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You are here: Home / Archives for fungal contamination

Bacterial and Fungal Contamination of Metalworking Fluids (MWFs)

Jackson Kung'u

Metalworking fluids are used to cool and/or lubricate metal works during machining, grinding, cutting, milling, etc. MWFs can get contaminated when good hygiene practices are not followed or when fluids are not properly managed or maintained. Bacterial and fungal contamination of metalworking fluids (MWFs) is a major concern in the industries which use these fluids. Contamination may cause equipment malfunction, off-odors, degradation in the fluid quality, economic losses and finally, they pose as a major health hazard. Several Gram +ve and Gram -ve bacteria are found as contaminants. These include Staphylococcus sp., Bacillus sp., Pseudomonas sp., Proteus sp. and Coliforms. Fungal contaminants include, Aspergillus sp., Penicillium sp., Fusarium sp. and Cephalosporium sp.

Major health concerns of bacterial and fungal Contaminated metalworking fluids include skin irritation, allergic contact dermatitis, irritation of the eyes, nose and throat, and, occasionally, breathing difficulties such as bronchitis and asthma. Learn more about contamination of metalworking fluids.

Filed Under: Bacteria, Fungi Tagged With: Aspergillus, Bacillus, Bacteria, Cephalosporium, coliform, contamination, fungal contamination, Fungi, Fusarium, metalworking fluids, penicillium, Proteus, Pseudomonas, Staphylococcus

Fungal investigations in public buildings, workplaces, and homes

Jackson Kung'u

Investigation of fungal contamination in indoor environments normally includes visual inspection and sampling. The samples to collect, the number, when and where to collect them and the methods to be used for sample analyses depends on the objectives or goal of the investigation. The samples that may be collected include air, dust or bulk samples. Swabs or clear cellophane tape can be used to sample for fungi from contaminated surfaces. The samples can be analyzed by either direct microscopy or by culture methods depending on the type of data required.

Filed Under: Fungi, Microbial Sampling Tagged With: air, bulk, dust, fungal contamination, Fungi, samples, swabs

Penicillium Species As Indoor Air Contaminants

Jackson Kung'u

In 1928, Alexander Fleming’s bacterial cultures were contaminated by airborne spores of a green mould. Fleming noticed that bacteria were not growing close to the green mould. He concluded that the mould was producing a compound that was killing or inhibiting the growth of bacteria. That is how Penicillins, the oldest and probably the best known of all the antibiotics were accidentally discovered. The green mould was later identified as Penicillium notatum. Penicillium notatum (now called Penicillium chrysogenum) is one of the most common indoor fungal contaminants.Spores of Penicillium chrysogenum

Penicillium is found worldwide. The spores of this mould are found everywhere in the air and soil. In indoor environment, this mould proliferates in damp conditions. Penicillium is commonly called the blue or green mould because (depending on the species) it produces enormous quantities of greenish, bluish or yellowish spores which give it the characteristic colour. The blue in the blue-cheese, for example, is the colour of the spores of the Penicillium species used in ripening the cheese. About 200 species have been described.

Penicillium species as contaminants of indoor air

In indoor environments, Penicillium is extremely common on damp building materials, walls and wallpaper, floor, carpet mattress and upholstered furniture dust. The spores of this mould are produced in dry chains and are exposed to the air hence their ease to become airborne. Spore sizes range from 3 to 5 micrometres. Because of their small size, they take long to settle and can be inhaled deep into the lungs. The spores are found indoors throughout the year. For air samples analysed by direct microscopy, it is hard to distinguish between spores of Penicillium from those of Aspergillus. Therefore these spores are often reported as Aspergillus/Penicillium. The most common Penicillium species in indoor environment is Penicillium chrysogenum. It produces a number of toxins of moderate toxicity. It is also allergenic and can infect immuno-compromised patients.
Picture of Penicillium chrysogenum on wood

Penicillium species as a health hazard

Many species of Penicillium are common contaminants on various organic materials and are recognized potential mycotoxin producers. The most well known toxin producing species in foods include P. citreonigrum, P. citrinum, P. crustosum, P. islandicum and P. verrucosum. Therefore, when it comes to food contamination, correct identification of Penicillium is important. Although, human pathogenic species are rare, opportunistic infections have been reported in individuals with weakened immune system such as the HIV/AIDS patients. The species commonly associated with opportunistic infections is P. marneffei.

