Browsing by Author "Oliveira, Manuela"
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- Absence of Synergism between a Dual-AMP Biogel and Antibiotics Used as Therapeutic Agents for Diabetic Foot InfectionsPublication . Soares, Rui Silva; Gomes, Diana; Serrano, Isa; Cunha, Eva; Tavares, Luís; Oliveira, ManuelaDiabetic foot infections (DFIs) are frequently linked to diabetic-related morbidity and death because of the ineffectiveness of conventional antibiotics against multidrug-resistant bacteria. Pexiganan and nisin A are antimicrobial peptides (AMPs), and their application may complement conventional antibiotics in DFI treatment. A collagen 3D model, previously established to mimic a soft-tissue collagen matrix, was used to evaluate the antibacterial efficacy of a guar gum gel containing pexiganan and nisin alone and combined with three antimicrobials toward the biofilms of Staphylococcus aureus and Pseudomonas aeruginosa isolated from infected foot ulcers. Antimicrobials and bacterial diffusion were confirmed by spot-on-lawn and bacterial growth by bacterial count (cfu/mL). Our main conclusion was that the dual-AMP biogel combined with gentamicin, clindamycin, or vancomycin was not able to significantly reduce bacterial growth or eradicate S. aureus and P. aeruginosa DFI isolates. We further reported an antagonism between dual-AMP and dual-AMP combined with antibiotics against S. aureus.
- Aeromonas spp. prevalence, virulence, and antimicrobial resistance in an ex situ program for threatened freshwater fish-a pilot study with protective measuresPublication . Grilo, Miguel; Amaro, Guadalupe; Chambel, Lelia; Marques, Carolina S.; Marques, Tiago A.; Gil, Fátima; Sousa-Santos, Carla; Robalo, Joana I.; Oliveira, ManuelaEx situ breeding programs are important conservation tools for endangered freshwater fish. However, developing husbandry techniques that decrease the likelihood of disease, antimicrobial resistance, and virulence determinants acquisition during this process is challenging. In this pilot study, we conducted a captivity experiment with Portuguese nase (Iberochondrostoma lusitanicum), a critically endangered leuciscid species, to investigate the influence of simple protective measures (i.e., material disinfection protocols and animal handling with gloves) on the dynamics of a potential pathogenic genus, Aeromonas, as well as its virulence profiles and antimicrobial resistance signatures. Our findings show that antimicrobial resistance in Aeromonas spp. collected from I. lusitanicum significantly increased during the extent of the assay (5 weeks), with all isolates collected at the end of the study classified as multidrug-resistant. Additionally, humans handling fishes without protective measures were colonized by Aeromonas spp. The use of protective measures suggested a decreasing trend in Aeromonas spp. prevalence in I. lusitanicum, while bacterial isolates displayed significantly lower virulence index values when virulence phenotypical expression was tested at 22 °C. Despite this study representing an initial trial, which needs support from further research, protective measures tested are considered a simple tool to be applied in ex situ breeding programs for aquatic animals worldwide. Furthermore, current results raise concern regarding antimicrobial resistance amplification and zoonotic transmission of Aeromonas spp. in aquatic ex situ programs.
