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Health Sciences Research Centre
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Publications
Evaluation of Bile Salts on the Survival and Modulation of Virulence of Aliarcobacter butzleri
Publication . Mateus, Cristiana; Maia, Cláudio J.; Domingues, Fernanda; Bücker, Roland; Oleastro, Mónica; Ferreira, Susana
Aliarcobacter butzleri is a Gram-negative bacterium associated with infections of the gastrointestinal tract and widely distributed in various environments. For successful infection, A. butzleri should be able to tolerate various stresses during gastrointestinal passage, such as bile. Bile represents an antimicrobial host barrier that acts against external noxious agents and consists of a variety of bile salts. The intestinal bile salts act as detergents involved in the antimicrobial host defense; although, on the bacterial side, they could also serve as a signal to activate virulence mechanisms. The aim of this work was to understand the effects of bile salts on the survival and virulence of A. butzleri. In our study, A. butzleri was able to survive in the presence of human physiological concentrations of bile salts. Regarding the virulence features, an increase in cellular hydrophobicity, a decrease in motility and expression of flaA gene, as well as an increase in biofilm formation with a concomitant change in the type of biofilm structure were observed in the presence of sub-inhibitory concentration of bile salts. Concerning adhesion and invasion ability, no significant difference was observed. Overall, the results demonstrated that A. butzleri is able to survive in physiological concentrations of bile salts and that exposure to bile salts could change its virulence mechanisms.
Effect of Atmospheric Conditions on Pathogenic Phenotypes of Arcobacter butzleri
Publication . Martins, Rodrigo; Mateus, Cristiana; Domingues, Fernanda; Bücker, Roland; Oleastro, Mónica; Ferreira, Susana
Arcobacter butzleri is an emergent gram-negative enteropathogenic bacterium widespread in different environments and hosts. During the colonization of the gastrointestinal tract, bacteria face a variety of environmental conditions to successfully establish infection in a new host. One of these challenges is the fluctuation of oxygen concentrations encountered not only throughout the host gastrointestinal tract and defences but also in the food industry. Oxygen fluctuations can lead to modulations in the virulence of the bacterium and possibly increase its pathogenic potential. In this sense, eight human isolates of A. butzleri were studied to evaluate the effects of microaerobic and aerobic atmospheric conditions in stressful host conditions, such as oxidative stress, acid survival, and human serum survival. In addition, the effects on the modulation of virulence traits, such as haemolytic activity, bacterial motility, biofilm formation ability, and adhesion and invasion of the Caco-2 cell line, were also investigated. Overall, aerobic conditions negatively affected the susceptibility to oxygen reactive species and biofilm formation ability but improved the isolates’ haemolytic ability and motility while other traits showed an isolate-dependent response. In summary, this work demonstrates for the first time that oxygen levels can modulate the potential pathogenicity of A. butzleri, although the response to stressful conditions was very heterogeneous among different strains.
Putative Role of an ABC Efflux System in Aliarcobacter butzleri Resistance and Virulence
Publication . Martins, Inês; Mateus, Cristiana; Domingues, Fernanda; Oleastro, Mónica; Ferreira, Susana
Abstract: Aliarcobacter butzleri is considered a ubiquitous microorganism and emergent pathogen,
for which increasing rates of multidrug resistance have been described. In line with this, the present
work aimed to evaluate for the first time the contribution of an ABC efflux system, the YbhFSR, in
the resistance and virulence of this bacterium. Following the in silico characterization of the YbhFSR
transporter, a mutant strain was constructed by inactivating the gene responsible for ATP-binding.
After ensuring that the mutation did not have an impact on bacterial growth, the resistance profile
of parental and mutant strains to different antimicrobial agents was evaluated. The results suggest
that the efflux pump may influence the resistance to benzalkonium chloride, ethidium bromide,
and cadmium, and several other compounds were identified as potential substrates. Regarding
the evaluation of the accumulation of ethidium bromide, a slight increase was observed for the
mutant strain, demonstrating a potential role of the YbhFSR efflux pump in the extrusion of toxic
compounds from A. butzleri. Subsequently, the role of this efflux pump on the A. butzleri known
virulence properties was evaluated, but no difference was seen among mutant and parental strains
for the motility, biofilm formation ability, susceptibility to oxidative stress, or the ability to adhere and
invade Caco-2 cells. However, in contrast to the parental strain, the mutant strain showed a resistance
to human serum. Overall, the results support the role of efflux pumps in A. butzleri resistance to
antimicrobials, highlighting the particular role of the YbhFSR system.
