HY Lecture notes:
Travelers diarrhea –> dude goes traveling and gets self-limiting watery diarrhea; sometimes green; but the point is it’s not liters and liters of rice-water stool, which is instead cholera. Mexico is an obvious location, but Middle East is on one of the newer 2CK IM assessments. Cause is ETEC HL and HS toxins.
Treat C. difficile with oral vancomycin. Used to be oral metro, but this is now a WRONG answer. As of February 2018, guidelines were updated for oral vancomycin first-line.
Vanc has terrible oral bioavailability and is usually given IV, but in the case of C. difficile, it makes sense that it should stay confined to the bowel.
Diagnose C. difficile with stool AB toxin test, NOT stool culture. If colonoscopy is performed, shows pseudomembranes.
Mechanism of colonocyte necrosis is cytoskeletal disruption (Step 1).
Toxic megacolon diagnose with abdominal x-ray. Do laparotomy.
C. jejuni you get from poultry (chicken), not beef. Most common cause of bacterial gastroenteritis in adults in the US. Bloody stool. Gram (-) rod with 1-3-day incubation period. Can cause Guillain-Barre syndrome.
Entamoeba histolytica causes bloody stool. Treat with metronidazole + iodoquinol. Can also use paromomycin.
Vaccines (also discussed a bit in internal medicine #7 lecture, sorry about occasional repeat info. But let that reinforce for you that certain things are really HY).
At birth: Hep B (+ vitamin K)
2, 4, 6 months: Pneumococcal PCV13, rotavirus (live oral), H. influenzae type B, TdP, Polio Salk (killed, IM), Hep B.
New guidelines might not require Hep B at 4 months.
Give MMR first dose at 12-15 months; second dose 4-6 years.
Varicella give 12-18 months.
HPV give age 9-45 years.
Influenza give starting at 6 months (killed IM); can give to pregnant women; give every year in fall/winter; can give live nasal spray vaccine to non-pregnant, non-immunocompromised persons age 2-49.
Yersinia enterocolitica causes bloody diarrhea with appendicitis-like pain (pseudoappendicitis). Can cause arthritis in adults.
Dude gets shortness of breath walking up stairs –> needs a stress test; classically ECG-excercise stress test. But if patient has abnormal baseline ECG (such as BBB), must do echo-exercise stress test.
USMLE loves pulmonary capillary wedge pressure (PCWP). Increased in cardiogenic shock, or any cause of left heart path, e.g., MI, LVH, mitral regurg, etc.
Pericarditis –> diffuse ST elevations on ECG; pain worse supine, better when leaning forward; treatment = NSAIDs, steroids, colchicine; can be caused by autoimmune disease like RA (serous); can also be caused by MI soon after (post-MI fibrinous pericarditis) or 2-6 weeks after MI (Dresser syndrome; also a fibrinous pericarditis but is antibody-mediated).
Pericardial effusion + tamponade = electrical alternans on ECG.
Tamponade is a pericardial effusion, but there’s also hemodynamic decompensation (low BP).
This is because the heart can’t fill bc of the pressure of the fluid compressing the heart.
Tamponade presents with Beck Triad (hypotension, JVD, muffled heart sounds). Also has pulsus paradoxus (drop in systolic BP >10 mm Hg with inspiration; reflects inability of heart to fill).
Acuteness of fluid accumulation is >>> more important than volume, i.e., stab wound or post-MI LV free-wall rupture with fast-accumulating low-volume effusion can cause tamponade, but higher volume effusion that accumulates slowly might not cause tamponade, e.g., lymphoma.
For tamponade, do echo before pericardiocentesis. Echo must be done first to confirm the tamponade, then the pericardiocentesis is done to treat. This is on the NBME.
Pericardial window can also be an answer instead of pericardiocentesis. There’s a question on one of the newer NBMEs for 2CK where there’s a woman with breast cancer leading to tamponade, and the answer is pericardial window (pericardiocentesis wasn’t listed as an answer).
