Which statement is true for diagnosing Bordetella pertussis infection?

• A. Most strains grow well on MacConkey agar.
• B. Cultures are the common diagnostic modality.
• C. Throat washes are recommended for isolation.
• D. Swabs for PCR analysis can be transported dry.

Answer: (D)

For diagnosing Bordetella pertussis, molecular detection by PCR from nasopharyngeal specimens is preferred because it is rapid and highly sensitive, even when bacterial numbers are low. Culture can be done, but it’s slower and less sensitive, so it isn’t the main diagnostic method in many labs. The best sample type is a nasopharyngeal swab or aspirate, not a throat wash, since the organism is more reliably collected from the nasopharynx. Bordetella pertussis does not grow well on MacConkey agar, and it requires selective media such as Regan-Lowe or Bordet-Gengou if culture is attempted. For PCR testing, swabs can be transported dry because PCR detects bacterial DNA and does not require viable organisms, simplifying transport and preserving nucleic acids.