Name
PNEUMONIA, PNEUMOCYSTIS
DESCRIPTION
DETAIL
CAUSES The ubiquitous Pneumocystis jiroveci may cause infection in normal hosts (65-100% of young children have positive serology) but will rarely cause symptoms in immunocompetent individuals. Studies suggest person to person transmission possible. -------------------------------------------------------------------------- DIFFERENTIAL DIAGNOSIS β’ Tuberculosis β’ Mycobacterium avium intracellulare β’ Viral pneumonias β’ Fungal pneumonias β’ Lymphoid interstitial pneumonitis (in children) β’ Bacterial pneumonia β’ CMV pneumonia (cytomegalovirus)LABORATORY β’ Serum LDH frequently elevated (mean elevation of 362 IU) β’ Arterial blood gases reveal hypoxemia and increased alveolar-arterial gradient (varies with severity of disease) β’ Sputum induced with inhaled 3-5% hypertonic saline may reveal pneumocystis on cytologic evaluation using various stains. An IF (immunofluorescence) technique is also available. (Sensitivity may be as high as 78% in labs with experienced personnel.) β’ CD4 cell count generally below 200 in HIV infected patients with PCP. SPECIAL TESTS Gallium scanning of the lungs is highly sensitive for PCP but is not very specific. May be useful when sputum studies are inconclusive and bronchoscopy is not available. IMAGING . Chest x-ray . Shows bilateral diffuse interstitial or perihilar infiltrate in 75% of cases . May also show a normal chest x-ray, unilateral disease, pleural effusions, abscesses or cavitations, pneumothorax, and lobar consolidations . Upper lobe infi ltrates may be present in patients on pentamidine prophylaxis DIAGNOSTIC PROCEDURES . Fiberoptic bronchoscopy with broncho-alveolar lavage or transbronchial biopsy is the preferred method of diagnosis when sputums are negative . Open lung biopsy is rarely required . A PCR test for pneumocystis may be useful in the future (on sputum, bronchoalveolar fluid)
TYPENOTES
RISK FACTORS: Immunodeficiency (premature infants, neoplasia, congenital, acquired or drug-induced immunodeficiency states, CD4 counts < 200 in adults), Patients with a history of previous PCPAPPROPRIATE HEALTH CARE Outpatient in mild cases, otherwise inpatient GENERAL MEASURES Oxygen therapy often necessary ACTIVITY As tolerated DIET No special diet DRUG(S) OF CHOICE β’ Trimethoprim-sulfamethoxazole (Bactrim, Septra) 15 mg/kg/day of trimethoprim component po in 3 divided doses or IV for 21 days. Reduce dose of trimethoprimsulfamethoxazole in patients with renal failure. β’ Adjunctive corticosteroid (prednisone or methyl prednisolone) therapy begun within 72 hours of diagnosis decreases mortality in AIDS patients (adults and children) with moderate to severe PCP (those with pO2<70 mmHg) ALTERNATIVE DRUGS β’ Pentamidine 4 mg/kg/day IV for 21 days β’ Dapsone 100 mg po daily plus trimethoprim 15 mg/kg/day po in 3-4 divided doses. Check G6PD level before beginning dapsone as hemolysis may result. β’ Clindamycin 300-400 mg po qid for 21 days plus primaquine 30 mg po daily for 21 days β’ Trimetrexate glucuronate 45 mg/m2 IV qd over 60-90 minutes with leucovorin 20 mg/m2 IV or po q6h - continue for 72 hours after last dose of trimetrexate. Recommended course of therapy is 21 days of trimetrexate and 24 days of leucovorin. Doses may need to be adjusted for hematologic toxicity - monitor CBC/differential and platelets. β’ Atovaquone suspension 750 mg bid for 21 days PATIENT MONITORING Serum LDH, pulmonary function tests and arterial blood gases generally normalize with treatment PREVENTION/AVOIDANCE β’ All AIDS patients with a history of PCP (or CD4 cells < 200 or evidence of immunodefi ciency) require prophylaxis with daily trimethoprim-sulfamethoxazole DS, daily dapsone 100 mg or monthly aerosolized pentamidine 300 mg. In patients intolerant of TMP-SMX, consider a rechallenge or desensitization with TMP-SMX; various protocols exist. β’ Prophylaxis may be discontinued in patients on antiretroviral therapy when CD4 cells > 200 for over 3 months β’ All babies born to HIV infected mothers need to be on prophylaxis after the first month of life. Drug of choice is TMP-SMX; 150 mg/m2/day (TMP component) 3 times weekly (on consecutive days). This should be continued until the baby is proven HIV negative or for the fi rst year of life, after which CD4 cell count may be used to guide prophylaxis. POSSIBLE COMPLICATIONS β’ Respiratory failure β’ Pneumothorax (even after successful treatment) β’ Extrapulmonary pneumocystis (especially in patients on inhaled pentamidine prophylaxis) EXPECTED COURSE/PROGNOSIS β’ Mortality from first episode PCP is 10-15%. With prophylactic therapy, mean survival has increased. β’ 40% of patients with PCP will have a recurrence without prophylaxis
RELATED DISEASE
Not Available Disease
DISEASE
INVESTIGATION
HIV I & II, X-RAY CHEST P.A. VIEW( NORMAL ), PCR, BRONCHO-ALVEOLAR LAVAGE FOR CYTOLOGY, SPUTUM FOR GRAM STAINING, SPUTUM FOR CULTURE & SENSTIVITY TEST, LUNG SCAN, BLOOD GASES