Antimicrobial resistance (AMR) is currently one of the main concerns worldwide, signalled by the World Health Organisation (WHO) as one of the top 10 global public health threats in 2019. Indeed, the prevalence of multi-resistant bacteria and the difficulty of treating bacterial infections in both animals and humans have increased in recent years. Moreover, AMR is considered a One Health issue, as it englobes animal, human and environmental health.
The current imbalance between AMR programmes and reported data limit the full understanding of an integrated One Health global AMR surveillance system [10]. In 2015, to address this issue, the Joint Tripartite formed by the Food and Agriculture Organisation of the United Nations, the World Organisation for Animal Health and the WHO adopted a Global Action Plan to ensure worldwide capacity to control and prevent AMR bacterial infectious diseases, with effective and safe medicines used responsibly and accessible to the world population [11]. Since then, the Joint Tripartite has been working to establish an integrated surveillance system platform to collect and assemble data reported by countries related to human, animal, food and environmental health. They also assess the implementation and development of the Global Action Plan on AMR in all sectors [11].
The current imbalance between AMR programmes and reported data limit the full understanding of an integrated One Health global AMR surveillance system [16]. In 2015, to address this issue, the Joint Tripartite formed by the Food and Agriculture Organisation of the United Nations, the World Organisation for Animal Health and the WHO adopted a Global Action Plan to ensure worldwide capacity to control and prevent AMR bacterial infectious diseases, with effective and safe medicines used responsibly and accessible to the world population [17]. Since then, the Joint Tripartite has been working to establish an integrated surveillance system platform to collect and assemble data reported by countries related to human, animal, food and environmental health. They also assess the implementation and development of the Global Action Plan on AMR in all sectors [17]. In the global scope, there are different programmes to control AMR in both production and companion animals. On the one hand, there are AMR Surveillance Programmes that study bacterial species present in animal infections and their AMR [12][13][18,19]. On the other hand, there are AMR Monitoring Programmes that take samples from healthy animals to study commensal bacteria as reservoirs of resistance genes [11][12][13][17,18,19]. However, in order to control AMR under the One Health perspective, it is also mandatory to start monitoring AMR in companion animals and to monitor AMC [7].Probiotics are live microorganisms that confer benefits to host health when administered in adequate doses [22]. There are also many microorganisms that have probiotic characteristics; the most common species to date are
Probiotics are live microorganisms that confer benefits to host health when administered in adequate doses [37]. There are also many microorganisms that have probiotic characteristics; the most common species to date areLactobacillus
spp.,Streptococcus
spp.,Lactococcus
spp. andBifidobacterium spp. [22][23]. Probiotics should at least be capable of modulating the immune response or some physiological parameters of the host, treating or preventing infectious and inflammatory diseases and acting as biological preventive control agents [21][24].
spp. [37,38]. Probiotics should at least be capable of modulating the immune response or some physiological parameters of the host, treating or preventing infectious and inflammatory diseases and acting as biological preventive control agents [36,39]. One study evaluating the benefits of a probiotic, based on canine-derivedBifidobacterium animalis, in dogs with acute idiopathic diarrhoea showed that the use of the probiotic combined with the improvement of nutritional management reduced the need to administer metronidazole to the diseased dogs [22].
, in dogs with acute idiopathic diarrhoea showed that the use of the probiotic combined with the improvement of nutritional management reduced the need to administer metronidazole to the diseased dogs [37].Prebiotics are non-digestible compounds that are metabolised by gut microorganisms and modulate the composition and activity of the gut microbiota, providing benefits to the host’s physiological bacteria [25].
Prebiotics are non-digestible compounds that are metabolised by gut microorganisms and modulate the composition and activity of the gut microbiota, providing benefits to the host’s physiological bacteria [40].According to the results reported by De Souza et al. (2019), in dogs fed a mixture of fibre and prebiotics, no negative effect on nutrient digestibility and faecal quality was observed, and increased digestibility of food was reported. In addition, beneficial changes were observed in the faeces, which may indicate support of gut health. While the test substances caused slight changes in faecal microbial populations in adult healthy dogs, they had a significant effect on faecal metabolite physiology, demonstrating a possible microbial improvement in dogs fed diets supplemented with prebiotics. However, further research is needed to establish the optimal doses according to the age of the animals and the disease stages and to understand what conditions can be prevented or treated with prebiotic supplements [26].
