Infectious DiseasesTier 2Disease (DEADMAN)

Infections in the immunocompromised host, such as those with diabetes mellitus, HIV, and those receiving immunosuppressive therapies

Description

Immunocompromised hosts (diabetes, HIV, immunosuppressive/biologic therapy, transplant recipients) face both elevated infection risk and atypical presentation - the specific pattern of immune impairment (neutrophil, cell-mediated, humoral) predicts the characteristic organism spectrum at risk, shaping empirical management before culture results return

An increasingly large and heterogeneous patient population given the growing use of immunosuppressive/biologic therapy across many specialties, alongside the persistent burden of diabetes and HIV globally

Neutrophil defects (chemotherapy-induced neutropenia) predispose to bacterial and fungal infection; cell-mediated (T-cell) defects (advanced HIV, calcineurin inhibitors, high-dose corticosteroids) predispose to intracellular pathogens (viral reactivation, fungal, mycobacterial, certain parasitic infections); humoral (B-cell/antibody) defects predispose to encapsulated bacterial infection - matching the specific deficit to its characteristic infection pattern narrows the differential substantially

Diagnostic threshold should be lower and investigation broader than in immunocompetent patients, given both higher pre-test probability of serious infection and blunted/atypical clinical signs (reduced fever response, reduced localising inflammatory signs) that can mask severity
Specific screening (e.g. latent TB, Strongyloides, hepatitis B) before starting significant immunosuppression identifies risks that could otherwise reactivate/progress once treatment begins

Empirical broad-spectrum treatment with a low threshold for clinical concern, given the risk of rapid deterioration and reduced ability to localise a source through clinical examination alone in significantly immunocompromised patients
Specific prophylaxis (e.g. Pneumocystis jirovecii pneumonia prophylaxis with significant T-cell suppression, antifungal prophylaxis in prolonged neutropenia) is used proactively in defined high-risk scenarios rather than only treating established infection

Febrile neutropenia (a specific emergency, see ), Pneumocystis jirovecii pneumonia (T-cell suppression), diabetes-associated infection risk (skin/soft tissue, invasive fungal - e.g. mucormycosis), opportunistic infection prophylaxis strategies

The specific pattern of immune impairment (neutrophil vs T-cell vs B-cell) predicts a distinct characteristic infection spectrum - understanding which arm of immunity is affected in a given patient (rather than treating "immunocompromised" as a single uniform risk category) allows more targeted empirical treatment and prophylaxis decisions

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