Search

Biofilms cause chronic infections in tissues or by developing on the surfaces of medical devices. Biofilm infections persist despite both antibiotic therapy and the innate and adaptive defence mechanisms of the patient. Biofilm infections are characterized by persisting and progressive pathology due primarily to the inflammatory response surrounding the biofilm. For this reason, many biofilm infections may be difficult to diagnose and treat efficiently. It is the purpose of the guideline to bring the current knowledge of biofilm diagnosis and therapy to the attention of clinical microbiologists and infectious disease specialists. Selected hallmark biofilm infections in tissues (e.g. cystic fibrosis with chronic lung infection, patients with chronic wound infections) or associated with devices (e.g. orthopaedic alloplastic devices, endotracheal tubes, intravenous catheters, indwelling urinary catheters, tissue fillers) are the main focus of the guideline, but experience gained from the biofilm infections included in the guideline may inspire similar work in other biofilm infections. The clinical and laboratory parameters for diagnosing biofilm infections are outlined based on the patient's history, signs and symptoms, microscopic findings, culture-based or culture-independent diagnostic techniques and specific immune responses to identify microorganisms known to cause biofilm infections. First, recommendations are given for the collection of appropriate clinical samples, for reliable methods to specifically detect biofilms, for the evaluation of antibody responses to biofilms, for antibiotic susceptibility testing and for improvement of laboratory reports of biofilm findings in the clinical microbiology laboratory. Second, recommendations are given for the prevention and treatment of biofilm infections and for monitoring treatment effectiveness. Finally, suggestions for future research are given to improve diagnosis and treatment of biofilm infections., (Copyright © 2014 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Viable bacteria were sought in 44 Maki-negative biofilms from central venous catheters (CVCs) using epifluorescence microscopy after live/dead staining. Thirty (77%) samples contained viable but non-culturable (VBNC) cells; the majority were positive on real-time PCR specific for Staphylococcus epidermidis (one also for Staphylococcus aureus). Viable cells were significantly (p<0.01) associated with CVCs from febrile patients, three of whom showed S. epidermidis-positive blood cultures, suggesting that CVC-associated biofilms can be reservoirs for staphylococci in the VBNC state. The possible role of VBNC staphylococci in persistent infections related to medical devices requires further investigation., (© 2012 The Authors. Clinical Microbiology and Infection © 2012 European Society of Clinical Microbiology and Infectious Diseases.)

In recent years the employment of implantable medical devices has increased remarkably, notwithstanding that microbial infections are a frequent complication associated with their use. Different strategies have been attempted to overcome this problem, including the incorporation of antimicrobial agents into the device itself. In this study a new approach to obtain intrinsically antimicrobial materials was developed. Polymer anionomers containing Ag(I), Cu(II), Zn(II), Al(III) and Fe(III) were prepared by neutralization of a carboxylated polyurethane. In the case of the PEUA-Ag, PEUA-Fe and PEUA-Cu ionomers the ion aggregates behaved as reinforcing filler particles, increasing the mechanical properties of the systems in terms of hardness and strength at break over the pristine carboxylated polymer. With the exception of the Al-containing polymer, all the other experimented ionomers showed satisfactory antimicrobial properties. The best antibacterial effect was obtained with the silver ion-containing polymer, which inhibited Staphylococcus epidermidis growth for up to 16days. Ciprofloxacin was also adsorbed onto the above mentioned ionomers. A synergistic effect of the antibiotic and silver ions on bacterial growth inhibition was observed for at least 25days., (2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Human infection with Aeromonas species is uncommon and most often due to trauma with exposure to contaminated water or soil. A 43-year-old HIV- and hepatitis C virus (HCV)-infected male, after a two-week course of corticosteroid therapy for an autoimmune anemia, developed diarrhea, dermatologic manifestations and a multiple organ dysfunction syndrome, resulting in death. Although stool samples were repeatedly negative, two sets of blood cultures obtained during a single peak of fever yielded the post-mortem isolation of a Gram-negative, oxidase-positive, beta-hemolytic bacillus that was identified as Aeromonas sobria. Empiric antibiotic therapy was unsuccessful. Evaluation of the virulence-associated traits of the clinical isolate (adhesion, cytotoxicity activity, biofilm production) showed that the strain was a poor producer of recognized virulence factors, thereby indicating that the unfortunate coexistence of HIV infection, HCV-related liver cirrhosis and corticosteroids played a key role in the clinical course.

Bacterial protein toxins, such as Clostridium difficile toxin A and the Escherichia coli cytotoxic necrotizing factor 1 are known to exert their cytotoxic action via a modification of some cytoskeletal components. The changes in actin organization caused by these toxins appear to be the primary events in the mechanism leading to cell death.

