A 31-year-old man is brought to the emergency department by his friends due to 2 weeks of headaches and progressive confusion. His friends note that he has also been aggressive and inappropriately suspicious, which is not typical for him. The patient is a flight attendant and frequently works on international flights. He has a history of HIV infection and sometimes skips antiretroviral therapy when he travels. His friends are unsure if he takes other prophylactic medications. Temperature is 38.6 C (101.5 F), blood pressure is 118/80 mm Hg, and pulse is 102/min. The patient appears unkempt and is disoriented. Neurologic examination shows ataxia and right-sided hemiparesis. Brain MRI findings are shown in the image below. Which of the following would have most likely prevented this patient's condition?

Question

A 31-year-old man is brought to the emergency department by his friends due to 2 weeks of headaches and progressive confusion.  His friends note that he has also been aggressive and inappropriately suspicious, which is not typical for him.  The patient is a flight attendant and frequently works on international flights.  He has a history of HIV infection and sometimes skips antiretroviral therapy when he travels.  His friends are unsure if he takes other prophylactic medications.  Temperature is 38.6 C (101.5 F), blood pressure is 118/80 mm Hg, and pulse is 102/min.  The patient appears unkempt and is disoriented.  Neurologic examination shows ataxia and right-sided hemiparesis.  Brain MRI findings are shown in the image below.  Which of the following would have most likely prevented this patient's condition?

Quizplus · Accepted Answer

11ec25c8_d471_6285_bc81_6bfa33b3a056_MD0003_00 This patient with HIV has neurologic symptoms (headache, confusion, focal deficits), fever, and evidence of ring-enhancing lesions on MRI, raising strong suspicion for toxoplasmosis. Most cases occur due to reactivation of Toxoplasma gondii, a widely prevalent intracellular protozoan, due to severe deficits in cell-mediated immunity (eg, AIDS with CD4 counts <100/mm³). Primary prophylaxis against toxoplasmosis is highly effective at preventing the condition in those with advanced AIDS. Therefore, all patients with HIV undergo laboratory evaluation (T gondii IgG testing) for exposure; those with positive serology who have a CD4 count <100/mm³ require primary prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX), which reduces the risk of toxoplasmosis to 0%-2%. Patients on antiretroviral treatment can usually discontinue TMP-SMX prophylaxis when their CD4 count is >200/mm³ for 3 months (and there is adequate viral suppression). TMP-SMX is also used for primary prophylaxis against Pneumocystis pneumonia for those with a CD4 count <200/mm³. (Choice A) Acyclovir is used to treat the herpes simplex virus (HSV). HSV encephalitis often causes focal neurologic findings and confusion, but an MRI usually reveals unilateral temporal lobe lesions (not widespread ring-enhancing lesions). Acyclovir primary prophylaxis is not generally recommended in patients with AIDS, but secondary prophylaxis (to prevent frequent flairs) is sometimes given. (Choice B) Albendazole is used for treatment of neurocysticercosis, which most commonly causes seizures and leads to cystic, enhancing, or calcified lesions on neuroimaging. Albendazole is not typically used as a primary preventive agent. (Choice C) Fluconazole is occasionally used for primary prophylaxis against coccidioidomycosis (for those in endemic areas with newly converted serology). Coccidioidomycosis primarily manifests with pulmonary disease but occasionally causes meningitis. However, multiple ring-enhancing lesions would be atypical. Fluconazole is also used as secondary prophylaxis (suppressive therapy) for those with a history of cryptococcus meningitis (when CD4 count is still low); fluconazole is not used as primary prophylaxis for cryptococcus, and cryptococcus does not typically cause ring-enhancing brain lesions. (Choice D) Ganciclovir can be used to treat cytomegalovirus (CMV) but is not typically used for primary prophylaxis in patients with AIDS. It is used for primary prophylaxis against CMV in some patients with solid organ transplantation. Educational objective: Toxoplasmosis is a common opportunistic infection in patients with AIDS who have CD4 counts <100/mm³. Primary prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX) prevents active infection; TMP-SMX is generally given to patients with AIDS who have CD4 counts <100/mm³ and positive Toxoplasma gondii IgG serology. TMP-SMX is also effective in preventing Pneumocystis pneumonia. References: Prevention and treatment of opportunistic infections in HIV-infected adults and adolescents: updated guidelines from the Centers for Disease Control and Prevention, National Institutes of Health, and HIV Medicine Association of the Infectious Diseases Society of America. (http://www.ncbi.nlm.nih.gov/pubmed/24585567)

A 31-Year-Old Man Is Brought to the Emergency Department by His