Clinical Background
Pneumocystis is a fungal organism that causes pneumonia predominantly in immunocompromised patients.
Epidemiology
- Incidence
- In AIDS patients, <1/100 person years
- In solid organ transplant patients - 5-10% prevalence in patients not taking prophylactic antibiotics
- Sex - in AIDS patients, M>F
- Transmission - airborne, as primary infection
Organism
- Classified as a fungus because RNA is homologous to fungal RNA
- Four morphological forms - trophozoites, cysts, precysts, sporozoites
- Cyst is diagnostic form and stains with Giemsa and methenamine silver stains
- Formerly known as Pneumocystiscarinii, sp. hominis
Risk Factors
- Immunocompromised patient (particularly solid organ transplant patients)
- AIDS (CD4+ <200 cells/µL)
Clinical Presentation
- Subacute to acute onset pneumonia
- Dyspnea, tachypnea, cyanosis, nonproductive cough, fever
- Coinfection with cytomegalovirus (CMV) not uncommon
- High risk for heart-lung transplant patients
Treatment
- Antibiotics
- Glucocorticoids - appear to accelerate recovery
- Most studied in AIDS patients
Prevention
- Prophylactic use of oral trimethoprim-sulfamethoxazole or inhaled pentamidine significantly reduces the disease rate in at-risk populations
See Also
Diagnosis
Diagnosis
- Laboratory testing
- Direct immunofluorescence staining using monoclonal antibodies on induced sputum or bronchoalveolar lavage (BAL)
- May also perform Grocott’s methenamine silver nitrate stain and/or Giemsa stain on lung tissue biopsies
- Cytopathologic examination of Pap-stained bronchoalveolar lavage fluid
- Imaging studies
- Chest X-ray - bilateral symmetric ground glass opacities
- 10% are normal
- CT (high resolution) - ground glass opacities
Tests generally appear in the order most useful for common clinical situations
| Test name: Pneumocystis jiroveci DFA
|
| ARUP #: 0060052 |
| Methodology: Direct Fluorescent Antibody Stain
|
| Use: Rapid identification of P. jiroveci |
| Test name: Malaria Smear (Giemsa Stain)
|
| ARUP #: 0049025 |
| Methodology: Stain
|
| Use: Rapid identification of P. jiroveci |
| Test name: Immunohistochemistry Stain Offering
|
| ARUP #: ARUP005 |
| Methodology: Immunohistochemistry
|
| Use: Rapid identification of P. jiroveci
(Grocott's methenamine silver [GMS] method) |
References
General References
Davaro RE, Thirumalai A. Life-threatening complications of HIV infection. J Intensive Care Med.
2007;
22(
2):
73-81.
Fujii T, Nakamura T, Iwamoto A. Pneumocystis pneumonia in patients with HIV infection: clinical manifestations, laboratory findings, and radiological
features. J Infect Chemother.
2007;
13(
1):
1-7.
Huang L, Morris A, Limper AH, Beck JM. An Official ATS Workshop Summary: Recent advances and future directions in pneumocystis pneumonia (PCP). Proc Am Thorac Soc.
2006;
3(
8):
655-664.
Kasper LH, Buzoni-Gatel D. Some Opportunistic Parasitic Infections in AIDS: Candidiasis, Pneumocystosis, Cryptosporidiosis, Toxoplasmosis. Parasitol Today.
1998;
14(
4):
150-156.
Morris A, Lundgren JD, Masur H, Walzer PD, Hanson DL, Frederick T, Huang L, Beard CB, Kaplan JE. Current epidemiology of Pneumocystis pneumonia. Emerg Infect Dis.
2004;
10(
10):
1713-1720.
Peterson JC, Cushion MT. Pneumocystis: not just pneumonia. Curr Opin Microbiol.
2005;
8(
4):
393-398.
Robberts FJ, Liebowitz LD, Chalkley LJ. Polymerase chain reaction detection of Pneumocystis jiroveci: evaluation of 9 assays. Diagn Microbiol Infect Dis.
2007;
58(
4):
385-392.
Wazir JF, Ansari NA. Pneumocystis carinii infection. Update and review. Arch Pathol Lab Med.
2004;
128(
9):
1023-1027.
Pneumocystis jiroveci (formerly Pneumocystis carinii). Am J Transplant.
2004;
4 Suppl 10:
135-141.
Medical Reviewers
Carney, Heather, M.D. Assistant Medical Director, Transfusion Services at ARUP Laboratories; Pathology, University of Utah
Petti, Cathy A., M.D. Medical Director, Infectious Diseases at ARUP Laboratories; Assistant Professor, Pathology and Medicine, University of Utah
Comprehensive Review: July 2008
Last Update: September 2008
