Organisms recovered from hands can be divided into two categories: transient and resident. The number of transient and resident organisms may vary greatly from HCW to HCW, yet it is often relatively constant for any one individual.17 Transient organisms are often acquired by HCWs during:
contact with a patient’s intact skin (e.g., when taking a pulse or blood pressure),
contact with nonintact skin and mucous membranes,
direct contact with blood and other potentially infectious material; and
contact with contaminated instruments, equipment, and environmental surfaces.
Transient organisms tend to colonize the superficial layers of skin and while they are amenable to removal by washing hands with plain (i.e., non-antimicrobial) soap and water, they are responsible for most healthcare-associated infections. Resident organisms are attached to deeper layers of the skin and while they are more resistant to removal, they are less likely to be associated with healthcare-associated infections. However, the hands of HCWs may become persistently colonized with transient pathogenic organisms (e.g., S. aureus, gram-negative bacilli, or yeast), which subsequently may be transmitted to patients. It is of interest to note that organisms are transferred in much larger numbers (i.e., >104 cell) from wet hands than from hands that have been thoroughly dried.18
The acquisition and transmission of healthcare-associated pathogens from one patient to another via the hands of HCWs must meet 4 criteria:1,3
Organisms present on the patient’s skin or mucous membranes, or on contaminated instruments, equipment, and environmental surfaces must be transferred to the hands of HCWs.
The organisms transferred must then be capable of surviving for at least several minutes on the hands of HCWs.
Hand hygiene by HCWs must be inadequate or omitted entirely, or the agent used for hand hygiene must be inappropriate.
The contaminated hands of HCWs must come in direct contact with another patient, or with an inanimate object that will come into direct contact with the patient.