According to the results reported by De Souza et al. (2019), in dogs fed a mixture of fibre and prebiotics, no negative effect on nutrient digestibility and faecal quality was observed, and increased digestibility of food was reported. In addition, beneficial changes were observed in the faeces, which may indicate support of gut health. While the test substances caused slight changes in faecal microbial populations in adult healthy dogs, they had a significant effect on faecal metabolite physiology, demonstrating a possible microbial improvement in dogs fed diets supplemented with prebiotics. However, further research is needed to establish the optimal doses according to the age of the animals and the disease stages and to understand what conditions can be prevented or treated with prebiotic supplements [41].Symbiotics can strengthen the beneficial effects that probiotics and prebiotics have on their own, as probiotics use prebiotics as food sources to extend their survival in the digestive tract, increasing the digestibility and availability of certain nutrients such as vitamins, minerals, and proteins [27].
Symbiotics can strengthen the beneficial effects that probiotics and prebiotics have on their own, as probiotics use prebiotics as food sources to extend their survival in the digestive tract, increasing the digestibility and availability of certain nutrients such as vitamins, minerals, and proteins [42].A study performed in dogs with acute diarrhoea, comparing the therapeutic effect of nutraceuticals and antibiotics on clinical activity, showed that the role of symbiotics in the positive effect seen in patients is unclear. Thus, more studies are needed both in vitro and in vivo, in companion animals, to further investigate the real effect of these supplements [28].
A study performed in dogs with acute diarrhoea, comparing the therapeutic effect of nutraceuticals and antibiotics on clinical activity, showed that the role of symbiotics in the positive effect seen in patients is unclear. Thus, more studies are needed both in vitro and in vivo, in companion animals, to further investigate the real effect of these supplements [43].Postbiotics are metabolites generated by the fermentation of probiotic bacteria in the gut [22]. In the last few years, they have had a great impact, as they have also been proposed as food supplements to regulate intestinal homeostasis instead of probiotics, since they reduce the possible risks of administering living bacteria [29]. Postbiotics are present in several species of
Postbiotics are metabolites generated by the fermentation of probiotic bacteria in the gut [37]. In the last few years, they have had a great impact, as they have also been proposed as food supplements to regulate intestinal homeostasis instead of probiotics, since they reduce the possible risks of administering living bacteria [44]. Postbiotics are present in several species ofBifidobacterium
(B. breve, B. lactis, B. infantis
),Bacteroides fragilis
,E. coli
Nissle 1917 andFaecalibacterium prausnitzii, among others [30], and it has been reported that they improve the integrity of the mucosal gut barrier through different mechanisms, as well as modulate the secretion of inflammatory mediators [29][30].
among others [45], and it has been reported that they improve the integrity of the mucosal gut barrier through different mechanisms, as well as modulate the secretion of inflammatory mediators [44,45]. In a study evaluating the postbiotic activities ofLactobacilli-derived factors in vitro, postbiotics were shown to have beneficial properties in relation to pathogen-induced inflammation and altered cytokine release [30].
-derived factors in vitro, postbiotics were shown to have beneficial properties in relation to pathogen-induced inflammation and altered cytokine release [45].However, as AMR is present in animal diseases and antibiotic treatment options sometimes do not work properly, efforts are being made to develop alternative treatments for ongoing infections [21].
However, as AMR is present in animal diseases and antibiotic treatment options sometimes do not work properly, efforts are being made to develop alternative treatments for ongoing infections [36].Faecal microbiota transplantation (FMT) involves the transfer of faeces from a healthy donor to the intestine of a diseased recipient with the aim of adjusting the gut microbiome of the diseased subject. The gut microbiota is seriously affected by the use of antibiotics or by inflammatory gastrointestinal diseases treated with antibiotics, which further aggravates a pathology [31].
Faecal microbiota transplantation (FMT) involves the transfer of faeces from a healthy donor to the intestine of a diseased recipient with the aim of adjusting the gut microbiome of the diseased subject. The gut microbiota is seriously affected by the use of antibiotics or by inflammatory gastrointestinal diseases treated with antibiotics, which further aggravates a pathology [46].Therefore, FMT is sometimes the only and last viable option [31][32]. Although more studies on FMT are needed, published clinical case reports for companion animals showed the improvement and restoration of the animal microbiota [33]. After treatment, animals recovered appetite and body weight, and the treatment might also help restore the integrity of the intestinal barrier, along with promoting the complete disappearance of the gastrointestinal and systemic symptomatology [31][32].
