Aspergillosis: Definition, Types, Symptoms, Diagnosis, Treatment and Prevention

It is the name given to a wide variety of diseases caused by the fungal infection of the genus Aspergillus.

Aspergillus is defined as a group of conidial fungi , that is, fungi in an asexual state.

Some of them, however, are known to have a teleomorph (sexual state) in the Ascomycota, so with DNA evidence coming soon, members of the genus Aspergillus can be tentatively considered members of the Ascomycota.

Members of the genus have the ability to grow where there is a high osmotic pressure (high concentration of sugar, salt, etc.).

Aspergillus species are highly aerobic and are found in almost all oxygen-rich environments, where they commonly grow as molds on the surface of a substrate, as a result of high oxygen tension.

Commonly, fungi grow on carbon-rich substrates such as monosaccharides (glucose) and polysaccharides (such as amylose).

Aspergillus species are common contaminants of starchy foods (such as bread and potatoes) and grow on many plants and trees.

In addition to the growth in carbon sources, many Aspergillus species demonstrate oligotrophy when they are able to grow in depleted nutrient environments or in environments with a complete lack of key nutrients.

Aspergillus niger is an excellent example of this; It can be found growing on damp walls, as a main component of mold. The Aspergillus are found in millions of pillows.

Most cases occur in people with underlying diseases, such as tuberculosis or chronic obstructive pulmonary disease (COPD), but with healthy immune systems.

Most commonly, aspergillosis occurs in the form of chronic pulmonary aspergillosis (CPA), aspergilloma, or allergic bronchopulmonary aspergillosis (ABPA).

Some forms are intertwined; for example, allergic bronchopulmonary aspergillosis and simple aspergilloma may progress to chronic pulmonary aspergillosis.

Other non-invasive manifestations include fungal sinusitis (both of an allergic nature and with established fungal balls), otomycosis (infection of the ear), keratitis (infection of the eye) and onychomycosis (infection of the nail).

In most cases, these are less severe and curable with effective antifungal treatment.

People with poor immune systems, such as patients undergoing hematopoietic stem cell transplantation, chemotherapy for leukemia or AIDS, are at risk of more widespread disease.

Without the body developing an effective immune response, fungal cells spread freely throughout the body and can infect important organs such as the heart and kidneys.

The most frequently identified pathogen is Aspergillus fumigatus, a ubiquitous organism that is capable of living under great environmental stress.

Aspergillus fumigatus is a fungus of the genus Aspergillus, and is one of the most common species of Aspergillus that causes diseases in individuals with immunodeficiency.

Aspergillus fumigatus, a saprotroph widely distributed in nature, is typically found in soil and decaying organic matter, such as compost heaps, where it plays an essential role in the recycling of carbon and nitrogen.

The colonies of the fungus produce from conidiophores thousands of tiny gray-green conidia (2μm – 3μm) that quickly become airborne.

For many years, it was thought that Aspergillus fumigatus only reproduced asexually, since no mating or meiosis had been observed.

In 2008, however, Aspergillus fumigatus was shown to have a fully functional sexual reproductive cycle, 145 years after its original description by Fresenius.

Although Aspergillus fumigatus is found in areas with very different climates and environments, it shows low genetic variation and lack of genetic differentiation of the population on a global scale.

Therefore, the ability to maintain sex is maintained even if there is little genetic variation.

The fungus can grow at 37 ° C or 99 ° F (normal temperature of the human body) and can grow at temperatures of up to 50 ° C or 122 ° F, with conidia that survive at 70 ° C or 158 ° F. It is found regularly in heaps of compost that warm themselves.

Their spores are ubiquitous in the atmosphere, and it is estimated that everyone inhales several hundred spores per day; typically these are quickly eliminated by the immune system in healthy individuals.

In immunocompromised people, as recipients of organ transplants and people with AIDS or leukemia, the fungus is more likely to become pathogenic, overcoming the weakened host defenses and causing a variety of diseases generally termed aspergillosis.

Several virulence factors have been postulated to explain this opportunistic behavior.

When the Aspergillus fumigatus fermentation broth was examined, several indole alkaloids with antimitotic properties were discovered.

The compounds of interest have been of a class known as tryprostatins, with spirotryprostatin B being of special interest as an anticancer drug.

