Table 3.

Issues Relating to Real-Time Polymerase Chain Reaction and Pertussis Serology

PCR:

• More expensive than culture

• May be difficult to perform (requires trained staff) and to implement outside the hospital setting (requires dedicated laboratory space)

• Sensitivity decreases with increasing cough duration

• Commercial kits are not widely available

• Subject to contamination, especially during outbreak situations

Serology:

• Testing is mostly done in immunologically nonnaive populations

• Testing is done with an antigen (pertussis toxin) that is contained in all acellular vaccines

• Immune response to vaccine antigens cannot be distinguished from response to infection

• Interpretation of serology depends on vaccination history

• Population-based cutoffs may need verification after change of vaccination calendar

• Problems in serodiagnosis of B. parapertussis infections

Abbreviation: PCR, polymerase chain reaction.