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Heterotrophic Plate Count: What is HPC and when is the right time to use it?

March 12, 2012 By

Heterotrophs are a group of microorganisms (bacteria, moulds and yeasts) that use organic carbon sources to grow and can be found in all types of water. In fact, the majority of bacteria found in drinking water systems are considered heterotrophs. Heterotrophic plate count (HPC) is a method that measures colony formation on culture media of heterotrophic bacteria in drinking water. Thus the HPC test (also known as Standard Plate Count) can be used to measure the overall bacteriological quality of drinking water in public, semi-public and private water systems.

 

The Limitations of HPC:

As stated by the Health Canada guidelines on HPC testing, “HPC results are not an indicator of water safety and, as such, should not be used as an indicator of potential adverse human health effects.” The World Health Organization (WHO) states that methods such as coliform testing are better indicators than HPC to test the sanitary conditions of water.

The HPC method does not indicate the specific heterotrophic bacteria present or their sources. Instead, HPC testing indicates the culturable organisms present, which could be as low as 1% of the total bacteria present. There are several factors that affect the genera of bacteria and their level of presence recovered by HPC. These factors include the type of medium used to grow the bacteria, what temperature is used for incubation, how long the plates are incubated, where the water sample was collected, the time of year and the age of the sample. It is also important to note that the concentrations and types of bacteria that are recovered at the same sampling location can vary over time.

Typically high levels of HPC bacteria in a distribution or plumbing system result from bacterial regrowth where bacteria that resisted treatment grow or those that were injured during treatment recover.

 

How do we interpret HPC results?

For HPC, regulations set out by Health Canada are followed under the Canadian Drinking Water Quality Guidelines: “No maximum acceptable concentration (MAC) is specified for heterotrophic plate count (HPC) bacteria in water supplied by public, semi-public, or private drinking water systems. Instead, increases in HPC concentrations above baseline levels are considered undesirable.”

In other words, sudden increases in HPC above levels typically seen may indicate a change in the quality of raw water or, that bacterial regrowth has occurred in the distribution system or plumbing. When steady increases of HPC are seen over time, this indicates a gradual decline in raw water quality.

As stated by the National Primary Drinking Water Regulations established by the U.S. EPA a “lower concentration of heterotrophic bacteria in the drinking water is linked to a better maintenance of the treatment and distribution systems.” According to these regulations, treatment techniques should aim to control HPC concentrations in surface waters and groundwaters influenced by surface waters to less than 500 CFU/mL (using standard methods). Note: “This is not a health-based standard, but reflects the concern that at concentrations above 500 CFU/mL, heterotrophic bacteria can interfere with some total coliform and E. coli recovery methods.”

 

Importance of HPC counts:

High HPC counts indicate ideal conditions for bacterial regrowth and should be corrected. Bacterial regrowth can lead to pipe corrosion, encourage slime growth, increase the need for disinfectants, cause foul-tasting water, and harbour secondary respiratory pathogens (ex. Legionella). Thus, HPC can be used as a marker for the underlying causes of some aesthetic problems (WHO, 2002).

 

Does having a positive HPC results mean the overall water quality is poor?

No, not necessarily.

Unlike other indicators, such as Escherichia coli or total coliforms, low concentrations of HPC organisms will still be present after drinking water treatment. In general, water utilities can achieve heterotrophic bacteria concentrations of 10 colony-forming units (CFU) per millilitre or less in finished water.

 

What are the health effects associated with HPC levels?

At an international meeting of experts in Geneva, Switzerland, it was concluded that heterotrophic bacteria in drinking water is not a health concern to the general public. However, some bacteria present in a heterotrophic population are opportunistic pathogens that could infect individuals with weakened immune systems.

“Heterotrophic bacteria belonging to the following genera have been associated with opportunistic infections: Acinetobacter, Aeromonas, Chryseobacterium (Flavobacterium), Klebsiella, Legionella, Moraxella, Mycobacterium, Serratia, Pseudomonas, and Xanthomonas. These organisms have been mainly associated with nosocomial (hospital acquired) infections, including wound infections, urinary tract infections, post-operative infections, respiratory infections, and infections in burn patients.”

 

What methods can be used to measure HPC?

