Personnel are probably the greatest source of microbial contamination in clean rooms. People are mobile, unpredictable and cannot be sterilized (in the microbiological sense of sterilization). Some may be greater potential sources of contamination than others; there may be sudden or periodic changes in their contamination potential for physical or even psychological reasons — the garments provided to them may be inappropriate (wrong fabric or fit); and none of this may be obviously evident to supervisors. It makes good sense to monitor personnel for microbiological contamination.
The main type of personnel monitor is the glove print (also referred to as a finger print, finger dab, etc.) where the tips of four fingers and the thumb of each gloved hand are pressed on an agar plate. This can be done at any time within a production shift; personnel should be taken into the changing room to make the glove print, and the gloves should then be discarded and replaced. The argument can be made that replacement of gloves after glove prints is unnecessary, because disinfection of gloved hands has been validated. The cost of a few extra pairs of gloves is insignificant in comparison to the cost of a batch of product rejected, or a patient harmed.
Other less common approaches to personnel monitoring include swabs or contact plates from garment surfaces. None of these should be allowed except at the end of a shift, when the garments are due to be discarded. The barrier properties of garment fabrics are impaired when wetted, as they are by swabbing.
Practically every part of the front of garments is monitored somewhere, most frequently the forearm, for obvious reasons. The chest region in front of the armpit gusset is often sampled because of the strain on the garment in movement, and the possible effects of perspiration. Masks and head covers are sometimes examined, particularly for operators who have difficulty in avoiding touching their faces. Swabs on overboots are also sometimes taken, but allowances must be made for periodic high counts.
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