Human breast carcinoma cells (CG5) and human laryngeal carcinoma cells (HEp-2) were exposed to 10 and 50 micrograms/ml of small (about 5 microns) chrysotile asbestos fibers. Morphological and ultrastructural changes were evaluated by means of immunocytochemistry and by scanning and transmission electron microscopy. Our attention was focused on the mechanisms of cell internalization and on transport of chrysotile fibers. The fibers appeared to penetrate the cell cytoplasm and to be translocated in proximity of the nucleus. Small chrysotile fibers could also be found inside the nucleus of interphase cells. Involvement of the main cytoskeletal components, i.e., microfilaments, intermediate filaments, and microtubules, in the cytotoxicity of chrysotile fibers was also evaluated. Our findings suggest that after fiber penetration, a rearrangement of the cytoskeletal apparatus occurs. It has also been observed that small fibers remain associated with the cytoskeletal framework, which can thus play a role in asbestos intracytoplasmic translocation in epithelial cells. Furthermore, after the cell has completely recovered its morphology, fiber internalization ultimately seems to lead to the formation of giant multinucleated cells. These data could be indicative of an interaction occurring between asbestos fibers and the normal mitotic process. The disturbance of the cell cytoskeleton and the close morphologic contact between asbestos fibers and the cell's nuclear region may be of importance in explaining the well-known carcinogenic effects of asbestos mineral fibers.

Clostridium difficile toxin B is a powerful cytopathic agent without enterotoxic activity which is believed to be involved in the pathogenesis of pseudomembranous colitis. Up until today, the mechanisms of toxin B cytotoxicity have not been elucidated. The results of in vitro studies performed on different cell lines by means of immunocytochemical and ultrastructural methods are reported here. Low doses (0.15 ng/ml) of toxin B cause cell rounding and arborization. Higher doses (up to 15 micrograms/ml) induce cell rounding and appearance of numerous surface protrusions with blister or bulb-like features. These "blebs" belong to the potocytotic type, the bleb matrix being devoid of cytoplasmic organelles and filled with ribosomes only. Furthermore, a peculiar role of cytoskeletal apparatus in this phenomenon has been detected. In fact, morphological rearrangement occurs in cytoskeletal elements, mainly represented by the presence, in the blebs, of tubulin and of the actin-binding proteins alpha-actinin, filamin, and calmodulin, while actin and intermediate filaments, keratin and vimentin, appear to be absent. Moreover, beta 2-microglobulin, considered as a surface protein marker, seems to undergo changes in its expression, being absent over the blebbing surface. The results of this study may support the view that C. difficile toxin B affects one or more subcellular components that regulate the structure and function of the actin cytoskeleton.

In this study we investigated the activity of halogeno-, cyano- and amidino-isoflavenes, isoflavans and flavans on the multiplication of human astroviruses. These are naked small round viruses which have been recognized as causative agents of human gastroenteritis, and whose capsid proteins are similar to those of picornaviruses. Although all drugs tested caused a dose-dependent reduction of viral antigen synthesis as monitored by immunofluorescence, the chloro derivatives were the most effective.

Receptors for IgM were detected on peripheral blood human eosinophils by a rosette technique with ox red blood cells coated with the IgM fraction of the specific immunserum. Between 14% and 43% (mean 27%) FcmuR positive cells were found after an overnight incubation period at 37 degrees C by using this technique. The specificity of the receptors for IgM was assessed by studying the inhibitory capacity of purified human IgM in the rosette assay. From an ultrastructural point of view, the EAM rosette-forming cells are mature eosinophilic granulocytes characterized by a nucleus with a variable number of lobes and a certain number of "first type" granules partially or totally devoid of their content.

Talc powders from national and international markets were analyzed in order to assess their fiber contents and the proportion of asbestos in the fibrous material. Samples of talc powders used as excipients in pharmaceutical and cosmetic preparations demonstrated fiber contents up to 30% of total particles. About a half of the talc powders revealed the presence of asbestos: in five samples chrysotile (a serpentine asbestos) was present, in the other ones tremolite and anthophyllite (an amphibole asbestos). The amounts of asbestos vary up to 90% in the different samples of the fibrous fraction. About 75% of observed asbestos fibers were thinner than 0.4 micron, i.e., below the resolving power of light microscopy which until now was the most utilized technique for evaluating the environmental pollution due to asbestos.

A purification procedure for a protein obtained from an pathogenic strain of E. coli is described. The protein-called CNF-is active in inhibiting the duplication of cultured mammalian cells. Since nuclei division is apparently normal, treatment of cultured cells with CNF leads to the formation of gigantic, polynucleated cells. The purified protein is chromatographically and electrophoretically homogeneous. A partial characterization of CNF protein is also given.

We studied the inorganic particulate contained in the lung parenchyma of 10 subjects (5 males and 5 females) resident in an urban area and not occupationally exposed to dusts. A total of 17 mineral types were identified, along with 16 metal elements in the form of oxides and sulfides. Approximately 70% of the minerals were made up of phyllosilicates, in particular clay, mica, and talc; three metal elements, Fe, Al, and Ti, accounted for more than 75% of the recovered oxide particles. The mean concentration of the observed inorganic particles was approximately 1.8 X 10(5) pp/mg dry tissue. No significant differences were observed in terms of total particulate concentration in the various areas of the lungs and between the right and left lung. Instead we observed a larger concentration of fibrous particles in the upper lobes. The analysis of the data made it possible to determine the presence of a high degree of correlation between the concentrations of silicates and the concentrations of metal oxides and sulfides, implying the existence of a ubiquitous environmental source of these mineral particles. The frequent observation of tremolite fibers is remarkable. This finding, confirmed elsewhere, indicates that the magnitude of the sources of these fibers in the environment, constituted by contaminated talc dusts, has been underestimated until today.