Oliveiro Caetano de Freitas Neto

Salmonella Minnesota ST548 has emerged as an important serovar in the poultry industry and has been detected in food products. Five nonclonal S. Minnesota isolates from poultry in southeastern Brazil were characterized using whole-genome sequencing (WGS), and 263 database sequences were analyzed for virulence genes, antimicrobial resistance genes, and phylogenetic relationships. Among the analyzed sequences, 191 multidrug-resistant (MDR) strains carried antimicrobial resistance genes (ARGs) conferring resistance to aminoglycosides ( aac(6′)-Iaa , aph(3′)-Ia and aadA1 ), quinolones ( qnrB19 ), tetracycline ( tetA ), sulfonamides ( sul2 ), and beta-lactams ( bla _CMY−2 , bla _CTX-M-8 , bla _CTX−M−55 and bla _TEM−126 ). Furthermore, several genes associated with virulence factors were identified, including adherence ( faeC , faeE , and fimB ), fimbrial adherence determinants ( pegA , staA , fimA , and csgD ), magnesium uptake ( mgtB and mgtC ), macrophage inducible genes (mig-14 ), toxin ( cdtB ) and secretion system ( ssaM , sseE and sseJ ). Twenty-five plasmid replicons and 53 distinct prophages were identified in the analyzed sequences. Phylogenetic analysis showed close relationships between nonclonal S . Minnesota poultry isolates from southeastern Brazil and S . Minnesota sequences associated with human outbreaks from other sources and countries. These findings highlight the need for surveillance of this serovar in both public and veterinary health.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

An emerging highly virulent S. Gallinarum strain caused uncommon respiratory and intestinal lesions.The intranasal route of challenge caused a more severe and systemic disease, with broader organ involvement.The emerging strain targeted novel organs including larynx, trachea, bursa of Fabricius, and bone marrow.

Salmonella Gallinarum is a bacterium that causes significant economic losses in poultry farming and usually infects adult birds. This study aims to characterize the unusual histological findings and genetic profile of a Salmonella Gallinarum (SG) strain isolated from a natural outbreak that affected 1,500 broiler chicks in their first week of life. To confirm the diagnosis, necropsy, histopathology, and immunohistochemistry were performed on 19 chicks, with bacterial isolation in two of them, followed by confirmation through PCR, genetic sequencing, and genomic analysis. The outbreak revealed unusual gross and histological lesions: in the intestines, there was macroscopic hemorrhage of varying severity, and microscopically, the lesions were characterized by histiocytic and heterophilic transmural typhlitis; in the lungs, there was histiocytic interstitial pneumonia of varying intensities. Additional lesions included splenitis, myocarditis, and hepatitis. Salmonella was in situ labeled in all mentioned organs using immunohistochemistry (IHC). Following the virulome and resistome analysis, which compared the genetic profile of the isolate with a reference SG genome, it was found that the isolate from this outbreak contains 36 exclusive virulence genes and six exclusive antimicrobial resistance genes. These genetic alterations may explain the severe systemic lesions observed in these chicks.

It was previously reported that utilization of tetrathionate and 1,2-propanediol by Salmonella spp. through the metabolic pathways encoded by ttr and pdu operons are related to overgrowth and out-competing microbiota in an anaerobic environment. However, recent knowledge demonstrated which strains in the absence of ttr and pdu genes provoke both higher intestinal colonization and spreading bacteria on faeces in relation to their respective wild-type strain, and generate more prominent inflammation as well. This study evaluated the immune response of different lineages of chicks infected by Salmonella Typhimurium (STM) and Salmonella Enteritidis (SE) with ttrA and pduA gene deletions. Our work was separated into two experiments, one for each strain, utilizing 108 chicks to collect spleen and caecal tonsils for measuring immune response through RT-qPCR. From the immune response analysis, Salmonella Enteritidis mutant and wild-type strains elicited upregulated pro-inflammatory cytokines on the first-day post-infection, the opposite occurred when compared to Salmonella Typhimurium strains (mutant and wild-type). However, the deletions did not impair the immune response produced by mutant strains related to the respective wild-type in the caecal tonsil and spleen, suggesting that these metabolic pathways are not essential for colonization success. In conclusion, SE and STM, in the absence of ttrA and pduA genes, provoke an immune response with the same intensity as respective wild-type strains.

Salmonella Gallinarum (SG) is a Gram-negative bacterium responsible for causing fowl typhoid (FT), a septicemic disease that results in significant losses in poultry farming. Although antimicrobials reduce clinical signs and mortality, they are not effective against the infection, as clinical signs may recur, and birds may continue to shed the pathogen after treatment. The irrational use of these drugs is one of the main factors related to the emergence of resistant strains, raising concerns for public and animal health. This report describes the alternative control of FT in cage-free laying hens on a poultry farm in Minas Gerais, Brazil. Following a sudden increase in mortality, five birds were sent to the Avian Diseases Laboratory at the Federal University of Minas Gerais for examination. Bacterial isolation, biochemical tests, rapid serum agglutination and PCR were performed, confirming SG infection in two birds. To control the outbreak, the live attenuated 9R vaccine was used in combination with the removal of sick birds, resulting in a reduction in mortality and clinical signs. It was concluded that, in the face of an outbreak of FT, biosecurity measures combined with vaccination using the 9R strain and removal of sick birds are effective in disease control.

