The gram-positive coccus Streptococcus pneumoniae.
Person to person through close contact via respiratory droplets.
Streptococcus pneumoniae is the most common bacterial cause of community-acquired pneumonia worldwide. Disease incidence is higher in developing than in industrialized countries. Risk is highest in young children, the elderly, and those with chronic illnesses or immune suppression.
The major clinical syndromes of pneumococcal disease are pneumonia, bacteremia, and meningitis. Pneumococcal pneumonia classically presents with sudden onset of fever and malaise, pleuritic chest pain, cough with purulent or blood-tinged sputum, or dyspnea. In the elderly, fever, shortness of breath, or altered mental status may be the initial symptoms. Pneumococcal meningitis is less common than pneumonia, and symptoms may include headache, lethargy, vomiting, irritability, fever, stiff neck, and seizures. People with cochlear implants are at increased risk of pneumococcal meningitis.
Isolation of S. pneumoniae from blood or other normally sterile body sites such as pleural fluid or cerebrospinal fluid (CSF). Tests are also available to detect pneumococcal antigen in body fluids.
A urinary antigen test for S. pneumoniae is commercially available, simple to use, and has reasonable specificity to detect pneumococcal infection in adults, making it a useful addition for diagnostic evaluation. A clinician should suspect pneumococcal pneumonia if a sputum specimen contains gram-positive diplococci, polymorphonuclear leukocytes, and few epithelial cells. Gram-positive diplococci on staining of CSF may indicate pneumococcal meningitis. High white blood cell counts should raise suspicion for bacterial infection.
Therapy depends on the syndrome, but patients who present with community-acquired pneumonia should be empirically treated for pneumococcal infection. Pneumococcal bacteria are resistant to ≥1 antibiotic in 30% of severe cases, although level and type of resistance varies among locations.
In outpatient settings, current clinical practice guidelines for pneumonia management recommend amoxicillin for children and macrolides (such as azithromycin) or doxycycline for previously healthy adults. For adults with chronic or immunosuppressing conditions, a respiratory fluoroquinolone (such as moxifloxacin or levofloxacin) or a β-lactam plus a macrolide is recommended. In inpatient settings, the initial treatment includes a broad-spectrum cephalosporin plus a macrolide or a respiratory fluoroquinolone alone. Vancomycin might be added until antibiotic susceptibility results are available.
Patients with presumptive pneumococcal meningitis by CSF staining should be treated with a broad-spectrum cephalosporin plus vancomycin until susceptibility results are available.
The 13-valent pneumococcal conjugate vaccine (PCV13) provides protection against the 13 serotypes responsible for most severe illness. PCV13 has been part of the US infant immunization schedule since 2010 and is also recommended for all adults aged ≥65 years and some adults aged 19–64 with immunocompromising conditions. A 23-valent pneumococcal polysaccharide vaccine (PPSV23) is recommended for all adults aged ≥65 years and people aged 2–64 years with underlying medical conditions. The intervals between PCV13 and PPSV23 given in series differ by age and risk group group (see www.cdc.gov/vaccines/vpd/pneumo/hcp/recommendations.html). PCV13 and PPSV23 should not be coadministered. Adults aged ≥65 years who are immunocompetent should receive PPSV23 ≥1 year after PCV13, while those with immunocompromising conditions should receive PPSV23 ≥8 weeks after PCV13.
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