A 62-year-old man with a history of chronic obstructive pulmonary disease (COPD) came to the emergency department because of a fever of 40° C, chills, nausea, vomiting, and hypotension. The patient also produced tenacious yellowish sputum that had increased in quantity over the preceding 3 days. His respiratory rate was 18 breaths/min, and his blood pressure was 94/52 mm Hg. Chest radiographic examination showed extensive infiltrates in the left lower lung that involved both the lower lobe and the lingula. Multiple blood cultures and culture of the sputum yielded S. pneumoniae. The isolate was susceptible to cefazolin, vancomycin, and erythromycin but resistant to penicillin.
1. What predisposing condition made this patient more susceptible to pneumonia and bacteremia caused by S. pneumoniae? What other populations of patients are susceptible to these infections? What other infections does this organism cause, and what populations are most susceptible?
2. What is the mechanism most likely responsible for this isolate’s resistance to penicillin?
3. What infections are caused by S. pyogenes, S. agalactiae, S. anginosus, S. dysgalactiae, and viridans streptococci?
4. What are the major virulence factors of S. pneumoniae, S. pyogenes, and S. agalactiae?
5. S. pyogenes can cause streptococcal toxic shock syndrome. How does this disease differ from the disease produced by staphylococci?
6. What two nonsuppurative diseases can develop after localized S. pyogenes disease?