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Intestinal microbes are taxonomically diverse and constitute an ecologically dynamic microbiom interactively performing various physiological and physiopathological processes. It has been proposed that normal intestinal microbiotas play a critical role in the host’s metabolic homeostasis and immune tolerance. The modulation of intestinal microbiota populations by prebiotics, probiotics, and synbiotics may be beneficial for the host’s health. Under certain conditions, the intestinal microbiota and the host’s homeostasis can be restored by introducing bacteria that co-mediate anti-inflammatory responses. Commensal microbes and probiotics exert their beneficial effect by at least three mechanisms. These include – the maintenance of the epithelial barrier function and the attenuation of changes in intestinal permeability through effects on tight junction, decreasing paracellular permeability, providing innate defense against pathogens, and enhancing the physical impediment of the mucous layer, – competitive exclusion by the application of probiotic bacteria stabilizing the indigenous microflora, – immunomodulatory capacity, affecting a variety of signaling pathways with modulation of proper immune, inflammatory and allergic responses. The epithelial gut barrier faces important challenges, since its function is to prevent pathogens and harmful elements of the gut lumen from penetrating into the internal environment. Competitive exclusion treatment can increase resistance to pathogen colonization and control intestinal disturbance. The dominance of symbiotic and probiotic bacteria among the gut microbiota favors a tolerogenic immune response. The release of secretory IgA stabilizes tight junctions between cells of the epithelial layer as well as hampers pathogens and symbionts invading deeper layers. The understanding of these vital processes may help to protect the host against infection, prevent chronic inflammation, and maintain mucosal integrity.
Staphylococcus pseudintermedius is considered to be a both commensal and opportunistic canine pathogen. The anal, perineal and nasal locations appear to be the main S. pseudintermedius colonization sites, from which bacteria are transmitted to other body sites, causing secondary infections. When the immune system is compromised because of an underlying condition, the skin becomes susceptible to infection. Thus, the host’s condition seems to play a crucial role in the pathogenesis of S. pseudintermedius infections. There are some predisposing factors, one of which is atopic dermatitis. The pathogenic effects of S. pseudintermedius are mediated by several virulence factors, for instance superantigens, which play an important role by causing dermatitis. The immune system has evolved many different mechanisms to recognize and deal with pathogens, but bacteria have also developed various strategies to evade them. In this review, we focus on early stages of the innate immune response with particular emphasis on the mechanisms of recognition of staphylococci and the action of antimicrobial peptides.
Chicken ceca contain an immense number of microorganisms collectively known as the microbiome. This community is now recognized as an essential component of the intestinal ecosystem and referred to as a metabolic organ exquisitely tuned to the host’s physiology. These functions include the ability to process otherwise indigestible components of the feed, converting them into energy and body mass. The gut microbiome can also affect intestinal morphology and modulate the development and function of the immune system. This microbiota contains a rich collection of genes encoding enzymes necessary for decomposition of dietary polysaccharides and oligosaccharides, nitrogen metabolism, fatty acid and lipid metabolism, and pathways involved in a hydrogen sink. Chickens, like most animals, lack the genes for glycoside hydrolase, polysaccharide lyase, and carbohydrate esterase enzymes that are necessary to facilitate the degradation of non-starch polysaccharides. During the decomposition of dietary polysaccharides, bacteria produce short-chain (volatile) fatty acids (SCFAs), such as acetic, propionic and butyric acid. These SCFASs are absorbed transepithelially and serve as a source of energy for the host. The accumulation of molecular hydrogen released during fermentation leads to fermentation slowdown or to the production of less energy-efficient substances, such as ethanol, butyrate and propionate. The presence of bacteria that act as a hydrogen sink results in a switch to the more productive fermentation into acetate and increased production of SCFAs. Such activity could lead to a significant improvement in poultry production and the associated economics.
