What are the diagnostic tests for botulism in a 5-week-old infant?

Diagnostic Testing for Botulism in a 5-Week-Old Infant

The definitive diagnostic test for botulism in a 5-week-old infant is stool testing (10-20 grams) for both botulinum toxin detection and Clostridium botulinum isolation, which should be collected immediately and coordinated through your state health department. 1, 2

Primary Diagnostic Approach

Stool specimen collection is the gold standard for laboratory confirmation of infant botulism and should be performed as follows: 1, 2

• Collect 10-20 grams of stool and refrigerate at 36°F-46°F (do not freeze) 2
• Preliminary toxin results are typically available in 24-48 hours, with final results in 96 hours 2
• Both toxin detection and organism isolation should be requested, as either finding confirms the diagnosis 2

Important Collection Details

If the infant cannot produce stool spontaneously: 2

• Use sterile, non-bacteriostatic water for enema (never tap water)
• Use non-glycerin-containing suppositories only
• Package with proper UN 3373 biological substance Category B labeling 2

Critical Clinical Context

Do not delay treatment while awaiting laboratory confirmation if the infant is symptomatic. 2 The CDC emphasizes that a substantial proportion of botulism cases have negative test results despite clinical certainty, especially when specimens are collected later in illness. 2

Clinical Diagnostic Criteria to Monitor

While awaiting test results, assess for these CDC clinical criteria (all three categories must be met): 1, 3

Temperature status:

• Afebrile (<100.4°F or <38°C) - fever is rare but slightly more common in infants than adults 3, 1

Acute onset of at least one symptom:

• Poor feeding, poor suck on breast or pacifier, or fatigue while eating 3
• Weak cry 3
• Constipation (often an early symptom in children) 3

At least one objective sign:

• Extraocular palsy or fatigability (inability to avert eyes from light shone repeatedly - typically used in infants) 3
• Facial paresis (loss of facial expression, pooling of secretions) 3
• Hypotonia (floppy baby) 3
• Ptosis, fixed pupils, or descending paralysis beginning with cranial nerves 3, 1

Coordination with Public Health

Contact your state health department immediately to coordinate testing, as this may be performed by the state laboratory or CDC. 2 Include completed CDC form 50.34 with test order CDC-10132 for Botulism Laboratory Confirmation. 2

Distinguishing Infant Botulism Syndrome from Foodborne Botulism

This distinction is critical because it determines treatment: 1

• Single sporadic case in an infant is usually presumed to be infant botulism syndrome (intestinal colonization by spores) and requires BabyBIG (human-origin anti-A, anti-B botulinum antitoxin) 1, 4
• Infant affected as part of a group outbreak likely has foodborne botulism and requires heptavalent BAT at 10-20% of adult dose 1, 2

Common Pitfalls to Avoid

Never wait for positive laboratory results to initiate treatment if clinical suspicion is high. 2 Infant botulism is frequently omitted from the differential diagnosis in very young neonates exclusively due to age, leading to costly and prolonged workups. 5 The disease has been documented in infants as young as the first few weeks of life. 5

Collect stool before antitoxin administration when possible, but do not delay treatment to obtain specimens. 2 Clostridium organisms may persist in stool even after antitoxin neutralizes toxin in serum. 2

Immediate Management Considerations

All infants with suspected botulism require admission to a unit with close neurologic and respiratory monitoring, serial complete neurologic examinations, and respiratory support as needed. 1 The onset of symptoms evolves over hours to a few days, and respiratory failure can develop rapidly. 3, 6