Biomedical subjects

Moreno Bondi

Publications and source records attributed to Moreno Bondi.

9 recordsLinked to original sources

PubMed2007

Biofilm on artificial surfaces.

Biofilms are microbial communities quite different from planktonic cells and most of common microbiological concepts had to be updated in recent years. The peculiar capacity to resist to disinfectants and antibiotics results in biofilms being a public health problem mainly when modern medical devices are used. All artificial surfaces used in medicine may be prone to biofilm attachment and could therefore represent a cause of acute or chronic infectious diseases. Uremic patients are at higher risk from biofilms as not only traditional causes, such as indwelling catheters, but also hemodialysis apparatuses contribute to bacterial exposure. Chemical or physical disinfections have been demonstrated partially active on sessile microorganisms and biofilm avoidance remains the goal to assure an adequate quality of dialytic treatment.

Anti-Bacterial Agents↗

PubMed2006

Ex-vivo evaluation of alginate microparticles for Polymyxin B oral administration.

A crosslinked alginate microparticle system for the targeting to the lymphatic system by Peyer's patches (PP) uptake was designed in order to improve the oral absorption of Polymyxin B (PMB). To verify mucoadhesion and PP uptake, microparticles labelled with fluorescein isothiocyanate (FITC) were prepared by spray-drying technique and crosslinking reactions with calcium ions and chitosan (CS), in vitro characterized and assayed by an ex vivo method. Microparticles showed a size less then 3 microm, an antibiotic loading level of 11.86 +/- 0.70%, w/w, a sustained drug release behaviour in simulated gastro-intestinal (GI) fluids and a preserved biological activity throughout the manufacture. The ex vivo study was performed by a perfusion method on intestinal tracts of just sacrificed adult rats. The recovered samples were analysed by epifluorescence microscope for mucoadhesion and PP uptake and by microbiological analysis for antibiotic activity preservation, providing evidence of mucoadhesion at the level of both PP and non-PP epithelium, uptake by PP and PMB microbiological activity in PP tissue. Furthermore, the study revealed the involvement of transport pathways across villous enterocytes.

Administration, Oral↗

PubMed2006

Water treatment and monitor disinfection.

Water treatment system and dialysis monitors are susceptible to microbial contaminations and periodical disinfection procedures are mandatory to obtain results requested from international standards and guidelines. Several chemical germicides or some physical treatments are on the market validated by device manufacturer according to medical device directives. With time, interfering substances from dialysis device or water are able to modify disinfection efficiency. Simulating-use testing is not a common procedure to validate disinfectants and recent data document as biofilm represents the most important cause of disinfection inefficacy. Some international standards include tests in the presence of various interfering substances but their use is not widespread. When using a disinfectant, residue toxicity, material compatibility and potential risks for the staff also have to be considered. A quality assurance program has to be implemented to obtain adequate performances and to improve results on patients.

Disinfection↗

PubMed2005

Vancomycin-resistant enterococci (VRE) in meat and environmental samples.

We investigated the spread of vancomycin-resistant enterococci (VRE) in strains from meat and environmental samples and the location of glycopeptide-resistance determinants in VanA isolates. VRE and VSE (vancomycin-sensitive enterococci) resistance patterns to six antimicrobials were also evaluated. A total of 59 meat isolates (35%) and 119 environmental isolates (26.5%) were glycopeptide resistant enterococci. In particular, 10.7% meat isolates belonged to the VanA, 8.3% to VanB and 16% to VanC phenotypes. Environmental samples presented 0.7% VanA, 14.5% VanB, and 11.4% VanC strains. Evident differences were not observed among the resistance patterns of VRE and VSE isolates. Neither an important difference was observed comparing the resistance patterns in enterococci from meat and environment. In particular a low incidence of beta-lactamic resistant strains was found, whereas high rates of resistance were observed for streptomycin (85.7% and 92.8%), kanamycin (79.7% and 96%) and gentamycin (85.1% and 91.7%). An intermediate rate of resistant bacteria emerged for erythromycin (35.1% and 10.5%). All VanA isolates independent of origin had more plasmids with different molecular weights. PCR amplification of the 732 bp fragment in plasmids from the VanA strains confirmed affiliation to the vanA gene cluster and the extrachromosomal location of the glycopeptide-resistance determinants. Our study suggests that food and environment play a potential role as reservoirs of resistance determinants, prompting the need to undertake epidemiological and molecular studies to evaluate the mobility of these genes.

Anti-Bacterial Agents↗

PubMed2005

Micro- and macromethod assays for the ecological study of Legionella pneumophila.

The survival of a strain of Legionella pneumophila (Lp-1) inoculated in artificial water microcosms was investigated with and without an amoebal host and varying environmental conditions, such as biofilm formation, amount of nutrients and incubation temperature. The results obtained using short (micromethod) and long (macromethod) term methods showed that L. pneumophila Lp-1 dies rapidly at 4 degrees C in the "macromethod" assay. When the same temperature (4 degrees C) was applied to the "micromethod" assay, L. pneumophila Lp-1 survived for three weeks, although it progressively decreased. At an incubation temperature of 30 degrees C, the aquatic environment was more favourable and better survival emerged in the "macromethod"; in contrast, this favourable temperature condition did not improve the survival of L. pneumophila Lp-1 cultured with the "micromethod". The role of the protozoa Acanthamoeba polyphaga proved to be indispensable for legionella survival only when environmental conditions become unfavourable.

