Spore Trapping And Counting
Spore trapping and counting is extensively used in crop protection to:
- determine the concentration of pathogenic spores carried by wind
- forecast a disease outbreak
- get facts about periodicity of spore showers on crops as one of several infection requirements
- determine correct timing of protectant sprays and other control measures.
Spore trapping and counting also provide useful information about airborne spores that cause respiratory allergies such as rhinitis, asthma, and farmers’ lung disease. In building environments, spore counting and trapping can be used for detecting dry rot or other hidden mould. Although there are no acceptable levels of airborne fungal concentration in indoor environment, spore trapping and counting can also help in determining if occupants were potentially exposed to high levels of allergenic fungal spores.
Results Of Tapelift Samples
When Laboratory Results Make No Sense
Use of tapelift sampling is a perfect method to determine the type of mould growing on a substrate, say on a wall, ceiling and other flat surfaces. Since the mould sticks on the tape with it’s structures intact, identification of most moulds is possible to genus if not species. Results from a tape sample are generally a listing of the identified moulds in a ranking order.
Due to lack of standardized methods labs tend to report analytical results of tape samples in different ways. Below are a few examples:
Laboratory 1:
- Cladosporium sp- Heavy growth
- Penicillium sp- Moderate growth
- Ulocladium sp- Slight growth
- Stachybotrys sp (a few spores)
Laboratory 2:
- Cladosporium sp- Major
- Penicillium sp- Minor
- Ulocladium sp- Trace
- Stachybotrys sp- trace
Laboratory 3:
- Spores, conidiophores and hyphae of Cladosporium detected
- Spores, conidiophores and hyphae of Penicillium detected
- Spores, conidiohores, and hyphae of Ulocladium detected
- Spores of Stachybotrys detected
Which of these lab results would be useful to a mould investigator? The only common factor in these results is that the 3 labs have identified the same types of mould. The additional information they have provided is rather subjective and/or confusing and hence of little if any practical use to a mould investigator.
One great disadvantage of tape sample is that the area analysed is very small. Unless one has taken hundreds of tape samples, trying to apply results of one or two tape samples to the whole building is a big mistake. For example if a lab reports that the growth on the tape was heavy, it’s a big mistake to say there was heavy growth of mould in the building. Visual assessment of the extent and density of mould growth in a building is more reliable and of practical use than the assessment of tape or bulk samples in the laboratory.
In conclusion, use of tape lift samples as a tool for mould investigation should be limited to determining the type of mould present on a specific surface.
Legionella
Apart from the global economic chaos, Ontario also seems to have been affected by a series of nasty bugs. First, it was the Listeriosis outbreak in Toronto and GTA last month. Then, the E.coli outbreak in North Bay and now it is Legionella. An update released by the Peel Public Health in September says that there has been an increase in legionellosis cases noted in Peel and other jurisdictions around the Golden Horseshoe. Hamilton Public Health also confirms seven cases of legionellosis since August 2008.
So, what is Legionella?
Legionella bacteria (gram negative, poorly staining rods) are naturally found in the environment, usually in water. They may be found in water distribution systems of hospitals, hotels, ships, public buildings, homes and commercial facilities. They can survive for several months in a wet environment and multiply in the presence of algae, protozoa and organic matter. Legionella acquired its name after a July, 1976 outbreak among people attending a convention of the American Legion in Philadelphia. The mystery disease sickened 221 persons, causing 34 deaths. The causative agent was identified by scientists at the Centres for Disease Control and Prevention (CDC) and subsequently named Legionella.
Symptoms
Legionella pneumophila is the causative agent of the legionellosis disease which presents itself in two forms:
- Legionnaires’ disease – the more severe pneumonic form
- Pontiac fever – the milder non-pneumonic illness
Legionnaires’ disease is a type of pneumonia that may be mild to fatal. Symptoms include high fevers, chills, nausea, cough and headache. There may be memory loss or a change in mental status. Pontiac fever is not associated with pneumonia and is milder. Symptoms include fever and headache.
Transmission
Legionella infections are acquired exclusively from environmental sources – through inhalation of contaminated aerosols – mist droplets containing the bacteria. These aerosols are formed from cooling towers, large central air conditioning systems, domestic hot-water systems, showers and faucets, fountains and similar water environments. Natural sources of Legionella include freshwater ponds and creeks. Legionella can travel at far as 6 km from its source by airborne spread. It is not spread from person to person. Older people (65 years or more) or immunocompromised patients are more susceptible to the infection.
