Pneumocystis pneumonia

OVERVIEW

  • Pneumocystis pneumonia: form of pneumonia caused by the yeast-like fungus Pneumocystis jirovecii, most commonly as an opportunistic infection in the immunosuppressed
  • the classical presentation is pneumonia in the immunosuppressed and it is an AIDS-defining illness in HIV patients
  • PCP is still an acceptable term (PneumoCystis Pneumonia) though PJP is now commonly used as an abbreviation

CAUSE

Pneumocystis pneumonia is caused by P. jirovecii

  • P. jirovecii was previously thought to be P. carinii (a species that actually infects rats!)
  • reclassified as a ‘yeast-like’ fungus on the basis of nucleic acid and biochemical features
  • Pneumocystis spp. cannot be cultured

CLINICAL FEATURES

History

  • subtle onset of progressive dyspnea, nonproductive cough, and low-grade fever
  • abrupt onset of respiratory insufficiency that may correlate with a tapered or increased dosage of immunosuppressant medications in non-AIDS patients
  • history of immunosuppression (e.g. HIV/AIDS, SLE, organ transplantation, immunosuppressants)
  • sudden onset chest pain and dyspnea suggests pneumothorax

Exam

  • tachypnea
  • tachycardia
  • signs of pneumothorax
  • lung exam usually unremarkable

INVESTIGATIONS

  • Induced sputum or BAL
    • Giemsa and methenamine silver stains (for microscopic visualization of characteristic cystic or trophic forms in respiratory specimens)
    • PCR (highly sensitive, detects colonisation as well  as infection)
  • Test for HIV and CMV (co-infection is common)
  • Consider other causes of immune-suppression (e.g. PCP in the context of a new severe presentation of SLE)
  • CXR: bilateral, symmetric, reticular (interstitial), or granular opacities; pneumatoceles; pneumothorax (may be bilateral)
  • HRCT Chest: ground glass opacities (must be present)

MANAGEMENT

Specific therapy

  • co-trimoxazole (trimethoprim 20mg/kg/day and sulphamethoxazole 150mg/kg/day in 4 divided doses) for 21 days (IV; PO for mild cases)
  • Second line:
    • pentamidine or
    • trimethoprim + dapsone or
    • clindamycin + primaquine or
    • atovaquone
  • Steroids should be used in patients with HIV and significant hypoxaemia (PaO2 <70 mmHg or A-a gradient >35 mmHg)
    • e.g. prednisolone 40m bd for 5 days, then taper over 21 days total
    • long term prophylaxis (see below)

Pneumothorax may require long-term chest drains

PROGNOSIS

  • 10-20% mortality for initial PCP infection in AIDS patients; much higher if requiring mechanical ventilation
  • 30-60% mortality for initial PCP infection in patients without AIDS

PROPHYLAXIS

Primary prophylaxis against PCP should be given if:

  • HIV positive and CD4+ count is less than 200 cells per millimeter
  • HIV positive and history of oropharyngeal candidiasis

Secondary prophylaxis is lifelong unless there is IRIS from HAART (i.e. CD4 >200)


References and Links

LITFL

Journal articles

  • Huang L, et al; International HIV-associated Opportunistic Pneumonias (IHOP) Study; Lung HIV Study. HIV-associated Pneumocystis pneumonia. Proc Am Thorac Soc. 2011 Jun;8(3):294-300. PMC3132788.
  • Krajicek BJ, Thomas CF, Limper AH. Pneumocystis pneumonia: current concepts in pathogenesis, diagnosis, and treatment. Clinics in chest medicine. 30(2):265-78, vi. 2009. [pubmed]
  • Thomas CF Jr, Limper AH. Pneumocystis pneumonia. N Engl J Med. 2004 Jun 10;350(24):2487-98. Review. PMID: 15190141pneumatoceles

FOAM and web resources


CCC 700 6

Critical Care

Compendium

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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