Acanthamoeba↗

PubMed2005

Antibiotic resistance and antibacterial activity in heterotrophic bacteria of mineral water origin.

Antibiotic resistance and antibacterial activity were determined on heterotrophic bacteria isolated from mineral waters. Of the 120 isolates Pseudomonas spp. (55.8%) was the predominant group followed by Acinetobacter spp. (14.17%), Flavobacterium spp. (10.83%), Achromobacter spp. (10%), Burkholderia cepacia (3.3%), Agrobacterium/radiobacter (2.5%), Moraxella spp. (1.7%), Aeromonas hydrophila (1.7%). Over 80% of the isolates were resistant to one or more antibiotics and the highest resistance was found for chloramphenicol, ampicillin, colistin and sulfamethizole (60%, 55%, 50% and 47.5%, respectively). Strains with multiple antibiotic resistance (MAR) represented 55% of isolates and the most resistant organism belonged to the genus Pseudomonas. Of 40 randomly selected strains, 27 (67.5%) had antibacterial activity towards one or more indicators. This activity, found in a high percentage in the genus Pseudomonas (92%), emerged mainly against closely related microorganisms. Several producers were active also against Escherichia coli, Salmonella, Listeria monocytogenes and Staphylococcus aureus. Forty-six percent of the isolates harboured 1 to 5 plasmids with molecular weights ranging from 2.1 to 41.5 MDa.

Anti-Bacterial Agents↗

PubMed2005

Water ecology of Legionella and protozoan: environmental and public health perspectives.

Ecological studies on Legionella spp. are essential to better understand their sources in the natural environments, the mechanism of their entry into man-made water systems and the factors enabling their survival and growth in aquatic habitats. Legionella spp. exhibits peculiar and multiple strategies to adapt to stressful environment conditions which normally impair other germ survival. These strategies include the ability to enter in a viable but non-cultivable (VBNC) state, to multiply intracellularly within a variety of protozoa, such as amoebae, to survive as free organisms within biofilms and to be enhanced/inhibited by the presence of other aquatic bacteria. The host-parasite interaction has been shown to be central in the pathogenesis and ecology of L. pneumophila. The bacterial-protozoan interaction contributes to the amplification of Legionella population in water systems, represents a shelter against unfavourable environmental conditions, acts as a reservoir of infection and contributes to virulence by priming the pathogen to infect human cells. Legionella is able to survive as free organism for long periods within biofilms which are widespread in man-made water systems. Biofilm provides shelter and nutrients, exhibits a remarkable resistance to biocide compounds and chlorination, thus representing ecological niches for legionella persistence in such environments. Further knowledge on biofilm-associated legionellae may lead to effective control measures to prevent legionellosis. Lastly, new perspectives in controlling legionella contamination can arise from investigations on aquatic bacteria able to inhibit legionella growth in natural and artificial water systems.

Animals↗

PubMed2005

Study of five penicillinase producing Neisseria gonorrhoeae isolated in Italy.

Five penicillinase producing Neisseria gonorrhoeae (PPNG) were isolated from urethral specimens of men admitted to the "Santa Chiara" Hospital (Trento, Italy). All strains proved to be resistant to penicillin and ampicillin, and sensitive to cefuroxime, erythromycin, tetracycline, spectinomycin, nalidixic acid and ciprofloxacin. PPNG plasmid profiles showed that four of the isolates carried the 3.2 MDa "Africa" plasmid and one the 4.5 MDa "Asia" plasmid, the two well-known phenotypes reported in the USA and Europe as well as in Asian and African countries. Membrane matings were performed using N. gonorrhoeae carrying the 24.5 MDa conjugative plasmid as donors and E. coli K12 J 53 as recipient. The transfer of beta-lactamic antibiotic resistance was supported by the presence of 4.5 or 3.2 MDa plasmid bands and by beta-lactamase production in the transconjugants. Restriction analysis of Asian and African plasmids is reported.

Anti-Bacterial Agents↗

PubMed2003

Bacteriocin-like substance (BLS) production in Aeromonas hydrophila water isolates.

30 Aeromonas hydrophila water isolates were tested for bacteriocin-like substance (BLS) production using a target panel of closely related microorganisms and other Gram-positive and Gram-negative bacteria, including food-borne pathogens. A. hydrophila showed antibacterial activity against one or more indicator microorganisms, but the activity emerged only with non-phylogenetically related genera or species. In particular all A. hydrophila showed antibacterial activity against one or more of the tested Staphylococcus strains, five against Listeria spp. (Listeria seeligeri, Listeria welshimeri and Listeria ivanovii), and eight presented a weak antagonistic activity towards Streptococcus agalactiae and Lactobacillus spp. Inhibitory activity was not observed against the other Gram-positive (Listeria monocytogenes, Listeria innocua and Enterococcus spp.) and Gram-negative tested strains, including Aeromonas sobria, Aeromonas caviae and the same A. hydrophila, when used as indicator. Anti-staphylococcal activity was observed with a gradual increase of the inhibition zone during incubation and seemed to be influenced by A. hydrophila hemolytic expression. Extrachromosomal analysis showed the presence, in 70% of the strains, of one to five plasmids with molecular masses ranging from 2.1 to 41.5 MDa, but it was not possible to relate this result with BLS production.

Aeromonas hydrophila↗