Pneumocystis Jirovecii Pneumonia

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

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
• (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)
• S-adenosyl methionine (SAM)
• Sputum induction

Imaging studies used in the diagnosis of PJP include:

Chest CT Scan- most pertinent finding is ground glass opacity (GGO) indicative of alveolar subtotal consolidation

Chest Radiography- nonspecific, can be normal, less common patterns have been reported, including lobar infiltrates, pulmonary nodules, and pneumatoceles and other cystic changes.

Differential Diagnosis

Thorough evaluation that includes physical examination, laboratory findings and/or imaging studies are warranted in order to make a specific diagnosis of PJP and to differentiate it from other conditions with similar presentation, which include but not limited to:

• Bacterial pneumonia
• Acute Respiratory Distress Syndrome
• Viral pneumonia
• Pulmonary Tuberculosis
• Pulmonary Embolism
• Mycobacterium Avium Complex
• Cytomegalovirus
• Histoplasmosis

Prognosis

A meta-analysis conducted by Liu et al, stated that risk factors associated with increased mortality rate including old age, female sex, longer time from onset of symptoms to diagnosis, respiratory failure, solid tumors, high lactate dehydrogenase, low serum albumin, bacterial, and aspergillus co-infection, etc. The findings of their study revealed that even in non-HVI patients, mortatlity rate for PJP infection is high.

A predictive model to evaluate mortality in HIV/AIDS patients with PCP was constructed by Wu L. et al, based on routine laboratory and clinical parameters, which may be a simple tool for physicians to assess the prognosis in HIV/AIDS patients with PCP in China. This includes 7 predictors, including LDH >350U/L, HR>130 times/min, room air PaO₂ <70mmHg, later admission to ICU, Anemia (HGB≤90g/L), CD4<50cells/ul, and development of a pneumothorax.

Pharmacological Management

• Trimethoprim/sulfamethoxazole (TMP-SMX)-  first-line agent for the treatment of mild to severe PJP
• Atovaquone- one of the oral treatment alternatives for mild and moderate PCP
• Pentamidine isethionate- preferred alternative drug regimen to TMP-SMX
• Clindamycin and Primaquine-good alternative choice for treatment of mild to moderate PJP
• Caspofungin

Prophylaxis

• TMP-SMX- recommended prophylactic agent
• Aerosolized pentamidine
• Atovaquone
• Dapsone

Physiotherapy Intervention

Physiotherapy interventions for the treatment of PJP would be the same as treating Pneumonia. This includes:

• Modified postural drainage
• Shaking and vibrations
• Coughing and huffing exercises
• Segmental and Diaphragmatic breathing exercises
• Mobilization of the patient
• General body conditioning exercises