Therefore, FMT is sometimes the only and last viable option [46,47]. Although more studies on FMT are needed, published clinical case reports for companion animals showed the improvement and restoration of the animal microbiota [48]. After treatment, animals recovered appetite and body weight, and the treatment might also help restore the integrity of the intestinal barrier, along with promoting the complete disappearance of the gastrointestinal and systemic symptomatology [46,47].Bacteriophages (or “phages”) are viruses that possess the natural characteristic of specifically targeting and killing bacteria [34]. One of the advantages of phages is their ability to adapt to bacterial strains due to decades of co-evolution, which is why they are considered ‘adaptive drugs’ [34]. Moreover, their ability to lyse different bacteria strains has been reported. Although phages are considered a promising tool as an alternative to antibiotics, in veterinary medicine studies have been focused on food-producing animals, so there are only a few in vivo studies in companion animals [34][35].
Bacteriophages (or “phages”) are viruses that possess the natural characteristic of specifically targeting and killing bacteria [49]. One of the advantages of phages is their ability to adapt to bacterial strains due to decades of co-evolution, which is why they are considered ‘adaptive drugs’ [49]. Moreover, their ability to lyse different bacteria strains has been reported. Although phages are considered a promising tool as an alternative to antibiotics, in veterinary medicine studies have been focused on food-producing animals, so there are only a few in vivo studies in companion animals [49,50]. Although most studies have been conducted in vitro, a clinical trial was carried out to study the treatment of otitis in dogs, caused byPseudomonas aeruginosa, with a mixture of bacteriophages [25]. The outcome showed that bacteriophages improved the ear condition and all the dogs remained afebrile. In addition, the treatment scope for bacteriophages is limited, as the ear microbiota should be respected, so mixtures of bacteriophages are required to cover a wide range of bacteria [36].
, with a mixture of bacteriophages [40]. The outcome showed that bacteriophages improved the ear condition and all the dogs remained afebrile. In addition, the treatment scope for bacteriophages is limited, as the ear microbiota should be respected, so mixtures of bacteriophages are required to cover a wide range of bacteria [51]. All the information collected in this section is summarised in Table 1. ![]() |
Living microorganisms that contribute to improve host health. - In a study in dogs with acute ideopathic diarrhoea, the use of probiotics with feed reduced the use of metronidazole compared to dogs treated without probiotics [37]. | Living microorganisms that contribute to improve host health. - In a study in dogs with acute ideopathic diarrhoea, the use of probiotics with feed reduced the use of metronidazole compared to dogs treated without probiotics [28]. |
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Non-digestible compounds used by beneficial gut flora. - Studies has shown that the use of prebiotics helps to improve food digestibility and gut microbiota [38]. | Non-digestible compounds used by beneficial gut flora. - Studies has shown that the use of prebiotics helps to improve food digestibility and gut microbiota [30]. |
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The synergistic combination of probiotics and prebiotics. - Although the use of synbiotics is promising, their full effects are not yet known and further studies are needed to assess their benefits in dogs and cats [37][39]. | The synergistic combination of probiotics and prebiotics. - Although the use of synbiotics is promising, their full effects are not yet known and further studies are needed to assess their benefits in dogs and cats [28,32]. |
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Compounds released by bacteria in metabolisation processes. - Some studies show that postbiotics help modulate the inflammatory response caused by a pathogen, however most studies are in vitro, so more in vivo studies are needed [40][41]. | Compounds released by bacteria in metabolisation processes. - Some studies show that postbiotics help modulate the inflammatory response caused by a pathogen, however most studies are in vitro, so more in vivo studies are needed [33,34]. |
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Transfer of faeces from a healthy patient to the intestine of a diseased patient to adjust the intestinal microbiota. - Studies have shown that animals regain body condition, appetite and help to restore the integrity of the intestinal wall after transplantation [21][42]. | Transfer of faeces from a healthy patient to the intestine of a diseased patient to adjust the intestinal microbiota. - Studies have shown that animals regain body condition, appetite and help to restore the integrity of the intestinal wall after transplantation [35,36]. |
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Viruses whose sole aim is to infect and attack bacteria. - Animals with infections treated with bacteriophages remained afebrile with a marked improvement of the affected area, however it was noted that given their small broad spectrum of action it is advisable to use combinations of bacteriophages [25]. | Viruses whose sole aim is to infect and attack bacteria. - Animals with infections treated with bacteriophages remained afebrile with a marked improvement of the affected area, however it was noted that given their small broad spectrum of action it is advisable to use combinations of bacteriophages [40]. |