Salmonellosis is one of the most important bacterial diseases in pigeons. The disease occurs in birds of different ages, and long-term Salmonella spp. carrier status is a major problem. The study included 499 samples from live pigeons and internal organs from 265 necropsied birds. The samples were cultured on a standard and selective media. Their antimicrobial susceptibility was carried out by the Kirby-Bauer diffusion method. Thirty one Salmonella spp. isolates were cultured. Most isolates were obtained from the internal organs of dead or euthanised pigeons, and only single isolates were obtained from droppings and cloacal swabs. A total of 4% of the samples tested were positive. The greatest percentage of isolates was susceptible to enrofloxacin (96.3%) and florfenicol (95.7%). Sulfamethoxazole and trimethoprim combination was effective against 73.9% of the isolates. Despite the fact of increasing antibiotic resistance of the investigated bacteria, it is comforting that enrofloxacin remains highly effective despite its widespread use in birds.
Escherichia coli is a common cause of infections in companion animals. In recent years the increasing prevalence of resistance to β-lactams, including extended-spectrum cephalosporins, antimicrobials frequently used in small animal veterinary practice, was observed in canine isolates of E. coli. The aim of this study was to detect and to characterize extended-spectrum β-lactamases (ESBLs) produced by E. coli isolated from diseased dogs in Poland. Four isolates out of 119 studied (3.4%) were ESBL-positive. They harbored the blaSHV-12, blaCTX-M-15, and blaTEM-116 genes. This study provides the first report of the occurrence of ESBL-producing E. coli in dogs in Poland.
The gastrointestinal tract in humans and animals contains a very large number of highly diverse microorganisms. This microbiota plays a major role in the host’s physiology, homeostasis, and well-being. It forms a barrier against infection, helps to develop and mature the immune system, and participates in the extraction of nutrients and energy from food. Various members of microbial community maintain the integrity of the intestinal barrier and promote epithelial repair after injury. The intestinal barrier defenses consist of the mucous layer, antimicrobial peptides, secretory IgA, and the epithelial barrier function by junctional adhesion complex. A healthy host exists in a state of balance with its microorganisms. A disruption of the microbial community increases the host’s susceptibility to infection. Although the immune response is necessary for the host to eliminate the invading pathogen, certain aspects of the host’s response may work to the pathogen’s advantage. Certain components of the microbiota have been shown to drive inflammatory response, which, if uncontrolled, has the potential to induce a pathological response, whereas others enhance or promote antiinflammatory responses. The effector microbial molecules are usually detected via receptor-signaling pathways including Toll-like receptors, NOD-like receptors, and C-type lectin receptors. These pattern-recognition receptors (PRRs) interact with and identify microbe-associated molecular patterns (MAMPs) of both commensal and pathogenic bacteria. PRRs signaling, once thought to exclusively yield pro-inflammatory activation by pathogenic bacteria, is now known to be differentially activated by commensal and probiotic bacteria to induce pathways involved in gut homeostasis, cytoprotection, epithelial cell proliferation, regulation of tight junctions, and antimicrobial peptide secretion. The microbial-epithelial cross-talk is fundamental in appreciating how the developing intestine achieves tolerance to bacteria and how dysregulation of this process may predispose the gut to inflammation and disease.
Coagulase-positive staphylococci (CoPS) are opportunistic veterinary pathogens, of which Staphylococcus aureus, S. delphini and S. intermedius can be isolated from pigeons. The biochemical identification of S. delphini and S. intermedius isolates may be incorrect, because of their phenotypic similarity. The purpose of the present study was to isolate and identify CoPS from domestic and feral pigeons and to determine their genetic relatedness by PFGE. A total number of 31 isolates of CoPS were obtained, 15 were identified as S. delphini group B, six as S. aureus, four as S. delphini group A, three as S. intermedius and three as S. schleiferi subsp. coagulans. The results indicate that S. delphini group B is the predominant CoPS species among pigeons studied. PFGE restriction patterns of S. delphini group A and S. delphini group B form separate clusters, demonstrating their genetic heterogeneity. Indistinguishable or very similar PFGE patterns observedamong S. delphini group B isolates from domestic and feral pigeons confirm the possibility of CoPS transmission between these birds.
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