Main pathologies associated with "Staphylococcus aureus" infections in rabbits: a review

[EN] Staphylococcus aureus is a versatile opportunistic pathogen that causes a wide spectrum of pathologies. In rabbits, this bacterium infects dermal lesions causing suppurative dermatitis, and invades subcutaneous tissues, causing different well-known disease conditions such as mastitis, abscesses (subcutaneously or affecting internal organs) and pododermatitis. However, the lesions associated with S. aureus have rarely been described in detail in the literature. The aim of this paper is to update the knowledge on rabbit staphylococcosis by focusing mainly on the different pathologies that this organism produces in commercial rabbits.The studies on staphylococcal infections in Dr. Corpa’s group are funded by the CEU-Cardenal Herrera University (PRUCH02/25, 04/11, 05/09, B06/18, 01/08, 23/08 and the Copernicus-Santander research programme of the CEUUCH and Banco de Santander), the Valencian Regional Government - Generalitat Valenciana - (GV05/202, ARVIV/2007/007, ACOMP/2009/207) and the Spanish Ministry of Science and Innovation (AGL2008-00273/GAN). The studies in the group of K. Hermans and F. Haesebrouck have been, and continue to be funded by the Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT Vlaanderen) and the Research Fund of Ghent UniversityUniversidad Cardenal Herrera CEU (UCH-CEU)Generalitat Valenciana (GV)Ministerio de Ciencia e Innovación (MICINN)Corpa, J.; Hermans, K.; Haesebrouck, F. (2009). Main pathologies associated with "Staphylococcus aureus" infections in rabbits: a review. World Rabbit Science. 17(3):115-125. https://doi.org/10.4995/wrs.2009.65111512517

Survival of Salmonella serovar Typhimurium inside porcine monocytes is associated with complement binding and suppression of the production of reactive oxygen species

Macrophages are thought to play a major role in the development of Salmonella carriers in swine. It was the aim of the present study to characterize the interactions of a Salmonella serovar Typhimurium strain with porcine peripheral blood monocytes. The production of reactive oxygen species (ROS) by monocytes and the numbers of intracellularly killed bacteria differed significantly between the different pigs used. Opsonization of Salmonella bacteria with complement significantly decreased bacterial killing. Interestingly, monocytic ROS production was suppressed by metabolically active bacteria. In conclusion, binding to host complement and suppression of monocyte ROS production enable ser. Typhimurium to survive for at least 6 hours in porcine monocytes. Moreover, individual differences of porcine monocytes to produce ROS and to kill the intracellular Salmonella bacteria might account for the development of the carrier state in some pigs and not in others

The influence of fatty acids on the expression of virulence genes of Salmonella Typhimurium and the colonization of pigs

Salmonella Typhimurium infections in pigs are a major source of human foodborne salmonellosis. To reduce the number of infected pigs, actdified feed or drinking water can be administrated. A study was carried out to evaluate the use of short-chain fatty acids (SCFA) and medium-chain fatty acids (MCFA) for the control of Salmonella Typhimurium infections in ptgs. Short-chain fatty acids formate, acetate, propionate and butyrate (pH 6, osm 600, cone 1 OmM) and medium-chain fatty acids caproic, caprylic and capric acid (pH6, osm 600, cone 2mM) were used

Efficacy of an autogenous vaccine against highly virulent "Staphylococcus aureus" infection in rabbits

