Pneumocystis jirovecii pneumonia: Difference between revisions

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== Background ==
''Note: this page is about the infection. For the drug PCP, see [[phencyclidine toxicity]]''
*Thought to be caused by opportunistic protozoan vs. fungal infection seen most commonly in immunocompromised patients
==Background==
**Risk factors: CD4 count < 200, immunosuppressive medications, cancer, primary immunodeficiencies, severe malnutrition
*Formerly known known as "pneumocystis ''carinii'' pneumonia" (i.e. "PCP")
*An atypical fungus <ref>Chapman, M., Muse, V., Mojica, J., &amp; Anahtar, M. (2021). Case 35-2021: A 50 Year Old woman with Pain in the Left Upper Quadrant and Hypoxemia. The New England Journal of Medicine, 385(21), 1995–2001. </ref>
*Most common opportunistic infection in [[AIDS]] patients
**Most common identifiable cause of death


== Clinical Features ==
===Risk factors===
*Non-HIV infected patients tend to present with fever, dry cough, and respiratory failure
*CD4 < 200
*HIV infected patients commonly present with dry cough, weakness, and chest pain lasting > 2 weeks
*Immunosuppressive medications
*Fever - 62%
*Cancer
*Crackles - 50%
*Primary immunodeficiencies
*High percentage of normal physical exams
*Severe malnutrition


== Diagnosis ==
==Clinical Features==
*Chest X-ray
*[[Fever]] (62%)
**Can be normal in 25% of cases
*Dry [[cough]]
**May see asymmetry, cysts, nodules, bullae, or pleural effusions
*[[Shortness of breath]] (progressive from exertion only to at rest)
*CT Chest
**High sensitivity ~ 100%
**Specificity 89%
**May see ground glass infiltrative pattern
*Lactate dehydrogenase level
**Suggestive of PCP
**may be used as prognostic indicator
*Immunofluorescent antibody staining
**Staining of sputum samples yields 100% specificity, but 50-90% sensitivity
**Staining of bronchoalveolar lavage samples has 97% diagnostic yield


== Work-Up ==
==Differential Diagnosis==
{{SOB DDX}}
 
{{HIV associated conditions}}
 
==Evaluation==
[[File:PMC3392316 jkss-83-50-g002.png|thumb|PA [[CXR]] and CT of pneumocystis jirovecii pneumonia before (A and B) and after (C and D) treatment.]]
[[File:PMC4536784 ccrpm-suppl.1-2015-019f3.png|thumb|CT of Pneumocystis jirovecii pneumonia, showing small nodular lesions surrounded by diffuse GGO.]]
[[File:PMC4536784 ccrpm-suppl.1-2015-019f2.png|thumb|CT of Pneumocystis jirovecii pneumonia, showing diffuse GGO with interlobular septal lines and cyst formation.]]
[[File:PMC4536784 ccrpm-suppl.1-2015-019f1.png|thumb|CT of Pneumocystis jirovecii pneumonia showing diffuse GGO with inhomogeneous distribution unrelated to secondary lobules and with spared peripheral lung parenchyma.]]
===Workup===
*CBC
*CBC
*Complete Metabolic Panel
*Chemistry
*Lactate dehydrogenase
*LDH elevation - sensitive but not specific
*Arterial blood gas
*[[ABG]]
*CD 4 count
*CD4 count
*Chest x-ray
*[[CXR]] - bat wing appearance (bilat interstitial infiltrates)
*Alveolar-arterial gradient
*A-a gradient
**P(A-a)O2 = 145 – PaCO2 – PaO2 (normal is <10 in young, healthy pts)  
**P(A-a)O2 = 150 – (PaCO2/0.8) – PaO2 at sea level on RA (normal is <10 in young, healthy patients)
**Increased in PCP pneumonia secondary to decreased diffusion thru thick aveoli
 
===Diagnosis===
*Imaging
**[[CXR]]
***Normal in 25% of cases
***Diffuse, interstitial infiltrates
**CT Chest
***Sn 100%, Sp 89%
***May see ground glass infiltrative pattern