Control
Legionella infection can be best reduced by good engineering practices in the operation and maintenance of air and water handling systems as emphasized by ASHRAE – American Society of Heating, Refrigerating and Air Conditioning Engineers. Common measures taken are cooling tower maintenance, increased heat shock treatments and use of biocides. Water treatment, prevention of scaling and algal build-up, periodic cleaning and maintenance of equipment are highly recommended.
Monitoring and Sampling
Air, water, sludge and sediments can be sampled for detection of Legionella. For sampling Legionella in water systems, several locations are recommended. Water at bottom drain and outlet pipes, water from hot and cold faucets, tanks, humidifiers, spas and fountains can be sampled in sterile containers and sent to the lab for analysis at the earliest. Swabs are recommended for surfaces like inside of faucets and shower heads or any surface showing biofilm formation. Culturable air sampling is done by using air sampling pumps that draw air directly onto culture media which can be further analysed for the presence of Legionella after incubation and other tests.
For further information and a detailed protocol on Legionella sampling, call us at 905-290-9101 or e-mail us at spanchal@moldbacteria.com.
Article by: Sneha Panchal, M.Sc.
Edited By: Dr. Jackson Kung’u, PhD.
How to collect bacteria samples
Various methods can be used to collect bacteria samples. The procedure will depend on what is being sampled and the type of data required. One may may be interested in a specific bacterium, in which case the method of sampling should be suitable for the recovery of that specific organism.
Sampling from surfaces
Sampling of bacteria from surfaces is usually performed using sterile swabs. Results from this test could be as simple as presence or absense of the bacterium of interest for example E. coli or Legionella. The test could also be detailed to include the amount of the bacterium present. It’s important to know how to collect samples for these different levels of analysis. If quantification is required, it’s important to swab a known surface area, for example 100 cm square. In this case the results would be expressed as “Number of colony forming units” per unit area.
Sampling bacteria samples from the air
To sample bacteria from the air, the air is impacted on some suitable growth media. The media to use will be determined by the type of bacteria being sampled for. If one is interested on a specific type of bacterium then a media that is selective for that bacterium should be used. To sample for the general population of bacteria in the air, then a media that can support the growth of many types of bacteria such as tryptic soy agar (TSA) should be used. Results are given as colony forming units per cubic meter of air.
Sampling for bacteria from water
Testing water for bacteria involves collecting a water sample in a sterile container and sending it to the lab for testing. The test results may just indicate the presence/absence of the bacterium of interest or may be detailed to include the amount present in terms of colony forming units per mililitre.
E.coli
Here we go again…talking about E.coli. Just a few days ago, we heard about the outbreak in North Bay, Ontario where the number of confirmed and suspected cases of E. coli O157:H7 poisoning has risen to 159. The source of the bacterium has been linked to a fast food restaurant this time.
So what is this E.coli and why is it so important? You can’t see it, smell it or taste it. But it can leave you fighting for your life, especially if your immune system is weak or compromised. E. coli or Escherichia coli (named after Escherich who first discovered it) are a type of bacteria commonly found in the intestines of animals and humans. There are hundreds of strains of the bacterium, but E. coli O157:H7 is possibly the most dangerous as it produces a powerful toxin that can cause severe illness.
E. coli O157:H7 was first recognized in the United States in 1982, when an outbreak of severe, bloody diarrhoea was traced to contaminated hamburgers. It was then called the “hamburger disease.” E. coli O157:H7 can contaminate ground beef during the butchering process. If it is present in the intestines of the slaughtered animal, it can get into the meat as it is ground into hamburger.
Canada’s worst-ever E. coli outbreak occurred in Walkerton, Ontario in May 2000, after the bacteria got into the town’s water supply. More than 2,300 people were affected. The source of the contamination was manure spread on a farmer’s field near one of the town’s wells. Health authorities across the country normally deal with a few thousand cases of E. coli illness every year.
Sources of E. coli
E. coli comes from human and animal wastes. During precipitation, E. coli may be washed into creeks, rivers, streams, lakes, or groundwater. When these are used as sources of drinking water — and the water is not treated or inadequately treated — E. coli may end up in drinking water. This is what we call the sewage or fecal contamination of water. It indicates that the water is not fit for human consumption.
