Page 14 - Microbiology in workplace

GMP Training – Microbiology in the Workplace by www.gmpsop.com

number, varies for each species. It may be as short as 15 minutes for E. coli, or
as long as 15 hours for M. tuberculosis.

This means that, if growth were unlimited, in 24 hours a single E. coli bacterium
could multiply enough to fill a total volume the size of an average factory! This
doesn't happen, of course, because other factors come into play that help
stabilise or reduce microbial populations, e.g. changes in oxygen, temperature,
pH, and the amount of nutrients.

How bacteria die

A population of micro-organisms, when faced with adverse conditions such as
disinfectants or increasing heat, will not die instantly. Some of the micro-
organisms will die immediately, while others will take several minutes. Some may
even survive. The pattern of death is also exponential.

Therefore, enough time must be allowed for the cleaning or sanitizing agent to
take effect in order to effectively reduce the number of micro-organisms in the

workplace.

Micro-organisms are mostly killed by exposure to heat above 55 - 60°C for
periods of time. The heat breaks down the cell wall, which kills the micro-
organism. The cell walls of spores, however, are resistant to anything but high

heat.

Similarly, alcohol is a good general sanitizing agent, but there are some micro-
organisms that are not killed by alcohol (such as spores).

A combination of heat and alcohol provides two methods of sanitizing. Of course,
sanitation will only be effective if a validated procedure is followed. Pay particular
attention to:

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