Synopsis
Predict infection from engraftment, graft-versus-host disease and immune recovery, investigate attenuated syndromes early, and integrate antimicrobials, viral surveillance and prophylaxis with transplant care.
- Before engraftment, neutropenia, mucositis and central access favour Gram-negative and Gram-positive bloodstream infection, enteric translocation, Candida, HSV and mould disease when neutropenia is prolonged.
- From engraftment to about day 100, impaired cellular immunity and acute graft-versus-host disease favour CMV, HHV-6, adenovirus, respiratory viruses, Pneumocystis and Aspergillus.
- After day 100, chronic graft-versus-host disease, corticosteroids, hypogammaglobulinaemia and delayed B- and T-cell recovery sustain VZV, Pneumocystis, mould and encapsulated-bacterial risk.
- Autologous HSCT usually has shorter neutropenia and no allogeneic graft-versus-host disease, so its prolonged opportunistic risk is lower unless treatment or disease creates another immune defect.
- First-line assessment always defines transplant type, day, engraftment, donor-recipient viral serology, graft-versus-host disease, current prophylaxis and the exact immunosuppressive regimen.
- Blood cultures and syndrome-led molecular tests come before antimicrobials when safe; CT, bronchoalveolar lavage, endoscopy or tissue may be needed because blood assays cannot prove every organ infection.
- Letermovir prevents CMV reactivation in eligible CMV-seropositive allogeneic recipients but has no HSV or VZV activity and does not replace quantitative CMV surveillance.
- The infection framework centres on immune phase and pathogen-directed sampling; conditioning toxicity, graft-versus-host disease treatment and donor-cell decisions remain owned by the transplant service.
Key red flags
Fever, hypothermia, rigors or any sepsis physiology before neutrophil recovery requires immediate neutropenic-sepsis treatment.
New hypoxaemia, dry cough or diffuse ground-glass change may be Pneumocystis, CMV, respiratory virus, mould, bacterial infection, diffuse alveolar haemorrhage or idiopathic pneumonia syndrome.
Severe watery or bloody diarrhoea, abdominal pain, ileus or dehydration requires urgent investigation for infection and gastrointestinal graft-versus-host disease.
Confusion, seizure, personality change, focal neurology or severe headache raises concern for HHV-6 encephalitis, fungal or bacterial CNS infection, toxoplasma, drug toxicity or posterior reversible encephalopathy.
Vesicular or disseminated rash, eye symptoms, mucosal ulceration or dermatomal pain may signal severe HSV or VZV and needs immediate antiviral and infection-control assessment.
Acute or chronic graft-versus-host disease requiring high-dose corticosteroids prolongs mould, CMV, Pneumocystis and encapsulated-bacterial risk beyond ordinary time boundaries.
Fever, rigors, mucositis, abdominal symptoms or line discomfort during profound neutropenia represents bacterial sepsis until treated, even when examination shows little inflammation.
Investigation priorities
Set the pre-test probability for bacterial, viral, fungal and non-infectious disease before selecting specialised tests.
Recover bacteria or yeast and detect marrow, kidney, liver, coagulation and perfusion abnormalities that change urgent therapy.
Management branches
Fever, rigors or clinical deterioration occurs before neutrophil recovery or during renewed profound neutropenia.
- Use the emergency neutropenic-sepsis pathway, take paired cultures rapidly and give locally approved antipseudomonal therapy without waiting for imaging or cell counts.
- Examine mouth, line, skin and abdomen, avoid rectal instrumentation and arrange urgent CT for abdominal danger signs or pulmonary features.
- Use previous colonisation and prophylaxis to identify resistant bacterial and breakthrough fungal gaps and involve microbiology at the first dose when standard cover may fail.
- Escalate persistent fever through CT, biomarkers and targeted sampling, then select mould-active treatment from prior prophylaxis, likely species, organ function and interactions.