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Pneumocystis Pneumonia, Emergency Medicine

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Pneumocystis Pneumonia, Emergency Medicine

Basics

Description

PCP in children is typically more severe. ‚

Constellation of dyspnea, fever, diffuse radiographic infiltrates, minimal or nonproductive cough, and slow progressive course suggests atypical cause of the pneumonia: ‚

Provide supplemental oxygen for symptomatic patients. ‚

Close follow-up must be arranged with infectious disease specialist to allow for outpatient management. ‚

  • Originally called Pneumocystis carinii pneumonia, then renamed Pneumocystis jirovecii but still referred to as PCP
  • Most common opportunistic infection in patients with HIV, even with PCP prophylaxis and antiretroviral therapy
  • Believed to be transmitted by respiratory-aerosol route:Cysts colonize respiratory tract.Cysts rupture and multiple trophozoites release and form foamy exudate in alveoli.
  • Most cases are believed to represent reactivation of latent disease, although person-to-person transmission suggested.
  • Actual mode of transmission is unclear.
  • Cysts colonize respiratory tract.
  • Cysts rupture and multiple trophozoites release and form foamy exudate in alveoli.

Etiology

  • Pneumocystis is classified as a fungus.
  • Pneumocystis occurs in hosts with altered cellular immunity:HIV infection (most common, especially when CD4 count <200 cells/mm3)CancerCorticosteroid treatmentOrgan transplantationMalnutrition
  • HIV infection (most common, especially when CD4 count <200 cells/mm3)
  • Cancer
  • Corticosteroid treatment
  • Organ transplantation
  • Malnutrition

Diagnosis

Signs and Symptoms

  • Subacute presentation
  • Up to 7% of patients can be asymptomatic.
  • Patients on inhaled pentamidine prophylaxis may have milder symptoms:Increased incidence of pneumothoraxIncreased incidence of extrapulmonary disease
  • Increased incidence of pneumothorax
  • Increased incidence of extrapulmonary disease
  • Fever
  • Cough with none or minimal amount of white sputum
  • Dyspnea on exertion or at rest:Progressive over days (most common in non " “HIV-immunocompromised hosts)Indolent, developing over weeks to months (more common in HIV-positive hosts)Oxygen desaturation with exercise
  • Chills
  • Fatigue
  • Weight loss
  • Chest pain
  • Progressive over days (most common in non " “HIV-immunocompromised hosts)
  • Indolent, developing over weeks to months (more common in HIV-positive hosts)
  • Oxygen desaturation with exercise
  • Tachypnea
  • Tachycardia
  • Crackles and rhonchi on lung exam

Essential Workup

  • CBC
  • Electrolytes
  • Arterial blood gas (ABG)
  • Lactate dehydrogenase (LDH)
  • Blood cultures
  • Chest x-ray

Diagnosis Tests & Interpretation

  • ABG:Obtain in all cases of PCP.Calculate the alveolar " “arterial (A " “a) gradient (usually increased).Adjunctive corticosteroid therapy for A " “a gradient >35 mm Hg or PaO2 <70 mm Hg
  • LDH:Elevated in HIV-positive patients with PCP compared to non-PCP pneumoniaHigher levels correlate with poorer prognosis.
  • Obtain in all cases of PCP.
  • Calculate the alveolar " “arterial (A " “a) gradient (usually increased).
  • Adjunctive corticosteroid therapy for A " “a gradient >35 mm Hg or PaO2 <70 mm Hg
  • Elevated in HIV-positive patients with PCP compared to non-PCP pneumonia
  • Higher levels correlate with poorer prognosis.
  • Chest radiograph:Classically reveals bilateral interstitial or central alveolar infiltratesRadiograph normal in up to 25% of patients with PCPEarly or mild infection associated with decreased sensitivityAtypical presentations include:Lobar infiltratesCystsPneumothoracesPleural effusionsNodular infiltratesProphylaxis with aerosolized pentamidine is a risk factor for developing predominantly upper lobe.Chest radiograph abnormalities can persist for months after treatment.
  • High-resolution chest CT:High sensitivity for PCP in HIV-positive patients.Reveals patchy ground-glass attenuation
  • Classically reveals bilateral interstitial or central alveolar infiltrates
  • Radiograph normal in up to 25% of patients with PCP
  • Early or mild infection associated with decreased sensitivity
  • Atypical presentations include:Lobar infiltratesCystsPneumothoracesPleural effusionsNodular infiltrates
  • Prophylaxis with aerosolized pentamidine is a risk factor for developing predominantly upper lobe.
  • Chest radiograph abnormalities can persist for months after treatment.
  • Lobar infiltrates
  • Cysts
  • Pneumothoraces
  • Pleural effusions
  • Nodular infiltrates
  • High sensitivity for PCP in HIV-positive patients.
  • Reveals patchy ground-glass attenuation
  • Induced sputum:Definitive diagnosis requires presence of Pneumocystis organisms in an appropriately stained respiratory specimen.Specificity approaches 100%, but sensitivity depends on quality of induced sputum and lab expertise.Less sensitive in patients on inhaled pentamidine prophylaxis and non " “HIV-positive patients
  • Bronchoalveolar lavage:Perform if the induced sputum is nondiagnostic and the suspicion for PCP is still high.Sensitivity 80 " “100%
  • Definitive diagnosis requires presence of Pneumocystis organisms in an appropriately stained respiratory specimen.
  • Specificity approaches 100%, but sensitivity depends on quality of induced sputum and lab expertise.
  • Less sensitive in patients on inhaled pentamidine prophylaxis and non " “HIV-positive patients
  • Perform if the induced sputum is nondiagnostic and the suspicion for PCP is still high.
  • Sensitivity 80 " “100%

