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L Bertuccini

Publications and source records attributed to L Bertuccini.

5 recordsLinked to original sources
PubMed2005

Clonality among Enterococcus faecium clinical isolates.

In the course of a survey to determine the epidemiology of enterococcal infections in Italy, a sudden increment, in a 1-year time, was noted in the number of glycopeptide resistant Enterococcus faecium isolated from different wards of the University Hospital in Rome, Italy. The isolates were characterized for clonal relatedness by comparing SmaI gel electropherotypes, presence of vancomycin-resistance genes, and expression of virulence factors. PFGE identified in a single pulsed type all the glycopeptide-resistant isolates but one. Resistance to high levels of aminoglycosides was expressed by these same isolates, which also included a majority of non biofilm-forming strains. Two esp gene-carrying strains were also identified in different PFGE types. Data indicates that a specific clone acquired, in the clinical setting, the genetic determinant for glycopeptide resistance, thus improving environmental adaptation and favoring its persistence and spread.

Drug Resistance, Multiple, Bacterial↗
PubMed2001

Antibiotic resistance and genotypic characterization by PFGE of clinical and environmental isolates of enterococci.

Fifty-four Enterococcus faecalis and 20 Enterococcus faecium isolates from clinical and non-human sources in Rome, Italy, were characterized by antibiotic resistance and pulsed field gel electrophoresis (PFGE). Resistance to vancomycin, teicoplanin, ampicillin, and ciprofloxacin was more frequent in E. faecium than in E. faecalis, whereas high-level resistance to aminoglycoside was found primarily in E. faecalis. Multi-resistance was found primarily among clinical isolates, but was also observed among environmental isolates. Common genotypes shared among clinical and environmental isolates were observed, however, the majority of isolates occurred as unique, source-specific clones. Several PFGE types were associated with shared features in their antibiotic resistance patterns; evidences of clonal spread between and within wards were also noted. This is the first report indicating clonal relatedness between human and environmental enterococci isolated in Italy.

Anti-Bacterial Agents↗
PubMed2001

Effect of iron limitation on slime production by Staphylococcus aureus.

The aim of this study was to examine the effect of growth conditions on slime production by Staphylococcus aureus clinical isolates. The addition of glucose to the medium enhanced slime production in the majority of Staphylococcus aureus isolates cultured from infections associated with orthopaedic prostheses. Iron limitation also stimulated this ability even in the absence of the additional carbohydrate source. Staphylococcus aureus isolates were classified as Group 1 [strains producing slime only in trypticase soy broth supplemented with 1% glucose (TSBG) or in iron-limited trypticase soy broth (TSB/Fe-)]; Group 2 (slime + only in TSB/Fe-); or Group 3 (slime+ only in TSBG). Seven repeatedly slime-negative strains were stimulated to produce slime by subpassaging in iron-limited medium. Low iron levels, usually found in vivo, could stimulate slime production by Staphylococcus aureus and support chronic infections associated with orthopaedic prostheses.

Bacterial Proteins↗
PubMed2001

Enterococcus spp. produces slime and survives in rat peritoneal macrophages.

Enterococcal clinical isolates were investigated for the ability to form biofilm on inert surfaces, as a measure of slime production, in an attempt to find new possible virulence factors for these microorganisms. This property was commonly found among Enterococcus faecalis. Also E. faecium isolates were able to form biofilm, although to a lesser extent; for this species, however, biofilm formation seemed more frequently associated with isolates from infection rather than with environmental strains or isolates from healthy individuals. Biofilm formation was strongly affected by the presence of an additional carbohydrate source in the medium, or by iron deprivation, indicating a role of slime for survival in stressful conditions. Slime-producing E. faecalis were able to survive inside peritoneal macrophages for extended periods compared to slime-negative strains or to slime-positive bacteria grown in conditions depressing slime production. In particular, slime-producing and slime-negative cells showed a decrease of 1 and 2 log units, respectively, at 1 h after infection; slime-negative cells were then rapidly killed, with clearance of bacterial cells at 24 h. Slime-producing bacteria persisted up to 48 h, which was the last time point examined, as after that time viability of both infected and non-infected macrophages started to decline. Scanning electron microscopy observations showed the presence of abundant amorphous extracellular material, of possible polysaccharide nature, embedding bacterial cells to form a multilayered biofilm. Even in conditions not supporting biofilm formation, bacterial cells appeared capsulated, suggesting that capsule and slime might represent different structures. Genes belonging to the epa locus or to a putative icaA homolog did not seem to be involved in synthesis and export of slime.

Animals↗