A 17-year-old boy comes to the emergency department because of a 3-day history of pain in his left wrist. That morning the pain increased and he started to have chills and malaise. Last week he had self-resolving left knee pain. He is otherwise healthy and has not had any trauma to the wrist. He recently returned from a camping trip to Minnesota. He is sexually active with one female partner, who uses a diaphragm for contraception. His temperature is 38.7°C (101.7°F). Examination shows several painless violaceous vesiculopustular lesions on the dorsum of both wrists and hands; two lesions are present on the left palm. There is swelling and erythema of the left wrist with severe tenderness to palpation and passive movement. Gram-negative bacteria isolated from this patient's blood produce an enzyme that splits the IgA molecule at the hinge region. Which of the following is likely to be the most important role of this bacterial enzyme in the course of the infection?

Question

A 17-year-old boy comes to the emergency department because of a 3-day history of pain in his left wrist. That morning the pain increased and he started to have chills and malaise. Last week he had self-resolving left knee pain. He is otherwise healthy and has not had any trauma to the wrist. He recently returned from a camping trip to Minnesota. He is sexually active with one female partner, who uses a diaphragm for contraception. His temperature is 38.7°C (101.7°F). Examination shows several painless violaceous vesiculopustular lesions on the dorsum of both wrists and hands; two lesions are present on the left palm. There is swelling and erythema of the left wrist with severe tenderness to palpation and passive movement. Gram-negative bacteria isolated from this patient's blood produce an enzyme that splits the IgA molecule at the hinge region.  Which of the following is likely to be the most important role of this bacterial enzyme in the course of the infection?

Quizplus · Accepted Answer

Eductional Objective: IgA protease is produced by Neisseria meningitidis, N gonorrhoeae, Streptococcus pneumoniae, and Haemophilus influenzae.  This enzyme cleaves secretory IgA at its hinge region, rendering it ineffective.  Secretory IgA exists on mucosal surfaces and in secretions and acts to bind and inhibit the action of pili as well as other cell surface antigens that normally mediate mucosal adherence and subsequent penetration.

A 17-Year-Old Boy Comes to the Emergency Department Because of a 3-Day