There are 3 methods used for routine testing of heterotrophic bacteria:

  1. Pour plate method (least desirable method because embedded colonies are slower growing and microaerobic environment is not ideal for growth and, bacteria could undergo heat shock during plating).
  2. Spread plate method (heat shock is eliminated by using solidified agar but only a small volume (0.1-0.5 mL) can be tested).
  3. Membrane filtration method (most flexible method because volumes upto 10L can be tested, heat shock is eliminated by membrane filter, and  it is ideal for HPC less than 10 CFU/mL but multiple dilutions may be required to count colonies on filter).

Here at MBL, we use membrane filtration to measure heterotrophic plate count. If you need to determine the level of heterotrophic bacteria, fecal coliforms, E.coli, total coliforms, Legionella or other type of bacteria in water call our Mississauga office at 905-290-9101 or our Burnaby office at 604-435-6555 or,  our toll free number at 1-866-813-0648.

 

References:

Health Canada (1996) Guidelines for Canadian Drinking Water Quality, 6th edn. Minister of Public Works and Government Services Canada, Ottawa, Ontario

Heterotrophic plate counts and drinking-water safety: The significance of HPCs for water quality and the human health. Edited by J. Bartram, J. Cotruvo, M.Exner, C. Fricker, A. Glasmacher. Published on behalf of WHO by IWA Publishing © WHO 2003: http://www.who.int/water_sanitation_health/dwq/HPCFull.pdf

Guidelines for Canadian Drinking Water Quality: Guideline Technical Document: Heterotrophic Plate Count (Prepared by the Federal-Provincial-Territorial Committee on Drinking Water of the Federal-Provincial-Territorial Committee on Health and the Environment (February 2006).  http://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/heterotrophic-heterotrophes/index-eng.php

For access to the BC Drinking Water Protection Act and the BC Drinking Water Protection Regulation, please refer to the following website: http://www.health.gov.bc.ca/protect/dw_index.html

Guidance on the Use of Heterotrophic Plate Counts in Canadian Drinking Water Supplies (Document for Public Comment Prepared by the Federal-Provincial-Territorial Committee on Drinking Water – Consultation period ended May 27, 2011): http://www.hc-sc.gc.ca/ewh-semt/consult/_2011/Heterotrophic-heterotrophes/Heterotrophic-heterotrophes-eng.php

US EPA (1989) 40 CFR Parts 141 and 142 Drinking Water; National Primary Drinking Water Rules and Regulations; filtration, disinfection; turbidity, Giardia lamblia, viruses, Legionella, and heterotrophic bacteria; final rule. US Environmental Protection Agency. Fed. Regist. 54(124), 27486–27541.

US EPA (2001) National Primary Drinking Water Standards. EPA 816-F-01-007, March, US Environmental Protection Agency, Washington, DC (www.epa.gov/safewater).

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Water pollution

February 15, 2012 By

Water pollution

There’s no doubt that water is important.  Water covers 70.9% of the earth’s surface, and is vital for all known forms of life which depend on water.

Life on earth has been distressed by the growing number of ecological problems that are mostly caused by humans themselves (factories, sewage treatment plants, underground mines, oil wells, oil tankers and agriculture, acid deposition from the air, traffic, pollutants that are spread through rivers or pollutants that enter the water through groundwater).  Water pollution takes place when pollutants are released directly or indirectly into bodies of water without sufficient treatment to eliminate damaging compounds.

Water pollution

  • affects drinking water, rivers, lakes and oceans all over the world. This consequently harms human health and the natural environment.
  • is the second most imperative environmental concern along with air pollution.
  • is any change or modification in the chemical, physical or biological quality of water that has a harmful effect on any living thing that drinks or uses or lives (in) it.
  • may not damage our health immediately but can be harmful after long term exposure.
  • can also make water unsuited for the desired use.
  • involves the contamination of surface waters and groundwater which may set off a series of diseases referred to as water pollution diseases.

Water can become contaminated in many ways. There are two main sources of contamination – bacterial and chemical.

Bacterial contamination is usually measured by the fecal coliform levels in the water. Fecal coliform is an indicator organism; it is easily measured and can signal the presence of other harmful bacteria in water. This sort of bacterial contamination can occur as a result of improper water treatment (for example, not chlorinating water from a wastewater treatment plant properly), as a result of rotten or corroded piping allowing bacterial growth in pipes, or as a result of poor water storage.

