Browsing by Author "Grilo, Miguel"
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- Aeromonas spp. Prevalence, virulence, and antimicrobial resistance in an ex situ program for tThreatened freshwater fish—A pilot study with protective measuresPublication . Grilo, Miguel; Amaro, Guadalupe; Chambel, Lélia; Marques, Carolina S.; Marques, Tiago A.; Gil, Fátima; Sousa-Santos, Carla; Robalo, Joana; 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.
- Molecular epidemiology, virulence traits and antimicrobial resistance signatures of aeromonas spp. in the critically endangered iberochondrostoma lusitanicum follow geographical and seasonal patternsPublication . Grilo, Miguel; Isidoro, Sara; Chambel, Lélia; Marques, Carolina S.; Marques, Tiago A.; Sousa-Santos, C.; Robalo, Joana; Oliveira, ManuelaDespite the fact that freshwater fish populations are experiencing severe declines worldwide, our knowledge on the interaction between endangered populations and pathogenic agents remains scarce. In this study, we investigated the prevalence and structure of Aeromonas communities isolated from the critically endangered Iberochondrostoma lusitanicum, a model species for threatened Iberian leuciscids, as well as health parameters in this species. Additionally, we evaluated the virulence profiles, antimicrobial resistance signatures and genomic relationships of the Aeromonas isolates. Lesion prevalence, extension and body condition were deeply affected by location and seasonality, with poorer performances in the dry season. Aeromonas composition shifted among seasons and was also different across river streams. The pathogenic potential of the isolates significantly increased during the dry season. Additionally, isolates displaying clinically relevant antimicrobial resistance phenotypes (carbapenem and fluroquinolone resistance) were detected. As it inhabits intermittent rivers, often reduced to disconnected pools during the summer, the dry season is a critical period for I. lusitanicum, with lower general health status and a higher potential of infection by Aeromonas spp. Habitat quality seems a determining factor on the sustainable development of this fish species. Also, these individuals act as reservoirs of important antimicrobial resistant bacteria with potential implications for public health.
- Sympatric threatened Iberian leuciscids exhibit differences in Aeromonas diversity and skin lesions’ prevalencePublication . Grilo, Miguel; Chambel, Lélia; Marques, Tiago A.; Sousa, Carla; Robalo, Joana; Oliveira, ManuelaAssessments regarding health aspects of Iberian leuciscids are limited. There is currently an information gap regarding effects of infectious diseases on these populations and their role as a possible conservation threat. Moreover, differences in susceptibility to particular agents, such as Aeromonas spp., by different species/populations is not clear. To understand potential differences in Aeromonas diversity and load, as well as in the prevalence and proportion of skin lesions, in fishes exposed to similar environmental conditions, an observational study was implemented. Using a set of 12 individuals belonging to two sympatric Iberian leuciscid species (Squalius pyrenaicus and Iberochondrostoma lusitanicum), the skin lesion score in each individual was analyzed. Furthermore, a bacterial collection of Aeromonas spp. isolated from each individual was created and isolates’ load was quantified by plate counting, identified at species level using a multiplex-PCR assay and virulence profiles established using classical phenotypic methods. The similarity relationships of the isolates were evaluated using a RAPD analysis. The skin lesion score was significantly higher in S. pyrenaicus, while the Aeromonas spp. load did not differ between species. When analyzing Aeromonas species diversity between fishes, different patterns were observed. A predominance of A. hydrophila was detected in S. pyrenaicus individuals, while I. lusitanicum individuals displayed a more diverse structure. Similarly, the virulence index of isolates from S. pyrenaicus was higher, mostly due to the isolated Aeromonas species. Genomic typing clustered the isolates mainly by fish species and skin lesion score. Specific Aeromonas clusters were associated with higher virulence indexes. Current results suggest potential differences in susceptibility to Aeromonas spp. at the fish species/individual level, and constitute important knowledge for proper wildlife management through the signalization of at-risk fish populations and hierarchization of conservation measures.
- The potential of Aeromonas spp. from wildlife as antimicrobial resistance indicators in aquatic environmentsPublication . Grilo, Miguel; Santos, Carla Sousa; Robalo, Joana; Oliveira, ManuelaDeclines in freshwater fish populations are occurring at a fast rate, increasing the importance of ex-situ conservation programs supported by sound knowledge of population dynamics and life-history traits of the target species. We analysed the growth and age structure of wild and captive stocks of the western ruivaco Achondrostoma occidentale, a Portuguese endangered cyprinid, targeted for captive breeding and restocking since 2007. Specifically, we compared maximum size, longevity, and length-at-age among captive and wild populations, restocked and non-restocked. We found considerable variation in length-at-age and longevity between captive-bred and wild fish, with the former generally growing faster and living longer. Analysis of length-age distributions among wild populations suggested a positive effect of restocking actions in fish abundance. Results highlight the value of captive breeding for the conservation of endangered cyprinids, and reinforce the need for detailed data on life-history trait variation between captive and wild stocks to assess the efficiency of ex-situ conservation programs.
- Variation of blubber thickness for three marine mammal species in the southern Baltic SeaPublication . Siebert, Ursula; Grilo, Miguel; Kesselring, Tina; Lehnert, Kristina; Ronnenberg, Katrin; Pawliczka, Iwona; Galatius, Anders; Kyhn, Line; Dähne, Michael; Gilles, AnitaEvaluating populational trends of health condition has become an important topic for marine mammal populations under the Marine Strategy Framework Directive (MSFD). In the Baltic Sea, under the recommendation of Helsinki Commission (HELCOM), efforts have been undertaken to use blubber thickness as an indicator of energy reserves in marine mammals. Current values lack geographical representation from the entire Baltic Sea area and a large dataset is only available for grey seals (Halichoerus grypus) from Sweden and Finland. Knowledge on variation of blubber thickness related to geography throughout the Baltic Sea is important for its usage as an indicator. Such evaluation can provide important information about the energy reserves, and hence, food availability. It is expected that methodological standardization under HELCOM should include relevant datasets with good geographical coverage that can also account for natural variability in the resident marine mammal populations. In this study, seasonal and temporal trends of blubber thickness were evaluated for three marine mammal species—harbor seal (Phoca vitulina), grey seal (Halichoerus grypus) and harbor porpoise (Phocoena phocoena)—resident in the southern Baltic Sea collected and investigated under stranding networks. Additionally, the effects of age, season and sex were analyzed. Seasonal variation of blubber thickness was evident for all species, with harbor seals presenting more pronounced effects in adults and grey seals and harbor porpoises presenting more pronounced effects in juveniles. For harbor seals and porpoises, fluctuations were present over the years included in the analysis. In the seal species, blubber thickness values were generally higher in males. In harbor seals and porpoises, blubber thickness values differed between the age classes: while adult harbor seals displayed thicker blubber layers than juveniles, the opposite was observed for harbor porpoises. Furthermore, while an important initial screening tool, blubber thickness assessment cannot be considered a valid methodology for overall health assessment in marine mammals and should be complemented with data on specific health parameters developed for each species