Time filter

Source Type

Duarte A.,University of Beira Interior | Santos A.,National Institute of Health Dr Ricardo Jorge | Manageiro V.,National Institute of Health Dr Ricardo Jorge | Martins A.,University of Lisbon | And 4 more authors.
International Journal of Antimicrobial Agents | Year: 2014

Infections by Campylobacter jejuni and Campylobacter coli are considered the major cause of bacterial gastroenteritis in humans, with food being the main source of infection. In this study, a total of 196 Campylobacter strains (125 isolates from humans, 39 from retail food and 32 from food animal sources) isolated in Portugal between 2009 and 2012 were characterised by multilocus sequence typing (MLST) and flaA short variable region (SVR) typing. Susceptibility to six antibiotics as well as the mechanisms underlying antibiotic resistance phenotypes was also studied. Based on MLST typing, C. coli strains were genetically more conserved, with a predominant clonal complex (CC828), than C. jejuni strains. In contrast, C. coli isolates were genetically more variable than C. jejuni with regard to flaA-SVR typing. A high rate of resistance was observed for quinolones (100% to nalidixic acid, >90% to ciprofloxacin) and, in general, resistance was more common among C. coli, especially for erythromycin (40.2% vs. 6.7%). In addition, most isolates (86%) were resistant to multiple antimicrobial families. Besides the expected point mutations associated with antibiotic resistance, detected polymorphisms in the cmeABC locus likely play a role in the multiresistant phenotype. This study provides for the first time an overview of the genetic diversity of Campylobacter strains from Portugal. It also shows a worrying antibiotic multiresistance rate and the emergence of Campylobacter strains resistant to antibiotics of human use. © 2014 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.


Ferreira S.,University of Beira Interior | Fraqueza M.J.,University of Lisbon | Queiroz J.A.,University of Beira Interior | Domingues F.C.,University of Beira Interior | Oleastro M.,National Institute Of Health Dr Ricardo Jorge
International Journal of Food Microbiology | Year: 2013

The genus Arcobacter is an emerging pathogen associated with several clinical symptoms. This genus is widely distributed and has been isolated from environmental, animal, food and human samples, where poultry is considered the major source. In this study, forty three Arcobacter butzleri strains isolated from poultry and environment of a Portuguese slaughterhouse, were characterized by pulsed field gel electrophoresis (PFGE) and assessed for antimicrobial susceptibility and ability to form biofilms. PFGE patterns obtained using restriction enzymes SmaI and SacII revealed high genetic diversity, with 32 distinct PFGE patterns. Most of A. butzleri isolates presented multiple antimicrobial resistance, exhibiting four different resistance profiles. All 43 isolates were susceptible to gentamicin and 2.3% were resistant to chloramphenicol, in contrast to twenty four (55.8%) that were resistant to ciprofloxacin. Among 36 selected isolates, 26 strains presented biofilm-forming ability, which was dependent on the atmosphere and initial inoculum density.Overall, the results showed that A. butzleri displays a high genetic diversity, and presents resistance to several antibiotics, which together with its biofilm formation ability may represent a potential hazard for foodborne infections and a considerable risk for human health. © 2013 Elsevier B.V.


Torres V.M.,ITQB UNL | Torres V.M.,National Institute of Health Dr Ricardo Jorge | Posa M.,ITQB UNL | Srdjenovic B.,ITQB UNL | Simplicio A.L.,University of Novi Sad
Colloids and Surfaces B: Biointerfaces | Year: 2011

