Antimicrobial resistance in the globalized food chain: a One Health perspective applied to the poultry industry.

Antimicrobial resistance (AMR) remains a major global public health crisis. The food animal industry will face escalating challenges to increase productivity while minimizing AMR, since the global demand for animal protein has been continuously increasing and food animals play a key role in the global food supply, particularly broiler chickens. As chicken products are sources of low-cost, high-quality protein, poultry production is an important economic driver for livelihood and survival in developed and developing regions. The globalization of the food supply, markedly in the poultry industry, is aligned to the globalization of the whole modern society, with an unprecedented exchange of goods and services, and transit of human populations among regions and countries. Considering the increasing threat posed by AMR, human civilization is faced with a complex, multifaceted problem compromising its future. Actions to mitigate antimicrobial resistance are needed in all sectors of the society at the human, animal, and environmental levels. This review discusses the problems associated with antimicrobial resistance in the globalized food chain, using the poultry sector as a model. We cover critical aspects of the emergence and dissemination of antimicrobial resistance in the poultry industry and their implications to public health in a global perspective. Finally, we provide current insights using the multidisciplinary One Health approach to mitigate AMR at the human-animal-environment interface.

Evaluation of transfer of maternal immunity to the offspring of broiler breeders vaccinated with a candidate recombinant vaccine against Salmonella Enteritidis.

Salmonella Enteritidis (SE) is a major cause of foodborne diseases in humans being frequently related to the consumption of poultry products. Therefore, guaranteeing early immunity to chicks is an important tool to prevent the colonization and infection by this pathogen. The present study evaluated the effectiveness of a candidate recombinant vaccine against SE. Thirty female and five male broiler breeders that were ten weeks-old were divided into 3 groups: unvaccinated (UV), vaccinated with recombinant vaccine candidate (VAC) and vaccinated with commercial bacterin (BAC). Samples of serum and embryonated egg were collected at seven and twelve weeks after the booster dose to quantify the transfer rate of IgY to egg yolks and offspring. Subsequently, forty day-old offspring were divided into two groups (UV and VAC) and challenged on the following day with 107 CFU/chick of SE. Samples of serum, intestine, liver, and cecal content were harvested. Throughout the experiment period, significantly higher levels of IgY were observed in the egg yolk and also in the serum of broiler breeders and offspring of the VAC group in comparison to the UV group. In addition, increased transfer rates of IgY were observed in the VAC group when compared to the BAC group. Furthermore, higher villus-crypt ratios were found out in duodenum, jejunum and ileum at four days post-infection in the offspring from the VAC group. A high challenge dose of SE (107 CFU per chick) was used and despite the stronger humoral immune response provoked by the candidate vaccine, there were no statistical differences in the recovery of viable SE cells from the offspring cecal contents. Therefore, the effect of vaccination to improve intestinal quality may affect the development of the chickens and consequently increase the resistance to lower SE challenge doses.

Inactivation of phoPQ genes attenuates Salmonella Gallinarum biovar Gallinarum to susceptible chickens

Abstract Salmonella Gallinarum is a host-restrict pathogen that causes fowl typhoid, a severe systemic disease that is one of the major concerns to the poultry industry worldwide. When infecting the bird, SG makes use of evasion mechanisms to survive and to replicate within macrophages. In this context, phoPQ genes encode a two-component regulatory system (PhoPQ) that regulates virulence genes responsible for adaptation of Salmonella spp. to antimicrobial factors such as low pH, antimicrobial peptides and deprivation of bivalent cations. The role of the mentioned genes to SG remains to be investigated. In the present study a phoPQ-depleted SG strain (SG ΔphoPQ) was constructed and its virulence assessed in twenty-day-old laying hens susceptible to fowl typhoid. SG ΔphoPQ did cause neither clinical signs nor mortality in birds orally challenged, being non-pathogenic. Furthermore, this strain was not recovered from livers or spleens. On the other hand, chickens challenged subcutaneously with the mutant strain had discreet to moderate pathological changes and also low bacterial counts in liver and spleen tissues. These findings show that SG ΔphoPQ is attenuated to susceptible chickens and suggest that these genes are important during chicken infection by SG.