Gizzard erosion and ulceration (GEU) is characterized by defects and necrosis in the koilin layer, particularly in broilers. This condition has been associated with growth retardation, runting, and economic implications for poultry producers; nevertheless, its influence on gut microbiota remains unknown. This study investigated the compositional changes in the bacterial community of the ileum of seven-day-old broiler chicks with GEU using next-generation sequencing (NGS) technology. Twenty-two samples were obtained from the ileal mucosa and contents of sixteen chicks with GEU and six without GEU raised in a conventional system located on a farm in southeast Brazil. The results revealed that bacterial phyla in both groups exhibited a similar composition, with Firmicutes representing the most abundant. Porphyromonas, Candidatus Arthromitus, and Limosilactobacillus were statistically more abundant in the group without GEU. The most prevalent genera in the group with GEU were Lactobacillus and Enterococcus, and the relative abundance of Enterococcus in the ilea of some chicks with GEU was considerable. Based on the results of the current study, necrosis in the koilin layer can change the composition of ileal microbiota. Therefore, further studies should be carried out to clarify whether GEU and consequently poor digestibility of the feed cause significant changes in the intestinal microbiota.

In mammals, enteric salmonellas can use tetrathionate (ttr), formed as a by-product from the inflammatory process in the intestine, as electron acceptor in anaerobic respiration, and it can fuel its energy metabolism by degrading the microbial fermentation product 1,2-propanediol. However, recent studies have shown that this mechanism is not important for Salmonella infection in the intestine of poultry, while it prolongs the persistence of Salmonella at systemic sites in this species. In the current study, we show that ΔttrApduA strains of Salmonella enterica have lower net survival within chicken-derived HD-11 macrophages, as CFU was only 2.3% (S. Enteritidis ΔttrApduA), 2.3% (S. Heidelberg ΔttrApduA), and 3.0% (S. Typhimurium ΔttrApduA) compared to wild-type strains after 24 h inside HD-11 macrophage cells. The difference was not related to increased lysis of macrophages, and deletion of ttrA and pduA did not impair the ability of the strains to grow anaerobically. Further studies are indicated to determine the reason why Salmonella ΔttrApduA strains survive less well inside macrophage cell lines. Graphical abstract

Runting and stunting syndrome (RSS) is an enteric viral disease in commercial poultry that directly affects gut health; however, its influence on gut microbiota remains unknown. This study aimed to investigate the compositional changes in the bacterial community of the ileum of 7-day-old broiler chicks naturally affected and not affected by RSS, using next-generation sequencing (NGS) technology. Twenty-one samples were obtained from the ileal contents and mucosa of 11 chicks with RSS and 10 healthy chicks, raised in a dark house system located on a farm in the state of Minas Gerais, Brazil. The results revealed overall changes in the gut microbiota of the chicks with RSS, including a decrease in microbial richness and diversity. In particular, there was a decrease in Lactobacillus and an increase in Candidatus Arthromitus and Clostridium sensu stricto 1. These results indicate a relationship between viral infection and the gut microbial composition, which can cause gut dysbiosis and may influence inflammation in this organ.RESEARCH HIGHLIGHTSRSS causes dysbiosis of the gut microbiota of the ilea of chicks.A difference was found in gut microbiota between chicks with and without RSS.Candidatus Arthromitus was predominant in chicks with RSS.Clostridium sensu stricto 1 was strictly associated with chicks with RSS.

Slow-growing breeds are more resistant to Salmonella infection compared to fast-growing broilers. However, it is unclear whether that is associated with innate resistance or rather rely on differences in Salmonella-induced gut responses. We investigated the microbial composition and gene expression of nutrient transporters, mucin, and interleukin in the gut of a fast-growing (Cobb500) and a slow-growing naked neck (NN) chicken breeds challenged with Salmonella Enteritidis. Hatchlings were inoculated at two days of age using sterile broth (sham) or Salmonella Enteritidis (SE) and distributed according to a completely randomized design into four treatments: Cobb-sham; Cobb-SE; NN-sham; and NN-SE. Cecal SE counting and microbial composition by 16 S rRNA sequencing were determined at 24-, 96-, and 168-hours post-inoculation (hpi). Gene expression of amino acid (Asct1) and peptide transporters (PepT1), glucose transporters (Sglt1, Glut2 and Glut5) and mucin (Muc2) in the jejunum and expression of interleukins (IL1 beta, IL8, IL17 and IL22) in the cecum was assessed by qPCR at 24 and 168 hpi. NN birds were colonized by SE just as Cobb birds but showed innate upregulation of Muc2, IL8 and IL17 in comparison to Cobb. While nutrient transporter mRNA expression was impaired in SE-challenged Cobb birds, the opposite was observed in NN. There were no differences in microbial diversity at different sampling times for Cobb-SE, whereas the other groups had higher diversity and lower dominance at 24 hpi compared with 96 hpi and 168 hpi. NN birds apparently develop earlier gut microbial stability, have higher basal level of mucin gene expression as well as differential nutrient transporter and interleukin gene expression in the presence of SE which might mitigate the effects of SE infection compared to Cobb birds.