Polluted water is unfit, unhealthy, and dangerous for drinking and for other consumption processes. It is also not suitable for agricultural and industrial assistance. This water pollution is harmful to human beings, plants, animals, fish and birds. Contaminated water also houses and contains viruses, bacteria, intestinal parasites, and other harmful microorganisms, which can originate waterborne diseases such as diarrhea, dysentery, and typhoid.

MBL Laboratories can help you to determine the level of bacterial contamination in the water. Our laboratory specializes in bacterial analysis of waters – wastewaters, lakes, rivers, ponds, storm waters, ground waters. If you need to determine the level of fecal coliforms, E.coli, total coliforms, heterotrophic plate count, Legionella or other type of bacteria in the water call our Mississauga office at 905-290-9101 or our Burnaby office at 604-435-6555.

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Listeria: How to avoid food poisoning caused by Listeria

January 6, 2012 By
listeria

Public awareness of the bacterium Listeria, an opportunistic pathogen, has been on the rise in recent years as the number of reported cases of listeriosis continues to grow. Listeriosis is an infection caused by the bacterium Listeria monocytogenes. The number of reported cases in Canada rose from 85 in 2003 to 239 in 2008.

In 2008, a widespread outbreak of listeriosis originated from a Maple Leaf Foods Bartor Road facility in North York, Ontario which caused infection in 57 people and took the lives of 23 of them (Table 1). In other words, 40% of the people affected in this outbreak died of this serious illness. 119 meat products produced by Maple Leaf Foods Bartor Road plant were recalled. It is believed that contamination with L. monocytogenes likely occurred during packaging.

Table 1. Listeria monocytogenes outbreak 2008

Province

Confirmed Cases

Deaths where Listeriosis was the underlying or   contributing cause*

Ontario

41

16

BC

5

2

Alberta

2

1

Saskatchewan

2

1

Manitoba

1

0

Quebec

5

2

New Brunswick

1

1

Total

57

23

*As recorded on death certificate or as assessed by attending physician.

http://www.phac-aspc.gc.ca/alert-alerte/listeria/listeria_20100413-eng.php

 

Occurrence

Most healthy individuals exposed to Listeria are usually at low risk of infection because our immune systems are strong enough to clear the bacterium from our bodies. Some healthy individuals and children can become infected but, they rarely become seriously ill. In fact, according to the Public Health Agency of Canada, of the 11 to 13 million annual cases of food-related illness in Canada, listeriosis cases are in the low hundreds. However, although this infection is rare, it causes serious health effects to those at risk and is responsible for ¼ of the deaths of all reported foodborne illnesses. The population at highest risk for listeriosis are infants, the elderly, pregnant women, and people with weakened immune symptoms.

 

Health Effects and Treatment

Most foodborne related bacteria, such as Salmonella cause infection within 12-72 hours after eating contaminated food. However, Listeria is unusual in that it can take 3 to 70 days (with a median of 3 weeks) for a mild or invasive infection to start. Once an infection occurs in humans, 1 out of 5 people die. Another difficulty when dealing with Listeria is that early symptoms of listeriosis can easily be mistaken for the flu. Generally, listeriosis is not diagnosed until laboratory reports of L. monocytogenes have been cultured from blood, cerebrospinal fluid or amniotic fluid.

The most common symptoms of listeriosis are:

  1. Sepsis (blood stream infection): infection results in high fever and very ill appearance. Infection of the heart valves and other organs can occur.
  2. Infection of the central nervous system (typically meningitis): results in high fever, intense headaches, neck stiffness, altered consciousness and convulsions.
  3. Miscarriage, still birth or premature delivery of a newborn. The infected pregnant mother may have a mild flu-like illness however; it can affect newborns by penetrating the endothelial layer of the placenta. If the baby is infected at the time of birth, it can develop a blood stream infection or meningitis.

Antibiotics such as ampicillin, ciprofloxacin and azithromycin are usually given intravenously to treat listeriosis. In spite of treatment however, 20-30% of cases results in death.

 

Disease Transmission

The majority of listeriosis cases reported are foodborne and result from eating food contaminated with L. monocytogenes. Listeria has been found in uncooked meats such as cold cuts/deli meats and hot dogs, raw and smoked fish, raw vegetables, fresh fruit such as cantaloupes, unpasteurized (raw) milk, unpasteurized dairy products and soft cheeses like feta, Brie or Camembert. Listeria can also be found in soil, stream water, sewage, and plants. Vegetables and plants can become contaminated with Listeria from soil, water or manure-based fertilizers. Farm animals that appear healthy can carry Listeria to contaminate meats and dairy products.

