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Laura Cerqueira

Laura Cerqueira
University of Minho · Institute for Biotechnology and Bioengineering - Centre of Biological Engineering

About

32
Publications
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Publications

Publications (32)
Article
Full-text available
Legionella are opportunistic intracellular pathogens that are found throughout the environment. The Legionella contamination of water systems represents a serious social problem that can lead to severe diseases, which can manifest as both Pontiac fever and Legionnaires’ disease (LD) infections. Fluorescence in situ hybridization using nucleic acid...
Article
Full-text available
Fluorescent in situ hybridization (FISH) is a powerful tool that for more than 30 years has allowed to detect and quantify microorganisms as well as to study their spatial distribution in three-dimensional structured environments such as biofilms. Throughout these years, FISH has been improved in order to face some of its earlier limitations and to...
Poster
Full-text available
Urinary tract infections (UTI) represent one of the most common healthcare- associated infections across EU countries, accounting for 18.9% of all cases [1]. These infections are caused by microbial pathogens, either bacteria or fungi, such as Candida species. Candiduria – is defined as presence of Candida species in urine, which diagnostics relies...
Presentation
Full-text available
Candida tropicalis is the second most prevalent Candida species in urinary tract infections (UTIs). However, urine cultures take from 18 to 48 h to completely identify the microorganism, which may be sufficient for the progression of the UTI. New developments in molecular biology, automation, and micro-electro-mechanical systems, could be transferr...
Article
Full-text available
Aspergillus fumigatus is the main causative agent of Invasive Aspergillosis. This mold produces conidia that when inhaled by immunocompromized hosts can be deposited in the lungs and germinate, triggering disease. In this paper, the development of a method using peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH) is described. The PN...
Article
Fluorescent in situ hybridization (FISH) has been extensively used in the past decades for the detection and localization of microorganisms. However, a mechanistic approach of the whole FISH process is still missing, and the main limiting steps for the hybridization to occur remain unclear. In here, FISH is approached as a particular case of a diff...
Article
Listeria monocytogenes is one of the most important foodborne pathogens due to the high hospitalization and mortality rates associated to an outbreak. Several new molecular methods that accelerate the identification of L. monocytogenes have been developed, however conventional culture-based methods still remain the gold standard. In this work we de...
Article
Full-text available
Background: Probe4Cronobacter test kit is based on the use of a fluorescence-labeled peptide nucleic acid probe (PNA) allied to fluorescence microscopy. A sample is taken after a 24 h enrichment of rehydrated 30 g portions of powdered infant formula (PIF). The method uses ready to use dropper solutions applied directly in the sample. This simple pr...
Article
Full-text available
Diagnostics based on fluorescence imaging of biomolecules is typically performed in well-equipped laboratories and is in general not suitable for remote and resource limited settings. Here we demonstrate the development of a compact, lightweight and cost-effective smartphone-based fluorescence microscope, capable of detecting signals from fluoresce...
Article
Full-text available
The fungus Aspergillus fumigatus is the main pathogenic agent responsible for invasive pulmonary aspergillosis. Immunocompromised patients are more likely to develop this pathology due to a decrease in the immune system’s defense capacity. Despite of the low occurrence of invasive pulmonary aspergillosis, this pathology presents high rates of morta...
Article
MicroRNAs (miRNAs) are small, non-coding RNA molecules that regulate gene expression post-transcriptionally. As a consequence of their function towards mRNA, miRNAs are widely associated with the pathogenesis of several human diseases, making miRNAs a target for new therapeutic strategies based on the control of their expression. Indeed, numerous w...
Article
Full-text available
Peptide nucleic acid fluorescence in situ hybridization (PNA-FISH) is a highly specific molecular method widely used for microbial identification. Nonetheless, and due to the detection limit of this technique, a time-consuming pre-enrichment step is typically required before identification. In here we have developed a lab-on-a-chip device to concen...
Article
ABSTRACT Aim: Developments on synthetic molecules, such as peptide nucleic acid (PNA), make FISH procedures more robust for microbial identification. Fluorochromes use might hinder a broader implementation of PNA-FISH, but colorimetric applications are inexistent so far. A biotin-labeled eubacteria probe was used to develop a colorimetric PNA-in si...
