What is the gold standard for diagnosing pertussis in infants?

The gold standard for diagnosing pertussis, particularly in infants, is nasopharyngeal culture. This method allows for the isolation of Bordetella pertussis, the bacterium responsible for whooping cough. By collecting a specimen from the nasopharynx, healthcare professionals can effectively culture the bacteria under appropriate laboratory conditions. This approach remains the most reliable method for confirming the diagnosis, especially in the early stages of the illness when the bacterial load is likely to be higher.

While PCR testing via a nasal swab is highly sensitive and can provide rapid results, it has not replaced culture as the gold standard because it may yield false positives. Blood culture is not typically used for diagnosing pertussis, as the bacterium primarily colonizes the respiratory tract rather than the bloodstream. Chest X-rays are also not helpful in confirming pertussis and are generally used to rule out other causes of respiratory symptoms or complications rather than for diagnosis itself. Thus, nasopharyngeal culture stands out as the definitive method for identifying pertussis in infants.