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lunes, 4 de diciembre de 2017

Shelf-Life of Chlorine Solutions Recommended in Ebola Virus Disease Response

In Ebola Virus Disease (EVD) outbreaks, it is widely recommended to wash living things (handwashing) with 0.05% (500 mg/L) chlorine solution and non-living things (surfaces, personal protective equipment, dead bodies) with 0.5% (5,000 mg/L) chlorine solution. Chlorine solutions used in EVD response are primarily made from powdered calcium hypochlorite (HTH), granular sodium dichloroisocyanurate (NaDCC), and liquid sodium hypochlorite (NaOCl), and have a pH range of 5–11. Chlorine solutions degrade following a reaction highly dependent on, and unusually sensitive to, pH, temperature, and concentration. We determined the shelf-life of 0.05% and 0.5% chlorine solutions used in EVD response, including HTH, NaDCC, stabilized NaOCl, generated NaOCl, and neutralized NaOCl solutions. Solutions were stored for 30 days at 25, 30, and 35°C, and tested daily for chlorine concentration and pH. Maximum shelf-life was defined as days until initial concentration fell to <90% of initial concentration in ideal laboratory conditions. At 25–35°C, neutralized-NaOCl solutions (pH = 7) had a maximum shelf-life of a few hours, NaDCC solutions (pH = 6) 2 days, generated NaOCl solutions (pH = 9) 6 days, and HTH and stabilized NaOCl solutions (pH 9–11) >30 days. Models were developed for solutions with maximum shelf-lives between 1–30 days. Extrapolating to 40°C, the maximum predicted shelf-life for 0.05% and 0.5% NaDCC solutions were 0.38 and 0.82 hours, respectively; predicted shelf-life for 0.05% and 0.5% generated NaOCl solutions were >30 and 5.4 days, respectively. Each chlorine solution type offers advantages and disadvantages to responders, as: NaDCC is an easy-to-import high-concentration effervescent powder; HTH is similar, but forms a precipitate that may clog pipes; and, NaOCl solutions can be made locally, but are difficult to transport. We recommend responders chose the most appropriate source chlorine compound for their use, and ensure solutions are stored at appropriate temperatures and used or replaced before expiring.
REFERENCIA:
Iqbal, Qais et al. “Shelf-Life of Chlorine Solutions Recommended in Ebola Virus Disease Response.” Ed. Vincent Jacobus Munster. PLoS ONE 11.5 (2016): e0156136.


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jueves, 30 de noviembre de 2017

Enterococcus hirae biofilm formation on hospital material surfaces and effect of new biocides

BACKGROUND: Nowadays, the bacterial contamination in the hospital environment is of particular concern because the hospital-acquired infections (HAIs), also known as nosocomial infections, are responsible for significant morbidity and mortality. This work evaluated the capability of Enterococcus hirae to form biofilm on different surfaces and the action of two biocides on the produced biofilms.
METHODS: The biofilm formation of E. hirae ATCC 10541 was studied on polystyrene and stainless steel surfaces through the biomass quantification and the cell viability at 20 and 37 °C. The effect of LHIDROXI FAST and LH ENZYCLEAN SPRAY biocides on biomasses was expressed as percentage of biofilm reduction. E. hirae at 20 and 37 °C produced more biofilm on the stainless steel in respect to the polystyrene surface. The amount of viable cells was greater at 20 °C than with 37 °C on the two analyzed surfaces. Biocides revealed a good anti-biofilm activity with the most effect for LH ENZYCLEAN SPRAY on polystyrene and stainless steel at 37 °C with a maximum biofilm reduction of 85.72 and 86.37%, respectively.
RESULTS: E. hirae is a moderate biofilm producer depending on surface material and temperature, and the analyzed biocides express a remarkable antibiofilm action.
CONCLUSION: The capability of E. hirae to form biofilm can be associated with its increasing incidence in hospital-acquired infections, and the adoption of suitable disinfectants is strongly recommended.
REFERENCIA:
Di Lodovico S, et al. Enterococcus hirae biofilm formation on hospital material surfaces and effect of new biocides. Environ Health Prev Med. 2017 Aug 2;22(1):63. doi: 10.1186/s12199-017-0670-3. PubMed PMID: 29165147; PubMed Central PMCID: PMC5664585.

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miércoles, 8 de noviembre de 2017

Guidance on regulations for the transport of infectious substances 2017–2018

This publication provides information for identifying, classifying, marking, labelling, packaging, documenting and refrigerating infectious substances for transportation and ensuring their safe delivery.
The document provides practical guidance to facilitate compliance with applicable international regulations for the transport of infectious substances by all modes of transport, both nationally and internationally, and include the changes that apply from 1 January 2017. The current revision replaces the document issued by the World Health Organization (WHO) in 2015 (document WHO/HSE/GCR/2015.2). This publication, however, does not replace national and international transport regulations.

Applicable as from 1 January 2017

Authors:
World Health Organization

Publication details

Number of pages40
Publication date2017
LanguagesEnglish
WHO reference numberWHO/WHE/CPI/2017.8

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lunes, 6 de noviembre de 2017

Biological samples transportation by drones: ready for prime time?

