P3C272: Infantile Botulism; An Alternative Diagnosis for Bronchiolitis?

Introduction: Clostridium botulinum, an anaerobic spore forming gram positive bacillus is found in air, water, and soil is a potent neurotoxin that affects infants more than older children. The spores germinate in the large bowels of infants due to their underdeveloped gut microbiome creating a large production of botulinum neurotoxin which leads to a descending paralysis. During 2018, there were 162 cases and one death reported in the United States with the average age of onset at 4 months old. Conversely, bronchiolitis is a leading cause of pediatric hospitalizations. It is uncommon for these two diagnoses to be confounded, but our case shows how an atypical presentation of infantile botulism (IB) can initially masquerade as bronchiolitis.

Case Description: An otherwise healthy 2-month-old female presented with one day of poor feeding, difficulty swallowing, and nasal congestion. Initial workup in the emergency room showed negative viral testing, no foreign body on imaging, no anatomical abnormalities on flexible laryngoscopy and she was admitted to the hospital for observation. Shortly afterwards, she developed increased work of breathing and increased secretions with presumed diagnosis of viral bronchiolitis. She had progression of respiratory distress and developed limpness with weak cry/suck and chest X-ray showed concern for pneumonia; she was started on antibiotics and transferred to the PICU. Her respiratory distress resolved, however she continued to have worsening weakness which progressed to areflexia, poor head control, and bulbar weakness. Neurology noted decreased lower motor nerve responses with intact sensory responses and electromyography that showed evidence of botulism. Lumbar puncture was reassuring and a meningoencephalitis panel was negative, but stool testing was positive for botulinum toxin. Patient improved after administration of BabyBIG, though continued to have difficulty with feeding.

Discussion: Viral bronchiolitis is an exceedingly common diagnosis in children < 2 years old, while IB, especially in the absence of history of consumption of raw honey, home-canned foods, or clear environmental exposures, is rare. This patient’s clinical course did not fit the classic description of IB or bronchiolitis. While it is possible for patients with bronchiolitis to present with poor oral intake, the strong early presence of neurologic deficits out of proportion from the degree of respiratory distress should prompt a broad differential diagnosis and an escalation of care.

Conclusion: It is critical to continually incorporate changes in patient symptoms into a shared mental model between team members and to recognize when the initial diagnosis needs adjusting. Updating a differential diagnosis should remain a dynamic process when a patient fails to progress as expected. In this case, the negative viral testing, the presence of feeding difficulties, and ongoing weakness, though potentially consistent with bronchiolitis, prompted consideration of neurologic etiology.