Tuesday, 31 May 2011

Progress towards a breath test for invasive Aspergillus fumigatus infections

The idea of a breath test is not novel - it is widely used to detect expired ethanol in many western countries as a drink driving test. As a tool in the diagnosis of respiratory infections it is well known that Pseudomonas aeruginosa and Strepotococcus milleri have distinctive odours associated with these pathogens, due to their production of volatile compounds.

A breath test to diagnose pulmonary aspergillosis is attractive because of the proximity of the lesion to the sample and ease and speed of obtaining a rapid diagnosis. Many different species of Aspergillus produce a whole host of volatile metabolites - but one in particular has attracted attention for A. fumigatus - as described by Stephen Chambers in a recent article published in Medical Mycology.

2-Pentylfuran is a promising marker as it is not known to be produced by humans or mammals as a result of any metabolic pathway. In addition it was not detectable in cultures of most types of respiratory pathogens with the possible exception of Streptococcus pneumonia.

Chambers et al studied two cases of severely immune compromised patients with invasive aspergillosis, who were infected with A. fumigatus. Breath tests of multiple samples revealed the presence of 2-pentylfuran in both patients - but which became undetectable on effective antifungal treatment. It is not known whether certain foodstuffs could give rise to levels of 2-pentlyfuran which could cause false positive tests, or indeed how much 2-pentylfuran could be produced by extensive lung inflammation.

But this data paves the way for a clinical trial on a larger patient group to evaluate this as a diagnostic marker for possible monitoring of invasive lung aspergillosis. If it proves successful - this could lead to a more cost effective and rapid diagnosis of pulmonary aspergillosis - which should lead to better outcomes for the patient.

Monday, 23 May 2011

New Respiratory Disease in US Soldiers Returning from Iraq and Afghanistan

The American Thoracic Society (ATS) is one of the most important bodies working towards better diagnosis and treatment of all diseases relating to the lungs.

This week they have released the following statement about a meeting that will take place on Wednesday 25th May 2011 at the annual scientific conference run by the ATS: ATS 2011

"We've described a new disease called Iraq-Afghanistan War lung injury (IAW-LI), among soldiers deployed to these countries as part of Operation Iraqi Freedom, Operation Enduring Freedom, and Operation New Dawn" said Anthony Szema, MD, who will co-chair with Dr. Rose. "Not only do soldiers deployed to Iraq and Afghanistan suffer serious respiratory problems at a rate seven times that of soldiers deployed elsewhere, but the respiratory issues they present with show a unique pattern of fixed obstruction in half of cases, while most of the rest are clinically-reversible new-onset asthma, in addition to the rare interstitial lung disease called nonspecific interstitial pneumonitis associated with inhalation of titanium and iron."
Iraq and Afghanistan veterans are faced with a barrage of respiratory insults, including: 1) dust from the sand, 2) smoke from the burn pits, 3) aerosolized metals and chemicals from exploded IEDs, associated with 4) blast overpressure or shock waves to the lung, 5) outdoor aeroallergens such as date pollen, and 6) indoor aeroallergens such as mold aspergillus. Dr. Szema and colleagues have experimentally exposed mouse models to samples of the dust taken from Iraq and Afghanistan and found that it produces extreme histological responses, underscoring the severe exposures that these soldiers undergo.
It isn't difficult to see that soldiers operating in one of the dustiest environments in the world will be breathing in a lot of microbial dust raised by weather conditions and explosions, not to mention the physical injury to lungs mentioned above and other inhaled toxins.

That dust will contain a lot of moulds and a lot of Aspergillus and given that we know that Aspergillus in particular can cause respiratory problems ranging from allergy, asthma exacerbations, sinusitis to invasive infections with deadly results, it would not be a major surprise if Aspergillus was involved in Iraq-Afghanistan War lung injury. Where possible perhaps the development & wearing of filtration masks should be a priority for soldiers and all workers in such areas of the world?

Source story: Newswise

Friday, 20 May 2011

Extracts of Asparagus Show Antifungal Activity Against Aspergillus Fumigatus

Asphodelus tenuifolius

 Panghal and colleagues show in a new research paper that it is possible to extract crude compounds from a common weed of the Middle East (Asphodelus tenuifolius) and asparagus (A. racemosus) that will inhibit growth of a clinical sample of Aspergillus fumigatus in the laboratory.

The extraction must be carried out using organic solvents e.g. benzene, chloroform as other solvents failed to extract active compounds e.g. water. Note: boiling this material in water isn't going to result in an 'antifungal brew'.

