Pneumocystis jiroveci Pneumonia

Pneumocystis pneumonia is the most common opportunistic infection associated with AIDS. The risk of Pneumocystis jiroveci pneumonia among HIV- infected patients rises markedly when circulating CD4+ T cell counts fall below 200 cells/L.

Tuberculosis in HIV patients occur when CD4 count is 100 cells/L.

Pneumocystis jiroveci – Prophylaxis should be started if the patient has

The appropriate stain is methenamine silver, and the requisition slip when submitting the wash fluid should have a reference to either Pneumocystis or methenamine silver, since routine hematoxylin and eosin does not adequately demonstrate the organisms. The cysts, when stained with methenamine silver, have a characteristic cup or boat shape; the trophozoites are difficult to demonstrate without electron microscopy. It is also worth knowing that sputum samples are not nearly as effective as bronchial washes in demonstrating the organisms.

Ans. is ‘d’ i.e., Pneumocytstis jiroveci

“The life cycle of pneumocystis probably involves sexual and asexual reproduction, although definitive proof awaits the development of a reliable culture system”. – Harrison

“Rhinosporidium seeberi has not been cultivated in media”. – Ananthnarayan.

Ans. is ‘a’ i.e., rRNA, Mitochondrial protein gene sequence & presence thymidylate synthase; `b’ i.e., Cell wall contains glucans; ‘c’ i.e., Antifungals are effective against p. carinii

.  The taxonomic classification of Pneumocystis as a fungus is based on factors:

1.   Analysis of gene sequence for ribosomal RNA, mitochondria! proteins and major enzymes.

2.   Presence of b-1, 3 glucan in the cell wall.

3.   The efficacy of antifungal drugs that inhibit b-glucan synthesis.

.    In contrast to most fungi.

1.   Pneumocystis lacks ergosterol

2.   Not susceptible to antifungal drugs that inhibit ergosterol synthesis.

Ans. is ‘a’ i.e., Fungi

Pneumocystis jirovcci (P. carinii)

.   Pneumocystis is an opportunistic fungal pulmonary pathogen.

.         Developmental stages

1. Pleomorphic trophic form
2. Thick walled cyst
3. Precyst – an intermediate stage

.    Risk factors

1. HIV (CD4 T cell <200 mL)
2. Immunosuppressive therapy (particularly glucocorticoids)
3. Primary immunodeficiency diseases
4. Premature malnourished infants.

   – Tachycardia – Cynosis

Chest X-ray

–  Bilateral diffuse infiltrates beginning in the perihilar regions —> classical finding.

– Upper lobe infiltrates who receive aerosolized pentamidine.

– Pneumothorax.

. Hypoxemia is most widely used prognostic factor for P carinii pneumonia.

.   Pneumocystosis cannot be cultured :‑

. ”The life cycle of pneumocystis probably involves sexual and asexual reproduction, although definitive proof awaits the development of a reliable culture system”.

Ans. is ‘c’ i.e., Pneumocystis jiroveci

.   Pneumocystis is an opportunistic fungal pulmonary pathogen.

Ans. is ‘a’ i.e., Sputum examination for trophozoites and cyst under microscope

D i.e. Pneumocystic carinii

Answer is B (Eosinophilic Alveolar Exudate):

The most characteristic histoputhological feature of pneumocystis carinii pneumonia in adults is predominantly alveolar, foamy vacuoloted, eosinophilic exudates.

Interstitial pneumonitis is usuall^y mild and shows infiltration with PML and mononuclear cells.

Answer is A (Usually associated with CMV infection):

Pneumocystis Jiroveci may be associated with CMV infection but it is not usually associated with CMV infection.

Pneumocystis Jiroveci is the new nomenclature for human infection with Pneumocystic carini (which is now used for organisms found in rats)

Pneumocystis infection in Humans : P. Jiroveci

Pneumocystis infection in Rats : P. Carini

Pneumocystic Jiroveci disease and immunosupression  `Pneumocystis Jiroveci does not cause disease in the absence of immuno supression’

Note

Pneumocystic Jiroveci may infect immunocompetent hosts but the disease (pneumocvstis pneumonia) occurs only when the host is immunosupressed

Most individuals are infected in early childhood But pneumonia occurs in immunocompromised patients only either due to reactivation or new infection.