Fullerene (C60), the third carbon allotrope, is a classical engineered material with the potential application in biomedicine. However, extremely high hydrophobicity of fullerene hampers its direct biomedical evaluation and application. In this work, we investigated the solubilization of fullerene using 9 different solubility enhancers: Tween 20, Tween 60, Tween 80, Triton X-100, PVP, polyoxyethylene (10) lauryl ether, n-dodecyl trimethylammonium chloride, myristyl trimethylammonium bromide and sodium dodecyl sulphate and evaluated its antioxidant activity in biorelevant media. The presence of C60 entrapped in surfactant micelles was confirmed by UV/VIS spectrometry. The efficacy of each modifier was evaluated by chemometric analysis using experimental data for investigating the relationship between solubilization and particle size distribution. Hierarchical clustering and principal component analysis was applied and showed that non-ionic surfactants provide better solubilization efficacy (>85%). A correlation was established (r=0.975) between the degree of solubilization and the surfactant structure. This correlation may be used for prediction of C60 solubilization with non-tested solubility modifiers. Since the main potential biomedical applications of fullerene are based on its free radical quenching ability, we tested the antioxidant potential of fullerene micellar solutions. Lipid peroxidation tests showed that the micellar solutions of fullerene with Triton and polyoxyethylene lauryl ether kept high radical scavenging activity, comparable to that of aqueous suspension of fullerene and BHT. The results of this work provide a platform for further solubilization and testing of pristine fullerene and its hydrophobic derivatives in a biological benign environment. © 2010 Elsevier B.V.


Manageiro V.,National Institute Of Health Dr Ricardo Jorge | Manageiro V.,University of Porto | Ferreira E.,National Institute Of Health Dr Ricardo Jorge | Canica M.,National Institute Of Health Dr Ricardo Jorge | Manaia C.M.,Catholic University of Portugal
FEMS Microbiology Letters | Year: 2014

In this study, we investigated the β-lactamase-encoding genes responsible for β-lactam resistance phenotypes detected among 56 Gram-negative isolates (Gamma- and Alpha-proteobacteria) recovered from wastewater, urban streams, and drinking water. The β-lactam resistance mechanisms detected in 36 isolates comprised the presence of class A (blaTEM-1, blaSHV-1, blaSHV-11, blaGES-5), class B (ImiS, L1), class C (blaCMY-2, blaCMY-34, blaCMY-65, blaCMY-89, blaCMY-90, blaACC-5, blaACT-13), and class D (blaOXA-309)β-lactamase-encoding genes, some variants described for the first time here. Notably, the results showed antimicrobial resistance genes related not only to commonly used antibiotics, but also to carbapenems, providing the first description of a GES-5-producing Enterobacteriaceae. The importance of ubiquitous bacteria thriving in aquatic environments as reservoirs or carriers of clinically relevant resistance determinants was confirmed, and the need to monitor water habitats as potential sources for the emergence and/or spread of antibiotic resistance in the environment was highlighted. © 2013 Federation of European Microbiological Societies.


Ferreira S.,University of Beira Interior | Julio C.,National Institute Of Health Dr Ricardo Jorge | Queiroz J.A.,University of Beira Interior | Domingues F.C.,University of Beira Interior | Oleastro M.,National Institute Of Health Dr Ricardo Jorge
Diagnostic Microbiology and Infectious Disease | Year: 2014

The present study was conducted to investigate the prevalence and diversity of Arcobacter and Campylobacter spp. in 298 stool samples of patients with diarrhoea, collected from 22 Portuguese hospitals, between September and November 2012. Detection of Arcobacter and Campylobacter spp. was performed using molecular-based detection techniques, such as real-time fluorescence resonance energy transfer PCR, species-specific PCR, and sequencing of amplified PCR products. Overall, 1.3% of the samples were positive for Arcobacter butzleri and 0.3% for Arcobacter cryaerophilus. Campylobacter spp. were found in 31.9% of diarrhoeic faeces. Campylobacter jejuni and Campylobacter concisus were the most prevalent species (13.7% and 8.0%, respectively). The prevalence of Arcobacter and Campylobacter spp. was significantly different between children and adults (39.7% versus 22.8%, P = 0.003). We underline the high prevalence of these pathogens in diarrhoeal samples among Portuguese patients, with particular relevance in the paediatric age group. © 2014 Elsevier Inc.


