Disease name and synonyms

Pneumocystis pneumonia (PCP), pneumocystis pneumonitis

Fungi responsible (links to these)

Pneumocystis jirovecii (formerly carinii)

Disease description

In HIV/AIDS patients, PCP is a subacute disease with fever, cough, weight loss, diarrhoea and increasing breathlessness. Prodromal features are often present for 2-3 weeks before the breathlessness becomes clinically problematic. In non-AIDS patients with other immunodeficiency, PCP is a more rapidly progressive disease with more prominent radiological findings and wheeze.

Frequency and global burden

Worldwide distribution. Approximately 2.8 million with advanced HIV/AIDS infection are at risk. Conservative estimates produce figures of around 400,000 cases annually, but this is likely to be an underestimate of the true burden. PCP rates rise accordingly with national GDP and decreasing numbers of TB cases, but the reasons for this are unclear.

Underlying problems and at risk patients

HIV/AIDS with CD4 cells <250 x 10⁶/L, usually <200 x 10⁶/L. Other patients include transplant recipients, corticosteroid-treated patients such as those with brain tumours on dexamethasone, malnutrition in children, hypogammaglobulinaemia and acute and chronic leukaemia and lymphoma patients.

Diagnostic testing

Induced sputum and bronchoalveolar lavage fluids are the usual diagnostic specimens. Spontaneously produced sputum and oral mouth wash samples can also be used. Detection is best with real-time PCR or immunofluorescence. Beta1,3-D-glucan in usually raised in blood and can assist with diagnosis. Culture is not possible because the microorganism does not grow in any known culture media. Lung or other tissue biopsy and subsequent histology  are sometimes necessary for diagnosis.

New RT PCR kit for pneumocystis jirovecii (2017)

BD max platform kit (BioGX)

Real Time PCR (Fast Track diagnostics Ltd)

Real Time PCR (Bird srl)

Treatments

First line therapy is cotrimoxazole/trimethoprim with corticosteroids for moderate of severe disease. Second –line therapies include pentamidine and the combination of clindamycin and primaquine. Mild cases can be treated with trimethoprim and dapsone or atavaquone. view ECCMID talk by Prof R Miller on PCP.

Outlook and prognosis

If diagnosed promptly, the survival is 80-90% in HIV/AIDS in the western world. In non-AIDS patients, the survival is only 50%. Prevention of subsequent episodes is critical with prophylaxis, while immunocompromised. Patients with PCP should be isolated in rooms as it is transmissible to other immunocompromised patients.