Persistence of microbial communities including Pseudomonas aeruginosa in a hospital environment: a potential health hazard.

BACKGROUND: The persistence of microbial communities and how they change in indoor environments is of immense interest to public health. Moreover, hospital acquired infections are significant contributors to morbidity and mortality. Evidence suggests that, in hospital environments agent transfer between surfaces causes healthcare associated infections in humans, and that surfaces are an important transmission route and may act as a reservoir for some of the pathogens.This study aimed to evaluate the diversity of microorganisms that persist on noncritical equipment and surfaces in a main hospital in Portugal, and are able to grow in selective media for Pseudomonas, and relate them with the presence of Pseudomonas aeruginosa. RESULTS: During 2 years, a total of 290 environmental samples were analyzed, in 3 different wards. The percentage of equipment in each ward that showed low contamination level varied between 22% and 38%, and more than 50% of the equipment sampled was highly contaminated. P. aeruginosa was repeatedly isolated from sinks (10 times), from the taps' biofilm (16 times), and from the showers and bedside tables (two times). Two ERIC clones were isolated more than once. The contamination level of the different taps analyzed showed correlation with the contamination level of the hand gels support, soaps and sinks. Ten different bacteria genera were frequently isolated in the selective media for Pseudomonas. Organisms usually associated with nosocomial infections as Stenotrophomonas maltophilia, Enterococcus feacalis, Serratia nematodiphila were also repeatedly isolated on the same equipment. CONCLUSIONS: The environment may act as a reservoir for at least some of the pathogens implicated in nosocomial infections. The bacterial contamination level was related to the presence of humidity on the surfaces, and tap water (biofilm) was a point of dispersion of bacterial species, including potentially pathogenic organisms. The materials of the equipment sampled could not be related to the microbial contamination level. The presence of a disinfectant in the isolation medium suggests that the number of microorganism in the environment could be higher and shows the diversity of disinfectant resistant species. The statistical analysis suggests that the presence of bacteria could increase the risk of transmission by hand manipulation.

[Rural work and health risks: a review into de "safe use" of pesticides in Brazil]. / Trabalho rural e riscos à saúde: uma revisão sobre o "uso seguro" de agrotóxicos no Brasil.

The paradigm of the "safe use" of pesticides is based on measures to control risks in the handling of these products. However, studies carried out in various regions of Brazil reveal a situation of widespread exposure and health damages among rural workers, revealing the ineffectiveness of this paradigm. This work presents a critical review of the "safe use" approach for pesticides in scientific papers published in Brazil in the past 15 years. Results indicate that these studies do not address, simultaneously, all the work activities that involve exposure and risk of intoxication (acquisition, transportation, storage, preparation and application, final disposal of empty containers and sanitization of contaminated clothes/ PPEs), nor do they comprehensively address the "safe use" measures recommended in safety manuals, which are mandatory for each activity. A total of 25 studies were selected and analyzed, revealing a high number of results and analyses regarding activities of preparation and application and final disposal of empty containers. The range of the approaches was seen to be timely in the six work activities. For future studies, a broader approach of the "safe use" of pesticides is recommended, seeking to reveal the complete infeasibility of this safety paradigm.

Metal-induced phosphate extracellular nanoparticulate formation in Ochrobactrum tritici 5bvl1.

Hexavalent chromium (Cr(VI)) is a toxic environmental contaminant which detoxification consists in reduction to Cr(III). In this work, the Cr(VI)-resistant and reducing Ochrobactrum tritici 5bvl1 produced phosphate nanoparticles upon exposure to Cr(VI) and Fe(III), effectively removing chromium from solution. Under Cr(VI) stress, higher siderophore production by strain 5bvl1 was observed. Cr(VI) toxicity was decreased in presence of Fe(III), increasing the growth and Cr(VI)-reduction rates in cell cultures, lowering the amount of morphologically compromised cells and promoting chromium immobilization as insoluble extracellular phosphate complexes. The formation of phosphate nanoparticles increased with Cr(VI) and Fe(III) concentrations and was also stimulated by Ni(II). Under these experimental conditions, nanoparticle formation occurred together with enhanced inorganic phosphate consumption by cells and increased polyphosphate kinase (PPK) activity. NMR analysis of the particles showed the presence of both polyphosphate and phosphonate together with orthophosphate, and FT-IR supported these results, also showing evidences of Cr(III) coordination. This work demonstrated that O. tritici 5bvl1 possesses protection mechanisms against chromium toxicity other than the presence of the Cr(VI) pump and SOD related enzymes previously described. Future assessment of the molecular regulation of production of these nanoparticles will open new perspectives for remediation of metal contaminated environments.