The clinical spectrum of infant botulism

Extraintestinal Foodborne Pathogens

In general, foodborne diseases present themselves with gastrointestinal symptoms caused by bacterial, viral, and parasitic pathogens well established to be foodborne. These pathogens are also associated with extraintestinal clinical manifestations. Recent studies have suggested that Escherichia coli and Klebsiella pneumoniae, which both cause common extraintestinal infections such as urinary tract and bloodstream infections, may also be foodborne. The resolution and separation of these organisms into pathotypes versus commensals by modern genotyping methods have led to the identification of key lineages of these organisms causing outbreaks of extraintestinal infections. These epidemiologic observations suggested common- or point-source exposures, such as contaminated food. Here, we describe the spectrum of extraintestinal illnesses caused by recognized enteric pathogens and then review studies that demonstrate the potential role of extraintestinal pathogenic E. coli (ExPEC) and K. pneumoniae as foodborne pathogens. The impact of global food production and distribution systems on the possible foodborne spread of these pathogens is discussed.

Clinical Characteristics and Ancillary Test Results Among Patients With Botulism-United States, 2002-2015

Background

Botulism is classically described as a bilateral, symmetric, descending flaccid paralysis in an afebrile and alert patient without sensory findings. We describe the reported spectrum of clinical findings among persons >12 months of age in the United States during 2002-2015.

Methods

The Centers for Disease Control and Prevention collects clinical findings reported by physicians treating suspected cases of botulism nationwide. We analyzed symptoms and signs, and neuroimaging and cerebrospinal fluid (CSF) results. A case was defined as illness compatible with botulism with laboratory confirmation or epidemiologic link to a confirmed case, and presence or absence of at least 1 sign or symptom recorded. Physicians' differential diagnoses were evaluated.

Results

Clinical information was evaluated for 332 botulism cases; data quality and completeness were variable. Most had no fever (99%), descending paralysis (93%), no mental status change (91%), at least 1 ocular weakness finding (84%), and neuroimaging without acute changes (82%). Some had paresthesias (17%), elevated CSF protein level (13%), and other features sometimes considered indicative of alternative diagnoses. Five of 71 (7%) cases with sufficient information were reported to have atypical findings (eg, at least 1 cranial nerve finding that was unilateral or ascending paralysis). Illnesses on the physician differential included Guillain-Barré syndrome (99 cases) and myasthenia gravis (76 cases) and, rarely, gastrointestinal-related illness (5 cases), multiple sclerosis (3 cases), sepsis (3 cases), and Lyme disease (2 cases).

Conclusions

Our analysis illustrates that classic symptoms and signs were common among patients with botulism but that features considered atypical were reported by some physicians. Diagnosis can be challenging, as illustrated by the broad range of illnesses on physician differentials.

Laboratory diagnostics of botulism

Botulism is a potentially lethal paralytic disease caused by botulinum neurotoxin. Human pathogenic neurotoxins of types A, B, E, and F are produced by a diverse group of anaerobic spore-forming bacteria, including Clostridium botulinum groups I and II, Clostridium butyricum, and Clostridium baratii. The routine laboratory diagnostics of botulism is based on the detection of botulinum neurotoxin in the patient. Detection of toxin-producing clostridia in the patient and/or the vehicle confirms the diagnosis. The neurotoxin detection is based on the mouse lethality assay. Sensitive and rapid in vitro assays have been developed, but they have not yet been appropriately validated on clinical and food matrices. Culture methods for C. botulinum are poorly developed, and efficient isolation and identification tools are lacking. Molecular techniques targeted to the neurotoxin genes are ideal for the detection and identification of C. botulinum, but they do not detect biologically active neurotoxin and should not be used alone. Apart from rapid diagnosis, the laboratory diagnostics of botulism should aim at increasing our understanding of the epidemiology and prevention of the disease. Therefore, the toxin-producing organisms should be routinely isolated from the patient and the vehicle. The physiological group and genetic traits of the isolates should be determined.

Biological neurotoxins

The authors divide biological toxins into animal, plant, and bacterial classes and discuss each within a context of demographic, clinical and research examples. Advances in our knowledge are highlighted, and the authors relate the implications of this knowledge to target-specific neurologic involvement.

Infant botulism: a case series and review of the literature

Little has been written about infant botulism in the emergency medicine literature, despite increasing references in the pediatric journals. We describe three cases diagnosed at The Children's Hospital in Denver, Colorado, over an 8-month period. A review of the literature follows, to discuss the clinical manifestations, differential diagnosis, diagnostic workup and treatment of the disease.

