miércoles, 20 de abril de 2016

Microbial stress priming: a meta-analysis

Priming by osmotic, physiological and temperature stress had the highest positive effect sizes on microbial response.
Microbes have to cope with complex and dynamic environments, making it likely that anticipatory responses provide fitness benefits. Mild, previous stressors can prepare microbes (stress priming) to further and potentially damaging stressors (triggering).

Quantitatively summarizing the findings from over 250 trials of 34 studies including bacteria and fungi, demonstrating that priming to stress has a beneficial impact on microbial survival. 
In fact, survival of primed microbes was about 10-fold higher compared with that in non-primed microbes.

Categorical moderators related to microbial taxonomy and the kind of stress applied as priming or as triggering revealed significant differences of priming effect size among 14 different microbial species, 6 stress categories and stressor combination.

Priming by osmotic, physiological and temperature stress had the highest positive effect sizes on microbial response. Cross-protection was evident for physiological, temperature and pH stresses.

Microbes are better prepared against triggering by oxidative, temperature and osmotic stress. Our finding of an overall positive mean effect of priming regardless of the microbial system and particular stressor provides unprecedentedly strong evidence of the broad ecological significance of microbial stress priming.

These results further suggest that stress priming may be an important factor in shaping microbial communities.

Source: Diana R. Andrade-Linares et al, 2016, Environmental Microbiology DOI: 10.1111/1462-2920.13223

martes, 19 de abril de 2016

CDC need bacterial cultures to study foodborne outbreaks

Culture-independent diagnostic tests are affecting outbreak monitoring.
Changes in the tests that diagnose foodborne illness are helping identify infections faster but could soon pose challenges to finding outbreaks and monitoring progress toward preventing foodborne disease, according to a report published today in CDC’s Morbidity and Mortality Week Report.
Culture-independent diagnostic tests (CIDTs) help doctors diagnose infections quickly because they provide results in hours instead of the days needed for traditional culture methods, which require growing bacteria to determine the cause of illness. However, without a bacterial culture, public health officials cannot get the detailed information about the bacteria needed to help find outbreaks, check for antibiotic resistance, and track foodborne disease trends.
In 2015, the percentage of foodborne infections diagnosed only by CIDT was about double with the percentage in 2012-2014.
“Foodborne infections continue to be an important public health problem in the United States,” said Robert Tauxe, M.D., M.P.H, director of CDC’s Division of Foodborne, Waterborne and Environmental Diseases. “We are working with partners to make sure we still get important information about harmful bacteria despite the increasing use of diagnostic tests that don’t require a culture.”
The increased use of CIDT could affect public health officials’ ability to monitor trends and detect outbreaks. In the short term, clinical laboratories should work with their public health laboratories to make sure a culture is done whenever a CIDT indicates that someone with diarrheal illness has a bacterial infection. For a long-term solution, CDC is working with partners to develop advanced testing methods that, without culture, will give health care providers information to diagnose illness and also give the detailed information that public health officials need to detect and investigate outbreaks.
Limited progress in reducing foodborne illness: The report included the most recent data from CDC’s Foodborne Diseases Active Surveillance Network, or FoodNet. It summarizes preliminary 2015 data on nine pathogens spread commonly through food. Overall, progress in reducing rates of foodborne illnesses has been limited since 2012, according to the report. The most frequent causes of infection in 2015 were Salmonella and Campylobacter, which is consistent with previous years.
CDC want to respond quickly to foodborne illness, but the true goal is to move forward with preventive measures that will be implemented from farm to table. In addition to collaboration with other government agencies at the local, state and federal level, the rules implementing under the FDA Food Safety Modernization Act will help the food industry minimize the risk of contamination to our food supply.

Source: http://www.foodpoisonjournal.com/food-poisoning-information/cdc-we-need-bacterial-cultures-to-catch-foodborne-outbreaks/#.VxYp5vnhCt8

