Browsing by Author "Nascimento, Maria"
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- Aeromonas spp. in Freshwater Bodies: Antimicrobial Resistance and Biofilm AssemblyPublication . Nascimento, Maria; Rodrigues, João; Matias, Rui; Jordão, LuisaAeromonas spp. are environmental bacteria able to infect animals and humans. Here, we aim to evaluate the role of biofilms in Aeromonas persistence in freshwater. Aeromonas were isolated from water and biofilm samples and identified by Vitek-MS and 16S rRNA sequencing. Antibiotic susceptibility profiles were determined according to EUCAST, and a crystal violet assay was used to assess biofilm assembly. MTT and the enumeration of colony-forming units were used to evaluate biofilm and planktonic Aeromonas susceptibility to chlorination, respectively. Identification at the species level was challenging, suggesting the need to improve the used methodologies. Five different Aeromonas species (A. salmonicida, A. hydrophila, A. media, A. popoffii and A. veronii) were identified from water, and one species was identified from biofilms (A. veronii). A. veronnii and A. salmonicida presented resistance to different antibiotics, whith the highest resistance rate observed for A. salmonicida (multiple antibiotic resistance index of 0.25). Of the 21 isolates, 11 were biofilm producers, and 10 of them were strong biofilm producers (SBPs). The SBPs presented increased tolerance to chlorine disinfection when compared with their planktonic counterparts. In order to elucidate the mechanisms underlying biofilm tolerance to chlorine and support the importance of preventing biofilm assembly in water reservoirs, further research is required.
- Espécies exóticas em lagos ornamentais: adorno ou fonte de desequilíbrio?Publication . Nascimento, Maria; Paulino, Sérgio; Faria, Sónia; Cano, Manuela; Rosa, Nuno; Rodrigues, João Carlos; Reis, Lúcia; Jordão, LuísaEste trabalho teve como objetivo analisar a evolução sazonal da população de microrganismos dum lago ornamental da região de Lisboa.
- Exploring a link between healthcare associated infections, biofilms and antimicrobial resistancePublication . Bandeira, Maria; Borges, Vítor; Nascimento, Maria; Duarte, Aida; Gomes, Joao Paulo; Jordão, LuísaHAIs are a major public health problem affecting 4 million patients per year in Europe. Here we present results of a retrospective study in wich the ability of K. pneumoniae isolates (collected during a period of 31 years) to assemble biofilms was evaluated; and an ongoing study of multispecies biofilms. In the first study, we found major differences in biofilm assembly kinetics, extracellular polymeric substances (EPS) content, which were further corroborated by in-depth EPS composition analysis. WGS analysis revealed a high nucleotide similarity within the core-genome, but relevant differences in the accessory genome that may account for the detected biofilm phenotypic dissimilarities, such as genes already associated with biofilm formation in other pathogenic bacteria (e.g., genes coding haemogglutinins and haemolysins). These data reinforce that the research efforts to defeat bacterial biofilms should take into account that their dynamics may be contingent on the medical devices-associated materials. The second study is ongoing and we aim at understanding the basis of multispecies biofilm assembly on different surfaces. Bacterial and fungi isolates have been used as models and until now all results suggest that the two microorganisms play different roles on biofilm onset.
- Insights on catheter-related bloodstream infections: a prospective observational study on the catheter colonization and multi-drug resistancePublication . Pinto, Miguel; Borges, Vítor; Nascimento, Maria; Martins, Filomena; Pessanha, Maria Ana; Faria, Isabel; Rodrigues, João; Matias, Rui; Gomes, João Paulo; Jordao, LuisaBackground: Central venous catheter-related bloodstream infection (CRBSI) is a huge public health concern with considerable impact on mortality and health costs. Aim: A three-year observational study enrolling three tertiary hospitals located in Lisbon, Portugal, was designed to identify the major aetiological agents of CRBSI, their ability to colonize central venous catheters and their antimicrobial resistance profiles. Methods: Aetiological agents of CRBSI were identified by Vitek 2. Whole-genome sequencing was used to confirm CRBSI by the most prevalent aetiological agents and characterize their resistome. Central venous catheter colonization (namely by biofilm assembly) was monitored by scanning electron microscopy. Findings: Staphylococci were the most prevalent causative agent (36/58, 62.0%), with S. aureus and coagulase-negative S. epidermidis accounting for 24.1% and 36.2% of CRBSIs, respectively. Fifty-nine of 72 staphylococci isolates were meticillin resistant. Comparative genomic analysis of central venous catheters/haemoculture pairs of isolates revealed genomic matches for 35 of 36 pairs and a good correlation between antibiotic susceptibility phenotype and the presence of antimicrobial resistance genetic determinants. Biofilms were present on 48.6% of the central venous catheters; nevertheless, no statistically significant association was established between biofilm assembly and CRBSI, and the presence/absence of ica operon and agr groups did not correlate with biofilm phenotypes, highlighting the need for further studies to elucidate biofilms' role on this healthcare-associated infection. Conclusion: Whole-genome sequencing was shown to be a valuable tool to confirm CRBSI. Although more than 42.3% of the central venous catheters were colonized by staphylococci, no statistically significant association was found between CRBSI and biofilms.
