Biofilm-Associated Gene Expression in Staphylococcus pseudintermedius on a Variety of Implant Materials.

OBJECTIVE: To evaluate the expression of biofilm-associated genes in Staphylococcus pseudintermedius on multiple clinically relevant surfaces. STUDY DESIGN: In vitro experimental study. SAMPLE POPULATION: Two strains of methicillin-resistant S. pseudintermedius isolated from clinical infections representing the most common international isolates. METHODS: A quantitative polymerase chain reaction (qPCR) assay for expression of genes related to biofilm initial adhesion, formation/maturation, antimicrobial resistance, and intracellular communication was developed and validated. S. pseudintermedius biofilms were grown on 8 clinically relevant surfaces (polymethylmethacrylate, stainless steel, titanium, latex, silicone, polydioxanone, polystyrene, and glass) and samples of logarithmic and stationary growth phases were collected. Gene expression in samples was measured by qPCR. RESULTS: Significant differences in gene expression were identified between surfaces and between bacterial strains for most gene/strain/surface combinations studied. Expression of genes responsible for production of extracellular matrix were increased in biofilms. Expression of genes responsible for initial adhesion and intracellular communication was markedly variable. Antimicrobial resistance gene expression was increased on multiple surfaces, including stainless steel and titanium. CONCLUSION: A method for evaluation of expression of multiple biofilm-associated genes in S. pseudintermedius was successfully developed and applied to the study of biofilms on multiple surfaces. Variations in expression of these genes have a bearing on understanding the development and treatment of implant-associated biofilm infections and will inform future clinical research.

Laparoscopic-assisted extirpation of falciform ligament hemangiosarcoma in a dog.

An 8-year-old, spayed female, bichon frisé dog had incidental nodules within its falciform ligament identified on routine abdominal ultrasonography. A laparoscopic-assisted technique provided both a diagnostic and a therapeutic treatment option. A histopathological diagnosis of hemangiosarcoma was made. This is the second case reporting hemangiosarcoma of the falciform fat.

Extraction assistée par laparascopie d'un hémangiosarcome du ligament falciforme chez un chien. Une chienne Bichon frisé stérilisée âgée de 8 ans avait des nodules secondaires dans le ligament falciforme qui ont été identifiés lors d'une échographie abdominale de routine. Une technique assistée par laparascopie a fourni un diagnostic et une option de traitement thérapeutique. Un diagnostic d'hémangiosarcome a été posé à l'histopathologie. Il s'agit du deuxième cas d'hémangiosarcome du gras falciforme signalé.(Traduit par Isabelle Vallières).

Identification of appropriate reference genes for qPCR studies in Staphylococcus pseudintermedius and preliminary assessment of icaA gene expression in biofilm-embedded bacteria.

BACKGROUND: Quantitative PCR is rapidly becoming the standard method for analyzing gene expression in a wide variety of biological samples however it can suffer from significant error if stably expressed reference genes are not identified on which to base the analysis. Suitable reference genes for qPCR experiments on Staphylococcus pseudintermedius have yet to be identified. RESULTS: Three reference genes in S. pseudintermedius were identified and validated from a set of eight potential genes (proC, gyrB, rplD, rho, rpoA, ftsZ, recA, sodA). Two strains of S. pseudintermedius were used, and primer specificity and efficiency were confirmed and measured. Ranking of the genes with respect to expression stability revealed gyrB, rho and recA as the best reference genes. This combination was used to quantify expression of a single biofilm associated gene, icaA, in logarithmic, stationary and biofilm growth phases, revealing that expression was significantly upregulated in the biofilm growth phase in both strains. CONCLUSION: Three reference genes, gyrB, rho and recA, were identified and validated for use as reference genes for quantitative PCR experiments in S. pseudintermedius. Also, the biofilm associated gene icaA was shown to be significantly upregulated in biofilm samples, consistent with its role in biofilm production.