FRAGMENT:
According to the concept originally introduced by George D. Lundberg in the 1980s, the total testing process entails three essential and sequential parts, that are the preanalytical phase, the analytical phase and the postanalytical phase (1). Briefly, the preanalytical phase encompasses all those (prevalently) manually-intensive activities designed for obtaining, handling, transporting, preparing and storing biological samples before testing (2). Reliable evidence, accumulated after decades of research aimed to improve the total quality of the testing process, underpins the notion that the vast majority of problems in laboratory diagnostics are attributable to incorrect or inappropriate preanalytical activities (3).
REFERENCE:
Lippi, Giuseppe, and Camilla Mattiuzzi. “Biological Samples Transportation by Drones: Ready for Prime Time?” Annals of Translational Medicine 4.5 (2016): 92. PMC. Web. 6 Nov. 2017.

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miércoles, 1 de noviembre de 2017

Molecular Viability Testing of UV-Inactivated Bacteria

The polymerase chain reaction (PCR) is effective at detecting bacterial DNA in samples, but it is unable to differentiate viable bacteria from inactivated cells or free DNA fragments. New PCR-based analytical strategies have been developed to address this limitation. Molecular viability testing (MVT) correlates bacterial viability with the ability to rapidly synthesize species-specific ribosomal RNA precursor (pre-rRNA) in response to brief nutritional stimulation. Previous studies demonstrated that MVT can assess bacterial inactivation by chlorine, serum, and low-temperature pasteurization. Here, we demonstrate that MVT can detect inactivation of Escherichia coli, Aeromonas hydrophila, and Enterococcus faecalis cells by ultraviolet (UV) irradiation. Some UV-inactivated E. coli cells transiently retained the ability to synthesize pre-rRNA post-irradiation (generating false-positive MVT results), but this activity ceased within one hour following UV exposure. Viable but transiently undetectable (by culture) E. coli cells were consistently detected by MVT. An alternative viability testing method, viability PCR (vPCR), correlates viability with cell envelope integrity. This method did not distinguish viable from UV-inactivated bacteria under some conditions, indicating that the inactivated cells retained intact cell envelopes. MVT holds promise as a means to rapidly assess microbial inactivation by UV treatment.
IMPORTANCE Ultraviolet (UV) irradiation is increasingly used to disinfect water, food, and other materials for human use. Confirming the effectiveness of UV disinfection remains a challenging task. In particular, microbiological methods that rely on rapid detection of microbial DNA can yield misleading results. This is due to the detection of “remnant” DNA associated with dead microbial cells. This report describes a novel method that rapidly distinguishes living from dead microbial cells after UV disinfection.
REFERENCE:
Kris M. Weigel, et al. Molecular Viability Testing of UV-Inactivated Bacteria. Appl Environ Microbiol. 2017 May 15; 83(10): e00331-17. Prepublished online 2017 Mar 10. Published online 2017 May 1. doi: 10.1128/AEM.00331-17. PMCID: PMC5411506

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viernes, 27 de octubre de 2017

#History 1990: Model for inactivation and disposal of infectious HIV and radioactive waste in a BL3 facility

A method is described for autoclaving low levels of solid infectious, radioactive waste. The method permits steam penetration to inactivate biologic waste, while any volatile radioactive compounds generated during the autoclave process are absorbed. Inactivation of radiolabeled infectious waste has been problematic because the usual sterilization techniques result in unacceptable radiation handling practices. If autoclaved under the usual conditions, there exists a high probability of volatilization or release of radioisotopes from the waste. This results in the radioactive contamination of the autoclave and the laboratory area where steam is released from the autoclave. Our results provide a practical method to inactivate and dispose of infectious radioactive waste. For our research, Bacillus pumilus spore strips and vaccinia virus were used as more heat-resistant surrogates of the human immunodeficiency virus (HIV). These surrogates were used because HIV is difficult to grow under most conditions and is less heat tolerant than the surrogates. In addition, B. pumilus has defined cell death values, whereas such values have not been established for HIV. Both B. pumilus and vaccinia virus are less hazardous to work with. The autoclave method is time efficient and can be performed by laboratory personnel with minimal handling of the waste. Furthermore, waste site handlers are able to visually inspect the solid waste containers and ascertain that inactivation procedures have been implemented.
REFERENCE:
Stinson MC, et al. Model for inactivation and disposal of infectious human immunodeficiency virus and radioactive waste in a BL3 facility. Appl Environ Microbiol. 1990 Jan;56(1):264-8.

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miércoles, 25 de octubre de 2017

Dead or Alive: Molecular Assessment of Microbial Viability

Nucleic acid-based analytical methods, ranging from species-targeted PCRs to metagenomics, have greatly expanded our understanding of microbiological diversity in natural samples. However, these methods provide only limited information on the activities and physiological states of microorganisms in samples. Even the most fundamental physiological state, viability, cannot be assessed cross-sectionally by standard DNA-targeted methods such as PCR. New PCR-based strategies, collectively called molecular viability analyses, have been developed that differentiate nucleic acids associated with viable cells from those associated with inactivated cells. In order to maximize the utility of these methods and to correctly interpret results, it is necessary to consider the physiological diversity of life and death in the microbial world. This article reviews molecular viability analysis in that context and discusses future opportunities for these strategies in genetic, metagenomic, and single-cell microbiology.
REFERENCE:
Cangelosi, Gerard A., and John S. Meschke. “Dead or Alive: Molecular Assessment of Microbial Viability.” Ed. H. L. Drake. Applied and Environmental Microbiology 80.19 (2014): 5884–5891. PMC. Web. 4 Sept. 2017.