Aspergillus fumigatus grown in certain building materials can produce genotoxic and cytotoxic mycotoxins, such as gliotoxin.

It is estimated that most humans inhale thousands of Aspergillus spores daily, but they do not affect the health of most people due to effective immune responses.

Taken together, the major chronic, invasive and allergic forms of aspergillosis account for around 600,000 deaths annually worldwide.

Aspergilosis invasiva

Acute invasive aspergillosis occurs when the immune system can not prevent Aspergillus spores from entering the bloodstream through the lungs.

Invasive aspergillosis (AI) is one of the most common fatal complications in immunocompromised patients. Voriconazole is currently the drug of choice for the treatment of invasive aspergillosis.

However, some patients with invasive aspergillosis suffer clinical deterioration despite treatment with voriconazole. The management of invasive aspergillosis refractory to voriconazole remains a challenge; no useful recommendations have been made.

Invasive aspergillosis refractory to voriconazole can also be categorized as disease attributable to misdiagnosis or coinfection with another mold; inadequate concentrations of tissue drugs attributable to angioinvasion; inflammatory syndrome of immune reconstitution; or infection with Aspergillus resistant to voriconazole.

Therefore, when faced with a case of invasive aspergillosis refractory to voriconazole, it is necessary to schedule sequential tests to decide whether medical treatment or surgical intervention is appropriate.

To adjust the dose of voriconazole through drug control; search for CYP2C19 polymorphisms; to control serum galactomannan levels; and to examine the susceptibility to drugs of the Aspergillus-causing species.

Invasive aspergillosis, especially invasive pulmonary aspergillosis (IPA), is an opportunistic infection that develops mainly in patients with neutropenia and in hematopoietic stem cell receptors and solid organ transplants.

In the time since a historical study of primary therapy of invasive aspergillosis showed that the mortality rate in a group treated with voriconazole (29%) was lower than in a group treated with amphotericin B (42%).

Invasive aspergillosis refractory to voriconazole can also be categorized as a disease attributable to:

  • Misdiagnosis or coinfection with another mold.
  • Inadequate levels of voriconazole in blood.
  • Inadequate concentrations of drug in tissue attributable to angioinvasion.
  • Inflammatory syndrome of immune reconstitution.
  • Infection with voriconazole-resistant aspergillus.

How is it spread?

The espergilosis is usually caused by the inhalation of small particles of mold. The mold is found in many places, including:

  • Soil, compost and rotten leaves.
  • Plants, trees and crops.
  • Dust.
  • Wet buildings.
  • Air conditioning systems.

You can not catch the aspergillosis of another person or animals.

Aspergillus, is very common both indoors and outdoors, so most people breathe fungal spores every day. It is probably impossible to completely avoid breathing some Aspergillus spores.

For people with healthy immune systems, breathing Aspergillus is not harmful.

However, for people who have a weakened immune system, breathing Aspergillus spores can cause an infection in the lungs or sinuses that can spread to other parts of the body.

Types of Aspergillus

There are approximately 180 species of Aspergillus, but less than 40 of them are known to cause infections in humans.

Aspergillus fumigatus is the most common cause of human infections with Aspergillus. Other common species include Aspergillus flavus, Aspergillus terreus and Aspergillus niger.

Aspergillus flavus

Aspergillus flavus is a saprotrophic and pathogenic fungus with a cosmopolitan distribution.

It is best known for its colonization of cereal grains, legumes and tree nuts. Postharvest rot typically develops during harvest, storage and / or transit.

Aspergillus flavus infections can occur while the guests are still in the field (before harvest), but often show no symptoms (latency) until storage and / or post-harvest transport.

In addition to causing infections before harvest and post-harvest, many strains produce significant amounts of toxic compounds known as mycotoxins, which, when consumed, are toxic to mammals.

Aspergillus flavus is also an opportunistic human and animal pathogen that causes aspergillosis in immunocompromised individuals.

Aspergillus terreus

Aspergillus terreus, also known as Aspergillus terrestris, is a fungus (mold) found throughout the world in the soil. Although it is believed to be strictly asexual until recently, it is now known that Aspergillus terreus is able to reproduce sexually.