The microbial isolates were taken from a series of patients undergoing treatment for cancer and who were known to be vulnerable to infection i.e. they were at least partially neutropenic, so any antimicrobial activity found could at least be said to be effective against organisms selected for their ability to infect patients - an important distinction.

Clear zones around antimicrobial discs
The authors carefully extracted material from several different plant species and tested them in the laboratory for activity against A. fumigatus and a series of other fungal & bacterial clinical isolates by growing the isolates on nutrient agar in the presence of discs of absorbant material impregnated with the extracted compounds. If the microbe was sensitive to any compound a clear region would develop around the disc. Three or four extracts were shown to be at least partially active against Aspergillus fumigatus.

Given the need for as many new antifungals as we can find this is an encouraging result but it isn't the first time antifungal substances have been found in plant extracts by any means. Nor does it mean that eating parts of the plants mentioned is likely to have a marked effect on an existing fungal infection as we know little about the properties of the substances being investigated. The human body is a very different place compared with a nutrient agar plate in a laboratory.

But perhaps we are asking too much of these remedies via that route of administration anyway. Herbalists seem to use the antifungal characteristics of their remedies as a treament for superficial infections rather than deep infections, much as in the same way we use creams and ointments containing antifungal drugs.

To develop new antifungals to treat infections deep in our bodies we need to look at how the compounds in plant material work, and then try to develop those compounds into one that we can get deep into body tissues.

It is notable that when the authors of this paper compared the strength of their new compounds with that of commercial antifungals such as ketoconazole they were weaker. That might be because the concentration of the substance was weaker and simply grinding up more plant material would increase the strength of the plant compound, or it might be the antifungal mechanism of the plant compound just doesn't work as well as the commercial compound.

Here again we come across problems caused by trying to use these herbal remedies by eating parts of the plant. The active ingredient is dispersed around our bodies after eating and is heavily diluted, so imagine how much you would have to eat to have any beneficial antifungal effect. Consider that the antifungal you are taking is intended to prevent infection of a plant that might weight a few hundred grammes. If you dilute that compound it will reduce in effectiveness. You are a thousand times bigger therefore you are going to have to eat a thousand plants! If you had to eat a large amount of plant material you are increasing the chances of 'side effects' as there are thousands of other substances in that material.

For these reasons and more it is much better that we isolate and purify the active ingredient.

To summarise
  1. These plants are not cheap alternatives to commercial drugs if you are treating aspergillosis or any other deep fungal infection
  2. These observations are good starting points for investigation into new antifungal drugs, but are not the end product in themselves. The antifungal activity is likely to be too dilute, too inaccessible or unsuitable for use in animals (they are after all intended to be active in plants)

Saturday, 14 May 2011

Airman's supreme challenge after tragic death of Steph By Hector Mackenzie

This article taken directly from the Ross-shire Journal with thanks in support of the Fungal Research Trust Appeal:

A ROSS-shire man robbed of the love of his life by a mystery infection is set to take on an astonishing feat of endurance in her memory.

Big-hearted pupils at two local schools this week lent a helping hand as Invergordon man Lewis Fraser geared up for the challenge of a lifetime.

His partner Steph Smith - a hugely accomplished trainee teacher who was pursuing her childhood dream - was just 21 when she took ill out of the blue in 2009. She was diagnosed a few days later with aspergillosis, an infection to which asthma sufferers are vulnerable. Tragically, just five days after diagnosis, Steph, who was a mild asthmatic, passed away at Raigmore Hospital. Distraught Lewis (26), an aircrew member at RAF Kinloss, promised himself after her death that he would do something to raise money for research into a condition about which little is known.

This October, he will attempt the Himalayan 100-mile Stage Race, an ultra-tough endurance test which involves tackling terrain climbing up to 11,500ft - and a marathon around Mount Everest. He's set himself a target of pulling in £5,000 for the Fungal Research Trust. Ninety-five per cent of the non-profit group's spending goes into research. Pupils at Maryburgh and Conon primary schools heard about his plight through big sister Dawn (28), who is a Dingwall-based active schools co-ordinator. They agreed to chip in with their own fundraising run, amounting to a cumulative 100 miles in itself.

That could boost his total by anything up to £1,000.

Lewis, who ran alongside some of the youngsters during their big-hearted effort this week, paid warm tribute to their kind gesture.

Talking about his motivation to help shed more light on the difficult to treat condition, which can also affect leukaemia and bone marrow transplant patients, Lewis said Steph had been "a beautiful young woman, in every sense of the word, both inside and out... who at the age of 21 had a tremendous life ahead of her".

He described her as "a vibrant, caring, thoughtful young woman with a zest for life". She had been on her final three month placement in her former primary school in Nairn when she became unwell. "At first it was thought that her symptoms were purely her asthma, and therefore this was what she was being treated for.