Contribution of flagella and motility to gut colonisation and pathogenicity of Salmonella Enteritidis in the chicken

ABSTRACT Salmonella Enteritidis causes fowl paratyphoid in poultry and is frequently associated to outbreaks of food-borne diseases in humans. The role of flagella and flagella-mediated motility into host-pathogen interplay is not fully understood and requires further investigation. In this study, one-day-old chickens were challenged orally with a wild-type strain Salmonella Enteritidis, a non-motile but fully flagellated (SE ΔmotB) or non-flagellated (SE ΔfliC) strain to evaluate their ability to colonise the intestine and spread systemically and also of eliciting gross and histopathological changes. SE ΔmotB and SE ΔfliC were recovered in significantly lower numbers from caecal contents in comparison with Salmonella Enteritidis at early stages of infection (3 and 5 dpi). The SE ΔmotB strain, which synthesises paralysed flagella, showed poorer intestinal colonisation ability than the non-flagellated SE ΔfliC. Histopathological analyses demonstrated that the flagellated strains induced more intense lymphoid reactivity in liver, ileum and caeca. Thus, in the present study the flagellar structure and motility seemed to play a role in the early stages of the intestinal colonisation by Salmonella Enteritidis in the chicken.

Contribution of flagella and motility to gut colonisation and pathogenicity of Salmonella Enteritidis in the chicken.

Salmonella Enteritidis causes fowl paratyphoid in poultry and is frequently associated to outbreaks of food-borne diseases in humans. The role of flagella and flagella-mediated motility into host-pathogen interplay is not fully understood and requires further investigation. In this study, one-day-old chickens were challenged orally with a wild-type strain Salmonella Enteritidis, a non-motile but fully flagellated (SE ΔmotB) or non-flagellated (SE ΔfliC) strain to evaluate their ability to colonise the intestine and spread systemically and also of eliciting gross and histopathological changes. SE ΔmotB and SE ΔfliC were recovered in significantly lower numbers from caecal contents in comparison with Salmonella Enteritidis at early stages of infection (3 and 5dpi). The SE ΔmotB strain, which synthesises paralysed flagella, showed poorer intestinal colonisation ability than the non-flagellated SE ΔfliC. Histopathological analyses demonstrated that the flagellated strains induced more intense lymphoid reactivity in liver, ileum and caeca. Thus, in the present study the flagellar structure and motility seemed to play a role in the early stages of the intestinal colonisation by Salmonella Enteritidis in the chicken.

Lack of acquired resistance in dogs to successive infestations of Rhipicephalus sanguineus ticks from Brazil and Argentina.

Comparative studies between brown dog tick Rhipicephalus sanguineus populations from Brazil (Jaboticabal, São Paulo) and Argentina (Rafaela, Santa Fé) showed significant biological, morphological and genetic differences between them. This work aimed to study, in a comparative way, the acquisition of resistance in domestic dogs to R. sanguineus from Jaboticabal and Rafaela, after successive and controlled infestations. Ticks were kept in a BOD incubator under controlled conditions (27 °C, 80 % relative humidity, 12-h photoperiod). Ten dogs, Dachshund breed, males and females, 6 months old, short- or long-haired, without prior contact with ticks, were used as hosts. They were distributed into two experimental groups composed of five animals each: G1 infested with ten adult couples of R. sanguineus (Jaboticabal) per animal, and G2 infested with ten adult couples of R. sanguineus (Rafaela) per animal. Ticks' biological parameters and titration of antibodies from the dogs' sera by ELISA test were used for comparison between the strains. Results of the biological parameters showed that the dogs did not acquire immunity to either of the R. sanguineus strains after repeated infestations. The ELISA test showed low antibody titers in sera of dogs from G2, in successive infestations, and higher antibody responses post second and third infestations in G1. It also demonstrated cross-reactivity between sera of dogs infested with R. sanguineus (Jaboticabal) and antigens from R. sanguineus (Rafaela) and vice versa. We conclude that Dachshund dogs did not develop resistance against neither Jaboticabal nor Rafaela strains of R. sanguineus.