- Pathogens in ornamental waters: a pilot studyPublication . Nascimento, Maria; Rodrigues, João; Reis, Lúcia; Nogueira, Isabel; Carvalho, Patricia; Brandão, João; Duarte, Aida; Jordão, LuísaIn parks, ornamental waters of easy access and populated with animals are quite attractive to children and yet might hide threats to human health. The present work focuses on the microbiota of the ornamental waters of a Lisboa park, characterized during 2015. The results show a dynamic microbiota integrating human pathogens such as Klebsiella pneumoniae, Aeromonas spp. and Enterobacter spp., and also antibiotic resistant bacteria. K. pneumoniae and Aeromonas spp. were present as planktonic and biofilm organized bacteria. In vitro K. pneumoniae and Aeromonas spp. showed an enhanced ability to assemble biofilm at 25 C than at 37 C. Bacteria recovered from biofilm samples showed an increased antibiotic resistance compared to the respective planktonic counterparts.
- Prospective observational study of health care associated infections with central venous catheters in three tertiary hospitals in Lisbon, PortugalPublication . Nascimento, Maria; Faria, Isabel; Pessanha, Maria Ana; Duarte, Aida; Martins, Filomena; Jordão, LuísaHealthcare Associated Infection (HAI) are a major public health problem affecting 4 million patients per year in Europe and contribute increase the costs associated with healthcare. Cathether related bloodstream infections (CRBSI) are an important group of HAIs registering high incidence (87%) and mortality rates (23%) particulary in intensive care units (ICUs). In this work, an observational prospective study aiming at documenting the occurrence of CRBSI in three hospitals in Lisbon was performed. The study has been ongoing for 2 years and have identified 40 cases of CRBSI. The etiological agent, health unit, patient and central venous catheter (CVC) were characterized. The majority of the CRBSI (92.5%) have as etiological agent a bacterium resistant to at least one antibiotic (28/37); however, 3 cases (7.5%) of Candida spp. infections were identified. Two cases of infection are due to 2 bacteria. It should be noted that 67% of the infections are caused by staphylococci, of which 55.6% are coagulase negative (14 S. epidermidis and 1 S. haemolyticus) and 44.4% coag positive (12 S. aureus). It was not possible to associate a particular microorganism with one of the 3 hospitals. This may be due, in part, to sample dimension. The distribution of cases according to the inpatient service was as follows: intensive care units (35%), medical specialties (32.5%), surgical specialties (17%), general surgery (10%) and internal medicine (5%). The adults (mean age 58 years: 14/40) and the elderly (mean age 74 years: 22/40) were the age groups with the highest number of cases. The remainder were recorded in newborns (<1 month: 2/40) and young adults (2/40). More than half of the CVCs were inserted into the patient's jugular and remained there for less than 4 weeks (75%). The results obtained demonstrate that coagulase negative staphylococci are major players in CRBSI and antibiotic resistance. Cases due to more than one etiological agent may be associated with colonization of CVCs by biofilms. This aspect is being investigated by researching these structures in the CVCs. The collection of more data and its statistical treatment will allow to establish / exclude possible relationships between the different factors that determine the establishment of HAI. This, together with a greater knowledge of the etiological agents resulting from the sequencing of its genome, will increase our knowledge and, in the long term, establish more effective methods of control and prevention of HAIs.
- Prospective observational study on the role of catheter colonization and multidrug-resistance associated with catheter-related bloodstream infectionsPublication . Pinto, Miguel; Borges, Vitor; Nascimento, Maria; Martins, Filomena; Pessanha, Maria Ana; Faria, Isabel; Rodrigues, Joao; Matias, Rui; Joao Paulo, Gomes; Jordao, LuisaBackground: Central venous catheter (CVC)-related bloodstream infection (CRBSI) is a huge public health consern with considerable impact on mortality and health costs. The emergence of antimicrobial resistant microorganisms associated or not with CVC colonization by biofilms makes the treatment of CRBSI even more challeging. Methods:A 3-year observational study enrolling 3 tertiary hospitals located in Lisbon (Portugal) was designed to identify the major etiological agent of 58 CRBSI, their ability to colonize CVCs and their antimicrobial resistance profiles. Etiological agents of CRBSI were idebtified by VITEK-2. Whole-genome sequencing was used to confirm CRBSI by the most prevalent etiological agents and characteriza their resistome. CVC's colonization (namely by biofilm assembly) was monitored by scanning electron microscopy. Results: Staphylococci were the most prevalent causative agent (36/58, 62%), with S. aureus and coagulase negative S. epidermidis accounting for 24.1% and 36.2% of CRBSIs, respectively. Comparative genomic analysis of CVCs/hemoculture pairs of isolates revealed genomic matches for 35/36 pairs and a good correlation between antibiotic susceptibility phenotype and the presence of antimicrobials resistance genetic determinants. CVCs colonization was observed mainly in the catheter lumen and presented different phenotypes ranging from isolated attached microorganisms to mature biofilms. The latest phenotype, mature biofilms of S. epidermidis and S. aureus were found for 50.0% and 48.6% of the CVCs, respectively. Nevertheless, no statistical significant association was established between biofilm assembly and CRBSI highlighting the need for further studies to elucidate biofilms' role on this HAI. Conclusion: WGS proved to be a valuable tool to confirm CRBSI. Despite staphylococci biofilms identification on a considerable number of CVCs, no statistically significant association was found between CRBSI and biofilms.