Differential Diagnosis

  • Chlamydia pneumoniae
  • Legionella
  • Mycoplasma
  • Tuberculosis
  • Viral pneumonia (especially cytomegalovirus)

Treatment

Pre-Hospital

Initial Stabilization/Therapy

  • ABCs
  • Provide adequate oxygenation with nasal cannula up to 100% nonrebreather.
  • Perform endotracheal intubation in those with refractory hypoxemia despite maximal oxygenation or hypercarbic respiratory failure.
  • At least 500 " “1,000 cc 0.9% normal saline IV bolus for hypotension, sepsis, dehydration

Ed Treatment/Procedures

  • Initiate antibiotics:IV Bactrim is the first-line agent.IV pentamidine for those who cannot tolerate BactrimOral therapy is an option for well-appearing patients.Alternative regimens include trimethoprim " “dapsone, clindamycin " “primaquine, and atovaquone.Continue antibiotics for 21 days.
  • Adjunctive corticosteroids in patients with A " “a gradient >35 mm Hg or PaO2 <70 mm Hg:Must start within 1st 72 hr of treatment
  • Isolate suspected PCP patients from others who are immunocompromised.
  • IV Bactrim is the first-line agent.
  • IV pentamidine for those who cannot tolerate Bactrim
  • Oral therapy is an option for well-appearing patients.
  • Alternative regimens include trimethoprim " “dapsone, clindamycin " “primaquine, and atovaquone.
  • Continue antibiotics for 21 days.
  • Must start within 1st 72 hr of treatment

Medication

  • Atovaquone: 750 mg (peds: Dosing not established) PO q12h
  • Clindamycin/primaquine: Clindamycin 900 mg (peds: Dosing not established) IV q8h or 300 " “450 mg PO q6h and primaquine 15 " “30 mg (peds: Dosing not established) PO per day
  • Pentamidine: 4 mg/kg/24h IV over 1 hr (peds: 3 " “4 mg/kg IM or IV once/day for 21 days)
  • Prednisone: 40 mg (peds: Dosing not established) PO q12h for 5 days, 40 mg PO per day for 5 days, then 20 mg PO per day for 11 days (IV methylprednisolone at 75% of the prednisone dose may be substituted)
  • Trimethoprim/dapsone: Trimethoprim 15 " “20 mg/kg/d IV div. q8h + dapsone 100 mg PO per day (peds: Dosing not established)
  • Trimethoprim/sulfamethoxazole (Bactrim): Trimethoprim 15 " “20 mg/kg/d IV div. q6h and sulfamethoxazole 100 mg/kg/d IV div. q6h (peds: Dosing same)
  • Treatment of choice is IV trimethoprim/sulfamethoxazole, followed by IV pentamidine.
  • Dosing for alternative medications not yet established (consult pediatric infectious disease specialist).

Follow-Up

Disposition

  • Moderate to severe disease (PaO2 <70 mm Hg or A " “a gradient >35 mm Hg)
  • Inability to digest medications
  • Inability to return for careful follow-up
  • Nontoxic clinical appearance
  • Mild disease state (no hypoxemia or A " “a gradient)
  • Ability to tolerate medications
  • Close follow-up arranged
  • If results of induced sputum are not available, add macrolide to empirical regimen.

Followup Recommendations

Pearls and Pitfalls

  • Include PCP in differential diagnosis in any patient presenting with shortness of breath who is immunocompromised or is suspected of having undiagnosed HIV.
  • Patients considered for PCP are also more likely to have TB or atypical bacterial pneumonia.
  • Well-appearing patients with low oxygen saturations are at higher risk for complications.

Additional Reading

  • Thomas ‚ CF Jr, Limper ‚ AH. Pneumocystis pneumonia. N Engl J Med. 2004;350:2487 " “2498.
  • Huang ‚ L, Quartin ‚ A, Jones ‚ D, et al. Intensive care of patients with HIV infection. N Engl J Med. 2006;355:173 " “181.
  • Kovacs ‚ JA, Masur ‚ H. Evolving health effects of Pneumocystis: One hundred years of progress in diagnosis and treatment. JAMA 2009;301:2578 " “2585.

See Also (Topic, Algorithm, Electronic Media Element)

  • HIV/AIDS
  • Pneumonia, Adult
  • Pneumonia, Pediatric
  • Tuberculosis

Codes

ICD9

ICD10

SNOMED

  • 415125002 Pneumocystosis jiroveci pneumonia (disorder)