Article
Full-text available
Despite the emergence of non-O157 Shiga toxin-producing Escherichia coli (STEC) infections, E. coli serotype O157 is still the most commonly identified STEC in the world. It causes high morbidity and mortality and has been responsible for a number of outbreaks in many parts of the world. Various methods have been developed to detect this particular...
Article
Full-text available
In this study, single and dual species biofilms of Pseudomonas aeruginosa and Escherichia coli, two common bacteria associated with urinary tract infections, were formed in silicon coupons immersed in artificial urine medium. In single species experiments, E. coli appeared to form biofilms more easily than P. aeruginosa. In mixed biofilms, both spe...
Article
Full-text available
Here, we evaluated a previously established peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH) method as a new diagnostic test for Helicobacter pylori clarithromycin resistance detection in paraffin-embedded gastric biopsy specimens. Both a retrospective study and a prospective cohort study were conducted to evaluate the specificity...
Article
Full-text available
In here, we evaluated a previously established PNA-FISH method as a new diagnostic test for H. pylori clarithromycin resistance detection in paraffin embedded gastric biopsies. Both a retrospective and a prospective cohort study were conducted to evaluate the specificity and sensitivity of a PNA-FISH method to determine H. pylori clarithromycin res...
Article
Several methods for the rapid and specific detection of Salmonella in food samples have been described. Here, we compare 4 of those methods in terms of assay time, procedure complexity, detection limit, sensitivity, specificity and accuracy. Milk, eggs and mayonnaise samples were artificially contaminated with Salmonella enterica serovar Enteritidi...
Article
Full-text available
Background Plating methods are still the golden standard in microbiology; however, some studies have shown that these techniques can underestimate the microbial concentrations and diversity. A nutrient shock is one of the mechanisms proposed to explain this phenomenon. In this study, a tentative method to assess nutrient shock effects was tested....
Data
Table A1 Values of colony forming units (CFU) and respective standard deviation obtained for all species at different times when exposed to water and then plated on R2A and TSA. Table A2 Values of colony forming units (CFU) and respective standard deviation obtained for all species at different times when exposed to TSB and then plated on R2A and T...
Article
Full-text available
Staphylococcus epidermidis is considered to be one of the most common causes of nosocomial bloodstream infections, particularly in immune-compromised individuals. Here, we report the development and application of a novel peptide nucleic acid probe for the specific detection of S. epidermidis by fluorescence in situ hybridization. The theoretical e...
Article
Full-text available
Triple therapy is the gold standard treatment for Helicobacter pylori eradication from the human stomach, but increased resistance to clarithromycin became the main factor of treatment failure. Until now, fastidious culturing methods are generally the method of choice to assess resistance status. In this study, a new genotypic method to detect clar...
Conference Paper
Helicobacter pylori is a Gram-negative rod that colonizes the human stomach and is associated with the gastrointestinal disorders such as chronic gastritis, peptic ulcer disease, and gastric carcinoma. The over usage of the standard treatments (triple therapy) led to an increased antibiotic resistance. So far, routine antibiotic- resistance charact...
Article
Full-text available
Fluorescence in situ hybridization (FISH) is a well-established technique that is used for a variety of purposes, ranging from pathogen detection in clinical diagnostics to the determination of chromosomal stability in stem cell research. The key step of FISH involves the detection of a nucleic acid region and as such, DNA molecules have typically...
Article
Full-text available
Part of the reason for rejecting aquatic environments as possible vectors for the transmission of Helicobacter pylori has been the preference of this microorganism to inhabit the human stomach and hence use a direct oral-oral route for transmission. On the other hand, most enteric bacterial pathogens are well known for being able to use water as an...
Article
Full-text available
After characterization of preferred conditions for Helicobacter pylori survival in the sessile state, it was observed that the bacterium transforms from spiral to coccoid under mild circumstances, whereas under extreme ones it is unable to undergo shape modification. This strongly supports the view that transformation into the coccoid form is an ac...