View source for Respiratory infection in an immunocompromised person

==Differential Diagnosis==

===By Defect===
{| class="wikitable"
!Risk Factor
!Differential Diagnosis
!Investigations
|-
! colspan="3" |Cell-Mediated Immunodeficiency
|-
|Steroids and solid organ transplantation
| rowspan="4" |opportunistic infections, systemic viruses, [[Pneumocystis]], [[Cryptococcus]], [[Mycobacteria]], [[Toxoplasma]]
| rowspan="4" |sputum and blood culture, antigenuria, multiplex viral PCR, [[CMV]]/[[HSV]]/[[VZV]] PCR, bronchoalveolar lavage, [[Toxoplasma]]/[[Cryptococcus]] PCR, induced sputum, beta-D glucan
|-
|[[Hairy cell leukemia]], [[acute T-cell leukemia]], [[T-cell lymphoma]]
|-
|[[Fludarabine]], [[ibrutinib]], [[alemtuzumab]]
|-
|[[HIV]]
|-
! colspan="3" |Humoural Immunodeficiency
|-
|Splenectomy and asplenism
| rowspan="5" |bacterial pneumonia ([[Streptococcus pneumoniae]], [[Neisseria meningitidis]], [[Haemophilus influenzae]])
| rowspan="5" |sputum and blood cultures, antigenuria, multiplex viral PCR
|-
|Complement deficiency
|-
|[[Common variable immunodeficiency]]
|-
|[[Rituximab]] and other anti-CD20 therapy
|-
|[[Multiple myeloma]] and [[CLL]]
|-
! colspan="3" |Phagocyte Defects
|-
|Steroids and solid organ transplantation
| rowspan="5" |systemic viruses, [[Aspergillus]], [[Mycobacteria]], [[Nocardia]], [[Mucorales]], [[Toxoplasma]]
| rowspan="5" |sputum and blood cultures, antigenuria, multiplex viral PCR, [[CMV]]/[[HSV]]/[[VZV]] PCR, induced sputum, bronchoalveolar lavage, fungal culture of sputum, [[β-D glucan]] and [[galactomannan]], Aspergillus PCR, Toxoplasma/Cryptococcus PCR
|-
|[[Neutropenia]]
|-
|[[Myelodysplastic syndrome]]
|-
|[[Acute myelogenous leukemia]]
|-
|[[Allogeneic hematopoietic stem cell transplantation]]
|}

===By CT Pattern===
{| class="wikitable"
!Pattern
!Differential Diagnosis
!Investigations
|-
|nodular lesions
|bacterial pneumonia, [[Aspergillus]], [[Nocardia]], [[Mucorales]]
|sputum and blood cultures, antigenuria, sputum with fungal culture, [[Aspergillus]]/[[Mucorales]] PCR, [[galactomannan]] and [[β-D glucan]], bronchoalveolar lavage
|-
|septal thickening
|atypical bacterial pneumonia
|sputum and blood cultures, antigenuria, bronchoalveolar lavage
|-
|cavitations
|[[Mycobacteria]], [[Histoplasma]], bacterial pneumonia including [[Staphylococcus aureus]]
|sputum and blood cultures, mycobacterial culture, [[Histoplasma]] PCR
|-
|excavated nodules
|bacterial pneumonia, [[Mucorales]], [[Nocardia]], [[Actinomyces]], [[Aspergillus]]
|sputum and blood cultures, [[Aspergillus]]/[[Nocardia]]/[[Mucorales]] PCR, [[galactomannan]] and [[β-D glucan]]
|-
|consolidation
|bacterial pneumonia, [[Aspergillus]]
|sputum and blood cultures, antigenuria, sputum for fungal culture, [[galactomannan]] and [[β-D glucan]]
|-
|pleural effusion
|bacterial pneumonia, [[tuberculosis]]
|sputum and blood cultures, antigenuria, mycobacterial blood culture, pleural aspiration and culture
|-
|ground glass opacities
|[[Pneumocystis]], viral pneumonia, atypical bacterial pneumonia
|sputum and blood culture, [[Legionella]] antigenuria, sputum for [[Pneumocystis]], β-D glucan, multiplex viral PCR, [[CMV]]/[[VZV]]/[[HSV]] blood PCR, bronchoalveolar lavage
|}

==Further Reading==

*Diagnosis of severe respiratory infections in immunocompromised patients. ''Intensive Care Med''. 2020;46:298-314. doi: [https://doi.org/10.1007/s00134-019-05906-5 10.1007/s00134-019-05906-5]

[[Category:Immunocompromised hosts]]
[[Category:Respiratory infections]]