

Background:  Animal models have been widely used to study Helicobacter pylori infection. Evaluation of H. pylori infection status following experimental inoculation of mice usually requires euthanasia. The 13C‐urea breath test (13C‐UBT) is both sensitive and specific for detection of H. pylori in humans. Thus, it would be very useful to have such a test with the same accuracy for the follow‐up of this infection in animal models of gastric infection. Accordingly, the purpose of this study was to develop and evaluate a 13C‐UBT method for following the course of H. pylori infection in a mouse model.

Burkholderia pseudomallei: First case of melioidosis in Portugal

Burkholderia pseudomallei is a Gram-negative bacillus and the causative agent of melioidosis, a serious infection associated with high mortality rate in humans. It can be naturally found as an environmental saprophyte in soil or stagnant water, and rice paddies that predominate in regions of endemicity such as Northeast Thailand. B. pseudomallei is a Biosafety Level 3 organism due to risks of aerosolization and severe disease and is now included in formal emergency preparedness plans and guidelines issued by various authorities in the United States and Europe. Here, we report the first case of imported melioidosis in Portugal. B. pseudomallei was isolated from the patients blood as well as from a left gluteal abscess pus. The isolate strain showed the unusual resistance profile to first-line eradication therapy trimethroprim/sulfamethoxazole. Whole genome sequencing revealed its similarity with isolates from Southeast Asia, suggesting the Thai origin of this Portuguese isolate, which is in agreement with a recent patients travel to Thailand.

Implementation of bioterrorism agents diagnosis by electron microscopy in Portuguese reference laboratory

between the duration of intubation and biofilm stage. Of the 17 positive cases with biofilm formation, colonization of the inner ETT surface occurred in 14 (70%) cases and 17 isolates were recovered. Five isolates were Gram positive, whereas the majority of isolates were Gram-negative bacilli. Seventeen patients developed pneumonia. All patients who developed biofilm also developed VAP. The occurrence of multidrug resistance among detected microorganisms was high. We concluded that the density of ETT biofilm increased with increased duration of intubation. We also concluded that ETT colonization with biofilm-producing organisms increased the risk of developing VAP with highly resistant microbes.

Human brucellosis in Portugal—Retrospective analysis of suspected clinical cases of infection from 2009 to 2016

Brucellosis is a zoonosis that is emerging in some regions of the world. Although brucellosis is a disease of obligatory declaration and is not eradicated in Portugal, no prevalence data is available in this country. In this study, we retrospectively analyzed the data available at the Reference Laboratory at the Portuguese National Institute of Health during the past 7 years (2009–2016) in order to get insight into the epidemiological scenario of brucellosis in Portugal. A total of 2313 biological samples from patients with clinical suspicion of brucellosis were subjected to immunological techniques for laboratory diagnosis. From 2010 to 2015, a subset of 259 samples was subjected to molecular methods. According to the available data, 167 out of 2313 (7.2%) samples had positive serology for Brucella spp. and 43 out of 259 samples (16.6%) were positive for B. melitensis by real time PCR, being classified as biovar 1 and 3. This study draws attention to the importance of integrating clinical and laboratory data of human cases in order to increase the efficacy of the response measures in case of outbreaks.

Ebola virus outbreak in West Africa – Portuguese laboratory response overview

This unit is the national reference laboratory for biological events or catastrophes and has skilled professionals, know-how, BSL-3 facilities, capacity to work 24h/7d and trained human resources to increase lab capacity in emergency situations. The laboratory diagnosis capacity includes the detection of bacteria, virus and toxins, which are considered bioterrorism agents, using Microbiology, Immunology and Molecular Biology techniques. In order to ensure quick and reliable results, a laboratory algorithm was developed taking in account the available human and technical resources. UREB also participates regularly in International External Quality Assessments, training courses and simulation exercises.