- An approach to assess actor's preferences and social learning to enhance participatory forest management planningPublication . Marques, Marlene; Oliveira, Manuela; Borges, Jose G.Forest management planning is often challenged by the need to address contrasting preferences from several actors. Participatory approaches may help integrate actors’ preferences and demands and thus address this chal- lenge. Workshops that encompass a participatory approach may further influence actors’ opinions and knowledge through social interaction and facilitate the development of collaborative landscape-level planning. Nevertheless, there is little experience of formal assessment of impacts of workshops with participatory approaches. This re- search addresses this gap. The emphasis is on the development of an approach (a) to quantify actors’ preferences for forest management models, post-fire management options, forest functions, and ecosystem services; (b) to assess the impact of participatory discussions on actors’ opinions; and (c) to evaluate the effect of social interac- tion on the actors’ learning and knowledge. The methodology involves a workshop with participatory approach, matched pre- and post-questionnaires, a non-parametric test, the Wilcoxon Signed-rank test for paired samples, and a self-evaluation questionnaire. We report results from an application to a joint forest management area in Vale do Sousa, in North-Western Por- tugal. Findings suggest that workshop and participatory discussions do contribute to social knowledge and learn- ing about forest management models. Actors debated alternatives that can address their financial and wildfire risk-resistance concerns. Also, during the participatory discussions, actors expressed their interest in multifunc- tional forestry. These findings also suggest an opportunity to enhance forest management planning by promoting landscape-level collaborative forest management plans that may contribute to the diversification of forest man- agement models and to the provision of a wider range of ecosystem services. However, more research is needed to strengthen the pre- and post-questionnaire approach, giving more time to actors to reflect on their preferences, to improve methods for quantifying social learning and to develop actors’ engagement strategies
- Analyzing the safety of the parasiticide fungus Mucor circinelloides : first insights on its virulence profile and interactions with the avian gut microbial communityPublication . Lozano, João; Cunha, Eva; Almeida, Cristina; Nunes, Mónica; Dias, Ricardo; Vicente, Eduardo; Sebastião, Daniela; Henriques, Sérgio; Madeira de Carvalho, Luís; Paz-Silva, Adolfo; Oliveira, ManuelaParasiticide fungi are considered an accurate, sustainable, and safe solution for the biocontrol of animal gastrointestinal (GI) parasites. This research provides an initial characterization of the virulence of the native parasiticide fungus Mucor circinelloides (FMV-FR1) and an assessment of its impact on birds’ gut microbes. The genome of this fungus was sequenced to identify the genes coding for virulence factors. Also, this fungus was checked for the phenotypic expression of proteinase, lecithinase, DNase, gelatinase, hemolysin, and biofilm production. Finally, an in vivo trial was developed based on feeding M. circinelloides spores to laying hens and peacocks three times a week. Bird feces were collected for 3 months, with total genomic DNA being extracted and subjected to long-read 16S and 25S-28S sequencing. Genes coding for an iron permease (FTR1), iron receptors (FOB1 and FOB2), ADP-ribosylation factors (ARFs) (ARF2 and ARF6), and a GTPase (CDC42) were identified in this M. circinelloides genome. Also, this fungus was positive only for lecithinase activity. The field trial revealed a fecal microbiome dominated by Firmicutes and Proteobacteria in laying hens, and Firmicutes and Bacteroidetes in peacocks, whereas the fecal mycobiome of both bird species was mainly composed of Ascomycetes and Basidiomycetes fungi. Bacterial and fungal alpha-diversities did not differ between sampling time points after M. circinelloides administrations (P = 0.62 and P = 0.15, respectively). Although findings from this research suggest the lack of virulence of this M. circinelloides parasiticide isolate, more complementary in vitro and in vivo research is needed to conclude about the safety of its administration to birds, aiming at controlling their GI parasites.
