Pneumocystis jiroveci, Molecular Detection, PCR
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Pneumocystis pneumonia is an important cause of opportunistic infection in immunocompromised patients, particularly those with HIV. The causative agent, Pneumocystis jiroveci, cannot be cultured in vitro and, therefore, laboratory detection has historically relied upon microscopic identification directly from patient specimens using fluorescent stains or antibodies. Unfortunately, stains often lack sensitivity and require expertise on the part of the reader in order to differentiate Pneumocystis jiroveci from staining artifacts and other fungi. This real-time PCR assay provides sensitive (21% more sensitive than direct detection using fluorescent calcofluor white stain), specific, and objective detection of Pneumocystis from bronchoalveolar lavage fluid and other specimens.
Preferred test for detection of Pneumocystis
A positive result indicates the presence of Pneumocystis DNA.
A negative result indicates the absence of detectable Pneumocystis DNA.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Test results should be used as an aid in diagnosis and should not be considered diagnostic in themselves. The literature indicates that Pneumocystis can cause asymptomatic colonization of healthy and immunocompromised individuals. Therefore, test results should be correlated with patient symptoms and clinical presentation.
A negative result does not rule out the presence of Pneumocystis or active disease because the organism may be present at undetectable levels.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Cushion MT: Pneumocystis. In Manual of Clinical Microbiology. Eighth edition. Edited by PR Murray, EJ Baron, JH Jorgensen, et al: Washington, DC, ASM Press, 2003, pp 1712-1725
2. Maskell NA, Waine DJ, Lindley A, et al: Asymptomatic carriage of Pneumocystis jiroveci in subjects undergoing bronchoscopy: a prospective study. Thorax 2003;58(7):594-597
3. Miller RF, Ambrose HE, Wakefield AE: Pneumocystis carinii f. sp. hominis DNA in immunocompetent health care workers in contact with patients with P. carinii pneumonia. J Clin Microbiol 2001;39(11):3877-3882
4. Takahashi T, Goto M, Endo T, et al: Pneumocystis carinii carriage in immunocompromised patients with and without human immunodeficiency virus infection. J Med Microbiol 2002;51(7):611-614
5. Vargas SL, Hughes WT, Santolaya ME, et al: Search for primary infection by Pneumocystis carinii in a cohort of normal, healthy infants. Clin Infect Dis 2001;32(6):855-861
6. Wakefield AE, Lindley AR, Ambrose HE, et al: Limited asymptomatic carriage of Pneumocystis jiroveci in human immunodeficiency virus-infected patients. J Infect Dis 2003;187(6):901-908