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Alternaria alternata

Alternaria alternata spores, picture

Alternaria alternata is one of the fungal species referred to as “leaf fungi” (phylloplane). It has a worldwide distribution and is frequently isolated from a wide range of plants, soil, food, and indoor air. In indoor environments, Alternaria alternata has been isolated from dust on floors, carpet and mattresses. It is occasionally found on damp walls, gypsum board and wallpaper. Alternaria alternata is closely related to Ulocladium chartarum.

Ulocladium spores, picture

It is possible that Ulocladium chartatum is commonly misidentified as Alternaria alternata in commercial microbiology laboratories.

Alternaria alternata has been associated with a number of respiratory problems such as rhinitis, asthma, allergic dermatitis and allergic sinusitis. The spores and the hyphal fragments are the cause of the allergic reactions.

If you have any question related to mould or bacteria, feel free ro contact us at 905-290-9101.

Testing For Mold Growth In Residential Houses

Do you have or suspect mold growth in your house? A number of molds may be found growing in houses with damp, humid conditions. The mold can grow on anything from paper, wood, carpet, wallpaper, ceiling tiles, drywall, insulation material, cloth, leather, books to concrete. Some of these molds such as some species of Stachybotrys, Aspergillus and Penicillium are toxigenic (toxic molds). Others like Alternaria and Cladosporium are well known causes of allergic reactions in sensitized individuals.

The good news is that not all molds that occur in indoor environment are hazardous. However, any mold growth in a home should be treated as potential hazard. Current Canadian mold guidelines advise building occupants to clean-up and/or remove visible mold growth. Mold growth can be controlled by eliminating or reducing moisture on surfaces of materials susceptible to mold attack.

What are the indicators of possible mold growth?

  • Excess moisture or water damage. Excess moisture may result from leaks (from pipes or roof), flooding, standing water, condensation, moisture from cooking or washing, and rising damp. Signs of moisture problem may include warping, peeling out of paint, efflorescence, rusting of metal and dampness to the touch.
  • Discoloration of surfaces of building materials that are susceptible to mold attack. These discolorations could be due to mold growth or just water stains.
  • Earthy or musty odours. Earthy odours are an indication of microbial growth. Lack of moldy odours does not mean there is no mold growth. Not all molds produce detectable odours and inactive or dead mold may not produce significant odours.

If you see mold growth or discolorations, you may send tape samples to a mold laboratory to determine whether the mold present is hazardous or is only of cosmetic concern. Cleaning large areas of hazardous mold requires special protection. To take a sample of visible mold growth, no special mold testing kit is required! For details on how to take a sample of visible mold growth click Tape Samples.

If there is earthy or musty odours but no visible mold growth, you can test the air for mold. Air testing may reveal hidden mold growth. Generally, a professional would be required to perform air testing. However, for peace of mind, homeowners can perform preliminary air testing using a cost-effective and easy-to-use mold sampling kit, which will enable them to take samples in their own homes and send them to a laboratory for analysis. For details on air quality testing click Residential Air Quality Testing: How To Test Home Air Quality.

If you have questions regarding mold growth in your home, give us a call at 905-290-9101. We may be able to help you or direct you to the right professionals or resources.

Cladosporium sphaerospermum

Cladosporium sphaerospermum pictureCladosporium sphaerospermum is common on wet building material such as gypsum board, ceiling board, windowsills, insulation material, acrylic and oil painted walls, painted wood and wallpaper. Cladosporium sphaerospermum may cause allergy to sensitive individuals.

Types Of Mold

Many people often ask what are the types of mold commonly found indoors. Generally the prevailing conditions determine the types of mold prevalent in a given environment. A highly humid environment is likely to be dominated by those molds that require a lot of water such Aspergillus fumigatus, Chaetomium globosum, Stachybotrys chartarum, Ulocladium chartarum, Fusarium solani, Trichoderma sp, while a relatively dry environment may be dominated by those molds that require less moisture to grow such as Aspergillus versicolor, Eurotium spp, and Wallemia sebi. For a more detailed discussion on the types of mold commonly found indoors and their hazard classes, visit the website http://www.mouldfacts.ca/mouldtypes.html.

If you have a question concerning indoor mold or bacteria, give us a call at (905)290-9101.

Indoor Air Testing For Mould

There are a number of methods that can be used to test air for airborne mould spores and fragments. The method chosen would depend on the objective of the investigation and subsequently the type of data required. The following methods can be used for testing air for airborne mould contamination.

Settle Plate Method For Detecting Viable Airborne Mould Spores And Fragments
With this method, a set of plates containing suitable growth media is exposed at table‑top level for half-hour to 4 hours. The mould spores and fragments suspended in the air settle by gravity onto the growth media. Light particles that remain suspended in the air for many hours are likely to be missed out. However, it is the cheapest way of sampling air since no other equipment is needed.

Volumetric Air Sampling For Detecting Viable Airborne Mould Spores And Fragments
The settle plate method is generally not recommended. A better method involves impacting a known amount of air on some suitable growth media. The media could be liquid or solid. With this method viable spores or vegetative material would form visible colonies (referred to colony forming units) in the media. These are counted in the lab and expressed as colony forming units (CFU) per cubic meter of air.

Volumetric Air Sampling For Detecting Total Airborne Mould Spores And Fragments
One disadvantage of impacting air on growth media is that only the viable propagules can grow on the media and hence detected. It is estimated that only about 10-15% of the mould spores may be viable. To enable us have a better estimation of how contaminated the air is, air is drawn on onto some inert sticky stuff. Depending on the efficiency of the sampling equipment used most of the spores and other airborne particulate matter including insect parts, pollen grain, and all sorts of fibres are trapped onto the sticky surface. Since these samples are directly examined under a microscope, the analyst is able to count the spores and vegetative fragments and express them as spores per cubic meter of air. It is also possible to identify some of the spores to genus level.

For more information on mould sampling visit our web page http://www.moldbacteria.com/sendingsamples.html.

Salmonella food poisoning and symptoms

Salmonella food poisoning has been a growing concern in recent news. It has frequently lead to recalls of beef, salads and organic products and, even peanut butter products. Salmonella food poisoning occurs when one eats raw or undercooked foods such meat, poultry, eggs or egg products. Properly cooked food can get contaminated with Salmonella if […]

Legionella pneumophila – Guidelines for Laboratory Interpretation

Legionella pneumophila is a Gram negative, aerobic bacteria that is characterized as an opportunistic pathogen. It is the cause of Legionnaires’ Disease, a severe form of pneumonia and, it is the cause of Pontiac fever, a non-pneumonic form of L. pneumophila infection. Legionella spp.’s mode of transmission is through aerosols or aspiration of contaminated water. The Public Health […]

The Indoor Mold Is An Early Warning Device

The mold (or mould, in the Queen’s English) has been the victim of a bad press. Mention the word and it conjures up an image of something rotting or in the process of decomposition. And yet, were it not for the mold that inspired the discovery of penicillin millions of lives would have been lost. […]