The Prevalence of Arcobacteraceae in Aquatic Environments: A Systematic Review and Meta-Analysis
Publication . Venâncio, Igor; Luís, Ângelo; Domingues, Fernanda; Oleastro, Mónica; Pereira, Luísa; Ferreira, Susana
Members of the family Arcobacteraceae are distributed widely in aquatic environments, and some of its species have been associated with human and animal illness. However, information about the diversity and distribution of Arcobacteraceae in different water bodies is still limited. In order to better characterize the health risk posed by members in the family Arcobacteraceae, a systematic review and meta-analysis-based method was used to investigate the prevalence of Arcobacteraceae species in aquatic environments based on available data published worldwide. The database search was performed using related keywords and considering studies up to February 2021. The pooled prevalence in aquatic environments was 69.2%, ranging from 0.6 to 99.9%. These bacteria have a wide geographical distribution, being found in diverse aquatic environments with the highest prevalence found in raw sewage and wastewater treatment plants (WWTP), followed by seawater, surface water, ground water, processing water from food processing plants and water for human consumption. Assessing the effectiveness of treatments in WWTP in eliminating this contamination, it was found that the wastewater treatment may not be efficient in the removal of Arcobacteraceae. Among the analyzed Arcobacteraceae species, Al. butzleri was the most frequently found species. These results highlight the high prevalence and distribution of Arcobacteraceae in different aquatic environments, suggesting a risk to human health. Further, it exposes the importance of identifying and managing the sources of contamination and taking preventive actions to reduce the burden of members of the Arcobacteraceae family.
Thymus mastichina (L.) L. and Cistus ladanifer L. for skin application: chemical characterization and in vitro bioactivity assessment
Publication . Oliveira, Ana S.; Rolo, Joana; Gaspar, Carlos; Ramos, Leonor; Cavaleiro, Carlos; Salgueiro, Lígia; Palmeira-de-Oliveira, Rita; Teixeira, João Paulo; Martinez-de-Oliveira, José; Palmeira-de-Oliveira, Ana
Ethnopharmacological relevance: Thymus mastichina (L.) L. (TM) and Cistus ladanifer L. (CL) are two Portuguese autochthonous species with traditional skin application in folk medicine. TM is majorly known for its antiseptic and wound healing properties, as an external anti-inflammatory agent and for its application in folk cosmetics and hygiene products. Its use in acne vulgaris has also been reported. CL is traditionally used in remedies for wounds, ulcers and other skin ailments such as psoriasis and eczema. Its application has been found useful due to its anti-inflammatory, astringent, wound healing and antiseptic properties.
Aim of the study: With this work, we aimed to investigate relevant bioactivities related with the traditional application of TM and CL essential oils (EOs) and hydrolates (by-products of EO production) in skin ailments. Specifically their in vitro antioxidant, anti-inflammatory, cytotoxic, wound healing and antimicrobial properties were evaluated. The chemical composition of both EOs and respective hydrolates was also characterized.
Materials and methods: Chemical characterization of EOs and hydrolates was performed by GC-FID and GC-MS. Cellular biocompatibility was evaluated using the MTT assay in macrophages (RAW 264.7) and fibroblasts (L929) cell lines. Anti-inflammatory activity was investigated by studying nitric oxide (NO) production by macrophages with Griess reagent. Wound healing potential was evaluated with the scratch-wound assay. The antioxidant potential was studied by the DPPH scavenging method. Antimicrobial activity was evaluated by broth microdilution assay against relevant microbial strains and skin pathogens, namely Staphylococcus aureus, Staphylococcus epidermidis, Cutibacterium acnes, Pseudomonas aeruginosa, Escherichia coli, Candida albicans and Aspergillus brasiliensis.
Results: The major compounds present in TM and CL EOs were 1,8-cineole and α-pinene, respectively. 1,8-cineole and E-pinocarveol were the major compounds in the correspondent hydrolates. CL EO presented the highest anti-inflammatory potential [EC50 = 0.002% (v/v)], still with significant cytotoxicity [IC50 = 0.012% (v/v)]. TM preparations presented anti-inflammatory potential, also presenting higher biocompatibility. The same profile was present on fibroblasts regarding biocompatibility of the tested preparations. CL EO and hydrolate increased fibroblasts' migration by 155.7% and 148.4%, respectively. TM hydrolate presented a milder activity than CL hydrolate, but wound healing potential was still present, increasing cell migration by 125.1%. All preparations presented poor antioxidant capacity. CL EO presented higher antimicrobial activity, with MICs ranging from 0.06% (v/v) to 2% (v/v), against different microorganisms.
Conclusions: Anti-inflammatory and skin repairing potential were present for CL preparations. TM hydrolate presented an interesting biocompatible profile on both cell lines, also presenting anti-inflammatory potential. Furthermore, EOs from both species presented antimicrobial activity against a panel of different microorganisms. These in vitro bioactivities support some of their traditional skin applications, specifically regarding their antiseptic, wound healing and anti-inflammatory uses.
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Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
6817 - DCRRNI ID
Funding Award Number
UIDP/00709/2020