Infant botulism: case report and clinical update

Infant botulism occurs in infants between 1 week and 11 months of age and results from the in vivo production of neurotoxin by Clostridium botulinum. The clinical spectrum ranges from asymptomatic carriers, through various degrees of paralysis, to sudden death. The classic clinical presentation is an afebrile child with constipation and generalized weakness manifested by poor head control, poor suck, and weak cry. Symptoms can progress to include cranial nerve palsies, respiratory arrest, and adynamic ileus. Treatment is supportive in an intensive care setting. Antibiotics and antitoxin are not indicated. The morbidity and mortality is less than 3% in hospitalized patients and complete recovery can be expected. The environmental and dietary factors associated with infection are discussed.

Infant botulism in the United States: an epidemiologic study of cases occurring outside of California

Data were obtained for the 96 hospitalized cases of infant botulism reported to the Centers for Disease Control between 1976-1980 from all states other than California. Forty-one cases were associated with Clostridium botulinum type A, 53 with type B, one with type F, and one with a strain of C. botulinum capable of producing both type B and F toxin. Cases occurred in 25 states; the disease was more common in the western part of the United States, with the highest attack rates reported for Utah and New Mexico. Birth-weights of hospitalized infants with infant botulism tended to be high compared with birth-weights in the United States population. Mothers of infants with infant botulism tended to be older and better educated than mothers in the general population. Seventy per cent of infants had been predominantly breast-fed; breast-feeding in type B cases was associated with a significantly older age at onset of illness.

Clinical electrophysiology of infantile botulism

Infantile botulism is a recently recognized cause of acute hypotonic paresis and respiratory failure in young infants. Electrophysiological testing has proven useful in early diagnosis in suspected cases by demonstrating abnormal neuromuscular transmission as is known to occur in botulism. Twenty-five infants with bacteriologically proven botulism were studied by uniform methods in our laboratory and characteristic electrophysiological abnormalities were found. Repetitive stimulation at 20 and 50 Hz was the most specific single test; 23 patients (92%) showed incremental responses. Stimulation at low rates was less specific. Concentric needle electromyography provided useful supplemental information. Short-duration, low-amplitude motor unit potentials were prominent in 22 patients (92%) accompanied by abnormal spontaneous activity in 13 patients (54%). Compound muscle action potential amplitudes were usually reduced, but motor and sensory conduction studies were otherwise normal. Electrodiagnostic testing demonstrated one or more characteristic abnormalities in all cases of infantile botulism. This constellation of electrophysiological abnormalities, combined with an appropriate clinical picture, was so distinctive as to allow early presumptive diagnosis of infant botulism, before the results of bacteriological testing were available.

Differentiation of Clostridium difficile toxin from Clostridium botulinum toxin by the mouse lethality test

The mouse lethality test is the most sensitive method for confirming the diagnosis of infant botulism. Both Clostridium difficile and Clostridium botulinum produce heat-labile toxins which are lethal for mice and can be found in the feces of infants. These two toxins can be distinguished from one another in this assay when both are present in the same fecal specimen because they appear to be immunologically distinct toxins.

Protective role of human milk against sudden death from infant botulism

We examined the possibility that human milk and formula milk might differentially affect the severity of the infant botulism because they differ in immunologic composition and in influence on the normal intestinal microflora against which Clostridium botulinum must compete. A beneficial effect of human milk was suggested by the different feeding experiences of the moderate, hospitalized patients and the sudden death cases. Of patients hospitalized in California, 66% (33/50) were still being nursed at onset of illness, a percentage significantly greater than that of matched controls (P less than 0.01). In contrast, all ten California cases of sudden infant death attributable to C. botulinum infection were being fed iron-supplemented formula milk at death) unlike their controls, P less than 0.02) and had received no human milk within ten weeks of death. A beneficial effect of human milk was also observed in differences in mean age at onset; hospitalized breast-fed patients were almost twice as old (13.8 +/- 6.7 weeks) as were hospitalized formula-fed patients (7.6 +/- 2.9 weeks) (P less than 0.01). Human milk (or possibly other factors associated with breast-feeding) appeared to have moderated the severity at onset of infant botulism, allowing time for hospital admission, whereas for some infants with this illness, formula milk (or possibly other factors associated with formula feeding) was linked to sudden unexpected death.

Progression of clinical signs in severe infant botulism. Therapeutic implications

The clinical evaluation of nine patients with severe infant botulism revealed an identifiable progression of signs due to blockade of the cholinergic synapse similar to that described for competitive blocking agents. This predictable sequence reflects different "margins of safety" for muscles involved in repetitive activities, diaphragmatic function and movement of the extremities. It is important for the clinician to realize that return of peripheral motor activity does not signify a completely recovered cholinergic synapse. Instead of having a four- to five-fold margin of safety, the infant remains close to the point of neuromuscular blockade. Added insults or stress to neuromuscular transmission may precipitate respiratory failure. An understanding of the signs associated with progressive impairment of cholinergic synapses both during onset and during resolution of disease will allow safe care of the infant and will diminish the risk of iatrogenic complications. Evaluation of head control is the most sensitive physical finding indicative of return of adequate neuromuscular function and signifies that oral feedings can be reinstituted.