Listeria monocytogenes can grow in temperatures from 4ºC (refrigerator temp) to 37ºC (body’s internal temp).

 

Prevention

Everyone has a role to play in ensuring the consumption of safe foods. Manufacturers of foods such as the Maple Leaf Foods Bartor Road plant must go above and beyond to ensure the necessary measures are taken to prevent another outbreak. From the CEO to the night janitor, all involved have a part to play. Ensuring proper sanitation and removal of all possible sources of Listeria growth and, monitoring and auditing of safe practice procedures must be performed daily. Manufacturers of food processing equipment are responsible for the proper design of food processing equipment that will enable thorough cleaning and disinfection as well as efficient and complete disassembly and assembly for effective cleaning.

Preventing Listeria growth requires effective sanitation of food contact surfaces. The four main types of sanitizers used in the meat industry are hot water, chlorine, iodophors and quatnerary ammonia. Quaternary ammonia and iodophors are the most effective when combined with post-processing steam and heat treatments. Alcohol alone is also effective against Listeria. Increasing the duration of contact time on food contact surfaces will improve sanitization procedures.

Precautionary measures need to be taken when preparing foods likely to contain Listeria such as ensuring raw vegetables are thoroughly washed before eaten. Those especially at risk should avoid consumption of refrigerated pâtés, smoked seafood, unpasteurized milk and milk products. Risks groups should also avoid eating luncheon meats, deli-meats and hot dogs unless they are steaming hot. Listeria can even survive and grow in vacuum-packed products. Thus, refrigerated foods in the home should be kept below 4 ºC to discourage Listeria growth.

The fluids from packages such as hot dogs contain more Listeria than hot dogs themselves. Steps should therefore be taken to avoid the fluid from coming into contact with other foods, cutting boards, utensils, dishes and food preparation surfaces. Hand washing can greatly reduce the spread of contamination.

 

Sampling of Listeria

Testing for Listeria is typically done using a swab, environmental sponge or the Microbial-Vac system((R)). Food contact surfaces (dairy board, stainless steel) or other non-food contact areas suspected of Listeria growth (such as brick, doorways, hall drains, floors, equipment panels, and aprons) can be tested. Specimens for sampling can also be taken from solid foods (such as cheese). Water from sources containing chlorine must be collected in a pre-sterilized bottle containing sodium thiosulfate. Samples must be collected and delivered to the laboratory as soon as possible.

 

Sample Handling and Storage

Optimal temperature conditions during transport and storage is below 4˚C. The holding time between collection and analysis must not exceed 48 h for water samples. All samples must be labeled according to the chain of custody.

 

Test Methods

Here at MBL we detect and enumerate Listeria spp. in environmental samples by the 3MTM petrifilm technique. 3MTM petrifilm plates are a thin, film, dehydrated, version of the conventional petri dish agar plate. Once a result is positive for Listeria spp., a confirmation step is performed. Benefits of this method are:

  1. It is a cost effective tool for the detection of environmental Listeria.
  2. Its quantitative results allow identification of hot spots in plant and you can track Listeria over time.
  3. Rapid turnaround time of results from sample collection; as little as 2-4 business days. Other methods of Listeria testing can take up much longer because of the increased number of steps and longer incubation times.
  4. It is safer and more reliable than other methods because it does not require an enrichment step which would increase exposure to potentially pathogenic Listeria and, it requires no culture transfers.

For more information on our Listeria testing or for a complete list of microbiological tests performed at Mold & Bacteria Consulting Laboratories, please call our Ontario, Mississauga Office at 905-290-9101 or the British Columbia, Burnaby Office at 604-435-6555.

 

References

“Controlling Listeria Contamination in Your Meat Processing Plant”. Government of Ontario. 27 February 2007. http://www.omafra.gov.on.ca/english/food/inspection/meatinsp/controllinglisteria.htm. Retrieved 2011-12-12.

Health Canada. Sept 2006. MFLP-11: Enumeration of Listeria Species in environmental Samples using 3M Petrifilm environmental Listeria plates.

Maple Leaf Foods assessing Listeria-killing chemical. ctv.ca (ctvglobemedia). 2008-10-12. http://www.ctv.ca/servlet/ArticleNews/story/CTVNews/20081012/maple_leaf_foods_081012/20081012?hub=Health. Retrieved 2011-12-15.

