Biogenic selenium nanoparticles: characterization, antimicrobial activity and effects on human dendritic cells and fibroblasts

Tailored nanoparticles offer a novel approach to fight antibiotic-resistant microorganisms. We analysed biogenic selenium nanoparticles (SeNPs) of bacterial origin to determine their antimicrobial activity against selected pathogens in their planktonic and biofilm states. SeNPs synthesized by Gram-negative Stenotrophomonas maltophilia [Sm-SeNPs()] and Gram-positive Bacillus mycoides [Bm-SeNPs(+)] were active at low minimum inhibitory concentrations against a number of clinical isolates of Pseudomonas aeruginosa but did not inhibit clinical isolates of the yeast species Candida albicans and C. parapsilosis. However, the SeNPs were able to inhibit biofilm formation and also to disaggregate the mature glycocalyx in both P. aeruginosa and Candida spp. The Sm-SeNPs() and Bm-SeNPs(+) both achieved much stronger antimicrobial effects than synthetic selenium nanoparticles (Ch-SeNPs). Dendritic cells and fibroblasts exposed to Sm-SeNPs(), Bm-SeNPs(+) and Ch-SeNPs did not show any loss of cell viability, any increase in the release of reactive oxygen species or any significant increase in the secretion of pro-inflammatory and immunostimulatory cytokines. Biogenic SeNPs therefore appear to be reliable candidates for safe medical applications, alone or in association with traditional antibiotics, to inhibit the growth of clinical isolates of P. aeruginosa or to facilitate the penetration of P. aeruginosa and Candida spp. biofilms by antimicrobial agents

In vivo imaging of the lung inflammatory response to Pseudomonas aeruginosa and its modulation by azithromycin

Chronic inflammation of the airways is a central component in lung diseases and is frequently associated with bacterial infections. Monitoring the pro-inflammatory capability of bacterial virulence factors in vivo is challenging and usually requires invasive methods

Application of space technologies to the surveillance and modelling of waterborne diseases.

Earth observing satellites, global positioning and geographic information systems are new tools that currently enable the scientific community to integrate ecological, environmental and medical data to develop predictive models for disease surveillance and modelling. A number of investigators have explored remotely sensed environmental factors that might be associated with waterborne disease ecology and human transmission risk. However, health specialists have not been fully familiarized with the capabilities of space technology, and in some cases it has not proved to be the wonder tool that scientists expected. New satellite capabilities and new sensors now allow exploration of risk factors previously beyond the capabilities of remote sensing and put researchers in a position to analyze the effects of environment on disease outbreaks

Vancomycin resistance is maintained in enterococci in the viable but nonculturable state and after division is resumed

Stressed vancomycin-resistant enterococci (VRE) can activate a survival strategy known as the viable but nonculturable (VBNC) state and are able to maintain vancomycin resistance. During restoration of division they continue to express the vancomycin resistance trait. We suggest that VBNC enterococci may constitute further reservoirs of VRE and therefore represent an additional risk for human health

Survival of enterococcal species in aquatic environments.

Analysis of the survival ability of faecal streptococci/enterococci in the environment has almost invariably been conducted using the standard culture method (CFU counts) despite the demonstration that these microorganisms are capable of entering a viable but nonculturable (VBNC) state. In this study we evaluated the fate, in terms of culturability and viability, of different enterococcal species under laboratory stress conditions mimicking those of the aquatic environment. The results indicate that enterococcal species may activate two different survival strategies, namely starvation and the VBNC state, depending on the specific environmental condition. Moreover, the different enterococcal species can be divided into three groups on the basis of the time needed to activate the VBNC state and the resuscitation capability. The differences in activation of the two survival strategies and the different kinetics observed among the enterococcal species reaching the VBNC state should be taken into consideration when the microbiological quality of waters has to be evaluated and because of their role as faecal contamination indicators

The activity of daptomycin on Enterococcus faecium protoplasts: indirect evidence supporting a novel mode of action on lipoteichoic acid synthesis

The effect of daptomycin, an acidic lipopeptide antibiotic active against Gram-positives, was studied in Enterococcus faecium protoplasts. This antibiotic killed 99% of the protoplasts within 60 minutes of treatment, while vancomycin was ineffective, thus excluding peptidoglycan synthesis as the only target of the action of daptomycin. As previously seen with whole cells, in protoplasts lipoteichoic acid synthesis was the earliest and most strongly inhibited among types of macro-molecular synthesis. Radioactive daptomycin tightly bound only to the cytoplasmic membrane, in which the enzymes involved in lipoteichoic acid synthesis are located. These conclusions strongly support our previous proposal that daptomycin, though active against peptidoglycan synthesis, primarily inhibits lipoteichoic acid synthesis

The High Incidence of Carbapenem-Resistant Klebsiella pneumoniae in Urine from Elderly Hospital Patients May Facilitate the Spread of Resistant Strains to the Community

Almost all European countries are affected by the expansion of carbapenem-resistant Enterobacteriaceae occurring during recent years. In the two hospitals of Verona, Italy, the incidence of carbapenem-nonsusceptible Klebsiella pneumoniae (CNSKP) began to increase by the first months of 2011, reached a peak in the summer of the same year, and currently is around 30%. Contrary to what was reported by other hospitals and although significant percentages of CNSKP were detected in respiratory samples, blood and pus, urine from hospitalized patients, mainly geriatrics, are the clinical samples with the highest incidence of these strains. Elder patients are frequently transferred from the hospital to their own homes or long-term care facilities and vice-versa. Moreover, urinary tract infections are not considered as a severe pathology and frequently is asymptomatic in elderly. For these reasons, the presence of carbapenem non-susceptible bacteria in the urinary tract of geriatric patients might be an underestimated cause of multiresistant strain spreading to the non-hospitalized population and the community