- Analyzing the safety of the parasiticide fungus Mucor circinelloides: first insights on its virulence profile and interactions with the avian gut microbial communityPublication . Lozano, João; Cunha, Eva; Almeida, Cristina; Nunes, Mónica; Dias, Ricardo; Vicente, Eduardo; Sebastião, Daniela; Henriques, Sérgio; Madeira de Carvalho, Luís; Paz-Silva, Adolfo; Oliveira, ManuelaParasiticide fungi are considered an accurate, sustainable, and safe solution for the biocontrol of animal gastrointestinal (GI) parasites. This research provides an initial characterization of the virulence of the native parasiticide fungus Mucor circinelloides (FMV-FR1) and an assessment of its impact on birds’ gut microbes. The genome of this fungus was sequenced to identify the genes coding for virulence factors. Also, this fungus was checked for the phenotypic expression of proteinase, lecithinase, DNase, gelatinase, hemolysin, and biofilm production. Finally, an in vivo trial was developed based on feeding M. circinelloides spores to laying hens and peacocks three times a week. Bird feces were collected for 3 months, with total genomic DNA being extracted and subjected to long-read 16S and 25S-28S sequencing. Genes coding for an iron permease (FTR1), iron receptors (FOB1 and FOB2), ADP-ribosylation factors (ARFs) (ARF2 and ARF6), and a GTPase (CDC42) were identified in this M. circinelloides genome. Also, this fungus was positive only for lecithinase activity. The field trial revealed a fecal microbiome dominated by Firmicutes and Proteobacteria in laying hens, and Firmicutes and Bacteroidetes in peacocks, whereas the fecal mycobiome of both bird species was mainly composed of Ascomycetes and Basidiomycetes fungi. Bacterial and fungal alpha-diversities did not differ between sampling time points after M. circinelloides administrations (P = 0.62 and P = 0.15, respectively). Although findings from this research suggest the lack of virulence of this M. circinelloides parasiticide isolate, more complementary in vitro and in vivo research is needed to conclude about the safety of its administration to birds, aiming at controlling their GI parasites.
- Antibiotic heteroresistance and persistence: an additional aid in hospital acquired infections by Enterococcus spp.?Publication . Geraldes, Catarina; Tavares, Luís; Gil, Solange; Oliveira, ManuelaEnterococcus, particularly E. faecium and E. faecalis, are responsible for many hospital-acquired infections. With their intrinsic antibiotic resistance and ability to form biofilms, enterococcal infections are already challenging to manage. However, when heterogenous populations are present, such as those exhibiting heteroresistance and persistence, the complexity of these infections increases exponentially not only due to their treatment but also due to their difficult diagnosis. In this study, we provide a summary of the current understanding of both heteroresistance and persistence in terms of mechanisms, diagnosis and treatment and subsequently review recent literature pertaining to these susceptibility types specifically in enterococci.
- Antibiotic resistance and virulence profiles of Gram-Negative bacteria isolated from loggerhead sea turtles (Caretta caretta) of the Island of Maio, Cape VerdePublication . Fernandes, Matilde; Grilo, Miguel; Cunha, Eva; Carneiro, Carla; Tavares, Luis; Patino-Martinez, Juan; Oliveira, ManuelaPrevious studies revealed high levels of antimicrobial resistance (AMR) in loggerhead sea turtles (Caretta caretta), describing this species as prime reservoir of antimicrobial-resistant bacteria. This study aimed to characterise, for the first time, the AMR and virulence profiles of Gram-negative bacteria isolated from 33 nesting loggerhead turtles of the island of Maio, Cape Verde. Cloacal, oral, and egg content swab samples (n = 99) were collected and analysed using conventional bacteriological techniques. Shewanella putrefaciens, Morganella morganii, and Vibrio alginolyticus were isolated from the samples under study. The isolates obtained from this loggerhead subpopulation (North-East Atlantic) revealed lower levels of AMR, compared with the results of studies performed in other subpopulations (e.g., Mediterranean). However, the detection of resistance to carbapenems and multiple antimicrobial resistance indices higher than 0.20, raises concern about the potential association of these animals to points of high antimicrobial exposure. Furthermore, virulence phenotypic characterisation revealed that the isolates presented complex virulence profiles, including the ability to produce biofilms. Finally, due to their pathogenic potential, and considering the evidence of illegal consumption of turtle-related products on the island of Maio, the identified bacteria may represent a significant threat to public health.
