A case of type F botulism in southern California.

BACKGROUND: Botulism caused by type F botulinum toxin accounts for less than 0.1% of all human botulism cases and is rarely reported in the literature.

CASE REPORT: A 45-year-old woman presented to an emergency department complaining of blurred vision, difficulty focusing, and dysphagia. The treating physician initially considered the possibility of paralytic shellfish poisoning due to a report of shellfish ingestion, which was later determined to be frozen shrimp and a can of tuna, but no gastroenteritis or paresthesias were present. During the emergency department observation, the patient developed respiratory distress with hypercapnea and required intubation and mechanical ventilation. Within hours, ptosis, mydriasis, and weakness in the arms and legs developed. Bivalent (A, B) botulinum antitoxin was administered approximately 24 h from the onset of initial symptoms, but over the next two days complete paralysis progressed to the upper and lower extremities. Shortly thereafter a stool toxin assay demonstrated the presence of type F botulinum toxin. The patient subsequently received an experimental heptavalent botulinum antitoxin on hospital day 7 but paralysis was already complete. Her three-week hospital course was complicated by nosocomial pneumonia and a urinary tract infection, but she gradually improved and was discharged to a rehabilitation facility. Anaerobic cultures and toxin assays have yet to elucidate the source of exposure.

CONCLUSION: We report a rare case of type F botulism believed to be foodborne in etiology. Administration of bivalent botulinum antitoxin did not halt progression of paralysis.