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Przeprowadzono analizę 24 przypadków izolacji z ran w znamiennej ilości Gram-dodatnich maczugokształtnych pałeczek (C. amycolatum, C. striatum, C. grupa G, Brevibacterium sp., C. jeikeium, C. urealyticum, C. grupa F1). Scharakteryzowano oporność na antybiotyki na podstawie wartości MIC oznaczonych metodą Etest. U 83,3% szczepów występowała jednocześnie oporność na erytromycynę i klindamycynę (mechanizm MLSB), u 75% oporność na kotrimoksazol, u 71,7% oporność na chloramfenikol, u 16,7% na antybiotyki beta-lakatamowe. Wszystkie szczepy wykazywały wrażliwość na wankomycynę i teikoplaninę.
Non-diphtherial corynebacteria are Gram-positive rods that cause opportunistic infections, what is supported by their ability to produce biofilm on artificial surfaces. In this study, the characteristic of the biofilm produced on vascular and urological catheters was determined using a confocal microscopy for the most frequently involved in infections diphtheroid species. They were represented by the reference strains of Corynebacterium striatum ATCC 6940 and C. amycolatum ATCC 700207. The effect of ciprofloxacin on the biofilm produced by the antibiotic-susceptible C.striatum strain was evaluated using three concentrations of the antimicrobial agent (2×, 4×, and 6× the MIC – the Minimum Inhibitory Concentration). The basis for the interpretation of results was the statistical analysis of maximum points readings from the surface comprising a total of 245 areas of the biofilm image under the confocal microscope. It was observed that ciprofloxacin at a concentration equal to 4×MIC paradoxically caused an enlargement of areas with live bacteria within the biofilm. Biofilm destruction required the application of ciprofloxacin at a concentration higher than 6×MIC. This suggests that the use of relatively low doses of antimicrobial agents may increase the number of live bacteria within the biofilm, and further facilitate their detachment from the biofilm’s structure thus leading to the spread of bacteria into the bloodstream or to the neighboring tissues. The method of biofilm analysis presented here provides the original and novel approach to the investigation of the diphtheroid biofilms and their interaction with antimicrobial agents.
Background. Coagulase negative staphylococci are at the forefront of etiologic agents of periprosthetic joint infections (PJIs). The purpose of the study was to characterise causative isolates (n=19) of Staphylococcus epidermidis (SE) – with emphasis on their phenotypic and genotypic heterogeneity. Material and methods. The isolates were cultured from multiple samples obtained perioperatively during revision surgery from 14 patients with clinically and/or microbiologically proven PJI. Phenotypic heterogeneity included variations of colony morphologies, drug resistance patterns and/or the capability of the biofilm formation and was verified by the DNA fingerprinting assay. Results. Phenotypic discrepancies were observed between isolates cultured from 5 patients (35.7%). The genotyping assay identified 3 pairs of isolates as unrelated; single pairs were genetically related and indistinguishable. The biofilm production was detected in 17 isolates, among which 5 (29.4%) were proficient biofilm formers harbouring the icaADBC genes. Additionally, one ica-positive isolate produced a moderate, protease-sensitive biofilm. The remaining isolates were moderate biofilm producers among which four developed protease-sensitive biofilms. Conclusions. The majority of PJIs are monoclonal; nevertheless, phenotypic diversity of SE is a frequent phenomenon which can complicate the diagnostic proceeding. Adherence ability is an important pathogenic trait of SE although the chemical composition of the resultant biofilm, its intensity and regulation of development can vary.
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