P. Jirovecii, (Pneumocytosis) Flashcards
What kind of pathogen is Pneumocystis Jirovecii (aka P. Carinii), and what is it famous for?
It’s a fungus that causes infections in the immunocomprimised exclusively. It is the most common opportunistic infection in HIV/AIDs patients.
How many different forms will this fungi exist in human infections?
3 forms: (a) Free trophic form, (b) a uninucleate sporocyst, or (c) a cust containing up to 8 fusiform intracystic bodies.
Main point of entry for C. Jirovecii? How does the infection occur?
Respiratory tract. It can be either a reactivation of an old infection or can also be a primary new infection.
Who are most as risk of C. Jirovecii?
This infection only occur in the immunocomprimised, especially those with HIV. Also to malnourished, debilitated patients with CD4 counts lower than 200 are at great risk.
Common clinical presentations of P. Jirovecii?
Pneumonia is the most common, but other extrapulmonary manifistations can be seen involving the lymph nodes, bones, spleen, liver, etc.
Hallmark of P. Jirovecii infection?
Interstitial pneumonitis with mononuclear infiltrates composed of primarily plasma cells.
Signs/symptoms of P. Jirovecii infection?
Dyspnea, tachypnea, cyanosis, non productive cough and fever.
What causes the actual death of Pt’s infected with pneumocytosis?
Respiratory failure.
What can x-rays show for pt’s with pneymocytosis?
It can be a normal chest x-ray, it can also show diffuse pulmonary infiltrates with ground glass appearance extending from the hilar region; can also show nodules or cavitations.
Histological findings of P. Jirovecii infections?
Foamy exudates can be seen in pulmonary alveolar space, with intense interstitial infiltrates composed of mostly plasma cells. Other findings can include diffuse alveolar damage, noncaseating granulomatous inflam, and infarct-like coagulative necrosis.
Dx of P. Jirovecii via lab tech?
Giemsa stains will see the fusiform form, GMS stain will see the cyst wall (both neither of these two techniques will see both). Immunofluroscent techniques will stain both however.
Definitive Dx of P. Jirovecii?
Almost entirely on microscopic examination of clinical specimen like the Bronchoalveolar Lavage (BAL), bronchial brushing, induced speutum, transbronchial or open lung biopsy specimen. However, BAL is sufficient.
Whats the problem with the induced speutum method of Dx-ing P. Jirovecii?
It only works on AIDS patients with a very high viral load; 25% false negative.
What is the cornerstone of the Px and Tx of P. Jirovecii?
Trimethoprim-sulfamethoxazole.