Although the bacteria are mainly found in meats, it is also present in unpasteurized milk and fruit juices, ham, turkey, chicken, roast beef, sandwich meats, raw vegetables, fruits and cheese. Once someone has eaten contaminated food, the infection can be passed from person-to-person, and by hand-to-mouth contact. The bacteria are most often spread from person-to-person.
Symptoms
These are characterized by severe abdominal cramping that can appear within hours of eating any contaminated food but could also take up to 10 days to show up. Some people may also be afflicted with bloody diarrhoea or non-bloody diarrhoea, nausea and fever. Some people may show no symptoms at all, but can still carry the bacteria and pass it on to people who will become sick.
Precautionary Measures
Since most cases of E. coli infections are contagious (passed from person to person), good personal hygiene is critical to protecting yourself.
- Wash your hands thoroughly and frequently.
- Don’t handle food if you are suffering from diarrhoea.
- Wash raw fruits and vegetables thoroughly before cooking or cutting them.
- Sanitize food preparation surfaces and utensils.
- Anyone known to be infected with E. coli, should not share dishes, cutlery or glasses with anyone else. Their towels, face cloths and bedding should be washed separately in hot water and bleach.
- Call your family doctor for any unusual symptoms that you notice in your health or that of your family.
Some of the proper food handling techniques to minimize exposure to E.coli include:
- Refrigerate or freeze meat as soon as possible after buying it and then thaw frozen meat in the refrigerator, not on the counter.
- Use a digital food thermometer when cooking ground beef, which should be cooked to an internal temperature of at least 71 C (160 F).
- Serve cooked meat immediately or keep it hot (60 C or 140 F).
- Clean and sanitize countertops and utensils after contact with raw meat.
- Don’t store raw and cooked food together.
- If you marinate meat, don’t use the liquid as a dip or to pour over cooked meat.
- Drink only pasteurized milk or juice fruit juices.
- Drink water from a supply known to be safe. If you have a private water supply (well) it should be tested several times a year.
If you need further information on E.coli or performing a water quality test, please visit our web-site www.moldbacteria.com or call us at 905-290-9101.
Article by: Sneha Panchal, M.Sc.
Sick Building Syndrome
What is Sick Building syndrome?
Sick Building Syndrome (SBS) is a term used to describe situations in which building occupants experience acute health symptoms that appear to be linked to the time spent in a building with no specific cause that can be identified. The complaints may be localized in a particular room or zone, or may be widespread throughout the building. SBS related complaints have increased in recent years and result when a building is operated or maintained in a manner that is inconsistent with its original design or prescribed operating procedures. Sometimes indoor air problems are a result of poor building design or occupant activities.
Indicators
Building occupants complain of symptoms associated with acute discomfort, e.g., headache, eye, nose, or throat irritation, dry cough, dry or itchy skin, dizziness and nausea, difficulty in concentrating, fatigue and sensitivity to odors. The cause of the symptoms is not known. Most of the complainants report relief soon after leaving the building.
Possible Causes
Many factors contribute to the sick building syndrome and sometimes it is difficult to pinpoint the cause.
- Inadequate ventilation: This implies insufficient outside air, insufficient airflow and inadequate circulation. An improper system design or operation, and occupant tampering with HVAC system may be the cause.
- Chemical contaminants from indoor sources: Copying and printing machines, computers, carpets, furnishings, cleaning materials, smoke, paints, adhesives, caulking, perfumes, hairsprays, solvents emit VOCs or volatile organic compounds that affect indoor air quality.
- Chemical contaminants from outdoor sources: Pollutants from motor vehicle exhausts; plumbing vents, and building exhausts (e.g., bathrooms and kitchens) can enter the building through poorly located air intake vents, windows, and other openings or a nearby garage.
- Biological contaminants: Bacteria, molds, pollen and viruses are types of biological contaminants. These contaminants may breed in humid and damp conditions, stagnant water that has accumulated in ducts, humidifiers and drain pans, or where water has collected on ceiling tiles, carpeting, or insulation. Sometimes insects or bird droppings can be a source of biological contaminants. Physical symptoms related to biological contamination include cough, chest tightness, fever, chills, muscle aches, and allergic responses such as mucous membrane irritation and upper respiratory congestion.
Possible Solutions
In order to overcome SBS, a detailed indoor air quality investigation is a prime requirement. This involves identifying underlying causes and determining corrective actions. It begins with gathering information on the following:
- the occupants’ activities
- the HVAC system
- possible pollutant pathways
- possible contaminant sources.
