Which organism is most likely to be isolated in cultures from the anterior nares of healthcare workers?

• A. Bacillus cereus
• B. Streptococcus pneumoniae
• C. Staphylococcus aureus
• D. Staphylococcus saprophyticus

Answer: (C)

Nasal carriage of Staphylococcus aureus is the most common situation for the anterior nares, making it the organism you’d most likely culture from healthcare workers’ noses. Many healthy people carry S. aureus in their nares, and healthcare workers are a prime source of transmission in hospital settings, which is why screening and awareness of nasal carriage are important for infection control.

Bacillus cereus is primarily an environmental contaminant and not a typical nasal resident. Streptococcus pneumoniae can inhabit the nasopharynx, especially in children, but it is not the usual nose flora in healthy adults. Staphylococcus saprophyticus is mainly associated with the female genital tract and urinary tract infections, not the anterior nares.