What is the most suitable specimen for the isolation of Bordetella pertussis?

The most suitable specimen for the isolation of Bordetella pertussis is the nasopharyngeal swab. This choice is correct because B. pertussis primarily colonizes the ciliated epithelium of the nasopharynx, making the nasopharyngeal area the most optimal site for obtaining a sample.

Using a nasopharyngeal swab allows for the collection of a specimen that has a higher concentration of the bacteria compared to other sample types. In addition, this specimen type can facilitate the growth of the bacteria in culture, which is essential for accurate identification.

Other specimen types, such as sputum, may not yield significant results because B. pertussis typically does not reside in the lower respiratory tract where sputum is collected. Similarly, while a throat swab may capture some pathogens from the throat area, it is less effective than a nasopharyngeal swab for isolating Bordetella pertussis specifically. Blood cultures are not relevant for this organism, as B. pertussis usually does not enter the bloodstream in significant quantities during infection.