5-Minute Emergency Consult
Opportunistic Infections
Basics
Description
Infections caused by organisms that do not normally cause disease but are pathogenic in an impaired immune system
Etiology
- Occurs in patients with HIV when the CD4 T-lymphocyte count falls below 200 cells/mm3:
- Pneumocystis jirovecii pneumonia (PJP)
- Mycobacterium tuberculosis
- Cryptosporidiosis
- Toxoplasmosis
- Histoplasmosis
- Cryptococcosis
- Mycobacterium avium complex
- Candidiasis
- Cytomegalovirus
- Human herpesvirus-8 (Kaposi sarcoma)
- JC virus (progressive multifocal leukoencephalopathy)
- Hepatitis B virus
- Penicilliosis marneffei
- Bacterial species
- Cell-mediated deficiency:
- Hematologic malignancies
- Lymphoma
- High-dose glucocorticoid therapy
- Autoimmune disorders
- Viral infections
- Cytotoxic drugs/chemotherapy
- Radiation therapy
- Associated with:
- Legionella
- Nocardia
- Salmonella
- Mycobacteria
- Neutrophil impairment/depletion:
- Cytotoxic drugs
- Aplastic anemia
- Drug reactions:
- Dapsone
- Neoplastic invasion of bone marrow
- Arsenic
- Penicillin
- Chloramphenicol
- Procainamide
- Vitamin deficiencies
- Associated with:
- Staphylococcus and α-hemolytic Streptococcus
- Enteric organisms and anaerobes
- Invasive aspergillosis
- Immunomodulatory drugs:
- TNF-α inhibitors
- Inflixamab > etanercept
- Rituximab
- Adalimumab
- Azathioprine
- TNF-α inhibitors
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Citation
Schaider, Jeffrey J., et al., editors. "Opportunistic Infections." 5-Minute Emergency Consult, 7th ed., Wolters Kluwer, 2027. Emergency Central, emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307680/2.1/Opportunistic_Infections_.
Opportunistic Infections. In: Schaider JJJ, Barkin RMR, Hayden SRS, et al, eds. 5-Minute Emergency Consult. Wolters Kluwer; 2027. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307680/2.1/Opportunistic_Infections_. Accessed July 17, 2026.
Opportunistic Infections. (2027). In Schaider, J. J., Barkin, R. M., Hayden, S. R., Wolfe, R. E., Barkin, A. Z., Shayne, P., & Rosen, P. (Eds.), 5-Minute Emergency Consult (7th ed.). Wolters Kluwer. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307680/2.1/Opportunistic_Infections_
Opportunistic Infections [Internet]. In: Schaider JJJ, Barkin RMR, Hayden SRS, et al, eds. 5-Minute Emergency Consult. Wolters Kluwer; 2027. [cited 2026 July 17]. Available from: https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307680/2.1/Opportunistic_Infections_.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC
T1 - Opportunistic Infections
ID - 307680
ED - Barkin,Adam Z,
ED - Shayne,Philip,
ED - Rosen,Peter,
ED - Schaider,Jeffrey J,
ED - Barkin,Roger M,
ED - Hayden,Stephen R,
ED - Wolfe,Richard E,
BT - 5-Minute Emergency Consult
UR - https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307680/2.1/Opportunistic_Infections_
PB - Wolters Kluwer
ET - 7
DB - Emergency Central
DP - Unbound Medicine
ER -
