Pneumonia, Pneumococcal

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

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

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

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

Therapeutic Procedures

• Pleural effusions developing after initiation of antimicrobial therapy usually are sterile, and thoracentesis need not be performed if the patient is otherwise improving

• Thoracentesis is indicated for an effusion present prior to initiation of therapy and in the patient who has not responded to antibiotics after 3–4 days

Follow-Up

• Repeat chest radiograph 6–8 weeks after treatment to ensure resolution of infiltrate

Complications

• Parapneumonic effusion is common cause of recurrent or persistent fever

• Empyema occurs in ≤ 5%

• Pneumococcal pericarditis (rare)

• Pneumococcal endocarditis usually involves aortic valve and often in association with meningitis

Prevention

PNEUMOCOCCAL VACCINE

• 23-valent purified polysaccharide from most common serotypes of S pneumoniae

• Current recommendations

  • Table 30–7

  • Patients at increased risk for developing severe pneumococcal disease (eg, asplenic patients, those with sickle cell disease)

  • Chronic illnesses (eg, cardiopulmonary disease, alcoholism, renal disease, cancer)

  • Persons over 65 years of age

  • Elderly individuals with unknown immunization status should be immunized once

• Revaccination

  • Recommended regardless of age for those with the highest risk of fatal pneumococcal disease (eg, asplenic patients, nephrotic syndrome or renal failure, HIV, leukemia, lymphoma, myeloma, immunosuppressive medications, transplant patients)

  • 65 years of age if primary vaccine was at least 5 years before

  • High-risk individuals previously immunized with 14-valent vaccine

Prognosis

• Mortality rates remain high in cases of

  • Advanced age

  • Multilobar disease

  • Hypoxemia

  • Extrapulmonary complications

  • Bacteremia

When to Refer

• All patients with suspected pneumococcal endocarditis or meningitis to an infectious disease specialist

• Extensive disease

• Seriously ill patient with pneumonia, particularly in the setting of comorbid conditions (eg, liver disease)

• Progression of pneumonia or failure to improve on antibiotics

When to Admit

• All patients in whom pneumococcal endocarditis or meningitis is suspected or documented should be admitted for observation and empiric therapy

• All patients with pneumococcal pneumonia that is multilobar or associated with significant hypoxemia

• Failure of outpatient pneumonia therapy, including inability to maintain oral intake and medications

• Exacerbations of underlying disease (eg, heart failure) by pneumonia that would benefit from hospitalization