Gram Positive Bacteria in Indoor Environments
The designation of a bacterium as “Gram positive” is based on the reaction of the organism in the Gram stain test. This test quickly classifies bacteria into two categories based on the structure of their cell walls, which – in Gram-positive bacteria – retain a crystal violet stain because of the thick peptidoglycan layer.
The cell walls of Gram-negative bacteria consist of an outer membrane and a thin peptidoglycan layer which cannot retain the violet stain. This difference in cell wall structure translates into differences in how these organisms behave in the environment. Gram-positive organisms tend to be more resistant to drying due to their thicker cell wall, but more susceptible to cleaning agents due to lack of an outer membrane. However, Gram-positive organisms that form spores are highly resistant to both drying and cleaning agents.
The concentrations of Gram-positive bacteria in indoor environments depend on a number of factors. These include the number and activity levels of individuals in the space, the types of clothing worn by individuals, the ventilation rate of the space, the presence of animals, and the presence of standing water.
In ISO-classified areas, the main source of microbial contamination is personnel and, to a lesser extent, materials transfer and infiltration of contaminated air.
Environmental laboratory testing of buildings, medical facilities, food preparation areas, and the like can aid in identifying threatening bacilli species and organism concentrations. Bacteria are hardy survivors and mainly pose risks where high bacterial loads of dangerous bacilli are present on surfaces or become airborne in public environments.
At U.S. Micro Solutions, our microbiology laboratory is a licensed, accredited source for thorough, cutting edge environmental testing, including USP 797, Legionella, indoor environmental testing, healthcare & medical testing, water analysis, and identification of specific pathogens. Visit our Laboratory Services page to learn more.
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