Pneumocystis Jiroveci Pneumonia in HIVAIDS

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Pneumocystis Jiroveci Pneumonia in HIV/AIDS
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Whats in a name?

• Discovered in 1909 by Chagas (in guinea pigs)
  in 1910 by Carini (in rats).
• In honor of Carini, named P carinii in 1912
• IDd in humans (premature and malnourished kids)
  in 1952 by Jirovec
• Species that affect humans renamed P jiroveci in
  2001
• 1 of the 2 species affecting rats is still known
  as P carinii

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Classification

• Initially thought to be a protozoan (as part of
  the life cycle of a trypanosome)
• Now classified as a fungus
• Atypical Lacks ergosterol in plasma membranes,
  not affected by anti-fungals, doesnt grow on
  fungal media

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Transmission / Mode of Infx

• ? Air-borne 65-100 have Abs by 4 yoa
• ? Latent infx vs re-infx

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Incidence

• Before 1981 -- lt 100 reported cases, mostly in
  pts w/ CA
• 1980s -- 2/3s w/ HIV had PCP
• Peaked in 1990 (20,000 cases/year)
• 1990s -- Prophylaxis HAART ? ?? in cases
• 1995 ? 1998 -- incidence in US decd 65 to 3.4
  per 100 person-years but still 10-20 incidence
  w/o prophylaxis

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Clinical Presentation

• Gradual onset progression over several wks
• Fever, dry cough (or w/ thin, clear mucous), SOB
  or DOE
• Tachypnea /- Crackles, rhonchi
• Extra-pulmonary (mostly w/ pentamidine) -- HSM,
  skin lesions, pleural effusions

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Classic Imaging
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Common Lab Abnls

• CD4 lt 200
• Elevd LDH (reflects lung injury)
• Impaired Oxygenation
• Hypoxemia / A-a gradient
• DLCO (PCP unlikely if 70 of predicted)
• Exercise-assocd arterial O2 desat

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Definitive Dx

• Need to ID the organism in a respiratory specimen
• Sputum induction (55-95 sens, 99 spec) or
  mini-BAL
• If non-dxc, need bronchoscopy w/ BAL (89-98
  sens, 99 spec in HIV pts)

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Treatment

• Primary Regimens -- 21 days
• TMP-SMX (1st choice) IV or PO
• Clindamycin-Primaquine IV or PO
• Atovaquone IV or PO
• Others Pentamidine Trimetrexate leucovorin
  TMP Dapsone
• Steroids if Pao2 lt 70 or a A-a gradient gt 35 on
  RA
• Equivalent of Prednisone 40 BID x 5 days, 40 QDay
  x 5 days, 20 QDay x 11 days
• Inpatient if severe enough for steroids, if using
  IV pentamidine (d/t SEs), or if CPL or lab
  monitoring will otherwise be difficult

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Prognosis

• Short-term mortality 10-20. If respiratory
  failure is present, mortality increases to 60
• Predicted by
• LDH level
• PaO2
• A-a gradient

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Prophylaxis

• CD4 lt 200
• H/o PCP
• HIV () unexplained fever gt 2 weeks or h/o
  oraopharyngel candidiasis
• Can d/c once CD 4 gt 200 x 3 months
• Only d/c 2? prophylaxis if CD4 count has incd
  from lt 200 to gt 200 for 3 mos d/t HAART

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Prophylaxis Regimens
NEJM. June 10, 2004 Volume 3502487-2498
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References

• Thomas CF, Limper AH. Pneumocystis pneumonia.
  NEJM 350(24) June 10, 2004.
• Wilkin A. and Feinberg J. Pneumocystic carinii
  pneumonia a clinical review. American Family
  Physician 60(6) October 15, 1999.
• Textbooks
• Cohen Powderly Infectious Diseases, 2nd ed
• Goldman Cecil Medicine, 23rd ed
• Mandell, Bennett, Dolin Principles and
  Practice of Infectious Diseases, 6th ed.
• Piccini Nilsson The Osler Medical Handbook,
  2nd ed.
• Other
• UpToDate
• CDC
• HIV InSite