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lunes, 23 de octubre de 2017

Schrödinger’s microbes: Tools for distinguishing the living from the dead in microbial ecosystems

While often obvious for macroscopic organisms, determining whether a microbe is dead or alive is fraught with complications. Fields such as microbial ecology, environmental health, and medical microbiology each determine how best to assess which members of the microbial community are alive, according to their respective scientific and/or regulatory needs. Many of these fields have gone from studying communities on a bulk level to the fine-scale resolution of microbial populations within consortia. For example, advances in nucleic acid sequencing technologies and downstream bioinformatic analyses have allowed for high-resolution insight into microbial community composition and metabolic potential, yet we know very little about whether such community DNA sequences represent viable microorganisms. In this review, we describe a number of techniques, from microscopy- to molecular-based, that have been used to test for viability (live/dead determination) and/or activity in various contexts, including newer techniques that are compatible with or complementary to downstream nucleic acid sequencing. We describe the compatibility of these viability assessments with high-throughput quantification techniques, including flow cytometry and quantitative PCR (qPCR). Although bacterial viability-linked community characterizations are now feasible in many environments and thus are the focus of this critical review, further methods development is needed for complex environmental samples and to more fully capture the diversity of microbes (e.g., eukaryotic microbes and viruses) and metabolic states (e.g., spores) of microbes in natural environments.
REFERENCE:
Emerson JB1,et al. Schrödinger's microbes: Tools for distinguishing the living from the dead in microbial ecosystems. Microbiome. 2017 Aug 16;5(1):86. doi: 10.1186/s40168-017-0285-3.

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jueves, 19 de octubre de 2017

Workplace Hazards to Reproduction and Development

This booklet contains information for those of you who are interested in identifying, evaluating, and reducing workplace reproductive and developmental health risks. The information provided ranges from descriptions of basic physiology and toxicology to specific guidance intended for health care providers, workplace health and safety personnel, workers, and employers.
REFERENCE:
Sharon L. Drozdowsky, B.S. and Stephen G. Whittaker, Ph.D.  Hazards to Reproduction and Development: A Resource for Workers, Employers, Health Care Providers, and Health & Safety Personnel. Safety and Health Assessment and Research for Prevention (SHARP). Washington State Department of Labor and Industries. Technical Report Number: 21-3-1999

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martes, 17 de octubre de 2017

Laboratory-acquired infections of Salmonella enterica serotype Typhi in South Africa

BACKGROUND: Workers in clinical microbiology laboratories are exposed to a variety of pathogenic microorganisms. Salmonella species is among the most commonly reported bacterial causes of laboratory-acquired infections. We report on three cases of laboratory-acquired Salmonella enterica serotype Typhi (Salmonella Typhi) infection which occurred over the period 2012 to 2016 in South Africa.
METHODS: Laboratory investigation included phenotypic and genotypic characterization of isolates. Phenotypic analysis included standard microbiological identification techniques, serotyping and antimicrobial susceptibility testing. Genotypic analysis included the molecular subtyping methodologies of pulsed-field gel electrophoresis analysis, multilocus sequence typing and whole-genome sequencing (WGS); with WGS data analysis including phylogenetic analysis based upon comparison of single nucleotide polymorphism profiles of isolates.
RESULTS: All cases of laboratory-acquired infection were most likely the result of lapses in good laboratory practice and laboratory safety. The following critical issues were highlighted. There was misdiagnosis and misreporting of Salmonella Typhi as nontyphoidal Salmonella by a diagnostic laboratory, with associated public health implications. We highlight issues concerning the importance of accurate fluoroquinolone susceptibility testing and interpretation of results according to updated guidelines. We describe potential shortcomings of a single disk susceptibility screening test for fluoroquinolone susceptibility and suggest that confirmatory minimum inhibitory concentration testing should always be performed in cases of invasive Salmonella infections. These antimicrobial susceptibility testing issues resulted in inappropriate ciprofloxacin therapy which may have been responsible for failure in clearance of pathogen from patients. Salmonella Typhi capsular polysaccharide vaccine was not protective in one case, possibly secondarily to a faulty vaccine.
CONCLUSIONS: Molecular subtyping of isolates proved effective to investigate the genetic relatedness of isolates. Molecular subtyping data interpreted together with epidemiological data allowed us to pinpoint the most likely sources for our cases of laboratory-acquired infection.
REFERENCE:
Smith AM, et al. Laboratory-acquired infections of Salmonella enterica serotype Typhi in South Africa: phenotypic and genotypic analysis of isolates. BMC Infect Dis. 2017 Sep 29;17(1):656.

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