Diagnostic and Management Errors in an Immunodeficient Patient with Pneumococcal Pneumonia with Bacteraemia due to Incorrect Assessment of the Patient's Immune Status.

A 79-year-old woman presented with fever and pleural chest pain. Based on the assessment of mild community pneumonia in an immunocompetent patient, outpatient follow-up was planned. However, the patient was admitted several hours later with a diagnosis of pneumococcal pneumonia with bacteraemia. In addition, selective immunoglobulin M deficiency was detected. In this case, although a history of recurrent osteomyelitis was provided, the physicians overlooked the information suggesting immunodeficiency, which led to an incorrect diagnostic and management decision. Obtaining the past medical history is essential, but utilizing it is even more important to avoid clinical decision-making errors. LEARNING POINTS: Knowing the immune status of patients with infectious disease is vital for accurate clinical decision-making.Patients are sometimes unaware of their immunodeficiency despite having signs indicating indolent immunodeficiency, such as a history of recurrent osteomyelitis.Inferring and clarifying the immunodeficiency behind the patient's history was the turning point in this diagnosis. © EFIM 2021.