Opportunistic Infection Prophylaxis
Pneumocystis jirovecii pneumonia (PCP), Toxoplasma gondii encephalitis, and Mycobacterium avium complex (MAC) are the three main ones you need to worry about.
What you need to memorize are the CD4 counts where you’d need to begin prophylaxis, and the drugs we use to prophylax with.
Conveniently, sulfamethoxazole-trimethoprim (SMZ/TMP) covers both PCP and toxoplasma. So when you start a patient on PCP prophylaxis, you are also covering toxo. MAC is covered with either azithromycin (preferred) or clarithromycin. To summarize;
CD4 < 200 = PCP (SMZ/TMP)
CD4 < 100 = Toxo (also SMZ/TMP)
CD4 < 50 = MAC (azithromycin or clarithromycin)