“More About Listeria”. University of Florida Medical School. http://www.med.ufl.edu/biochem/DLPURICH/morelist.html. Retrieved 2011-12-18.

Pagotto, Franco, Karine Hébert and Jeff Farber. Feb 2011. Isolation of Listeria monocytogenes and other Listeria spp.from foods and environmental samples.

Weatherill, Shiela. July 2009. Report of the independent investigator into the 2008 listeriosis outbreak. http://www.listeriosis-listeriose.investigation-enquete.gc.ca/index_e.php?s1=rpt&page=tab. Retrieved 2011-12-12.

http://www.guardian.co.uk/world/2011/sep/29/listeria-outbreak-us-cantaloupe-melons?newsfeed=true. Retrieved 2011-12-14.

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Canadian Air Quality Testing Laboratory

July 11, 2011 By

Mold & Bacteria Consulting Laboratories (MBL) is a leading commercial Canadian air quality testing laboratory in North America. Serving mainly the Canadian market, MBL specializes in lab analysis of air and surface samples for fungi (yeasts and mold) and bacteria. MBL is accredited by the Canadian Association for Laboratory Accreditation (CALA). Routine tests at MBL include:

  •  Bacteria testing: All environmental bacteria including coliforms testing, E. coli testing and Legionella testing
  • Mold testing: Culturable air samples collected using BioCassette, Andersen, SAS, RCS, etc.
  • Mold testing: Direct Microscopic Examination including tape, bulk, swab, water and soil samples
  • Mold testing: Spore trap (or non-viable) samples such as Air-O-Cell, BioAire, and Micro5 cassettes, Allergenco, Burkard and BioSIS slides.
  • Algae: Water samples, etc.

For more information on our air quality testing laboratory or for a complete list of  microbiological tests performed at Mold & Bacteria Consulting Laboratories, please call our Ontario, Mississauga Office at 905-290-9101 or the British Columbia, Burnaby Office at 604-435-6555.

MBL, your indoor air quality testing laboratory. 

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Is There a Difference Between Total Microbe Test and Total Coliform Test?

February 13, 2011 By

Question: Is there a difference between total microbe test and a total coliform test. What do the following results mean as far as safe drinking water is concerned, (5-10)(10-20)(400-500) (800-1000) Colony forming units(CFUs) of aerobic bacteria?

Thank you.

Answer: There is a difference between total microbes test and total coliform test. The former is a non-specific test for everything including the coliforms (if they are present). This test is commonly referred to as Heterotrophic Plate Count (HPC) or Total Aerobic Plate Count. HPC does not give an indication of the types of organisms present or their sources. The total coliform test is designed to detect bacteria belonging to the coliform group.

I am not sure whether the results above were CFUs per litre or per 100 mL. Assuming these were per 100 mL of water the first set of results would be considered insignificant provided coliforms were not present. The second two sets of results suggests the water is either not properly treated or is getting contaminated after treatment.

Below are the Health Canada Microbiological Guidelines for Canadian Drinking Water Quality.

Guidelines for microbiological parameters

Currently available detection methods do not allow for the routine analysis of all microorganisms that could be present in inadequately treated drinking water. Instead, microbiological quality is determined by testing drinking water for Escherichia coli, a bacterium that is always present in the intestines of humans and other animals and whose presence in drinking water would indicate faecal contamination of the water.

Bacteriological guidelines

Escherichia coli

The maximum acceptable concentration (MAC) of Escherichia coli in public, semi-public, and private drinking water systems is none detectable per 100 mL.

Testing for E. coli should be carried out in all drinking water systems. The number, frequency, and location of samples for E. coli testing will vary according to the type and size of the system and jurisdictional requirements.

Total coliforms

The MAC of total coliforms in water leaving a treatment plant in a public system and throughout semi-public and private supply systems is none detectable per 100 mL.

For distribution systems in public supplies where fewer than 10 samples are collected in a given sampling period, no sample should contain total coliform bacteria. In distribution systems where greater than 10 samples are collected in a given sampling period, no consecutive samples from the same site or not more than 10% of samples should show the presence of total coliform bacteria.

Testing for total coliforms should be carried out in all drinking water systems. The number, frequency, and location of samples for total coliform testing will vary according to the type and size of the system and jurisdictional requirements.