Ferreira S.,University of Beira Interior | Queiroz J.A.,University of Beira Interior | Oleastro M.,National Institute Of Health Dr Ricardo Jorge | Domingues F.C.,University of Beira Interior
Microbial Pathogenesis | Year: 2014

Even though Arcobacter butzleri has been implicated in some human disease as diarrhoea and bacteraemia, much of its pathogenesis and virulence factors remain unclear.In this work we have compared pathogenic and genotypic properties of six A.butzleri isolates from human and non-human sources. The tested isolates showed to be susceptible to tetracyclines and aminoglycosides, however non-human isolates were all resistant to quinolones. The ability to form biofilms was variable among the tested strains, and all of them showed a weak haemolytic activity. The presence of nine putative virulence genes was determined, with cadF, ciaB, cj1349, mviN, pldA, tlyA being detected in all strains, while irgA (3/6), hecA (5/6), hecB (4/6) were detected only in some strains. High levels of adhesion were observed for A.butzleri on Caco-2 cells, with pre-existing inflammation showing no significant effect on the adherence ability; yet variable levels of invasion were observed. A.butzleri isolates were able to survive intracellularly in Caco-2 cells and to induce a significant up-regulation of interleukin-8 secretion and structural cell rearrangements. These data brings new insights on A.butzleri virulence and highlights its pathogenic potential. © 2014 Elsevier Ltd.


Barbosa A.R.,National Institute Of Health Dr Ricardo Jorge | Giufre M.,Instituto Superiore Of Sanita | Cerquetti M.,Instituto Superiore Of Sanita | Bajanca-Lavado M.P.,National Institute Of Health Dr Ricardo Jorge
Journal of Antimicrobial Chemotherapy | Year: 2011

Objectives: The aim of this study was to characterize ampicillin resistance mechanisms in clinical isolates of Haemophilus influenzae from Portugal. Association between specific patterns of amino acid substitutions in penicillin-binding protein 3 (PBP3) (with or without β-lactamase production) and β-lactam susceptibility as well as genetic relatedness among isolates were investigated. Methods: Two-hundred and forty non-consecutive H. influenzae isolates chosen according to their different ampicillin MICs [101 β-lactamase-non-producing ampicillin-resistant (BLNAR) isolates, 80 β-lactamase-producing ampicillin-resistant (BLPAR) isolates and 59 β-lactamase-non-producing ampicillin-susceptible (BLNAS) isolates] were analysed. The β-lactamase-encoding blaTEM-1 gene was detected by PCR. The ftsI gene encoding PBP3 was sequenced. Genetic relatedness among isolates was examined by PFGE. Results: Of the 240 H. influenzae isolates, 141 had mutations in the transpeptidase domain of the ftsI gene, including most BLNAR strains (94/101, 93.1%) and a high percentage of BLPAR strains (47/80, 58.8%). As previously reported, the latter have been described as β-lactamase-positive amoxicillin/clavulanic acid resistant (BLPACR). The most common amino acid substitutions were identified near the KTG motif: N526K (136/141, 96.5%), V547I (124/141, 87.9%) and N569S (121/141, 85.8%). The 141 strains were divided into 31 ftsI mutation patterns and included six groups (I, IIa, IIb, IIc, IId and III-like). BLNAR strains were genetically diverse but close genetic relationships were demonstrated among BLPACR strains. Conclusions: This study shows that the non-enzymatic mechanism of resistance to β-lactams is widespread among H. influenzae isolates in Portugal. Clonal dissemination of BLPACR strains showing high resistance to ampicillin and reduced susceptibility to amoxicillin/clavulanic acid was documented. © The Author 2011. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.


Oleastro M.,National Institute of Health Dr Ricardo Jorge | Menard A.,French Institute of Health and Medical Research | Menard A.,University of Bordeaux 1
Biology | Year: 2013

Helicobacter pylori is one of the most successful human pathogens, which colonizes the mucus layer of the gastric epithelium of more than 50% of the world's population. This curved, microaerophilic, Gram-negative bacterium induces a chronic active gastritis, often asymptomatic, in all infected individuals. In some cases, this gastritis evolves to more severe diseases such as peptic ulcer disease, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. H. pylori has developed a unique set of factors, actively supporting its successful survival and persistence in its natural hostile ecological niche, the human stomach, throughout the individual's life, unless treated. In the human stomach, the vast majority of H. pylori cells are motile in the mucus layer lining, but a small percentage adheres to the epithelial cell surfaces. Adherence to the gastric epithelium is important for the ability of H. pylori to cause disease because this intimate attachment facilitates: (1 colonization and persistence, by preventing the bacteria from being eliminated from the stomach, by mucus turnover and gastric peristalsis; (2 evasion from the human immune system and (3 efficient delivery of proteins into the gastric cell, such as the CagA oncoprotein. Therefore, bacteria with better adherence properties colonize the host at higher densities. H. pylori is one of the most genetically diverse bacterial species known and is equipped with an extraordinarily large set of outer membrane proteins, whose role in the infection and persistence process will be discussed in this review, as well as the different receptor structures that have been so far described for mucosal adherence. © 2013 by the authors; licensee MDPI, Basel, Switzerland.


