A 5-month-old boy is brought to the emergency department due to poor feeding, weakness, and complete loss of extremity muscle tone. Vaccinations are up to date, and there is no significant medical history. The patient receives formula as his sole source of nutrition except for occasional fruit juice and honey. Which of the following is most likely to confirm the diagnosis in this patient?

Question

A 5-month-old boy is brought to the emergency department due to poor feeding, weakness, and complete loss of extremity muscle tone.  Vaccinations are up to date, and there is no significant medical history.  The patient receives formula as his sole source of nutrition except for occasional fruit juice and honey.  Which of the following is most likely to confirm the diagnosis in this patient?

Quizplus · Accepted Answer

11ec160b_37f8_dc29_9249_47725500a468_MD0001_00 This 5-month-old patient has consumed honey, a food notorious for contamination with Clostridium botulinum spores. When an infant consumes C botulinum spores, the bacteria can germinate in the gastrointestinal tract. Bacteriolysis releases botulinum toxin, which is absorbed systemically and blocks release of acetylcholine from cholinergic presynaptic terminals. Constipation is usually the first manifestation of infant botulism, followed days to weeks later by mild weakness, lethargy, and reduced feeding. In rare, severe cases, infants can have weakened suckling and crying, diminished gag reflex, and symmetric, descending flaccid paralysis with loss of head control that can cause the infant to appear "floppy." In contrast, adult botulism usually results from ingestion of preformed toxin (eg, contaminated canned foods) and is almost always very severe. While infant botulism can be diagnosed based on the clinical presentation and food consumption history, the diagnosis is usually confirmed through identification of C botulinum spores or toxin in stool samples. (Choice A) Measurement of blood liver enzyme levels can indicate damage to hepatic cells in hereditary fructose intolerance (genetic deficiency in aldolase B). Although patients with fructose intolerance can have poor feeding shortly after juice and honey are added to the diet, other classic manifestations include hypoglycemia, vomiting, and hepatomegaly rather than loss of extremity muscle tone. (Choice B) Serum viral titers are frequently used in the evaluation of patients with viral hepatitis or suspected Epstein-Barr or cytomegalovirus infections. Poor feeding with loss of extremity muscle tone is more characteristic of infant botulism. (Choice D) Allergic proctocolitis in infants can present after introduction of different food groups, and the diagnosis can be supported by stool studies that are positive for gross or occult blood. However, these infants usually appear well despite persistent diarrhea and/or rectal bleeding. (Choice E) Patients with amino acids in their urine may have an inborn error of metabolism (eg, maple syrup urine disease) with symptoms usually manifesting in the neonatal period or early infancy. (Choice F) High levels of urine glucose and ketones, together with hyperglycemia and metabolic acidosis, can support a diagnosis of diabetic ketoacidosis. Educational objective: Infant botulism can result from consumption of honey, which frequently contains C botulinum spores that can germinate and produce botulinum toxin. Symptoms of infant botulism include constipation, mild weakness, lethargy, poor feeding, and, in severe cases, flaccid paralysis. The diagnosis can be confirmed by identification of C botulinum spores or toxins in the stool.

A 5-Month-Old Boy Is Brought to the Emergency Department Due