Objective:

To describe the clinical, laboratory, and management characteristics of critically ill infants with Bordetella pertussis in southwestern Saudi Arabia, with a focus on comparing survival and non-survival outcomes.

Approach:

• Data Collection: Collected demographic details, presenting symptoms, comorbidities, vital signs, laboratory parameters including white blood cell count and inflammatory markers, treatments received, and clinical outcomes.

Key Findings:

• Median age of infants was 3 months, with 46.4% aged < 3 months.
• Non-survivors had significantly higher leukocyte counts (median WBC, 87.5 × 10³/µL) and inflammatory markers compared to survivors.
• Clinical features like apnea, seizures, and hypoxemia were strongly associated with death.
• All fatal cases involved severe pulmonary hypertension requiring aggressive interventions, and non-survivors exhibited higher rates of coexisting conditions such as congenital heart disease and genetic disorders.

Interpretation:

Critical pertussis primarily affects unimmunized infants <3 months and is associated with severe illness.

Limitations:

• Retrospective design may limit the ability to establish causality and may introduce bias.
• Screening for other respiratory pathogens was not performed.

Conclusion:

Critical pertussis primarily affects unimmunized infants <3 months and is associated with severe illness.