MRSA in the Dental Office

Laura A. Stokowski, RN, MS


April 01, 2011

In This Article

Modes of Transmission of Infection-Causing Organisms

In dental healthcare settings, modes of transmission of infection-causing organisms (including but not limited to MRSA) are both direct and indirect:

  • Blood, saliva, or other body fluids from an infected patient;

  • Contaminated objects (instruments, equipment, environmental surfaces) or contaminated hands of dental healthcare personnel if hand hygiene is not performed before touching another patient;

  • Spray/droplets of contaminated body fluid generated by dental procedures or by coughing or sneezing; and

  • Inhalation of airborne organisms.

The "chain of infection" requires a pathogenic organism of sufficient virulence and in adequate numbers, a reservoir that allows the pathogen to survive and multiply, a mode of transmission, and a portal of entry to a susceptible host (Figure 2).[7] Infection control measures are effective when they interrupt the links in this chain.[7]

Figure 2. Conditions that must be met to complete the "chain of infection." Effective infection control strategies prevent disease transmission by interrupting one or more links in the chain of infection. From Kohn WG, et al. MMWR Recomm Rep. 2003;52:1-61.[7]

Aerosols and Droplets

Dental procedures that use mechanical instruments produce airborne particles from the oral cavity.[15] Aerosols (particles < 50 µm in diameter) are small enough to remain airborne for an extended period of time before being inhaled or settling on environmental surfaces.[15] Spatter, on the other hand, is believed to contain larger particles (> 50 µm in diameter) known as droplets of water, blood, and/or saliva. Typically too large to remain suspended, droplets are airborne only briefly before settling on surrounding surfaces.

Aerosols pose a threat because of their ability to remain airborne and because they are small enough to reach the lower respiratory tract.[15] Droplet nuclei, however, have been associated with transmission of organisms such as Mycobacterium tuberculosis (TB) and the virus that causes severe acute respiratory syndrome (SARS). Patients known to have these infections should not receive routine dental care in the dental office because a higher level of respiratory protection is required.[16] In treating the patient with active TB, among other precautions, staff must participate in a respiratory protection program, receive annual training, and wear fit-tested N95 respirators because standard surgical face masks do not protect against TB transmission.


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