== DDX ==
==Management==
*See [[Dyspnea (SOB)]]
===[[Antibiotics]]===
*Require [[HCAP]] or [[CAP]] ([[ceftriaxone]] and [[azithromycin]]) coverage as well<ref>Rothmans RE, Marco CA, Yang S. Human immunodeficiency virus infection and acquired immunodeficiency syndrome, in Tintinalli JE, Stapczynski JS, Ma OJ, et al (eds): Tintinalli’s Emergency Medicine, ed 7. New York, The McGraw-Hill Companies Inc., 2011.</ref>
{{PCP pneumonia antibiotics}}


== Treatment ==
===Corticosteroids===
*Trimethoprim-Sulfamethoxazole
''When used early, found to reduce the risk of progression of hypoxemia, respiratory failure, and death. <ref>Chapman, M., Muse, V., Mojica, J., &amp; Anahtar, M. (2021). Case 35-2021: A 50 Year Old woman with Pain in the Left Upper Quadrant and Hypoxemia. The New England Journal of Medicine, 385(21), 1995–2001. </ref>''
**Oral/intravenous regimen: Trimethoprim 20 mg/kg/day + Sulfamethoxazole 75 mg/kg/day divided bid-tid x21 days
*Only in patients with [[HIV]] with severe respiratory parameters:
***Average adult - Bactrim DS 2 tabs PO q8hrs
**Room air PaO2 < 70 mmHg
**Consider intravenous regimen for:
**'''OR''' A-a gradient > 35 mmHg
***Severe respiratory distress
***A-a gradient above 45 mm Hg
***PaO2 < 60 mm Hg
*Steroids
**Oral regimen: Prednisone 40 mg PO BID x5 days with taper
**Indicated for:
***A-a gradient above 35 mm Hg
***PaO2 < 70 mm Hg
*Other regimens
**Pentamidine (IV)
***Side effects: renal failure, hypoglycemia, hypotension, induction of diabetes
**Clindamycin + primaquine (IV/PO)
***Caution when using primaquine in patients with G6P deficiency
**Atovaquone (PO)
***Indicated only in mild cases of PCP
**Dapsone + TMP (PO)
***Caution when using dapsone in patients with G6P deficiency


== Disposition ==
*Treatment schedule for moderate to severe PCP<ref>Wilken A, Feinberg J. Pneumocystis carinii Pneumonia: A Clinical Review. Am Fam Physician. 1999 Oct 15;60(6):1699-1708. http://www.aafp.org/afp/1999/1015/p1699.html.</ref>
*Symptoms usually worsen after 2-3 days of treatment
**Day 1-5: 40mg [[prednisone]] BID
*Patients with disease severe enough to warrant IV therapy or corticosteroids should be admitted for close monitoring
**Day 6-10: 40mg [[prednisone]] once daily
**Day 11-21: 20mg [[prednisone]] once daily
**Patients too ill to take PO may take equivalent IV methylprednisolone


== Source ==
==Disposition==
*Uptodate
*Symptoms usually worsen 2-3d after start of treatment
*Rosen
*Patients with disease severe enough to warrant IV therapy or steroids should be admitted


==References==
<references/>
[[Category:ID]]
[[Category:ID]]

Latest revision as of 18:06, 2 December 2021

Note: this page is about the infection. For the drug PCP, see phencyclidine toxicity

Background

  • Formerly known known as "pneumocystis carinii pneumonia" (i.e. "PCP")
  • An atypical fungus [1]
  • Most common opportunistic infection in AIDS patients
    • Most common identifiable cause of death

Risk factors

  • CD4 < 200
  • Immunosuppressive medications
  • Cancer
  • Primary immunodeficiencies
  • Severe malnutrition

Clinical Features

Differential Diagnosis

Acute dyspnea

Emergent

Non-Emergent

HIV associated conditions

Evaluation

PA CXR and CT of pneumocystis jirovecii pneumonia before (A and B) and after (C and D) treatment.
CT of Pneumocystis jirovecii pneumonia, showing small nodular lesions surrounded by diffuse GGO.
CT of Pneumocystis jirovecii pneumonia, showing diffuse GGO with interlobular septal lines and cyst formation.
CT of Pneumocystis jirovecii pneumonia showing diffuse GGO with inhomogeneous distribution unrelated to secondary lobules and with spared peripheral lung parenchyma.