Heterotrophic plate count

No MAC is specified for heterotrophic plate count (HPC) bacteria in water supplied by public, semipublic, or private drinking water systems. Instead, increases in HPC concentrations above baseline levels are considered undesirable.

Emerging pathogens

No MAC for current or emerging bacterial waterborne pathogens has been established. Current bacterial waterborne pathogens include those that have been previously linked to gastrointestinal illness in human populations. Emerging bacterial waterborne pathogens include, but are not limited to, Legionella, Mycobacterium avium complex, Aeromonas hydrophila, and Helicobacter pylori.

Protozoa

Although Giardia and Cryptosporidium can be responsible for severe and, in some cases, fatal gastrointestinal illness, it is not possible to establish MACs for these protozoa in drinking water at this time. Routine methods available for the detection of cysts and oocysts suffer from low recovery rates and do not provide any information on their viability or human infectivity. Nevertheless, until better monitoring data and information on the viability and infectivity of cysts and oocysts present in drinking water are available, measures should be implemented to reduce the risk of illness as much as possible. If the presence of viable, human-infectious cysts or oocysts is known or suspected in source waters, or if Giardia or Cryptosporidium has been responsible for past waterborne outbreaks in a community, a treatment and distribution regime and a watershed or wellhead protection plan (where feasible) or other measures known to reduce the risk of illness should be implemented. Treatment technologies in place should achieve at least a 3-log reduction in and/or inactivation of cysts and oocysts, unless source water quality requires a greater log reduction and/or inactivation.

Viruses

Although enteric viruses can be responsible for severe and, in some cases, fatal illnesses, it is not possible to establish MACs for enteric viruses in drinking water at this time. Treatment technologies and watershed or wellhead protection measures known to reduce the risk of waterborne outbreaks should be implemented and maintained if source water is subject to faecal contamination or if enteric viruses have been responsible for past waterborne outbreaks. Where treatment is required, treatment technologies should achieve at least a 4-log reduction and/or inactivation of viruses.

For more details on Canadian Guidelines for drinking water click Guidelines for Canadian Drinking Water Quality.

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What’s The Chance Of Getting A Positive Result For Legionella Tests?

February 10, 2011 By

Question: Hi, I am a student working on an environmental research project. I’m considering to have some water sample tested for Legionella species especially Legionella pneumophila. From your experience, what is the chance of getting a positive result for the tests? How much does the tests cost, for both PCR and culturable methods?

Thank you for your attention.

Answer: Legionella species are ubiquitous in natural and artificial water environments worldwide. They survive in a wide range of environmental conditions. Chances of getting positive Legionella results from water depends on the following:

  • The Source of water. Legionella species thrive at temperatures between 20 °C and 50 °C. Therefore, the bacteria are rarely found in municipal water supplies. They tend to colonize warm water systems and point-of-use devices, particularly hot-water systems.
  • Isolation method. Legionella species are usually a very minor component of the total bacterial population in environmental samples and are rarely present in high numbers. Thus, it’s possible to get negative results if the bacteria in the sample were not concentrated prior to analysis.
  • Concentration: Legionella may be present in concentrations too low to be detected using culture methods.

    • Currently we use cultural methods for Legionella identification. We’re accredited by the Canadian Association for Laboratory Accreditation (CALA) to ISO/IEC 17025:2005. For pricing please call 604-435-6555 in British Columbia or 905-290-9101 in Ontario.

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    Filed Under: Bacteria, Legionella, MBL Answers, Water Testing Tagged With: ,

    Health Hazards in Pools, Hot Tubs and Spas

    February 4, 2011 By

    Pools, hot tubs and spas occasionally get contaminated with harmful bacteria such as E. coli, Legionella pneumophila, Pseudomonas aeruginosa, Mycobacterium avium, Streptococcus and Salmonella. These bacteria are known to cause serious diseases in humans such as infection of the skin, eyes, ears, hair follicles, intestines and urinary tract.

    More serious illnesses are the Legionaires’ Disease and Pontiac Fever acquired from inhaling airborne Legionella cells. This occurs when Legionella becomes airborne by way of aerosol mists produced in spas and hot tubs.

    Legionella bacteria are able to survive in low temperatures, but thrive at temperatures between 20oC and 45oC. Legionella cannot survive at temperatures of 60oC and above.