Nogueira P.J.,National Institute Of Health Dr Ricardo Jorge
Euro surveillance : bulletin européen sur les maladies transmissibles = European communicable disease bulletin | Year: 2010

The experience reported in an earlier Eurosurveillance issue on a fast method to evaluate the impact of the 2003 heatwave on mortality in Portugal, generated a daily mortality surveillance system (VDM) that has been operating ever since jointly with the Portuguese Heat Health Watch Warning System. This work describes the VDM system and how it evolved to become an automated system operating year-round, and shows briefly its potential using mortality data from January 2006 to June 2009 collected by the system itself. The new system has important advantages such as: rapid information acquisition, completeness (the entire population is included), lightness (very little information is exchanged, date of death, age, sex, place of death registration). It allows rapid detection of impacts (within five days) and allows a quick preliminary quantification of impacts that usually took several years to be done. These characteristics make this system a powerful tool for public health action. The VDM system also represents an example of inter-institutional cooperation, bringing together organisations from two different ministries, Health and Justice, aiming at improving knowledge about the mortality in the population.


Manageiro V.,National Institute of Health Dr Ricardo Jorge | Jones-Dias D.,National Institute of Health Dr Ricardo Jorge | Ferreira E.,National Institute of Health Dr Ricardo Jorge | Louro D.,National Institute of Health Dr Ricardo Jorge | Canica M.,National Institute of Health Dr Ricardo Jorge
International Journal of Antimicrobial Agents | Year: 2012

In this study, 116 multidrug-resistant Acinetobacter baumannii (MDR-Ab) isolates recovered in various regions of Portugal were studied. All isolates were non-susceptible to tigecycline; one isolate was also non-susceptible to colistin, making it a step closer to pandrug resistance. Among 72 isolates tested by PFGE, 98.6% carried blaOXA-66, 1.4% blaOXA-104, 77.8% blaOXA-23, 23.6% blaOXA-24, 18.1% bla TEM-1 and 1.4% blaCTX-M-15-like genes. No OXA-58 or metallo-β-lactamase-encoding genes were detected. ISAba1 was found in 58/72 isolates (80.6%). Among these, ISAba1 was found upstream of bla OXA-51-like in 54 isolates. All but two of these isolates also carried ISAba1-blaOXA-23, highlighting the coexistence of ISAba1-blaOXA-51-like and ISAba1-blaOXA-23 genetic platforms, emphasising the importance of mobile genetic elements in the dissemination of carbapenem-hydrolysing class D β-lactamase genes. Tn2006-like and Tn2008-like, found within ST92 and ST118, may reflect either multiple genetic structures in the origin of blaOXA-23 acquisition or interclonal complex evolution. These results indicate that there may exist different genetic origins for carbapenem resistance among MDR-Ab isolates. Six PFGE profiles were associated with three major sequence types, with ST118 (OXA-23- or OXA-24-producer) being widely disseminated since 2009. ST98 (described so far as endemic in Portugal) and ST92 (which co-existed with ST98 before 2009) appeared to have been gradually replaced by ST118. The new ST188 (OXA-104-producer) was detected for the first time in this country. Identification of an extensively drug-resistant ST118 and carbapenem-resistant ST92, ST98 and ST118 isolates, both in community and healthcare facilities, demonstrates the menace of A. baumannii-associated infections. © 2012 Elsevier B.V. and the International Society of Chemotherapy.

Loading National Institute Of Health Dr Ricardo Jorge collaborators
Loading National Institute Of Health Dr Ricardo Jorge collaborators