Purpura Fulminans Secondary to Haemophilus influenzae in an Infant.

Purpura fulminans (PF) is a hematological emergency that requires timely diagnosis for effective management. In this report, we discuss the case of a five-month-old previously healthy male who presented to the emergency department due to sudden-onset lethargy and rash in the setting of intermittent fevers, emesis, and diarrhea. Shortly after admission, the patient was noted to have rapidly progressive PF and was intubated due to impeding respiratory failure and hemodynamic instability requiring the institution of vasopressors and steroids for catecholamine-resistant, refractory septic shock. He was initially managed with a course of broad-spectrum antimicrobials, including ceftriaxone, doxycycline, and vancomycin, while awaiting the results from his blood and urine cultures. Unfortunately, our patient progressed to multi-organ failure and disseminated intravascular coagulation requiring advanced organ support, including the need for continuous renal replacement therapy. He was transferred to another facility for evaluation and continued management of his necrotic and gangrenous tissues, where he ultimately died after experiencing septic shock in the setting of bacteremia. Although blood and urine cultures were negative, his microbial cell-free DNA sequencing (Karius test) was positive for Haemophilus influenzae, the likely causal pathogen. Haemophilus influenzae is a Gram-negative coccobacillus that is commonly associated with invasive bacterial infections in the pediatric population. With the widespread implementation and utilization of the H. influenzae type B vaccine as part of routine vaccinations, the incidence of severe illness is rare. Only a handful of cases of H. influenzae causing PF are reported in the literature, and it is uncommon in the pediatric population, emphasizing the need to report and understand such occurrences. This case specifically highlights the importance of early recognition and timely management of PF, a rapidly degenerative clinical condition, in the setting of severe sepsis and multi-system organ failure secondary to an unlikely pathogen.