Bacteria and Toxins Flashcards
Major virulence of LPS
Lipid A
Question
B. H flu
This patient with a history of chronic obstructive pulmonary disease (COPD) has worsened respiratory status (dyspnea, wheezes, pursed breathing) and purulent sputum production, raising strong suspicion for COPD exacerbation. The majority of COPD exacerbations are caused by infections of the upper airway. Infection results in mucus hypersecretion, damage to ciliated cells, cytokine-mediated airway inflammation, and increased respiratory capillary permeability, which can worsen existing airflow obstruction and lead to COPD exacerbation.
Most COPD exacerbations are due to common upper respiratory pathogens including Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis, and rhinovirus. However, patients with severe COPD are also at risk for more opportunistic pathogens such as Pseudomonas aeruginosa. COPD exacerbation can also be induced by exposure to allergens (leading to eosinophilic inflammation of the airway) and environmental pollution.
(Choice A) Bordetella pertussis causes whooping cough, which is characterized by a week or two of nonspecific symptoms followed by severe, paroxysmal cough. It is not a typical cause of COPD exacerbation, partially because vaccination against B pertussis makes this pathogen less common.
(Choice C) Klebsiella pneumoniae is a common cause of nosocomial pneumonia and may cause community-acquired pneumonia in patients with COPD; it is characterized by “currant-jelly” sputum and early abscess formation.
(Choice D) Legionella pneumonia is a common cause of atypical pneumonia and often presents with a few days of gastrointestinal symptoms followed by high fever and pulmonary symptoms.
(Choice E) Staphylococcus aureus is a common cause of postinfluenza pneumonia. However, patients with pneumonia have an infiltrate on chest x-ray (unlike this patient).
(Choice F) Streptococcus pyogenes is a common cause of acute bacterial pharyngitis but does not usually cause COPD exacerbation.
Educational objective:
Most chronic obstructive pulmonary disease exacerbations are caused by infection with an upper respiratory pathogen. The leading bacterial cause is Haemophilus influenza and the leading viral cause is rhinovirus.
Question
C. stool test bacterial toxins
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.
Infantile Botulism
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.
Infantile Botulism pathogenesis
Infantile Botulism presentation
Infantile Botulism Dx
