Which illness requires droplet precautions?

Droplet precautions are used for pathogens transmitted through large respiratory droplets (greater than 5 microns) that travel short distances, typically less than 3 feet. Pneumonia caused by organisms such as Mycoplasma pneumoniae, Haemophilus influenzae, or Neisseria meningitidis requires droplet precautions, including a surgical mask when within 3 feet of the patient and a private room when possible. Tuberculosis is transmitted via small airborne particles (droplet nuclei less than 5 microns) that remain suspended in air for prolonged periods; it therefore requires airborne precautions, including an N95 respirator and a negative-pressure isolation room. Varicella (chickenpox) requires both airborne and contact precautions because it is spread via airborne droplet nuclei as well as direct contact with lesions. Scabies is caused by a mite and is transmitted by direct skin-to-skin contact, requiring contact precautions only. Students frequently confuse airborne and droplet precautions; the key distinction is particle size and transmission distance. Pneumonia is the only option in this set that correctly matches droplet precaution requirements.