Persons at risk for Pneumocystic disease (Pneumocystosis)

• Acquired Immunodeficiency Disease (eg AIDS)
• Patients Recieving Immunosupressive therapy (especially Glucocorticoids) for cancer, organ transplantation etc.
• Children with primary immunodeficiency diseases
• Premature malnourished infants (immunodeficient)
• Pneumocystic Pneumonia : Diagnosis

Diagnosis of Pneumocystic Pneumonia is based on specific identification of organism in respiratory specimen with appropriate histological staining

Pneumocystis infection is usually diagnosed b^y sputum examination

Sputum samples should always be obtained by induction (with hypertonic saline)

Routine sputum specimen is often inadequate (Washington manual of Pulmonary medicine)

BAL forms the mainstay of diagnosis for Pneumocvstic Pneumonia

If organisms are not seen on induced sputum examination a Bronchoalveolar lavage specimen should be obtained. BAL forms the mainstay of diagnosis for Pneumocystic Pneumonia – Harrisons 16th

Pne imocvstic Pneumonia and CMV infection (Pneumocystic Pneumonia’ by Wolzer & Cushion 3rd/418) `Several studies have indicated that CMV is a risk factor for Pneumocystis Pneumonia in Renal transplant patients

These is however no convincing evidence to show a direct effect of the CMV virion on Pneumocystis’

Thus we conclude

Pneumocystic may be associated with CMV infection but in a few selected cases and special circumstances like Renal tansplantation. CMV is not usually associated with pneumocystic pneumonia.

Pneumocvstis Pneumonia and Pneumatocele

Pneumocystic Pneumonia may be associated with pneumotocele formation but Pneumatoceles are not associated in all cases of Pneumocystic pneumonia

Pneumatocele: Differential Diagnosis (CT scan of the body by Mathias /362)

• Post infectious (Staphylococcal° and other bacterial infections)
• Pneumocystic
• Post traumatic (Laceration )
• After treatment of metastasis (rare)

Answer is A and C

Indications for prophylaxis against Pneumocystic carinii

• An absolute CD₄ count <200/pt (CD₄percentage
• Oropharyngeal candidiasis (Primary prophylaxis)
• Prior Pneumocystic carinii pneumonia (Secondar^y prophylaxis)

Remember

Criteria for discontinuing primary prophylaxis CD₄ + Tcell count > 200_, for 3 months

The drug of choice for primary and secondary prophylaxis is TM P- SMX

Answer is D (Fluoroquinolones):

Fluoroquinolones are not used in the treatment (#. P. carinii infection. Drugs used for treatment of Pneumocystis carinii infection include:

Drug of choice for all forms of pneumocystosis: Trimethoprim-Sulfamethoxazole (Cotrimoxazole)

Answer is B (Cotrimoxazole):

Trimethoprim/sulfamethoxazole or Cotrimoxazole is the drug of choice for all firms of Pneumocystis Pneumonias.

‘Trimethoprim-Sulfamethoxazole which acts by inhibiting folic acid synthesis is considered the drug of choice for all forms of Pneumocystis Pneumonias. Therapy is continued for 14 days in Non-HIV-Infected patients and for 21 days in HIV-Infected patients’ – Harrison 18th/1672

Ans. is ‘d’ i.e., Meningitis

Ans. is ‘a’ i.e., CD₄ count < 200

PROPHYLAXIS OF PNEUMOCYSTIC CARINH PNEUMONL4

Primary prophylaxis is indicated for

• Patients with CD4- cell counts of< 200/4
• History of oropharyngeal candidiasis

Secondary prophylaxis is indicated for

• Both HIV infected and non HIV infected patients.
• Who have recovered from pneumocystosis.

Primary and secondary prophylaxis may be discontinued in HIV infected persons once.

• CD4+ counts have risen to > 200/p1 and remained at that level for 3 months.

Also know

First choice agent for prophylaxis

• Trimethoprim, sulphamethoxazole.

Other agents used in prophylaxis.

• Dapsone, pentamidine.