Tuesday, 23 September 2008

Aspergillus threatens crops damaged by Hurricane Ike

The power of a hurricane
Hurricane Ike swept through the US state of Ohio last week just as fields of grain were ripening.



This article discusses the damage done by the storm to crops and the potential for infection by Aspergillus.

The most severe damage seem to be done to crops stressed by drought which collapse to the ground when blown by severe winds.

The plant is therefore already vulnerable to infection, presumably because there are already several dead leaves on the plant due to early growth dying back when little water is available. All that is needed is sufficient moisture and direct contact with spores - both of which happen if lying on moist soil.

The next immediate threat is from mycotoxins - toxic chemicals produced by Aspergillus and other fungi which will make the crop inedible. There are specific conditions required before the infecting fungus can produce mycotoxins (e.g. Aflatoxin) which are mentioned in the article:

Aspergillus can infect grain and produce aflatoxin under a wide range of conditions: temperature between 54 degrees and 108 degrees Fahrenheit; kernel moisture between 15 percent and 25 percent; and relative humidity above 80 percent.

“Downed corn will certainly be exposed to these conditions, especially high moisture if it rains, and since aspergillus is a soil-borne fungus infection could easily occur,” said Paul.

But, he added, growers should also pay attention to such ear mold diseases as fusarium and diplodia, which could develop if damaged ears come in contact with moist soils.

Any condition that increases moisture in the grain, puts maturing grain in contact with the soil, restricts drying, and makes harvest operation difficult could promote fungal growth and toxin contamination.

Tuesday, 16 September 2008

Aspergillus produces most of the world's citric acid

Citric acid is used for a multitude of purposes around the world, most obviously as a food & drink additive (E330) for flavouring or as a preservative but also for purposes as diverse as soaps & detergents, hair dying, explosives, industrial pipe cleaning, photography and many more - even heroin users seek it out.

1.7 million metric tonnes of citric acid are produced worldwide per year, and most of that is made by Aspergillus niger. The ability of A. niger to make citric acid was originally identified in 1917 by James Currie and industrial level production began two years later by Pfizer. Up to that point when citric acid was needed citrus fruit juices were employed.

The process of citric acid production by A. niger is pretty simple, the Wikipedia entry is as follows:
In this production technique, which is still the major industrial route to citric acid used today, cultures of Aspergillus niger are fed on a sucrose or glucose-containing medium to produce citric acid. The source of sugar is corn steep liquor, molasses, hydrolyzed corn starch or other inexpensive sugary solutions. After the mold is filtered out of the resulting solution, citric acid is isolated by precipitating it with lime (calcium hydroxide) to yield calcium citrate salt, from which citric acid is regenerated by treatment with sulfuric acid.
More modern techniques separate the growing fungus from the sugary liquid using a rotatory biological contactor (RBC). The fungus grows on the RBC and is rotated allowing alternate exposure to the liquid, then the air, then liquid again some 10 times per minute.
This makes the process more efficient as there is no longer a need to filter out the fungus when purifying the product and the sugar solution can be replaced many times before the fungus has to be replaced.

Tuesday, 9 September 2008

FDA Alert: TNF-blockers can increase the risk of fungal infection


The FDA is concerned that it is not widely enough known that the use of TNF-blockers (used to treat a variety of conditions such as rheumatoid arthritis, juvenile idiopathic arthritis, psoriatic arthritis, plaque psoriasis, ankylosing spondylitis, and Crohn's disease) also suppresses the immune systems of patients taking the drug.

Patients with a suppressed immune system are more vulnerable to potentially serious and difficult to treat infections such as Aspergillosis.

The announcement went as follows:
FDA ALERT [9/4/2008]: FDA is notifying healthcare professionals that histoplasmosis and other invasive fungal infections are not consistently recognized in patients taking tumor necrosis factor-α blockers (TNF blockers), Cimzia (certolizumab pegol), Enbrel (etanercept), Humira (adalimumab), and Remicade (infliximab). This has resulted in delays in appropriate treatment, sometimes resulting in death.

FDA has received reports of patients developing pulmonary and disseminated histoplasmosis, coccidioidomycosis, blastomycosis and other opportunistic infections while taking TNF blockers. In some patients, the diagnosis of histoplasmosis was initially unrecognized and antifungal treatment was delayed. Some of these patients died from histoplasmosis. There were also deaths in patients with coccidioidomycosis and blastomycosis.

For patients taking TNF blockers who present with signs and symptoms of possible systemic fungal infection, such as fever, malaise, weight loss, sweats, cough, dypsnea, and/or pulmonary infiltrates, or other serious systemic illness with or without concomitant shock, healthcare professionals should ascertain if patients live in or have traveled to areas of endemic mycoses. For patients at risk of histoplasmosis and other invasive fungal infections, clinicians should consider empiric antifungal treatment until the pathogen(s) are identified. Consultation with an infectious diseases specialist should be sought when feasible. As with any serious infection, consider stopping the TNF blocker until the infection has been diagnosed and adequately treated.

FDA will require the makers of the tumor necrosis factor-α blockers (TNF blockers) to further highlight the information about the risk of invasive fungal infections, such as histoplasmosis, in the Boxed Warning and Warnings sections of the drugs’ prescribing information and the Medication Guide for patients. FDA will also require that the makers of the TNF blockers educate prescribers about this risk.

More detail of this report here.

Friday, 5 September 2008

New rtPCR kit to detect Aspergillus infection


Rapid detection of aspergillus infections are of prime importance for a good patient prognosis (see review). Existing methods are very slow (culture) or lack sensitivity for some applications (antigen or antibody detection).
Real-Time Polymerase Chain Reaction (RT-PCR) is very quick (less than 2 hours from start to finish) and can be very sensitive and specific, providing a way to improve on many of the aformentioned problems. Myconostica are launching a new assay based on RT-PCR technology in an attempt to take advantage of this potential:

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FXGTM: RESP (Asp +) - a new Real-Time PCR assay for the detection of Aspergillus spp. in clinical respiratory samples

FXGTM: RESP (Asp +) is a rapid, molecular based assay for detecting the common respiratory fungal pathogens Aspergillus spp. (and Pneumocystis jirovecii) in human clinical respiratory specimens.

The kit is designed for use by qualified laboratory professionals; its results assist physicians to arrive at the correct diagnosis in immunocompromised adult patients suspected of having a life-threatening respiratory infection. Myconostica's kit offers increased sensitivity, specificity and speed of diagnosis, all of which are key factors critical to improving patient survival rates.

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There are two other kits on the market in the EU, both of which can also be found in the EU Approved Kits part of the Diagnosis section.

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