What laboratory tests are recommended for confirming a diagnosis of pertussis in adults?

Laboratory tests recommended for confirming pertussis in adults include:

• Polymerase chain reaction (PCR) testing of nasopharyngeal swabs is the preferred diagnostic method during the early phase of illness, as it detects Bordetella pertussis DNA with high sensitivity and specificity.
• Culture of nasopharyngeal specimens remains the gold standard but is less sensitive and more time-consuming; it is most useful within the first 2 weeks of cough onset.
• Serologic testing for pertussis toxin antibodies can be used in later stages of illness (after 2-3 weeks of cough) when PCR and culture sensitivity decline, especially in adults where symptoms may be prolonged.

These tests should be interpreted in the context of clinical presentation and timing of sample collection relative to symptom onset. Combining PCR and serology improves diagnostic accuracy in adults, who often present later in the disease course (Cherry et al., 2005; Mi et al., 2024).

UK clinical guidelines do not provide detailed pertussis-specific laboratory testing protocols but emphasize nucleic acid amplification tests (NAATs) such as PCR for respiratory pathogens, aligning with international expert consensus on pertussis diagnosis (Cherry et al., 2005; Mi et al., 2024).