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    Choosing a mold testing laboratory that is right for you

    February 1, 2009 By

    Mold testing professionals and other users should consider several factors in choosing a mold testing laboratory. This article refers to laboratories that specializes in identification and enumeration of mold and bacteria commonly detected in air, fluids and bulk samples collected from homes, schools, offices, hospitals, industrial, agricultural, and other work environments. Mold testing laboratories are generally not regulated by provincial or federal agencies. Consequently, it is important for mold testing professionals to investigate these laboratories by obtaining information about their performance, operation, and service before sending mold samples for analysis. A mold testing professional requires assurance that the test results will be of quality, be credible, and meaningful. Specific guidelines are discussed here to aid the mold testing professional in evaluating a mold testing laboratory.

    Factors to Consider
    Test Methods – The use of appropriate test methods is very important in order to accurately identify and/or enumerate mold spores or colony forming units (CFU) in an air sample.

    Laboratory Proficiency – The proficiency of a mold testing laboratory refers to its ability to produce accurate and precise test results. It is difficult for a laboratory to independently assess this factor. Thus, reputable labs participate in AIHA sponsored EMPAT program. The Environmental Microbiology Proficiency Analytical Testing (EMPAT) Program is a voluntary performance evaluation program, administered by the American Industrial Hygiene Association (AIHA), for environmental microbiology laboratories. A main purpose of the EMPAT is to provide proficiency testing samples to laboratories who wish to monitor and improve the quality of their mold testing data. Participating laboratories receive a summary of their performance for each field of testing (FoT). Continued self-evaluation and adjustment improves the integrity of the mold test results. A prospective client should ask the laboratory management if they are members of the EMPAT program.

    Laboratory’s EMPAT Results – It is important that a representative of the mold testing laboratory review with the potential client their EMPAT quarterly test results with those summarized for all EMPAT participating laboratories. Information for each FoT of interest to the client should be included. Mold testing professionals should ask for this comparison in order to make a good decision about a laboratory. Some laboratories that participate in the EMPAT program are not proficient.

    Other Customers – The potential client should ask the mold testing laboratory to provide the names and telephone numbers of some customers. This allows the mold testing professional to evaluate the laboratory from the perspective of users like themselves.

    Laboratory Results – Ask a laboratory representative for copies of sample results and ask them to explain the meaning of the units if they are unclear.

    Turn-Around Time – Ask how long it takes the mold testing laboratory to do the routine mold testing and return the results. In order for the results and recommendations to be useful, the turn-around time must be as short as possible. A good laboratory should be able to provide the results in two to three working days for the routine mold tests of direct microscopic examination. It is also very important to make sure the laboratory does not sacrifice accuracy by short cutting the methods to attain this turn-around time. It is a good idea to check the turn-around time with those who have used the laboratory.

    Visiting the Laboratory – Where possible, it is important to visit the mold testing laboratory before submitting samples. A representative of the laboratory should not hesitate to show a potential client the testing area. During the visit, observe the orderliness and cleanliness of the work area. Ask how the samples are handled. In addition, ask how the data is handled and ask about quality control that is used.

    Sampling Supplies – Most mold testing laboratories supply test media such as agar, air-0-cells, and swabs to their customers. Find out about the supplies and how they are obtained from the laboratory.

    Professionals Mycologists – Find out if the mold testing laboratory has professionals who are trained in mycology (the study of molds and yeasts) or microbiology to work with the customer. Before deciding on a mold testing laboratory, visit the laboratory and meet with a professional to discuss concerns about testing mold. When visiting a mold testing laboratory, ask to review the educational credentials of the professionals. Find out about the training background of the analysts.

    Laboratory Test Prices – Prices for mold testing often vary greatly from one laboratory to the next. Ask about the prices. Determine if the price for each test or test package is given in writing. Also find out if discounts are given for large numbers of samples and whether prices are negotiable.

    If you’re looking for a mold testing laboratory, please call 905-290-9101.

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    Legionella: Health Effects, Occurrence and Sampling

    August 23, 2007 By

    Health effects of Legionella

    In 1976, in Philadelphia, USA, over 200 attendees of the US-American Legion, developed pneumonia. The disease was later called “Legionnaires’ disease”. The causative agent, a Gram-negative bacterium, was named Legionella pneumophila. Legionella pneumophila causes 85-90% of all cases of Legionella infections (legionellosis). There are over 40 species of Legionella.

    Legionella pneumophila can cause very severe infection of the respiratory system. However, Legionnaires’ disease epidemics are rare but the disease is fatal if untreated. The disease may develop within 2 to 13 days (average 5-6 days).

