Pneumocystis jirovecii Pneumonia

PJP is a respiratory infection seen in immunocompromised pts, usually associated with a CD4 cell count <500/μL.

Can affect pts with both acquired and congenital immunodeficiency syndromes.

Seen in both males and females and all age groups.

Often associated with chronic HIV infection, particularly if not treated with HAART.

Respiratory failure often necessitating mechanical ventilatory support with high airway pressures even when ventilating with low tidal volumes; often accompanied by severe dyspnea independent of gas exchange.

Hemodynamic instability associated with induction of anesthesia, initiation of positive pressure ventilation.

Pneumothoraces.

Persistent expiratory airflow reduction after resolution of acute infection.

Bronchiectasis, lung cysts.

Often associated with other comorbidities related to immune deficiency.

Progressive respiratory failure with diffuse bilateral interstitial infiltrates.

Pneumothoraces, either spontaneous or associated with positive-pressure ventilation.

Persistent pulm dysfunction.

Common cause of nonproductive cough, dyspnea, fevers in immunosuppressed pt

Associated with other opportunistic infections, particularly CMV and Candida albicans esophagitis.

Toxicity from therapy with sulfa antimicrobials, including methemoglobinemia, anemia, leukopenia, and severe skin rashes.

High incidence of drug resistance.

Indolent disease; can progress to severe respiratory failure.

May be cause for nonproductive cough in high-risk pt.

High incidence of spontaneous pneumothoraces.

Extrapulmonary sites of Pneumocystis infection are rare.

May be associated with other infections (tuberculosis, bacterial, viral, fungal) and malignancies (Kaposi sarcoma, lymphoma) in immunosuppressed pts.

P. jiroveci (previously carinii ), originally characterized as a parasite, is now classified as a fungus.

Organisms reside in the lungs, usually as latent infection; activated in an immunosuppressed host.

High prevalence of antibodies to P. jirovecii in nonimmunosuppressed humans, suggesting that most individuals are “colonized” early in life.

Human-to-human transmission has not been documented.