Explanations for the 2019 Official Step 1 Practice Questions

The 2019 set was recently updated in February. Of the 117 questions in the PDF, only two have been changed, which I’ve answered below. The order and content otherwise appear unchanged, including the three multimedia questions at the end of the online version.


Please see last year’s 2018 explanations for the remainder.

The many comments at the bottom of that page may prove helpful for those with additional questions. You’re never the only one to struggle.


48. E – When people go camping, you should be thinking of zoonotic infections. Fun fact, New Mexico leads the country in cases of plague. Yes, that plague: Yersinia pestis. The “bubonic” part of bubonic plague refers to the swollen infected nodes (“buboes”) characteristic of the disease, which often involve the groin (bubo is the Greek word for groin, who knew?). In this case, they’re also describing a necrotic epitrochlear node. Classic treatment is with aminoglycosides, which bind to the 30s ribosomal subunit.

69. E – Catalase and coagulase-positive gram-positive cocci = staph aureus. mecA-positivity means the bacteria carry the gene that confers methicillin-resistance, hence MRSA. Of the choices, MRSA is treated with vancomycin.

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