Pneumonia, Pneumococcal

Key Features

Essentials of Diagnosis

• Productive cough, fever, rigors, dyspnea, early pleuritic chest pain

• Consolidating lobar pneumonia on chest radiograph

• Lancet-shaped gram-positive diplococci on Gram stain of sputum

General Considerations

• The most common cause of community-acquired pyogenic bacterial pneumonia

• Predisposing factors

  • Alcoholism

  • Asthma

  • HIV infection

  • Sickle cell disease

  • Splenectomy

  • Hematologic disorders

Clinical Findings

Symptoms and Signs

• High fever, productive cough, occasional hemoptysis, and pleuritic chest pain

• Rigors may occur initially but are uncommon later in the course

• Bronchial breath sounds are an early sign

• Differentiating pneumococcal from other bacterial pneumonias is not possible clinically or radiographically because of significant overlap in presentations

Differential Diagnosis

• Pneumonia due to other causes, eg, Haemophilus influenzae, influenza

• Aspiration pneumonia or lung abscess

• Pulmonary embolism

• Myocardial infarction

• Acute exacerbation of chronic bronchitis

• Acute bronchitis

• Hypersensitivity pneumonitis

Diagnosis

Laboratory Tests

• A rapid urinary antigen test for Streptococcus pneumoniae, with sensitivity of 70–80% and specificity > 95%, can assist with early diagnosis

• A good-quality sputum sample (less than 10 epithelial cells and more than 25 polymorphonuclear leukocytes per high-power field) shows gram-positive diplococci in 80–90% of cases

• Blood cultures are positive in up to 25% of selected cases and much more commonly so in HIV-positive patients

Imaging Studies

• Chest radiograph shows findings of consolidation, often with a lobar distribution, infiltrates, pleural effusion

Treatment

Medications

• Initial antimicrobial therapy of pneumonia is empiric pending isolation and identification of the causative organism (Table 9–8)

OUTPATIENT

• Amoxicillin, 750 mg twice daily orally for 7–10 days

• Cephalosporins may also be used

  • Cefpodoxime, 200 mg orally twice daily

  • Cefdinir, 300 mg twice daily

• Alternatives include

  • Azithromycin, one 500-mg dose orally on the first day and 250 mg orally for the next 4 days

  • Clarithromycin, 500 mg twice daily orally for 10 days

  • Doxycycline, 100 mg twice daily orally for 10 days

  • Levofloxacin, 750 mg orally for 5 days

  • Moxifloxacin, 400 mg orally for 7–14 days

INPATIENT

• Aqueous penicillin G (susceptible strains), 2 million units every 4 hours intravenously

• Ceftriaxone, 1 g every 24 hours intravenously

• For a highly penicillin-resistant strain, vancomycin, 1 g every 12 hours intravenously

• Alternatively, a fluoroquinolone (eg, levofloxacin, 750 mg) can be used

• Total duration of therapy is not well defined but 5–7 days is appropriate for patients who have an uncomplicated infection and demonstrate a good clinical response

• Corticosteroid use remains controversial in community-acquired pneumonia and should not be administered routinely

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