martes, 12 de abril de 2016

Multi-country outbreak of Shiga toxin-producing E. coli infection

At least three children died due to hemolytic uremic syndrome
A multi-country outbreak of Shiga toxin-producing Escherichia coli (STEC) infection associated with haemolytic uraemic syndrome (HUS) and affecting mostly young children has been reported in the last two months in Romania. In addition, Italy reported one related HUS case through the Early Warning and Response System (EWRS) on 21 March 2016. Overall, 25 cases were identified as associated with this outbreak, of which 19 developed HUS and three died. Twelve cases had microbiological and/or serological evidence of STEC O26 infection; 13 additional cases met the probable case definition by developing HUS, testing positive for another STEC O serogroup (O157) or by testing positive by PCR for stx1 and/or stx2 and eae genes.
Information collected from patients pointed towards a milk-processing establishment (the Romanian operator) as a possible source of infection. The implicated milk-processing establishment exported a particular type of cheese to four EU countries (Belgium, Germany, Italy and Spain) and one Italian importer further distributed this product to France and Germany. In Romania, one fresh cheese product made of cow’s milk produced by the Romanian operator tested positive for E. coli O26 not possessing stx virulence genes. Other dairy products produced by the Romanian operator tested positive for E. coli virulence genes stx1, stx2 and eae.
In Italy, a STEC O26 strain (positive for stx1, stx2 and eae) was isolated from a sample of the cheese that had been produced by the Romanian operator. The product was consumed by a Italian child that later developed HUS (stool samples negative for STEC but serum samples positive for the presence of antibodies against the LPS of E. coli O26).
The PFGE analysis suggests multiple strains from a common source or from multiple sources. Multi-strain STEC outbreaks have been reported in the past [1]. Therefore, probably the outbreak is associated to a source contaminated by different strains. The last Romanian case associated with this outbreak had onset of symptoms on 14 March. Recalls were conducted in Romania in March 5 and in Italy in 15 March. Other Member States subsequently undertook recalls. The withdrawal of potentially contaminated dairy products following a recall has been limited in Member States, with the exception of Romania. It is therefore possible that affected products are still present in households, and detection of new cases cannot be excluded. In order to minimize the spread of the infection and investigate possible new cases in a timely manner, Romania, Italy and other Member States that are possibly involved could consider enhancing surveillance for STEC cases.
Further food and environmental studies in suspect premises to identify the vehicle of Multi-country outbreak of infection. Whole genome sequencing (WGS) on isolates will confirm about possible links between cases.

viernes, 1 de abril de 2016

Chemicals that mimic transcriptional changes associated with autism, brain aging and neurodegeneration.

More than 480,000 chemicals are registered for use in the environment.
Environmental factors, including pesticides, have been linked to autism and neurodegeneration risk using retrospective epidemiological studies. Here we sought to prospectively identify chemicals that share transcriptomic signatures with neurological disorders, by exposing mouse cortical neuron-enriched cultures to hundreds of chemicals commonly found in the environment and on food. We find that rotenone, a pesticide associated with Parkinson’s disease risk, and certain fungicides, including pyraclostrobin, trifloxystrobin, famoxadone and fenamidone, produce transcriptional changes in vitro that are similar to those seen in brain samples from humans with autism, advanced age and neurodegeneration (Alzheimer’s disease and Huntington’s disease).

Powerful new sequencing technologies have been used to systematically identify hundreds of candidate gene mutations associated with autism spectrum disorder (ASD) risk. Heritability studies suggest that environmental factors also contribute to autism risk.
Indeed, gestational exposure to pesticides, including maternal proximity to pesticide applications and runoff, is reproducibly associated with increased ASD risk in epidemiological studies.

However, epidemiological studies are retrospective and cannot ascertain prospectively, precisely or systematically which chemicals, of the 480,000 chemicals registered for use in the environment, have the greatest potential to harm the developing or adult brain.

Existing in vivo neurodevelopmental and neurotoxicological assays with animal models are labour intensive and costly, thus hindering throughput, whereas higher-throughput toxicological assays frequently use non-neuronal cells or focus on neuron death as an end.
As a result, these tests fail to interrogate molecular and physiological processes that are unique to neurons or that differentiate normal from diseased human brains.

There is growing recognition that brain transcriptional changes are associated with ASD.
This ASD transcriptional signature is defined by reduced expression of genes involved in synaptic transmission and elevated expression of genes involved in immune and microglial function.

Here we hypothesized that this transcriptional signature might guide the prospective identification of candidate chemical risks for ASD. To test this hypothesis, we exposed mouse cortical neuron-enriched cultures to hundreds of environmental-use chemicals and then monitored global transcriptional changes.

We identify six chemical groups, one of which mimics the transcriptional changes seen in ASD, but surprisingly also shares transcriptional similarity to the aged brain and certain neurodegenerative conditions. Our findings suggest these neurological conditions share a molecular pathology, as hypothesized by others, despite different ages of onset and distinct behavioral symptoms. Moreover, this study shows that a transcriptional approach can be used to systematically scan a diverse chemical space and identify potential environmental threats to the human brain.

Source: Brandon L. Pearson et al., Nature Communications DOI: 10.1038/ncomms11173.