1,721,069 research outputs found
Analysis of virulence factors in cases of enterococcal endocarditis.
No full textClin Microbiol Infect. 2004 Nov;10(11):1006-8.
Analysis of virulence factors in cases of enterococcal endocarditis.
Baldassarri L, Creti R, Arciola CR, Montanaro L, Venditti M, Di Rosa R.
Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Istituto Superiore di Sanita, Rome, Italy. [email protected]
Eleven isolates of Enterococcus faecalis causing endocarditis were screened for possible virulence factors with PCR and phenotypic assays. The gene coding for the enterococcal surface protein (esp) was detected in one isolate only, and haemolysin was produced by two isolates. Aggregation substance, biofilm formation and gelatinase were present in seven, nine and eight isolates,
respectively. Predisposing factors, particularly hospitalisation and multiple antibiotic therapy, appeared to be more relevant to the development of enterococcal endocarditis following bloodstream infections than the pattern of virulence factors
Prevalence of cna, fnbA and fnbB adhesin genes among Staphylococcus aureus isolates from orthopedic infections associated to different types of implant.
No full textFEMS Microbiol Lett. 2005 May 1;246(1):81-6.
Prevalence of cna, fnbA and fnbB adhesin genes among Staphylococcus aureus isolates from orthopedic infections associated to different types of implant.
Arciola CR, Campoccia D, Gamberini S, Baldassarri L, Montanaro L.
Research Unit on Implant Infections, Rizzoli Orthopedic Institute, Via di Barbiano 1/10, 40136 Bologna, Italy. [email protected]
Here are reported data on virulence determinants of Staphylococcus aureus from orthopedic surgical infections, emphasizing on the genes encoding fibronectin (fnbA, fnbB) and collagen (cna) adhesins. 191 S. aureus strains from orthopedic
infections (53 from internal fixation devices, 29 external fixation devices, 15 knee arthroprostheses, 30 hip arthroprostheses, 45 surgical reconstruction and 19 non-associated to medical devices) were investigated for the presence of the genes of the collagen-binding protein Cna and of the two fibronectin-binding
proteins, FnbA and FnbB. 87 (46%) strains were found to be cna+ without significant variations across the different surgical categories considered. Conversely, the fnbA and the fnbB genes were almost always present in all surgical categories. The finding that, among the investigated adhesins, fibronectin-adhesins are present in the majority of the implant associated S. aureus clinical isolates encourages the development of strategies to specifically block the interaction of bacteria with matrix fibronectin by antagonist ligands
A multiplex PCR method for the detection of all five individual genes of ica locus in Staphylococcus epidermidis. A survey on 400 clinical isolates from prosthesis-associated infections
No full textJ Biomed Mater Res A.
A multiplex PCR method for the detection of all five individual genes of ica locus in Staphylococcus epidermidis. A survey on 400 clinical isolates from prosthesis-associated infections.
Arciola CR, Gamberini S, Campoccia D, Visai L, Speziale P, Baldassarri L, Montanaro L.
Research Unit on Implant Infections, Rizzoli Orthopedic Institute, Via di Barbiano, 1/10, 40136 Bologna, Italy.
[email protected]
In Staphylococcus epidermidis, ica locus encodes for the synthesis of a polysaccharide intercellular adhesin (slime or biofilm). A multiplex polymerase chain reaction (PCR) for the detection of the five individual genes of ica locus was developed, with the aim to probe the set of genes in a large collection of Staphylococcus epidermidis clinical isolates. Single representative fragments
for icaR, icaA, icaD, icaB, and icaC genes were selected. Multiplex PCR was applied to two reference Staphylococcus epidermidis strains [the non-biofilm-forming ATCC 12228 and the biofilm-forming ATCC 35984 (RP62A)] and to 400 clinical isolates of Staphylococcus epidermidis from orthopedic prosthesis associated infections. The gene profile was compared with the phenotypic biofilm-forming ability, evaluated by means of an optimized Congo red agar (CRA) plate test. Among the clinical isolates, 228 (57%) turned out completely ica positive and were biofilm producing. Among the 172 non-biofilm-forming strains (43%), 164 (41%) were completely ica negative and 8 strains (2%) harbored all five ica genes. The ica locus thus proves to be a cluster of strictly linked genes, without any evidence of single gene deletion.
