Background
Pertussis infection has been recognized as a global cause of morbidity and mortality, especially amongst infants in the first months of life. The most severe course of infection is seen in unvaccinated infants, who can develop life-threatening complications.
Case Presentation Summary
A 6 week-old boy was admitted to PICU from a local hospital due to respiratory collapse. The diagnosis of pertussis was made 1 week after initial symptoms including coughing, and he started a 10-day course of erythromycin, 4 days after which he was admitted to our PICU. Despite treatment with azithromycin and cefotaxime, he deteriorated clinically, developing pronounced leukocytosis. While in extremis he obtained two blood exchange transfusions and intravenous immunoglobulin with good clinical effect. The pertussis strain identified showed resistance to erythromycin, clarithromycin and azithromycin. The bacteria had good sensitivity to trimethoprim-sulfamethoxazole and he was therefore given this treatment for 19 days. The total length of antibiotic treatment was 23 days. The patient required invasive mechanical ventilation and high-flow nasal therapy (Optiflow®) for 16 days and 11 days respectively. On day 25 he could be transferred to the standard paediatric department.
His mother had not been vaccinated in childhood, and developed similar symptoms few weeks before him.
Learning Points/Discussion
The vaccination of pregnant women, which is well described, can significantly decrease the severe courses of pertussis infection in neonates and infants. Usual treatment of pertussis with antibiotics can fail due to bacterial resistance. Blood exchange transfusion is an important therapy to consider in severe cases of pertussis infection with significant leukocytosis.

MACROLIDE RESISTANT PERTUSSIS IN AN INFANT WHOSE MOTHER WAS NOT VACCINATED AGAINST PERTUSSIS