A Review of Opportunistic Infections in Modern Immunosuppressed Populations
Article Sidebar
Main Article Content
Abstract
Opportunistic infections are a major clinical concern in individuals with impaired immune systems. More widespread organ transplantation, chemotherapy, biologic therapies and long-term corticosteroids had created a population at greater risk of such infections. Consequently, a variety of patients including not only those with late-stage HIV infection have been affected by opportunistic pathogens.
The type and degree of immune deficiency affect the range of potential infections. Neutropenia, for example, is known to come with severe bacterial and invasive fungal infection; defects in T-cell immunity led to increased susceptibility to viral reactivation and infections by intracellular pathogens. Early recognition and application of appropriate diagnostic strategies are key to maximizing patient outcomes.
New diagnostic tools, including molecular tests and metagenomic sequencing have enhanced pathogen diagnosis in the immunocompromised. Successful management requires early initiation of antimicrobial therapy, targeted adjustment of immunosuppression and supportive clinical care. Other critical preventive strategies include vaccination, antimicrobial prophylactic measures, screening for latent infections and establishing infection-control practices.
This review describes the common pathogens, risk factors, diagnostic approaches and preventive measures relevant to opportunistic infections in modern immunocompromised populations.
Article Details
This work is licensed under a Creative Commons Attribution 4.0 International License.
References
Fishman JA. Infection in solid-organ transplant recipients. N Engl J Med. 2007;357(25):2601–14. doi:10.1056/NEJMra064928.
Fishman JA. Opportunistic infections—coming to the limits of immunosuppression? Cold Spring Harb Perspect Med. 2013;3(10):a015669. https://doi.org/10.1101/cshperspect.a015669.
Dropulic LK, Lederman HM. Overview of infections in the immunocompromised host. Microbiol Spectr. 2016;4(4).
Duhaniuc A, Păduraru D, Nastase EV, et al. Multidrug-Resistant Bacteria in Immunocompromised Patients. Pharmaceuticals (Basel). 2024;17(9):1151. doi:10.3390/ph17091151
Ullah N, Fusco L, Ametrano L, et al. Diagnostic Approach to Pneumonia in Immunocompromised Hosts. J Clin Med. 2025;14(2):389. doi:10.3390/jcm14020389
Azoulay E, Russell L, van de Louw A, et al. Diagnosis of severe respiratory infections in immunocompromised patients. Intensive Care Med. 2020;46(2):298–314. doi:10.1007/s00134-019-05906-5.
Wang H, Zhao B. Diagnostic value of bronchoalveolar lavage fluid metagenomic next-generation sequencing for pulmonary infections in patients with connective tissue disease: a retrospective study. Sci Rep. 2025;15:20042.
Costa VS, Cidade JP, Medeiros I, Fidalgo P, Moreira H, Miranda T, Póvoa P. Pneumocystis jirovecii Pneumonia Diagnosis with Oropharyngeal Wash PCR in Immunocompromised Patients-A Systematic Review. J Clin Med. 2025;14(18):6572. doi: 10.3390/jcm14186572.
NIH ClinicalInfo. Pneumocystis Pneumonia: Adult and Adolescent OIs. Updated Sep 9, 2025. https://clinicalinfo.hiv.gov/en/guidelines/hiv-clinical-guidelines-adult-and-adolescent-opportunistic-infections/pneumocystis.
NIH ClinicalInfo. Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents with HIV (compiled guideline PDF). 2025. https://clinicalinfo.hiv.gov/en/guidelines/hiv-clinical-guidelines-adult-and-adolescent-opportunistic-infections/introduction.
NIH ClinicalInfo. Bacterial Enteric Infections: Adult and Adolescent OIs. Updated Jan 26, 2026. https://clinicalinfo.hiv.gov/en/guidelines/hiv-clinical-guidelines-adult-and-adolescent-opportunistic-infections/bacterial-enteric
Taplitz RA, Kennedy EB, Bow EJ, et al. Antimicrobial prophylaxis for adult patients with cancer-related immunosuppression:. ASCO and IDSA Clinical Practice Guideline Update. J Clin Oncol. 2018;36(30):3043-54. doi: 10.1200/JCO.18.00374.
Pagano, L., Maschmeyer, G., Lamoth, F. et al. Primary antifungal prophylaxis in hematological malignancies. Updated clinical practice guidelines by the European Conference on Infections in Leukemia (ECIL). Leukemia 2025; 39:1547–57. https://doi.org/10.1038/s41375-025-02586-7
Van Rhijn N, White PL. Antifungal treatment strategies and their impact on resistance development in clinical settings. J Antimicrob Chemother. 2025;80(12):3208-3226. doi: 10.1093/jac/dkaf382.