- Antimicrobial Resistance and Virulence Potential of Bacterial Species from Captive Birds of Prey—Consequences of Falconry for Public HealthPublication . Magalhães, Rita; Tavares, Luís; Oliveira, ManuelaFalconry has been practiced for thousands of years and is nowadays frequently employed in activities such as pest control, hunting, falcon racing, and environmental education. Antimicrobial resistance levels have risen in the past years, constituting an emerging global problem with a direct impact on public health. Besides both topics being studied on their own, information on the role of captive birds of prey in the potential dissemination of virulence factors and antimicrobial resistance determinants of bacterial origin is scarce. Multidrug-resistant bacteria, including some extended-spectrum β-lactamase producers, have already been found in several captive birds of prey. Most of the virulence factors found in captive raptors’ bacteria were related to adherence and invasion abilities, toxin production, and flagella. These birds may acquire these bacteria through contaminated raw food and the exchange of animals between keepers and zoological facilities. More studies are required to confirm the role of captive birds of prey in disseminating resistant bacteria and on the routes of interaction between synanthropic species and humans.
- Antimicrobial resistance and virulence profiles of Enterobacterales isolated from two-finger and three-finger sloths (Choloepus hoffmanni and Bradypus variegatus) of Costa RicaPublication . Fernandes, Matilde; Carneiro, Carla; Villada Rosales, Ana Maria; Grilo, Miguel; Ramiro, Yolanda; Cunha, Eva; Nunes, Telmo; Tavares, Luis; Sandi, Janet; Oliveira, ManuelaBackground: Wildlife has been recently recognized as an environmental reservoir for antimicrobial resistance (AMR). However, less information on this topic is available in animals released back into the wild after rehabilitation in wildlife facilities, compared with studies performed exclusively in captive or free-ranging wildlife. This study aimed to evaluate the potential influence of captivity and/or treatment while in captivity of wild sloths on the AMR and virulence profiles of sloths’ Enterobacterales. Methods: Oral and rectal swab samples were collected from 39 two-finger (Choloepus hoffmanni) and three-finger sloths (Bradypus variegatus) of Costa Rica (n = 78) and analyzed using conventional bacteriological techniques. A generalized linear mixed model was applied to estimate the isolates’ multiple antimicrobial resistance and virulence indices as a function of animal status. Results: A considerable level of resistance was detected, especially for Citrobacter youngae and Escherichia coli, with 17.5% of isolates classified as multidrug-resistant. Virulence indices of isolates from rehabilitated sloths were significantly higher than the ones from sloths being hand-reared for shorter periods. Conclusions: To our knowledge, this is the first description of sloths’ antimicrobial resistant Enterobacterales, suggesting that sloths’ rehabilitation and consequent exposure to humans, may promote the selection of bacteria with higher virulence. Ultimately, these bacteria may represent a threat to human and animal health due to their zoonotic potential and AMR and virulence profiles.
- Antimicrobial, Antioxidant and Anti-Inflammatory Activities of the Mucus of the Tropical Sea Slug Elysia crispataPublication . Lopes, Diana; Cunha, Eva; Conde, Tiago; Moreira, Anthony; Cruz, Sónia; Domingues, Pedro; Oliveira, Manuela; Cartaxana, PauloElysia crispata (Sacoglossa, Gastropoda) is a tropical sea slug known for its ability to incorporate functional chloroplasts from a variety of green macroalgae, a phenomenon termed kleptoplasty. This sea slug, amenable to laboratory cultivation, produces mucus, a viscous secretion that serves diverse purposes including protection, locomotion, and reproduction. In this study, we profiled the antimicrobial, antioxidant, and anti-inflammatory activities of the mucus of this sea slug. Results revealed inhibitory activity against several bacterial strains, more pronounced for Gram–negative bacteria. Particularly interesting was the strong inhibitory effect against Pseudomonas aeruginosa, a bacterial species classified by the WHO as a high-priority pathogen and associated with high-risk infections due to its frequent multidrug-resistant profile. Similar inhibitory effects were observed for the mucus native protein extracts, indicating that proteins present in the mucus contributed significantly to the antimicrobial activity. The mucus also showed both antioxidant and anti-inflammatory activities. The latter activities were associated with the low molecular weight (<10 kDa) fraction of the mucus rather than the native protein extracts. This study opens the way to further research on the biotechnological applications of the mucus secreted by this unique marine organism, particularly as an antimicrobial agent.