[EN] The efficacy of an autogenous vaccine consisting of a whole cell suspension of formalin killed bacteria in sterile buffered saline against Staphylococcus aureus infections was determined, using a well-established rabbit skin infection model. Thirteen eight-week-old rabbits were vaccinated twice subcutaneously with a two-week interval while ten rabbits were injected twice with sterile buffered saline. Two weeks after the last injection, ten vaccinated and all PBS-injected rabbits were inoculated intradermally with 108 cfu of a S. aureus strain which had been shown to be highly virulent for rabbits. Three vaccinated animals served as negative controls and were intradermally injected with sterile buffered saline. All rabbits were examined daily for the development of skin lesions until fourteen days after the experimental infection when all rabbits were euthanised. All animals experimentally infected with S. aureus developed skin abscesses within 24 hours post-inoculation, but in the vaccinated group the maximum abscess diameter was significantly lower than in the non-vaccinated group (P=0.048). The difference between the autovaccinated and non-vaccinated group increased over time (P<0.001). These results indicate that vaccination with an inactivated whole cell bacterin may be useful for control of staphylococcosis in rabbits but does not prevent abscess formation in animals inoculated with a high dose of a highly virulent S. aureus strain.Meulemans, G.; Haesebrouck, F.; Lipinska, U.; Duchateau, L.; Hermans, K. (2011). Efficacy of an autogenous vaccine against highly virulent "Staphylococcus aureus" infection in rabbits. World Rabbit Science. 19(1):1-9. https://doi.org/10.4995/wrs.2011.8121919

Macrolide resistance in porcine streptococci: a human health hazard?

In order to obtain better insights into the possible exchange of resistance genes between human and porcine streptococci, macrolide and lincosamide resistant streptococci from tonsillar and colon swabs from pigs and pork carcass swabs were isolated and their resistance phenotypes and genotypes were determined. The sequences of the erm(B) genes of 21 human streptococci, 22 porcine streptococci and 15 streptococci isolated from pork carcasses were compared. From each of the 33 pigs and from 88 of 99 carcass swabs, at least one resistant streptococcal strain was isolated. The predominant phenotype was the constitutively expressed MLSB phenotype, mostly encoded by the erm(B) gene. Identical erm(B) gene sequences were present in strains from humans, pigs and pork carcasses

Relation between antimicrobial use and resistance in Belgian pig herds

The aim of this study was to determine the link between the characteristics of antimicrobial therapy and occurrence of antimicrobial resistance in Escherichia coli of clinically healthy pigs exposed to antimicrobial treatments. A total of 918 Escherichia coli isolates were obtained from faecal samples, collected from 50 pig herds at the end of the fattening period and susceptibility was tested towards 15 different antimicrobial agents, using the disk diffusion method

A comparison of Helicobacter pylori and non-Helicobacter pylori Helicobacter spp. Binding to Canine Gastric Mucosa with Defined Gastric Glycophenotype

Background: The gastric mucosa of dogs is often colonized by non-Helicobacter pylori helicobacters (NHPH), while H. pylori is the predominant gastric Helicobacter species in humans. The colonization of the human gastric mucosa by H. pylori is highly dependent on the recognition of host glycan receptors. Our goal was to define the canine gastric mucosa glycophenotype and to evaluate the capacity of different gastric Helicobacter species to adhere to the canine gastric mucosa. Materials and Methods: The glycosylation profile in body and antral compartments of the canine gastric mucosa, with focus on the expression of histo-blood group antigens was evaluated. The in vitro binding capacity of FITC-labeled H. pylori and NHPH to the canine gastric mucosa was assessed in cases representative of the canine glycosylation pattern. Results: The canine gastric mucosa lacks expression of type 1 Lewis antigens and presents a broad expression of type 2 structures and A antigen, both in the surface and glandular epithelium. Regarding the canine antral mucosa, H. heilmannii s.s. presented the highest adhesion score whereas in the body region the SabA-positive H. pylori strain was the strain that adhered more. Conclusions: The canine gastric mucosa showed a glycosylation profile different from the human gastric mucosa suggesting that alternative glycan receptors may be involved in Helicobacter spp. binding. Helicobacter pylori and NHPH strains differ in their ability to adhere to canine gastric mucosa. Among the NHPH, H. heilmannii s.s. presented the highest adhesion capacity in agreement with its reported colonization of the canine stomach.We kindly thank Prof. Thomas Boren from the Department of Medical Biochemistry and Biophysics, Umea University, Sweden for providing the 17875/Leb and 17875babA1A2H. pylori strains. The authors thank Dr. Fernando Rodrigues, Dr. Ana Laura Saraiva, and Cristina Bacelar who kindly provided technical support. I. Amorim (SFRH/BD/76237/2011) and A. Magalhães (SFRH/BPD/75871/2011) acknowledge FCT for financial support. This study was partially funded by the Portuguese Foundation for Science and Technology (PTDC/CTM-BPC/121149/2010; PTDC/CVT/117610/2010; PTDC/BBB-EBI/0786/2012). The Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP) is an Associate Laboratory of the Portuguese Ministry of Science, Technology and Higher Education and is partially supported by FCT