Cornely OA, Alastruey-Izquierdo A, Arenz D, et al. Global guideline for the diagnosis and management of mucormycosis: an initiative of the European Confederation of Medical Mycology in cooperation with the Mycoses Study Group Education and Research Consortium. Lancet Infect Dis. 2019;19(12):405-421. doi:10.1016/S1473-3099(19)30312-3
Kotton CN, Kumar D, Manuel O, et al. The Fourth International Consensus Guidelines on the Management of Cytomegalovirus in Solid Organ Transplantation.Transplantation.2025;109(7):1066-1110. doi:10.1097/TP.0000000000005374
CDC. Treatment for Latent Tuberculosis Infection. Updated Apr 17, 2025. https://www.cdc.gov/tb/hcp/treatment/latent-tuberculosis-infection.html
CDC. Clinical Overview of Latent Tuberculosis Infection. Updated Apr 17, 2025.https://www.cdc.gov/tb/hcp/clinical-overview/latent-tuberculosis-infection.html
Palomba E, Liparoti A, Tonizzo A, et al. Nocardia Infections in the Immunocompromised Host: A Case Series and Literature Review. Microorganisms. 2022;10(6):1120. doi:10.3390/microorganisms10061120
Strick LB, Wald A, Celum C. Management of Herpes Simplex Virus Type 2 Infection in HIV Type 1–Infected Persons. Clinical Infectious Diseases. 2006;43(3):347–356.
NIH Clinical Info. Varicella-Zoster Virus Disease: Adult and Adolescent OIs. Updated Sep 7, 2022. https://clinicalinfo.hiv.gov/en/guidelines/hiv-clinical-guidelines-adult-and-adolescent-opportunistic-infections/varicella-zoster
NIH ClinicalInfo. Progressive Multifocal Leukoencephalopathy/JC Virus: Adult and Adolescent OIs. Updated Oct 19, 2022. https://clinicalinfo.hiv.gov/en/guidelines/hiv-clinical-guidelines-adult-and-adolescent-opportunistic-infections/progressive
Pappas PG, Kauffman CA, Andes DR, et al. Clinical Practice Guideline for the Management of Candidiasis: 2016 Update by the Infectious Diseases Society of America, Clin Infect Dis. 2016;62(4):e1–50. https://doi.org/10.1093/cid/civ933
Patterson TF, Thompson GR 3rd, Denning DW, et al. Practice Guidelines for the Diagnosis and Management of Aspergillosis: 2016 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2016;63(4):e1-e60. doi:10.1093/cid/ciw326
Sauvat L, Denis L, Nourrisson C, Poirier P, Ruivard M and Le Guenno G (2024). Pneumocystis jirovecii pneumonia in non-HIV patients: need for a more extended prophylaxis. Front. Med. 11:1414092. doi: 10.3389/fmed.2024.1414092
Lee R, Huh K, Kang CK, Kim YC, Kim JH, Kim H, Park JS, Park JY, Sung H, Jung J, Kim CJ, Song KH. Diagnosis of Pneumocystis jirovecii Pneumonia in Non-HIV Immunocompromised Patient in Korea: A Review and Algorithm Proposed by Expert Consensus Group. Infection & Chemotherapy. 2025 ;57(1):45-62. doi:10.3947/ic.2024.0148.
NIH ClinicalInfo. Cryptococcosis: Adult and Adolescent OIs. Updated Oct 29, 2024.
NIH ClinicalInfo. Histoplasmosis: Adult and Adolescent OIs. Updated Oct 29, 2024.
NIH ClinicalInfo. Coccidioidomycosis: Adult and Adolescent OIs. Updated Oct 29, 2024.
NIH ClinicalInfo. Toxoplasma gondii Encephalitis: Adult and Adolescent OIs. Updated Sep 9, 2025.
NIH ClinicalInfo. Cryptosporidiosis: Adult and Adolescent OIs. Updated Jan 18, 2023.
NIH ClinicalInfo. Microsporidiosis: Adult and Adolescent OIs. Updated Nov 14, 2023.
CDC. Clinical Overview of Strongyloides. Feb 11, 2026.
CDC. Clinical Care of Strongyloides. Feb 16, 2024.
CDC. Altered Immunocompetence: Vaccines & Immunizations Best Practices. Updated Jun 26, 2024.
Carnino L, Gobbi F, Angheben A, Bonazzetti C, Buonfrate D, Bisoffi Z, et al. Screening for Parasitic Infection and Tuberculosis in Immunosuppressed and Pre-Immunosuppressed Patients: An Observational Study. Tropical Medicine and Infectious Disease. 2021;6(3):170. doi:10.3390/tropicalmed6030170.