A caucasian male infant of 4-months was brought to the emergency department with a six-day history of decreased feeding. The mother reported that he had passed his last stool nine days back and also she had noticed that the baby is unusually weak for the last month. He was no longer able to hold his neck either.
Physical examination revealed a hypotonic baby with minimal interaction and a weak cry. Bilateral ptosis was noted. His vital signs were normal but bowel sounds were markedly diminished. Initially, doctors suspected cerebral infections, therefore, the baby was immediately started on ceftriaxone, acyclovir, dexamethasone and IV dextrose. Upon receiving laboratory results, cerebral infections and other differential diagnoses were ruled out due to normal CSF analysis, metabolic profile and negative results for viruses.
Although the baby improved clinically, the hypotonia, constipation, and ptosis remained partially unresolved. Gradually, respiratory muscle weakness ensued leading to oxygen desaturation. He was then intubated and shifted to the intensive care unit for mechanical ventilation and close monitoring. Infantile botulism was suspected so tests were conducted to rule it out. Electromyography revealed presynaptic block and stool samples confirmed the presence of botulinum toxin. The baby was given the botulism immunoglobulin and enteral nutrition. The baby improved symptomatically within the first 48 hours of treatment. He made a complete recovery in a month without any longterm complications.
Infantile Botulism (IB) is rare but a life-threatening condition, seen in infants (<1 year) due to the ingestion of Clostridium botulinum spores that release the neurotoxins.
Where do infants get these spores from?
Clostridium botulism is a gram-positive, anaerobic bacterium that produces spores and synthesizes toxins. These bacteria are heat-resistant and can survive without oxygen, so expect these in canned foods, honey, soil, and anywhere in the environment. For instance, in some cultures, babies are given honey as a first kick to their taste buds at birth. If the honey is contaminated, spores enter the digestive tract of the baby, colonize the intestines and produce the toxins. These toxins, being neurotoxic, irreversibly block the acetylcholine receptors at the neuromuscular junction thereby inhibiting acetylcholine causing muscle paralysis. The symptoms depend upon the severity of the disease and the affected muscle groups. Usually, a descending pattern of weakness is observed. Some of the symptoms include
- Constipation/intestinal obstruction
- Lethargy/ hypotonia
- Weak cry
- Inability to feed
- Seizures
- Autonomic dysfunction like Hypotension, neurogenic bladder, etc.
- Ptosis and facial weakness
- Respiratory difficulty (a late sign)
- Absent or weak gag reflex
Due to a considerable overlap of the signs and symptoms of IB with other neurological diseases, and due to its rarer incidence, often there is a delay in the diagnosis. A range of investigations is carried out to exclude cerebral infections and other common metabolic causes before botulism is tested.
Stool samples for detecting botulinum toxin and electromyography are the commonly used tests for the diagnosis. For infant botulism, polymerase chain reaction (PCR) and enzyme-linked immunosorbent assays (ELISA) can be used too. Recently, mouse neutralization bioassay is introduced as an alternative test to detect botulinum toxins.
Management largely revolves around supportive care and neutralizing the toxins using the botulism immunoglobulin, a human-derived antitoxin. Counselling of the parents is indispensable. Parents should be made aware of the excellent prognosis as well as the higher chances of relapse during the first month after resolution. Above all, counselling should be done to point out the preventive measures because we all know prevention is better than cure!