SPI-2 of Salmonella Typhimurium is not necessary for long term colonization of pigs

Unravelling the role of Salmonella virulence factors in the porcine host could greatly contribute to the development of control measures such as vaccination. The virulence genes located on the Salmonella Pathogenicity Island 2 (SPI-2) are indispensable for the induction of systemic disease and persistence in BALB/c mice. The role of this pathogenicity island in the pathogenesis of Salmonella Typhimurium infections in pigs is not documented. Therefore, in the present study, the interactions of a porcine field strain of Salmonella Typhimurium and a non-polar isogenic SPI-2 (D-ssrA) deletion mutant were compared in both in vitro and in vivo models. The ssrA mutant strain displayed decreased SPI-2 expression levels in vitro and was attenuated in a mouse model after oral inoculation. No difference was seen in the expression of SPI-1 related virulence genes. Through flowcytometric analysis, the ssrA mutant strain was found to be moderately attenuated in intracellular replication in porcine macrophages in vitro. In an infection experiment, 2 groups of 10 piglets were orally inoculated with the wild type or the ssrA mutant strain. The infection of the animals inoculated with the ssrA mutant strain followed a similar course as the animals infected with the wild type strain. At days 5 and 28 post inoculation, the animals of both groups were infected to the same extent in the gut and gut-associated lymphoid tissue, as well as in the mternal organs. These results suggest that SPI-2 of Salmonella Typhimurium may not contribute to the colonization of pigs to the same extent as it contributes to the colonization of BALB/c mice

Stress induced Salmonella Typhimurium re-excretion by pigs is associated with cortisol induced increased intracellular proliferation in porcine macrophages

Infections of pigs with Salmonella enterica subspecies enterica serovar Typhimurium (Salmonella Typhimurium) often result in the development of carriers that intermittently excrete Salmonella in very low numbers. During periods of stress, recrudescence of Salmonella may occur

Laser capture microdissection of intestinal tissue from sea bass larvae using an optimized RNA integrity assay and validated reference genes

The increasing demand for a sustainable larviculture has promoted research regarding environmental parameters, diseases and nutrition, intersecting at the mucosal surface of the gastrointestinal tract of fish larvae. The combination of laser capture microdissection (LCM) and gene expression experiments allows cell specific expression profiling. This study aimed at optimizing an LCM protocol for intestinal tissue of sea bass larvae. Furthermore, a 3'/5' integrity assay was developed for LCM samples of fish tissue, comprising low RNA concentrations. Furthermore, reliable reference genes for performing qPCR in larval sea bass gene expression studies were identified, as data normalization is critical in gene expression experiments using RT-qPCR. We demonstrate that a careful optimization of the LCM procedure allows recovery of high quality mRNA from defined cell populations in complex intestinal tissues. According to the geNorm and Normfinder algorithms, ef1a, rpl13a, rps18 and faua were the most stable genes to be implemented as reference genes for an appropriate normalization of intestinal tissue from sea bass across a range of experimental settings. The methodology developed here, offers a rapid and valuable approach to characterize cells/tissues in the intestinal tissue of fish larvae and their changes following pathogen exposure, nutritional/environmental changes, probiotic supplementation or a combination thereof