Modes of Transmission

The principal avenues of transmission of hospital-acquired infections are contact, droplet, airborne and common-vehicle.

Contact transmission is the most common and most preventable means of transmission. Contact transmission can be divided into direct and indirect contact.

• Direct contact involves body surface to body surface contact with a physical transfer of microorganisms.
• Indirect contact (cross-contamination) involves body surface contact with a contaminated intermediate object.
• Washing and drying hands can help reduce transmission via common contact surfaces.

Proper hand hygiene, before and after contact, eliminates or significantly reduces the possibility of infection transmission.

Droplet transmission occurs when droplets containing microorganisms from an infected person are propelled through the air and land on the mouth, eyes, or nose of another person. Droplets are generated primarily when a person is coughing, sneezing, or talking. Droplets do not remain suspended in the air and should not be confused with airborne transmissions.

Airborne transmission results when a droplet containing microorganisms evaporates and remains suspended in the air for a long time. Airborne transmission also occurs with dust particles containing infectious agents. If working in close contact (3 feet or less), cover nose, mouth and eyes, if possible.

Common vehicle transmission refers to contaminated items such as food, water, medications, devices, and equipment.