Pneumocystis Jirovecii Pneumonia

Original Editor - Donald John Auson Top Contributors - Donald John Auson, Kim Jackson, Lucinda hampton and Nupur Smit Shah

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Introduction

Pneumocystis Jirovecii Pneumonia (PJP) was previously called as Pneumocystis Carinii Pneumonia (PCP), it is one of the most common opportunistic fungal infection in immuno-compromised conditions such as haematological malignancy, congenital immunodeficiency, organ transplantation, immunosuppressive therapy, under medication and predominantly in HIV/AIDS.

Epidemiology

PJP has a high incidence before the advent of prophylaxis treatment and highly active antiretroviral therapy (HAART). A study about the epidemiology of PJP showed that the incidence has significantly decreased both for the adult and pediatric population.  However, the same study showed that there is difference with the prevalence of PJP in industrialized countries, such as those in Europe and North America, and in developing countries , such as in Southeast Asia and Sub-Saharan Africa, wherein the former has a continuous decline while the latter is at a greater risk of incidence.

A recent nationwide study in Spain, conducted by Pereira-Diaz et al, reported that PJP is an emerging disease in patients without HIV infection of which risk factors include haematological neoplasms, chronic lung diseases and, non-hematological cancers with high mean mortality and hospitalization costs.

Etiology

The pathogen responsible for PJP is Pneumocystis Jirovecii, an organism classified as a fungus.

Pathophysiology

Signs and Symptoms

• Subacute onset exertional dyspnea
• Dry and non-productive cough
• Fever or subfebrile temperatures
• Chest pain
• Tachypnea
• Tachycardia
• Cyanosis
• Weight loss

Diagnostic Procedures

Diagnosis of PJP relies on combination of laboratory findings and diagnostic imaging together with physical examination and history-taking.

Laboratory procedures and findings pertinent to PJP diagnosis include:

• Quantitative polymerase chain reaction (qPCR)- more accurate way to diagnose PJP
• Sputum induction- highly specific but less sensitive
• (1–3)-β-d-glucan (BG) -most reliable serologic biomarker for PJP diagnosis
• Krebs von den Lungen-6 antigen (KL-6)- together with BG, is the most accurate serologic apptoach for PJP diagnosis
• Lactate dehydrogenase (LDH)- has high sensitivity but non-specific, can be used as an initial work-up
• S-adenosyl methionine (SAM)

Imaging studies used in the diagnosis of PJP include:

Chest CT Scan

Chest Radiography