Pneumocystis Jiroveci : Clinical Features, Microbiology

Pneumocystis Jiroveci                                         

Pneumocystis Jiroveci is the most common opportunistic organism causing infection in AIDS/ HIV+ patients or any immunocompromised patient on steroids, a child with nephrotic syndrome on steroids, an Ankylosing spondylitis patient on infliximab or a person who has undergone kidney or bone marrow transplantation (Hemopoietic stem cell transport)

This organism has a tropism for lungs. It causes Lobar pneumonia, which can be heard by the physician as bronchial breathing.

The Route of transmission of Pneumocystis Jiroveci is person to person via respiratory droplet infection or due to reactivation of latent infection. It is an important cause of pneumonia in AIDS patients. The leading cause of pneumonia in AIDS-positive patients is Pneumococcus, which is more common & prevalent in the community. In AIDS-positive patients with CD₄ count less than 200 with perihilar infiltrates, nonproductive cough, the cause is Pneumocystis Jiroveci. For such AIDS patients, prophylactic management is done with Cotrimoxazole.

Clinical Features of Pneumocystis Jiroveci                                             

• Shortness of breath 
• Dyspnea 
• Fever 
• Nonproductive cough: Neutrophilic Infiltration and Alveolar Exudate can be seen.

Microbiology: Stains Used in Pneumocystis Jiroveci

The image shows a Gomori methenamine stain, a fungal stain. The black color here represents cysts.

Other stains like Giemsa and IFA can also be used.

Workup for Pneumocystis Jiroveci

• A chest X-ray is performed initially and is mostly normal; however, Perihilar diffuse infiltrates can be seen on a chest X-ray in the later part of the illness.
• HRCT will show that Ground glass opacities might have cysts present. Thus, pneumothorax can also develop in these patients, which may cause sudden deterioration of the patient's condition.
• An open lung biopsy is done as well to make a certain diagnosis.
• β 1,3 Glucan test shows pan fungal antigen to identify the infection.
• Real-time PCR cannot distinguish colonization of the airways, so we can`t say whether it is infection or colonization.
• The investigation of choice is Broncho Alveolar Lavage (BAL). Then, the specimen is stained with Giemsa or Gomori methenamine stain.

Diagnosis (Non-Invasive Tests) of Pneumocystis Jiroveci

• IFA can be done with a Broncho Alveolar Lavage specimen to identify the infection.
• LDH is elevated, and the A-a gradient in PFT [(n) 5-15 mmHg] is increased, reducing SpO2.
• PCR can’t distinguish between colonization and infection.

Treatment of Pneumocystis Jiroveci

The infection needs to be treated, and the Drug of choice for Pneumocystis Jiroveci infection is IV Trimethoprim-Sulfamethoxazole. The same drug is also used to prevent the disease.

The treatment is given for 21 days. The Mode of action of Trimethoprim-Sulfamethoxazole is that it inhibits folate metabolism.

Prevention and management of Pneumocystis Jiroveci

• IV pentamidine is given as a nebulizer for prevention)
• Clindamycin
• Primaquine
• Atovaquone
• Steroids are also useful in prevention.
  • Cytokines are produced on the destruction of organisms, so steroids will help reduce symptoms of inflammation when organisms die). Reduced cytokine-mediated damage.
  • Indication Pa0₂ < 70mmHg
  • A-a gradient more than 35mmHg

Frequently Asked Questions:

Q: Beta 1,3 glucan test is positive in all except? (AIIMS NOV 2019)

1. Aspergillus
2. Candida
3. Mucormycosis
4. Pneumocystis jiroveci

Answer: c. Mucormycosis

Q: What is the investigation of choice for Pneumocystis Jiroveci?

Answer: Broncho Alveolar Lavage (BAL)

Q: What is the treatment of choice for Pneumocystis Jiroveci infection?

Answer: IV Trimethoprim-Sulfamethoxazole 

Q: Which patients have the highest risk of getting Pneumocystis Jiroveci infection?

Answer: Immunocompromised patients suffering from chronic diseases are at the highest risk of contracting the infection.

Q: What drug is used for Prophylaxis of P. Jiroveci infection?

Answer: Cotrimoxazole

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