A previously healthy 3-week-old infant is brought to the emergency department 6 hours after the onset of fever and persistent irritability. He had been well until 2 days ago, when he started feeding poorly and sleeping more than usual. He appears lethargic and irritable when roused for examination. His temperature is 39.0°C (102°F). He cries when he is picked up and when his neck is flexed. The remainder of the physical and neurological examinations show no other abnormalities. His serum glucose is 95 mg/mL. His total serum bilirubin is 6.3 mg/dL. CSF culture grows numerous gray colonies on blood agar, with a narrow area of clearing surrounding each colony. Gram staining shows gram-positive cocci in short chains. Which of the following virulence factors is primarily involved in the pathogenesis of this patient's infection?

Question

A previously healthy 3-week-old infant is brought to the emergency department 6 hours after the onset of fever and persistent irritability. He had been well until 2 days ago, when he started feeding poorly and sleeping more than usual. He appears lethargic and irritable when roused for examination. His temperature is 39.0°C (102°F). He cries when he is picked up and when his neck is flexed. The remainder of the physical and neurological examinations show no other abnormalities. His serum glucose is 95 mg/mL. His total serum bilirubin is 6.3 mg/dL. CSF culture grows numerous gray colonies on blood agar, with a narrow area of clearing surrounding each colony.  Gram staining shows gram-positive cocci in short chains.  Which of the following virulence factors is primarily involved in the pathogenesis of this patient's infection?

Quizplus · Accepted Answer

Eductional Objective: Group B Streptococcus is a common cause of neonatal meningitis.  Its major virulence factor is a polysaccharide capsule with abundant sialic acid, which dramatically reduces the effectiveness of host defense mechanisms due to molecular mimicry.

A Previously Healthy 3-Week-Old Infant Is Brought to the Emergency