Infections in Immunocompromised Hosts

source: Pocket Medicine, 2022

• Many Pts have ≥1 risk (eg, DM, ESRD, transplant, extremes of age)
• Accurate dx of opportunistic infections and targeted Rx key in this population
• The following is not an exhaustive list, but a delineation of common or classic etiologies

Predisposition	Classic Infectious Etiologies
Humoral immune dysfunction (eg, CVID, myeloma) and asplenia	Encapsulated bacteria: **S. pneumo, H. flu, N. meningitidis (vaccinate against these 3, ideally prior to splenectomy) Other bacteria:E. coli and other GNRs, Capnocytophaga Parasites:** _Babesia, Giardia; _*Viruses: *VZV, echovirus, enterovirus
Granulocytopenia or neutropenia (includes DM, ESRD → functional impairment)	Bacteria: Gram positive: coag ⊖ staph, S. aureus, viridans strep, S. pneumo, other strep; Corynebacterium spp., Bacillus spp. Gram negative: E. coli, Klebsiella, Pseudomonas Fungi: Yeast: Candida albicans and other Candida spp. Molds: Aspergillus, Mucor spp., endemic fungi and others Viruses: VZV, HSV1 and 2, CMV
Impaired cell-mediated immunity (CMI) (eg, HIV/AIDS, chronic steroids, posttransplant, DM, ESRD, autoimmune dis.)	Bacteria: Salmonella spp., Campylobacter, Listeria, Yersinia, Legionella(Lancet 2016;387:376), Rhodococcus, Nocardia, TB, non-TB mycobacteria Fungi: Candida, Crypto, Histo, Coccidio, Aspergillus, Pneumocystis, Zygomycetes spp. and other molds Viruses: HSV, VZV, CMV, EBV, JC virus, BK virus Parasites: Toxoplasma, Cryptosporidium, Isospora, Microsporidia Babesia; Strongyloides
Organ dysfunction	Liver (esp. cirrhosis): Vibrio spp., encapsulated bacteria ESRD: impaired granulocyte fxn and CMI as above Iron overload (or deferoxamine Rx): Yersinia, Zygomycetes
Biologics (eg, TNF inhibitors, anti-B-cell Rx; ✓ for TB before starting)	Bacteria: sepsis, septic arthritis, TB, NTM, Listeria, Legionella Fungi: Pneumocystis, Histo, Coccidio, Aspergillus, endemic fungi Viruses: JC virus (PML), EBV, HSV, VZV, HBV Parasites: Strongyloides reactivation