Review Question - QID 106715

This patient has pneumococcal (streptococcus pneumoniae) infection. A pneumococcal polysaccharide vaccine is recommended for adults over age 65 to prevent this disease.

There are two types of pneumococcal vaccine, the pneumococcal conjugate vaccine (PCV13, Prevnar) and the pneumococcal polysaccharide vaccine (PPSV23, Pneumovax). All adults age 65 and older should receive both vaccines. The conjugate vaccine contains polysaccharides from 13 Streptococcus pneumoniae serotypes linked to conjugate protein: the polysaccharides elicit a T cell independent serotype antibody response and the conjugate protein elicits a T cell dependent immune response. In contrast, the polysaccharide vaccine contains polysaccharide antigens only that induce a T cell independent serotype-specific antibody response. A T cell dependent response to vaccination is preferable because it provides longer immunologic memory.

Lutfiyya et al. review the diagnosis and management of community acquired pneumonia. Community acquired pneumonia is one the leading causes of morbidity and mortality in the US. Vaccination against both influenza and pneumoccocal disease have led to a decrease in death rates from pneumonia for the most vulnerable populations, including the elderly and immunocompromised.

Tomczyk et al. discuss recommendations for pneumococcal vaccine in adults ages 65 and older. This population, assuming no prior pneumococcal vaccination history, should receive a dose of the 13-valent pneumococcal conjugate vaccine followed by the 23-valent pneumococcal polysaccahride vaccine 6-12 months later.

Figure A shows a Gram stain of a sputum sample that contains Streptococcus pneumoniae; note the pairs and chains of lancet-shaped Gram-positive cocci. Illustration A shows an algorithm for determining which patients should receive pneumococcal vaccination. Illustration B shows the mechanism of polysaccharide conjugate vaccines; note the combination of both T cell induction as well as B cell antibody production.

Incorrect Answers:
Answer 1: The pneumococcal vaccine recommended for adults age 65 is a polysaccharide conjugate vaccine, Prevnar. Conjugate monosaccharide vaccines are not used.
Answer 3: Inactivated vaccines are composed of previously virulent organisms that were destroyed. Examples of inactivated vaccines include influenza, polio (Salk), typhoid, cholera, and pertussis.
Answer 4: Live attenuated vaccines are live organisms whose virulent properties have been disabled; examples include yellow fever, oral polio (Sabin), measles, mumps, rubella, influenza nasal spray, and varicella.
Answer 5: Toxoid vaccines are made from inactivated toxic compounds, not the organism itself; examples include tetanus and diphtheria.