Community-Acquired Pneumonia: Treatment

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Duration of Treatment

Most patients with CAP respond to appropriate therapy within 72 hours. IDSA/ATS guidelines recommend that patients with routine cases of CAP be treated for a minimum of 5 days. Despite this, many patients are treated for an excessive amount of time, with over 70% of patients reported to have received antibiotics for more than 10 days for uncomplicated CAP.26 There are instances that require longer courses of antibiotics, including cases caused by Pseudomonas aeruginosa, S. aureus, and Legionella species and patients with lung abscesses or necrotizing infections, among others.27

Hospitalized patients do not need to be monitored for an additional day once they have reached clinical stability (Table 4), are able to maintain oral intake, and have normal mentation, provided that other comorbidities are stable and social needs have been met.6 C-reactive protein (CRP) level has been postulated as an additional measure of stability, specifically monitoring for a greater than 50% reduction in CRP; however, this was validated only for those with complicated pneumonia.28 Patients discharged from the hospital with instability have higher risk of readmission or death.29

Criteria for Clinical Stability

Transition to Oral Therapy

IDSA/ATS guidelines6 recommend that patients should be transitioned from intravenous to oral antibiotics when they are improving clinically, have stable vital signs, and are able to ingest food/fluids and medications.

Management of Nonresponders

Although the majority of patients respond to antibiotics within 72 hours, treatment failure occurs in up to 15% of patients.15 Nonresponding pneumonia is generally seen in 2 patterns: worsening of clinical status despite empiric antibiotics or delay in achieving clinical stability, as defined in Table 4, after 72 hours of treatment.30 Risk factors associated with nonresponding pneumonia31 are:

  • Radiographic: multilobar infiltrates, pleural effusion, cavitation
  • Bacteriologic: MRSA, gram-negative or Legionella pneumonia
  • Severity index: PSI > 90
  • Pharmacologic: incorrect antibiotic choice based on susceptibility

Patients with acute deterioration of clinical status require prompt transfer to a higher level of care and may require mechanical ventilator support. In those with delay in achieving clinical stability, a question centers on whether the same antibiotics can be continued while doing further radiographic/microbiologic work-up and/or changing antibiotics. History should be reviewed, with particular attention to exposures, travel history, and microbiologic and radiographic data. Clinicians should recall that viruses account for up to 20% of pneumonias and that there are also noninfectious causes that can mimic pyogenic infections.32 If adequate initial cultures were not obtained, they should be obtained; however, care must be taken in reviewing new sets of cultures while on antibiotics, as they may reveal colonization selected out by antibiotics and not a true pathogen. If repeat evaluation is unrevealing, then further evaluation with computed tomography (CT) scan and bronchoscopy with bronchoalveolar lavage and biopsy is warranted. CT scans can show pleural effusions, bronchial obstructions, or a pattern suggestive of cryptogenic pneumonia. A bronchoscopy might yield a microbiologic diagnosis and, when combined with biopsy, can also evaluate for noninfectious causes.

As with other infections, if escalation of antibiotics is undertaken, clinicians should try to determine the reason for nonresponse. To simply broaden antimicrobial therapy without attempts at establishing a microbiologic or radiographic cause for nonresponse may lead to inappropriate treatment and recurrence of infection. Aside from patients who have bacteremic pneumococcal pneumonia in an ICU setting, there are no published reports pointing to superiority of combination antibiotics.20

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