Airborne Bacteria In Indoor Environments

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Airborne Bacteria In Indoor Environments

By Kung'u

http://www.moldbacteria.com/myblog/2007/10/airborne-bacteria-in-

indoor.html

Significance Of Airborne Bacteria In Indoor Environments

Indoor Bacteria have not received as much publicity as the mould.

Are indoor bacteria of health significance?

Bacteria are found virtually in every environment including the hot

springs, deep-sea hydrothermal vents, glaciers, swamps, and mines!

Some heat-loving bacteria (hyperthermophiles) thrive best above 176 °

F (80 °C) whereas the psychrophiles (cold-loving) can survive far

below 0 °C.

In indoor environments bacteria are present in air and on surfaces.

High levels of bacteria concentration indoors is an indication of

high occupancy rate, poor ventilation, or poor building maintenance.

Similar to mould, some bacteria are associated with water-damaged

building materials.

Significance Of Airborne Bacteria

While bacteria do not receive as much publicity as mould when it

comes to indoor air quality, they are a health hazard. Some are

serious human pathogens and others especially the gram negative

bacteria produce toxic compounds (endotoxins) from the outer

membrane of their cell wall. Endotoxins may have a role in sick

building syndrome.

Indoor airborne bacteria can loosely be categorized into bacterial

pathogens and environmental bacteria associated with water-damaged

building materials. Bacterial pathogens are capable of causing

severe diseases in humans if inhaled, ingested or if they come into

contact with the skin. The most important airborne bacterial

infections in indoor environments are tuberculosis, nosocomial

pneumonia, and legionellosis. These infections are primarily

acquired through inhalation of the causative agents.

Environmental bacteria generally associated with mouldy building

materials include Acinetobacter, Bacillus, Flavobacterium, Nocardia,

Streptomyces, and Thermomonospora. Also associated with water-

damaged material are the filamentous bacteria, the Actinomycetes.

Some airborne bacteria such as Staphylococcus spp and Micrococcus

spp are dispersed into the air from human skin, oral and nasal

surfaces, and hair. These bacteria are associated with nosocomial

infections in health care facilities.

Sampling For Airborne Bacteria

The commonly used sampling method for airborne bacteria is the

impaction of air onto agar media using volumetric samplers such as

Andersen, SAS, or RCS. Samples can also be collected by impingement

into liquid media. However, for routine air quality monitoring agar

based sampling is recommended. Trypticase soy agar (TSA) media is

usually used when sampling for bacteria. It is important to select a

medium suitable for growth of the target organism, for example when

sampling for some specific bacteria such as Legionnela. Sampling

time depends on the sampler used but generally not more than 10

minutes. Shorter times are recommended in heavily contaminated

areas. Samples are kept cool and shipped for overnight delivery to

the laboratory for incubation and identification of the dominant

species.

References

Chin, S. Yang, A. Heinsohn (Editors). Sampling and analysis

of indoor microorganisms. 2007. Wiley & Sons, Inc.(ISBN-13:978-

0-471-73093-4

Flannigan, B., R.A. Samson, and J.D. (Editors).

Microorganisms in home and indoor work environments: diversity,

health impacts, investigation and control. 2001. London, UK:

& Francis (ISBN: 0-415-26800-1).

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.

Labels: Bacteria