Clinical characteristics and outcomes of Bordetella parapertussis compared with Bordetella pertussis: a retrospective observational study

The objective of this study was to evaluate patient characteristics and clinical outcomes in cases of Bordetella parapertussis compared with B. pertussis.

This retrospective observational study utilized a database of multicentre electronic medical records. Patients with B. parapertussis infection were compared with those with B. pertussis for clinical outcomes using propensity score matching, including hospitalization and admission to critical care. Odds ratios (ORs) for each outcome were estimated with 95% CIs.

A total of 2554 patients with B. parapertussis and 8058 patients with B. pertussis were microbiologically confirmed. The ORs for hospitalization and critical care admission in the B. parapertussis group compared with the B. pertussis group among all participants after matching were 1.75 (1.46-2.10; p < 0.001) and 1.94 (1.28-2.93; p 0.001), respectively. For subgroup analysis by age, the ORs for hospitalization in the B. parapertussis group compared with the B. pertussis group were 0.69 (0.49-0.96; p 0.028), 3.34 (2.27-4.91; p < 0.001), 4.22 (2.62-6.79; p < 0.001), and 1.76 (1.06-2.94; p 0.029) among those aged <1 year, 1 to 4 years, 5 to 17 years, and ≥18 years, respectively.

Severe outcomes, including hospitalization, were not uncommon after B. parapertussis infection. Although B. pertussis caused more severe disease in young infants, the significantly greater odds of severe outcomes in older children infected with B. parapertussis underscore the importance of strengthening preventive and therapeutic strategies targeting this pathogen.