A 42-year-old woman with a history of multiple sclerosis and recurrent urinary tract infections comes to the emergency department because of flank pain and fever. Her temperature is 38.8°C (101.8°F). Examination shows left-sided costovertebral angle tenderness. She is admitted to the hospital and started on intravenous vancomycin. Three days later, her symptoms have not improved. Urine culture shows growth of Enterococcus faecalis. Which of the following best describes the most likely mechanism of antibiotic resistance in this patient?
AIncreased efflux across bacterial cell membranes
BProduction of beta-lactamase
CAlteration of penicillin-binding proteins
DAlteration of peptidoglycan synthesis
EAlteration of ribosomal targets
A 45-year-old man comes to the physician because of a 1-month history of fever and poor appetite. Five weeks ago, he underwent molar extraction for dental caries. His temperature is 38°C (100.4°F). Cardiac examination shows a grade 2/6 holosystolic murmur heard best at the apex. A blood culture shows gram-positive, catalase-negative cocci. Transesophageal echocardiography shows a small vegetation on the mitral valve with mild regurgitation. The causal organism most likely has which of the following characteristics?
AProduction of dextrans
BProduction of CAMP factor
CConversion of fibrinogen to fibrin
DFormation of germ tubes at body temperature
EReplication in host macrophages
An investigator is studying the growth of an organism in different media. The organism is inoculated on a petri dish that contains heated sheep blood, vancomycin, nystatin, trimethoprim, and colistin. The resulting growth medium is incubated at 37°C. Numerous small, white colonies are seen after incubation for 48 hours. This organism is most likely to cause which of the following conditions?
APontiac fever
BPseudomembranous colitis
CHemolytic uremic syndrome
DOral thrush
EGonorrhea
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