Culture confirmed empyema in the absence of biomarker elevation: immune response dissociation.

We report a man in his 90s who was referred to our pleural clinic with a left-sided moderate large pleural effusion. Despite the absence of systemic inflammatory features and normal serum inflammatory markers, pleural fluid microbiology was diagnostic of empyema. Initially, the patient was treated with a short course of antibiotics, as the clinical impression of the multidisciplinary team was that the presentation did not align with typical systemic inflammatory features of empyema. However, recurrence of the effusion after drainage led to further bacterial growth from repeat samples, ultimately clarifying the diagnosis. This illustrates how an attenuated systemic inflammatory response, consistent with immunosenescence, can complicate the diagnosis and management of pleural infection in elderly patients.