"However, on Tuesday, March 31, 2009, with her breathing causing her much distress, Steph was admitted to Raigmore Hospital in Inverness with a serious asthma attack and within a few days she was diagnosed as suffering from the disease known as aspergillosis. This dreadful disease tragically got a hold of Steph and her immune system was unable to fight it off.

"The disease had become so aggressive even in that short space of time, that it literally invaded her lungs and body, and antibiotics, specifically for this type of fungal infection, were ineffective in treating her."

The couple, who met by chance in Nairn, had lived together for a year - which Lewis describes as the best of his life - before she took ill. A young leader within the Girl Guides, the former head girl at Nairn Academy was working towards her Queen's Badge.

She was also an accomplished Highland and ballet dancer whose memory has been honoured by Aberdeen University, where she studied. The university commissioned a glass sculpture to be presented once a year to a student teacher who has shown the highest level of personal commitment and professional values throughout their study.

Said Lewis, "She had a heart of gold, was so selfless and with her trademark smile was immensely popular among her peers. She was everybody's friend."

Although a very mild asthmatic all her life, it was a condition which never hindered her in her activities in her all too short life. Lewis will tackle the tough October challenge with his friend, Aaron McKevitt. He has already paid from his own resources for the cost of travel and accommodation.

A former pupil of Park Primary and Invergordon Academy - his parents Sanders and Caroline live in the town's King Street - he admitted to being daunted by the challenge. He lost a stone training for the Nairn 10K and recounts on his blog that in the first couple of miles. "I was constantly being overtaken by everyone!" Undeterred, he is building up to a cross-country marathon in July.

* To sponsor Lewis, or find out more about his fundraising and the Fungal Research Trust, see uk.virginmoneygiving.com/team/himalayanchallenge online or type The Steph Smith Appeal into a search engine.

Friday, 6 May 2011

Advances in the Detection of Aspergillus Developing Drug Resistance

Researchers here at the University of Manchester and the National Aspergillosis Centre have developed a sophisticated method of identifying strains of Aspergillus that are likely to be resistant to many of the antifungal drugs currently available.
Traditionally testing is done by growing samples of the isolates under test and then treating them with ever increasing doses of antifungal - there is a video giving an explanation of this process by Senior Clinical Scientist Nicola Duddy who works at the National Aspergillosis Centre

Notes taken at the meeting

This procedure takes several days and cannot be carried out if nothing grows out of a clinical specimen - something that happens regularly (10-50% failure rate).

The research at the National Aspergillosis Centre uses rapid molecular techniques (PCR) to detect tiny amounts of DNA in clinical samples, whether or not the sample contains fungi that will grow out in culture, thus removing the requirement to grow out a sample prior to testing, saving many days. DNA is detected in 96% of clinical samples taken from patients with confirmed invasive pulmonary disease (IPA) whereas there is a success rate of 91% when attempting to grow cultures from these clinical specimens - a significant  improvement but hardly a step change in detection rates.

The PCR technique looks much more impressive when we look at its ability to detect fungal DNA in other types of aspergillosis.  Allergic Bronchopulmonary Aspergillosis (ABPA) and Chronic Pulmonary Aspergillosis (CPA) are both forms of chronic infection that are treated with long term courses of antifungals - situations where the development of resistance is quite likely over time so it would be of great benefit to the patient if we could detect resistance as early as possible. Once resistance is established these patients may well deteriorate if not switched to a new antifungal.

The culture technique identified no Aspergillus in ABPA patients  and only 16.7% of CPA patients had a positive Aspergillus culture in this experiment. In stark contrast the new PCR technique identified the presence of Aspergillus in 79% of ABPA patients and 71% of CPA patients - a huge increase. This is tempered slightly by the control part of the experiment that shows Aspergillus detected in 36% of uninfected people so in one sense half of those detected in ABPA & CPA may be 'false positive' though this can be explained by the fact that all of use are breathing in Aspergillus in the air all of the time - these 'false positives' are likely to be genuine positive results.

Perhaps more importantly when markers for resistance to antifungals were looked at using the PCR technique it was found that amongst those clinical specimens that had NOT given a positive culture (and would thus have been completely missed using traditional techniques) 50 (CPA) to 75% (ABPA) showed signs of resistant populations building up.

Although these experiments were carried out on quite small populations there are quite clear signs that this technique has the potential to allow us to identify resistance in many more clinical samples than was previously possible, and identify them much more quickly than before. More work is necessary but this is most probably a significant advance in the treatment of several different types of aspergillosis.

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