Once the information is available, air sampling may be conducted to assess the level and types of chemical and biological contaminants. Moulds are serious biological contaminants that severely affect the indoor air quality. They can cause many health related symptoms like allergies, cough, cold, irritation, nausea, fatigue and fevers. Mould can be sampled using a simple air pump or a tape. You may refer the following link for a demonstration on Air Sampling for mould:
http://www.moldbacteria.com/presentations/index.html
Primary assessment confirms presence and further tests reveal the identity of moulds. This could help draw conclusions on factors that contribute to SBS.
Based on all information and evidence gathered, a strategic solution may be developed. Pollution source removal and air cleaning would be the basic approach. Proper ventilation rates and air distribution can help minimise SBS. Effective communication between building occupants, management and maintenance personnel can help find the causes and consequences of SBS. Awareness about indoor air quality issues can aid in overcoming the SBS.
Testing Carpets For Mold
Carpets are reservoirs of health hazard particulates including mold spores, dust mites, and animal hair. These particulates are allergenic to some people when inhaled. Mold spores are very tiny and easily become airborne when the carpet is disturbed as people walk in the house or when the carpet is being cleaned.
Cleaning the carpet with a good vacuum cleaner on regular basis significantly reduces the number of settled mold spores and other particulates. In fact there is no need to test carpets for mold if they are well maintained.
Carpets can be tested for:
- Settled mold spores
- Mold growth.
To test a carpet for settled spores a dust sample is required. Dust can be collected from an area of 1 square meter. It’s important to ensure that enough dust is collected to enable the laboratory perform both culture analysis and direct microscopic examination of the dust.
When is it necessary to test a carpet for mold growth? You can test a carpet for mold growth following water damage if the carpet was not completely dried within 48 hours. This test may involve cutting a piece of carpet from the affected area and sending it to the laboratory for testing.
Monitoring And Documenting Air Quality
Monitoring and documenting air quality, especially in hospitals, pharmaceutical, cosmetics, and food industries environments is very important. Contamination of these environments can originate from nearby or far away sewage plants, landfill sites, and waste separation plants. Therefore, monitoring on a regular basis of air quality in operating rooms, production lines, and other controlled areas is critical.
To assess the level of microbial contamination in the air, air is sampled for analysis by direct microscopy (sometimes referred to as nonviable analyses) or by culture analysis. For direct microscopy, the air is sampled using various cassettes including Air O Cell, Allergenco, Millipore filters and others. The samples are examined at between 600 and 900X magnification. Fungal spores and mycelial/hyphal fragments are enumerated. Millipore filters are first cleared using acetone and fixed with triacetine and then analysed in a similar manner as the Air-O-Cell or Allergenco samples. The filters have a major advantage over the other spore traps in that, having a large surface area, they can be used in highly contaminated environments, where other spore traps would easily be overloaded with dust thus rendering them difficult to analyse.
Direct microscopic analysis of air samples allows determination of total spore counts regardless of whether the spores were dead or alive. In hospital environments both dead and living spores are of concern because even if the spores were dead, they could be as toxigenic or allergenic just like living spores.
To sample air for culture analysis requires the air to be impacted on suitable agar media. Commonly used types of samplers are the Reuter Centrifugal Sampler (RCS) and the Andersen samplers. However there are many other samplers. The air is impacted on media such as MEA and DG18. Culturable air samples are incubated for 3-5 days and the resulting colonies counted. The colonies are then transferred onto suitable agar media for identification. In general, number of fungal propagules determined by cultural method is far much smaller (1-50% of total counts in some cases) than the total number of spores and fungal propagules determined by direct microscopic examination.
To assesss air for bacterial contamination, a general purpose media such as Tryptic Soy Agar (TSA) can be used. However, if sampling for a specific type of bacterium such as Legionella spp, then a selective media such as Buffered Charcoal Yeast Extract (BCYE) Agar is recommended.
Chaetomium
Chaetomium species are strong producers of the enzyme cellulase. They are, therefore, adapted to growing on cellulosic (cellulose containing) materials. They thrive particularly on paper, straw and cotton. Chaetomium species have caused problems in libraries, military equipment and food. Apart from causing spoilage of various materials, they are also producers of mycotoxins. Because of their strong ability to biodegrade organic materials, several strains are used in mold growth testing.
The species commonly encountered in chronically water-damaged buildings is Chaetomium globosum. Chaetomium globosum is also a common “weed” of mushroom beds, where it inhibits the growth of cultivated mushrooms.