(c) 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2005
Search for the insertion element IS256 within the ica locus of Staphylococcus epidermidis clinical isolates collected from biomaterial-associated infections.
No full textBiomaterials. 2004 Aug;25(18):4117-25.
Search for the insertion element IS256 within the ica locus of Staphylococcus epidermidis clinical isolates collected from biomaterial-associated infections.
Arciola CR, Campoccia D, Gamberini S, Rizzi S, Donati ME, Baldassarri L, Montanaro L.
Research Laboratory on Biocompatibility of Implant Materials, Rizzoli
Orthopaedic Institute, and Experimental Pathology Department, University of Bologna, Italy. [email protected]
Staphylococcus epidermidis biofilm-forming strains produce a polysaccharide intercellular adhesin (PIA), which mediates bacterial cell aggregation and favours the colonisation on prosthetic implants. PIA synthesis is regulated by the icaADBC locus. In vitro, by repeated subcultures of a biofilm-producing strain, the loss of the ability to produce biofilm appears associated with the
insertion of the IS256 element into the ica locus. This study was aimed (i) to investigate if the five genes of ica locus are always all present in different strains of S. epidermidis, and (ii) to search if IS256 insertion naturally occurs in ica locus without making recourse to the experimental procedure of repeated subcultures of strains. 120 S. epidermidis clinical isolates from peri-prosthesis infections were investigated both by an original multiplex PCR
analysis of the ica genes and by PCR amplification of the IS256 element. Also two reference strains (the biofilm-negative S. epidermidis ATCC 12228 and the biofilm-forming ATCC 35984 [RP62A]) and two biofilm-negative RP62A-derived acriflavin mutants (D9 and HAM892) were analysed. D9 e HAM892 were for the first time shown to contain in ica locus, at the base 3319, a 1300-bp insertion with a DNA sequence corresponding to IS256. Among the 120 clinical isolates, 51 (43%) turned out completely ica-positive, 69 completely ica-negative (57%). The genes of the ica locus appear, in all cases of the present collection, strictly linked
each other, so they are either all present or all absent. In this collection, IS256 was present in eight out of the 69 ica-negative strains and in 34 out of the 51 ica-positive strains. IS256, also when present in bacterial genomic DNA, was never found inside the ica locus, thus suggesting that insertion/excision of this element is not a natural occurring mechanism for off/on switching of
biofilm production
Le infezioni da Streptococco B in Italia: un problema importante per la salute della donna e del bambino
No full textNO ABSTRAC
Underestimated collateral effects of antibiotic therapy in prosthesis-associated bacterial infections
No full textAntibiotic treatment of infections associated with the use of indwelling medical devices in ageing and/or severely ill patients represents a significant healthcare problem due to the difficulty of treating such infections and to the various collateral effects that may be observed following the often aggressive therapy. We summarize some effects of antibiotics on the expression of virulence factors of the microorganisms which cause such infections. These effects, particularly those resulting in a stimulation of bacterial virulence, might be usefully included among the other well-known collateral effects of antibiotic therapy
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The Alpha-like surface proteins: An example of an expanding family of adhesins
No full textThe Alpha-like protein (Alp) family, repeat-containing surface proteins once thought to be important adhesion factors confined to pathogenic streptococci and enterococci, is broader than previously known. Analysis of the annotated microbial genomes has identified new potential members of the Alp family not only in other Gram- positive opportunistic pathogens but also in commensal microflora of the human gut and the skin. This finding has highlighted the importance of genome sequencing projects for unraveling in greater detail lateral gene transfer events involving virulence factors between pathogens and commensals. These should receive constant attention not only as part of infectious disease prevention programs, but also in the food and biotechnology industrie
Clostridi elicoidali: nuovi patogeni intestinali? Comparazione tra un ceppo umano e ceppi di provenienza animale
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