Penicillium species as food spoilage organisms

Penicillium species are common causes of spoilage of fruits, cheese, cold meats, old sandwiches, cereals and cereal products and a host of other agricultural and animal products. For example, Penicillium italicum and Penicillium digitatum are common causes of rot of citrus fruits, while Penicillium expansum is known to spoil apples. As mentioned above, most Penicillium species produce toxins. It is a good practice to discard foods with any visible mould growth. It is important to know some species of Penicillium are beneficial to humans. For example, cheeses such as Roquefort, Camembert and others are ripened with species of Penicillium.Penicillium on food

References

  1. Introduction to food and airborne fungi. Seventh Edition. Samson, Robert A., Hoekstra, Ellen S., Frisvad, Jens C (Editors). Centraalbureau voor Schimmelcultures, 2004.
  2. Microorganisms in home and indoor work environments: Diversity, Health Impacts, Investigation and control. Flanning Brian, Samson, Robert A., and Miller, David J (Ed.), Tayler and Francis, 2001.

For more information on Penicillium species,please visit http://www.moldbacteria.com/learnmore/moldlist.html or call 905-290-101.

Filed Under: Fungi, Indoor Air Quality Tagged With: air contaminants, fungal contamination, health risks, Penicillium chrysogenum, penicillium notatum

Non-viable Fungal Air Sampling Alone May Not Be Adequate

Jackson Kung'u

Non-viable Air Sampling

 

 

 

VersaTrap air sampling casette Air-O-Cell air sampling casette Allergenco air sampling casette

Indoor air sampling for airborne fungi is frequently conducted to assess the levels of fungal contamination and subsequently the potential risk to building occupants. It is also used to determine if there was hidden mould growth in the building or to determine the effectiveness of remediation procedures. One of the most cited advantages of non-viable air sampling is that detection of fungal structures (spores, hyphal fragments, etc) is not dependent on their viability or the suitability of agar media. Non-viable air samples are collected with samplers such as Air-O-Cell, Allergenco, VersaTrap, Burkard, Cyclex, Cyclex-d and Micro-5 among others. The spores (whether viable or dead) and other particulates are trapped on the sticky surface of the spore trap and can then be directly enumerated and identified under a microscope. Since both viable and nonviable spores can be enumerated, an efficient non-viable air sampler is expected to give a better estimate of the level of airborne fungal contamination than a viable air sampler.

Viable Air Sampling

Picture of Colony Forming Units: CFUViable air samples are often collected on agar media either in strips (if using Reuter Centrifugal Sampler) or in Petri-dishes for Andersen sampler. Unlike non-viable air sampling, detection and subsequent enumeration and identification of airborne fungal particulates collected on growth media depends on whether the spores and hyphal fragments are viable and whether the media used can support their growth into colonies. For this reason, colony counts are usually lower than spore counts. Even if all the fungal structures were viable, colony counts are likely to be lower than the spore/hyphal fragment counts because what is counted as a single colony could have developed from more than a single spore or hyphal fragment. In one study it was found that the ratios between the total fungal spores collected by the Burkard sampler and the viable fungi collected by the Andersen sampler ranged between 0.29 and 7.61.

Non-viable Air Sample

Picture of Chaetomium and Aspergillus/Penicillium sporesIs Non-viable Fungal Air Sampling Alone Adequate? In most cases viable air sampling is only used in situations where identification of the moulds to species level is required. However, our observation in the lab seems to suggest use of spore traps alone may not be adequate for airborne fungal sampling. On many occasions we have recovered moulds in viable samples that were not observed in non-viable samples even when viable and non-viable samples were taken side by side. For example Chaetomium and Stachybotrys spores, which are fairly easy to identify from spore traps have appeared in viable samples, yet, they were not detected from the non-viable samples. We have also observed that although non-viable sampling gives higher counts than viable sampling in most cases, this is not always the case. There are many factors that can contribute to these “unexpected” results.

Conclusion

Picture of Viable Air Samples On RCS Agar StripsSince both non-viable and viable air sampling have limitations, using either method singly is not adequate. To obtain conclusive information on the level of contamination and the diversity of airborne fungi in a building, taking both viable and non-viable air samples is preferable. We recommend the Calgary Health Region’s protocol, “Fungal Air Testing, Investigation and Reporting Requirements for Residential Marihuana Grow Operations (Revised May 2006)”. With few exceptions, the protocol requires that fungal air sampling consist of both viable samples (e.g. RCS or similar) and non-viable samples (e.g., Air-O-Cell) taken side by side.

References

Adhikari A., Sen M.M., Gupta-Bhattacharya S., Chanda S. (2004). Airborne viable, non-viable, and allergenic fungi in a rural agricultural area of India: A 2-year study at five outdoor sampling stations. Science of the Total Environment, 326 (1-3), pp. 123-141.

Calgary Health Region (2006). “Fungal Air Testing, Investigation and Reporting Requirements for Residential Marihuana Grow Operations (Revised May 2006)”.

Filed Under: Fungi, Microbial Sampling Tagged With: air sampling, Air-O-Cell, airborne fungal spores, Allergenco, Burkard, Cyclex, Cyclex-d, fungal contamination, Micro-5, mould growth, non-viable samples, spores, VersaTrap, viable

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