Acquisition and Transmission of Healthcare-associated Pathogens

Microbes recovered from hands can be divided into two categories: transient and resident organisms. Transient microorganisms 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 HAIs. 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 HAIs.

The number of transient and resident organisms may vary greatly among HCP, yet it is often relatively constant for any one individual.15 Transient organisms are acquired during:

  1. contact with a patient’s intact skin (e.g., when taking a pulse or blood pressure),
  2. contact with nonintact skin and mucous membranes,
  3. direct contact with blood and OPIM; and
  4. contact with contaminated instruments, equipment, and environmental surfaces.

The hands of HCP may also 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 note that organisms are transferred in much larger numbers from wet hands than from hands that have been thoroughly dried.16 The transmission of healthcare-associated pathogens from one patient to another via the hands of HCP 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 HCP.
  • The organisms transferred must then be capable to survive for at least several minutes on the hands of HCP.
  • Hand hygiene by HCP must be inadequate or omitted entirely, or the agent used for hand hygiene is inappropriate.
  • The contaminated hands of HCP must come in direct contact with another patient, or with an inanimate object that will come into direct contact with the patient.

To prevent or reduce the risk of occupational exposure, the standard of care mandates that HCP wear gloves.1,3,17 However, gloves do not provide complete protection against cross-infection. Bacterial flora colonizing patients have been recovered from the hands of ≥30% of HCP who wore gloves during patient contact.18,19 The acquisition of hepatitis B, hepatitis C, and herpes simplex viruses (HSV-1) by HCP wearing gloves has also been documented.2,20,21

It is also of note that at least 70% of the population shed HSV-1 asymptomatically at least once a month, many individuals shed the virus >6 times a month, and the virus can survive for several hours in a variety of fluids, on dental charts, and environmental surfaces.22 Since pathogens can be transmitted via small defects in gloves or by contamination of the hands during glove removal, wearing gloves does not eliminate the need for appropriate hand hygiene practices.18-21,23