American Board of Internal Medicine (ABIM) Certification Practice Exam

In which scenario is ampicillin indicated for meningitis treatment?

1. Patients younger than 50 years with no immunodeficiency

2. All patients diagnosed with meningitis

3. Patients older than 50 years or with impaired cell-mediated immunity

4. Only patients with bacterial meningitis

The correct answer is: Patients older than 50 years or with impaired cell-mediated immunity

Ampicillin is indicated in the treatment of meningitis in patients who are older than 50 years or who have impaired cell-mediated immunity due to its effectiveness against Listeria monocytogenes, which is a common cause of meningitis in these specific populations. In older adults and those with compromised immune systems, the risk of infection caused by Listeria increases, making ampicillin a critical choice in their treatment regimen. In the case of patients younger than 50 years with no immunodeficiency, commonly encountered pathogens such as Streptococcus pneumoniae and Neisseria meningitidis are typically addressed with other antibiotics, rendering ampicillin unnecessary for that demographic. While all patients diagnosed with meningitis require antibiotic treatment, the choice of antibiotic would depend on their specific risk profile, and not all cases would necessitate the use of ampicillin. Additionally, while bacterial meningitis is the context in which ampicillin is considered, it is vital to select it based on the patient's age and immune status, rather than applying it indiscriminately to all types of meningitis or patients.