This saprotrophic fungus is prevalent in warmer climates, such as tropical and subtropical regions. In addition to being located on the ground, Aspergillus terreus has also been found in habitats such as the decomposition of vegetation and dust.

Aspergillus terreus is commonly used in industry to produce important organic acids, such as itaconic acid and cis-aconitic acid, as well as enzymes, such as xylanase.

It was also the initial source of the drug mevinolin (lovastatin), a drug to lower serum cholesterol.

Aspergillus terreus can cause opportunistic infection in people with poor immune systems. It is relatively resistant to amphotericin B, a common antifungal drug.

Aspergillus terreus also produces asteropyric acid and 6-hydroxamelein, inhibitors of pollen development in Arabidopsis thaliana.

Aspergillus niger

Aspergillus niger is a fungus and one of the most common species of the genus Aspergillus.

It causes a disease called black mold in certain fruits and vegetables such as grapes, apricots, onions and peanuts, and is a common contaminant in foods.

It is ubiquitous in soil and is commonly reported in indoor environments, where its black colonies can be confused with those of Stachybotrys (species that have also been called black mold).

Some strains of Aspergillus niger produce potent mycotoxins called ochratoxins; other sources do not agree, claiming that this report is based on an erroneous identification of the fungal species.

Recent evidence suggests that some true strains of Aspergillus niger produce ochratoxin A. It also produces isoflavone orobol.

Aspergillus niger is less likely to cause human disease than other species of Aspergillus. In extremely rare cases, humans can get sick, but this is due to severe lung disease, aspergillosis, that can occur.

Aspergillosis is particularly common among horticultural workers who inhale peat dust, which can be rich in Aspergillus spores. It has been found in the mummies of ancient Egyptian tombs and can be inhaled when disturbed.

Aspergillus niger is one of the most common causes of otomycosis (fungal infections of the ear), which can cause pain, temporary hearing loss and, in severe cases, damage to the ear canal and tympanic membrane.

Symptoms of aspergillosis

A fungal ball in the lungs may not cause symptoms and may be discovered only with a chest x-ray, or it may cause repeated coughing of blood, chest pain and occasionally severe and even fatal bleeding.

A rapidly invasive Aspergillus infection in the lungs often causes cough, fever, chest pain and shortness of breath.

Poorly controlled aspergillosis can spread through the bloodstream and cause widespread damage to organs. Symptoms include fever, chills, shock, delirium, seizures and blood clots.

The person can develop kidney failure , liver failure (which causes jaundice ) and breathing difficulties. Death can happen quickly.

Aspergillosis of the auditory canal causes itching and occasionally pain. Draining fluid from the ear during the night can leave a spot on the pillow.

Aspergillosis of the paranasal sinuses causes a sensation of congestion and sometimes pain or discharge. It can extend beyond the paranasal sinuses.

Different types of aspergillosis can cause different symptoms. The symptoms of allergic bronchopulmonary aspergillosis (ABPA) are similar to the symptoms of asthma, which include:

  • Wheezing
  • Short of breath.
  • Tos.
  • Fever (in rare cases).

Symptoms of allergic sinusitis due to Aspergillus include:

  • Stuffiness.
  • Runny nose.
  • Headache.
  • Reduced capacity of smell

Invasive aspergillosis usually occurs in people who are already sick due to other medical conditions, so it can be difficult to know which symptoms are related to an Aspergillus infection.

However, the symptoms of invasive aspergillosis in the lungs, aspergilloma (fungal ball) and chronic pulmonary aspergillosis include:

  • Fever.
  • Chest pain.
  • Tos.
  • Cough blood
  • Short of breath.

Other symptoms may occur if the infection spreads from the lungs to other parts of the body.

Contact your health care provider if you have symptoms that you think are related to any form of aspergillosis.

In addition to the symptoms, an x-ray tomography or computed tomography (CT) scan of the infected area provides clues to the diagnosis.

Whenever possible, a doctor sends a sample of infected material to a laboratory to confirm the identification of the fungus.

Diagnosis

On chest radiography and computed tomography, pulmonary aspergillosis is classically manifested as a halo sign and, later, as a crescent sign.

In haematological patients with invasive aspergillosis, the galactomannan test can make the diagnosis in a non-invasive way.

