Infeksi, Imunologi, dan Hematologi
Core concepts
Infectious disease: interpret fever with a focus on source, use cultures before antibiotics when feasible, and know common pathogens by site and host. Understand sepsis and septic shock bundles, antimicrobial stewardship, and the principles of isolation. HIV: testing, staging, opportunistic infection prophylaxis, and antiretroviral principles. Immunology: primary immunodeficiency warning signs, anaphylaxis, and vaccination principles. Haematology: anaemia classification by mean corpuscular volume, iron studies, and the approach to bleeding and thrombosis, including heparin-induced thrombocytopenia and disseminated intravascular coagulation.
Traps
Do not delay antibiotics for cultures in septic shock - take cultures rapidly but treat within the hour. Iron deficiency has low ferritin; anaemia of chronic disease has normal or high ferritin with low transferrin saturation. In DIC, platelets and fibrinogen fall while D-dimer rises. Anaphylaxis is treated with intramuscular adrenaline first, not antihistamines. Remember that a normal white cell count does not exclude serious infection.
Worked example
A 28-year-old with fever, hypotension, tachycardia, and a suspected urinary source. Diagnosis: septic shock. Rule of thumb: obtain blood and urine cultures, give broad-spectrum antibiotics within one hour, and give 30 mL/kg crystalloid for initial resuscitation, then reassess perfusion and start vasopressors if hypotension persists.