    Another form of legionellosis is Pontiac fever, named after an outbreak in 1968 in Pontiac, USA. This form of disease, caused by a number of Legionella species, is milder than Legionnaires’ disease. Pontiac fever develops within 48 to 72 hours and the illness may clear in 2-5 days. No fatal cases have been reported in relation to Pontiac fever. This disease mainly appears as epidemics. Pontiac fever is believed to be a reaction to inhaled Legionella antigens rather than an infection.

    Disease transmission

    There is no evidence for transmission of legionellosis from person to person or by ingestion. Legionella infection occurs when people inhale the bacterium via fine water droplets as aerosols from the environment. Indoor transmission of legionellosis has been reported via contaminated hot water supplies in hospitals, hotels and other public buildings, respiratory therapy equipment, jacuzzis, spas and air-humidifiers.

    Occurrence

    Legionella bacteria are part of the natural aquatic bacterial population of lakes and rivers. They are present in all types of fresh water, including tap water. Legionella multiply in water, using other microorganisms like bacteria, algae and protozoa. Their concentration in fresh water is influenced mainly by the temperature. They are isolated more frequently and in higher concentrations from warm water (30 to 50 °C.). However, Legionella also survive at much lower temperatures indoors as well as outdoors. At temperatures above 60 °C Legionella can’t survive.

    Sampling Of Legionella

    Sampling of Legionella in indoor air or water on a routine basis is not recommended. However, sampling is recommended to:

    • determine the source of outbreaks of legionellosis
    • check the effectiveness of maintenance practices and control measures for hot water supplies and humidified ventilation systems
    • guarantee the safe use of hot water supplies and humidified ventilation systems.

    When investigating the water services within a building for Legionella, the condition of pipes, the joining methods used, the presence of lagging, sources of heat, and the standard of protection afforded tanks should be noted, as well as disconnected fittings, ‘dead-ends’, and cross-connections with other services.Water Sampling
    Water samples should be collected in sterile autoclavable plastic containers. The samples should be taken from:

    • the incoming supply;
    • tanks;
    • an outlet close to, but downstream of, each tank;
    • the distant point of each service;
    • the water entering and leaving any fitting under particular suspicion.

    Surface Sampling
    Using swabs, surface samples should be taken from shower heads, pipes and taps. Also, sludge, slime or sediments within building water services or humidifiers can also be collected, particularly where accumulation occurs.

    Sample Handling and Storage
    Samples should be stored at room temperature (20 ± 5 °C.) in the dark and should be processed within 2 days. That means the samples should be sent to the laboratory within 24 hours. It is also important to confirm with the lab that they have the necessary media before sampling is done.

    Air sampling
    The presence of Legionella in indoor air can be investigated using Reuter Centrifugal Sampler (RCS) or the Andersen sampler. Regardless of the sampler used, the recommended sampling agar at present is BCYE-agar.

    References

    1. Flannigan, B., R.A. Samson, and J.D. Miller (Editors). Microorganisms in home and indoor work environments: diversity, health impacts, investigation and control. 2001. London, UK: Taylor & Francis (ISBN: 0-415-26800-1).
    2. Wanner, H-U, AP Verhoeff, A Colombi, B Flannigan, S Gravesen, A Mouilleseux, A Nevalainen, J Papadakis, and K Seidel. 1993. Biological Particles in Indoor Environments. Indoor Air Quality and Its Impact On Man. Brussels: Commission of the European Communities. Report No. 12.

    For more information on indoor bacteria, please visit http://www.moldbacteria.com/ or call 905-290-101.

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    Bacteria in the Water: Coliforms, Iron and Sulfur Bacteria

    October 23, 2006 By

    In the past we’ve discussed Legionnaires’ disease, which is a disease caused by a waterborne bacterium. In our September newsletter entitled, Bacteria in the Water: Coliforms, Iron and Sulfur Bacteria, we have discussed three types of waterborne bacteria: coliforms, which, although not usually harmful, can be a sign of other bacteria that are harmful; and iron and sulfur bacteria, which are seen as annoyances rather than a health threat. For more details read our September Newsletter.

    If interested in bacteria testing, visit the web page http://www.moldbacteria.com/bacteria.html or call 905-290-9101.

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    Filed Under: Bacteria, Coliforms, Iron And Sulfur Bacteria, Water Testing Tagged With: , , , ,