Workup

  • CBC
  • Chemistry
  • LDH elevation - sensitive but not specific
  • ABG
  • CD4 count
  • CXR - bat wing appearance (bilat interstitial infiltrates)
  • A-a gradient
    • P(A-a)O2 = 150 – (PaCO2/0.8) – PaO2 at sea level on RA (normal is <10 in young, healthy patients)
    • Increased in PCP pneumonia secondary to decreased diffusion thru thick aveoli

Diagnosis

  • Imaging
    • CXR
      • Normal in 25% of cases
      • Diffuse, interstitial infiltrates
    • CT Chest
      • Sn 100%, Sp 89%
      • May see ground glass infiltrative pattern

Management

Antibiotics

Mild Disease

  • TMP/SMX 2 DS tablets PO q8hrs daily OR
    • High incidence of allergy in HIV
  • Dapsone 100mg PO once daily + TMP 5mg/kg PO q8hrs OR
    • caution: dapsone can cause methemoglobinemia
  • Atavaquone 750mg PO q12hrs OR
  • Primaquine 30mg PO q24hrs + Clindamycin 450mg PO q8hrs

Severe Disease

  • TMP/SMX 5mg/kg IV q8hrs daily x 21 days OR
  • Pentamidine 4mg/kg IV daily infused over 60 minutes OR
    • Watch for side effects of hypoglycemia and hypotension
  • Primaquine 30mg PO once daily + Clindamycin 900mg IV q8hrs daily

Prophylaxis

  • TMP/SMX 1 double strength tablet daily, but one single strength tablet daily or one double-strength three times weekly is acceptable.[4]

Corticosteroids

When used early, found to reduce the risk of progression of hypoxemia, respiratory failure, and death. [5]

  • Only in patients with HIV with severe respiratory parameters:
    • Room air PaO2 < 70 mmHg
    • OR A-a gradient > 35 mmHg
  • Treatment schedule for moderate to severe PCP[6]
    • Day 1-5: 40mg prednisone BID
    • Day 6-10: 40mg prednisone once daily
    • Day 11-21: 20mg prednisone once daily
    • Patients too ill to take PO may take equivalent IV methylprednisolone

Disposition

  • Symptoms usually worsen 2-3d after start of treatment
  • Patients with disease severe enough to warrant IV therapy or steroids should be admitted

References

  1. ↑ Chapman, M., Muse, V., Mojica, J., & Anahtar, M. (2021). Case 35-2021: A 50 Year Old woman with Pain in the Left Upper Quadrant and Hypoxemia. The New England Journal of Medicine, 385(21), 1995–2001.
  2. ↑ Gutteridge, David L MD, MPH, Egan, Daniel J. MD. The HIV-Infected Adult Patient in The Emergency Department: The Changing Landscape of the Disease. Emergency Medicine Practice: An Evidence-Based Approach to Emergency Medicine. Vol 18, Num 2. Feb 2016.
  3. ↑ Rothmans RE, Marco CA, Yang S. Human immunodeficiency virus infection and acquired immunodeficiency syndrome, in Tintinalli JE, Stapczynski JS, Ma OJ, et al (eds): Tintinalli’s Emergency Medicine, ed 7. New York, The McGraw-Hill Companies Inc., 2011.
  4. ↑ CDC Guidelines for Prophylaxis Against Pneumocystis carinii Pneumonia for Children Infected with Human Immunodeficiency Virus http://www.cdc.gov/mmwr/preview/mmwrhtml/00001957.htm
  5. ↑ Chapman, M., Muse, V., Mojica, J., & Anahtar, M. (2021). Case 35-2021: A 50 Year Old woman with Pain in the Left Upper Quadrant and Hypoxemia. The New England Journal of Medicine, 385(21), 1995–2001.
  6. ↑ Wilken A, Feinberg J. Pneumocystis carinii Pneumonia: A Clinical Review. Am Fam Physician. 1999 Oct 15;60(6):1699-1708. http://www.aafp.org/afp/1999/1015/p1699.html.
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