False positive tests for Aspergillus galactomannan have been found in patients on intravenous therapy with some antibiotics or fluids containing gluconate or citric acid, such as some transfusion platelets, parenteral nutrition or PlasmaLyte.

In microscopy, Aspergillus species are reliably demonstrated by silver stains, for example, Gridley stain or Gomori methenamine silver. These give the fungal walls a gray-black color.

The hyphae of the Aspergillus species have a diameter of 2.5 μm to 4.5 μm. They have septated hyphae, but these are not always evident, and in such cases they can be confused with Zygomycota.

Aspergillus hyphae tend to have a dichotomous branch that is progressive and mainly at acute angles of about 45 °.

Treatment for aspergillosis

Current medical treatments for invasive aggressive aspergillosis include voriconazole and liposomal amphotericin B in combination with surgical debridement.

For the findings of less aggressive allergic bronchopulmonary aspergillosis, the use of oral steroids is suggested for a prolonged period, preferably for 6-9 months in allergic aspergillosis of the lungs.

The Itraconazole is administered with steroids, as it is considered to have an effect of “steroid sparing” which makes steroids more effective, allowing lower doses.

Other medications are used, such as amphotericin B, caspofungin (only in combination therapy), flucytosine (only in combination therapy) or itraconazole to treat this fungal infection.

Prevention

The prevention of aspergillosis implies a reduction of exposure to mold through the control of environmental infections. Antifungal prophylaxis can be administered to high-risk patients.

Posaconazole is often given as prophylaxis in severely immunosuppressed patients .

It is difficult to avoid breathing the Aspergillus spores because the fungus is common in the environment. For people who have weakened immune systems , there may be some ways to reduce the chances of developing a serious Aspergillus infection.

Protect yourself from the environment

It is important to bear in mind that, although these actions are recommended, they have not been shown to prevent aspergillosis.

Try to avoid dusty areas such as construction or excavation sites. If you can not avoid these areas, wear an N95 respirator (a type of mask) while you are there.

Avoid activities that involve close contact with soil or dust, such as gardening or gardening.

Wear shoes, long pants and a long-sleeved shirt when doing outdoor activities such as gardening, gardening or visiting wooded areas. Wear gloves when handling materials such as dirt, moss or manure.

To reduce the chances of developing an infection on the skin, thoroughly clean skin wounds with soap and water, especially if they have been exposed to soil or dust.

Antifungal medication

If you have a high risk of developing invasive aspergillosis (for example, if you have had an organ transplant or a stem cell transplant), your health care provider may prescribe medications to prevent aspergillosis.

Scientists are still learning which transplant patients are most at risk and how to best prevent fungal infections.

Early infection test

Some high-risk patients may benefit from blood tests to detect invasive aspergillosis. Talk to your doctor to determine if this type of test is right for you.

Aspergillosis infections in animals

Although it is relatively rare in humans, aspergillosis is a common and dangerous infection in birds, particularly in domestic parrots. Mallards and other ducks are particularly susceptible as they will often turn to poor food sources during bad weather.

Captive birds of prey, such as hawks, are susceptible to this disease if they are kept in poor condition and especially if they are fed with pigeons, which are often carriers of “asper”. It can be acute in chicks, but chronic in mature birds.

Aspergillosis has been the culprit of several rapid deaths among waterfowl. From December 8 to December 14, 2006, more than 2,000 wild ducks died in the Burley, Idaho, USA area. UU An agricultural community approximately 150 miles southeast of Boise.

The suspect source is the moldy waste from the croplands and feedlots in the area. An outbreak of similar aspergillosis caused by moldy grain killed 500 wild ducks in Iowa, USA. UU., In 2005.

While there is no connection between aspergillosis and the H5N1 strain of bird flu (commonly called “bird flu”), rapid deaths caused by aspergillosis can cause fears of bird flu outbreaks. Laboratory analysis is the only way to distinguish avian flu from aspergillosis.

In dogs, aspergillosis is a rare disease that affects only the nasal passages (nasal aspergillosis). This is much more common in dolichocephalic breeds.

It can also spread to the rest of the body; This is called disseminated aspergillosis and is rare, usually affects people with underlying immune disorders.