# Special Populations and Follow-Up in Community-Acquired Pneumonia — ATS/IDSA 2019

## Influenza-Associated CAP

### Antiviral Therapy

- **Recommendation:** Prescribe anti-influenza treatment (e.g., oseltamivir) for all adults with CAP who test positive for influenza, regardless of duration of illness before diagnosis (Strong recommendation, Moderate quality of evidence).
- **Oseltamivir** 75 mg orally twice daily for 5 days is the standard regimen.
- Antiviral therapy applies to both inpatient and outpatient settings.

### Antibacterial Therapy in Influenza Pneumonia

- **Recommendation:** Standard antibacterial therapy should be prescribed in addition to antiviral therapy for adults with CAP who test positive for influenza (Strong recommendation, Low quality of evidence).
- **Rationale:** Bacterial co-infection is common in influenza pneumonia (most frequently S. pneumoniae and S. aureus), and it is clinically difficult to distinguish viral-only from viral-bacterial co-infection at presentation.
- Do NOT withhold antibiotics solely because influenza is confirmed.

### Corticosteroids in Influenza Pneumonia

- **Recommendation:** Do NOT routinely use corticosteroids in adults with severe influenza pneumonia (Conditional recommendation, Low quality of evidence).

## Corticosteroid Use in CAP

### Nonsevere CAP

- **Recommendation:** Do NOT routinely use corticosteroids in adults with nonsevere CAP (Strong recommendation, High quality of evidence).

### Severe CAP (Non-Influenza)

- **Recommendation:** Do NOT routinely use corticosteroids in adults with severe CAP (Conditional recommendation, Moderate quality of evidence).
- **Rationale:** While some studies have suggested benefit of short-course corticosteroids in severe CAP, the overall quality of evidence at the time of guideline publication was insufficient to recommend routine use.
- **Exception:** Corticosteroids remain indicated for refractory septic shock per Surviving Sepsis Campaign guidelines independently of CAP management.

## Aspiration Pneumonia

- **Recommendation:** Do NOT routinely add anaerobic coverage for suspected aspiration pneumonia in adults with CAP (Conditional recommendation, Very low quality of evidence).
- **When to add anaerobic coverage:**
  - Lung abscess is suspected or confirmed on imaging.
  - Empyema is suspected or confirmed.
- **Rationale:** Oropharyngeal aspiration is common, but anaerobic organisms are infrequently the sole cause of CAP. Standard CAP regimens (e.g., beta-lactam plus macrolide) typically provide adequate coverage.

## Follow-Up Chest Imaging

- **Recommendation:** Do NOT obtain routine follow-up chest imaging in adults with CAP whose symptoms have resolved within 5-7 days (Conditional recommendation, Low quality of evidence).
- **When to obtain follow-up imaging:**
  - Symptoms fail to resolve or worsen after 5-7 days of appropriate therapy.
  - Concern for underlying malignancy (e.g., patients > 50 years, smokers, recurrent pneumonia in the same location).
  - Presence of complications at presentation (pleural effusion, cavitation, abscess).
- **Rationale:** Radiographic abnormalities may persist for weeks after clinical resolution, and routine follow-up imaging rarely changes management in patients who are clinically improving.

## Special Considerations by Population

### Elderly Patients

- PSI score is heavily age-weighted, which may appropriately identify elderly patients at higher mortality risk.
- However, elderly patients may present with atypical symptoms (absence of fever, altered mental status rather than classic respiratory symptoms).
- A low clinical threshold for hospitalization is appropriate even if severity scores suggest outpatient management.

### Immunocompromised Patients

- The 2019 ATS/IDSA guideline explicitly **excludes** immunocompromised patients from its recommendations. This includes:
  - Patients receiving solid organ transplant
  - Patients receiving active chemotherapy or immunosuppressive therapy
  - HIV-infected patients (particularly with CD4 count < 200 cells/mm3)
  - Patients with primary immunodeficiency
- These patients require a broader differential and empiric coverage that extends beyond standard CAP management.

### Patients with Structural Lung Disease

- Patients with bronchiectasis or cystic fibrosis may have chronic colonization with P. aeruginosa or other multidrug-resistant organisms.
- The guideline's risk factor framework (prior respiratory isolation within the past year) applies here; empiric antipseudomonal coverage should be guided by prior microbiologic data.

## Discharge and Transition of Care

- Patients should be clinically stable (meeting all stability criteria) for at least 24 hours before discharge.
- Ensure completion of the antibiotic course: if IV antibiotics were initiated, transition to an appropriate oral agent before discharge.
- Outpatient follow-up should be arranged, particularly for patients with comorbidities, severe CAP at presentation, or slow clinical response.
- Assess vaccination status: pneumococcal and influenza vaccination should be provided or recommended at discharge if not up to date.
