What are pneumococcal infections? |

Definition

Pneumococcal infection is caused by the encapsulated, gram-positive bacterium
Streptococcus pneumoniae, also known as pneumococcus.
The term “pneumococcus” was first used in the 1880’s to describe this type of
infection, because pneumococcus was considered the most common cause of bacterial pneumonia.

Causes

Pneumococcal disease is caused by an infection of the bacterium S. pneumoniae.

Risk Factors

Children younger than age two years are at greatest risk of pneumococcal
disease. The next most commonly affected are adults age sixty-five years and
older. Conditions that cause deficits in the immune system
(such as human
immunodeficiency virus infection, malignancy, and absence of
the spleen) or conditions associated with decreased lung function (such as
asthma, chronic bronchitis, and cigarette
smoking) are associated with increased risk of pneumococcal disease. Absence of
breast-feeding, day care attendance, and lack of vaccination can increase the risk
of disease too. Native Alaskans, Navajo and Apache Indians, and African Americans
are more commonly affected than other ethnic groups.

Symptoms

Pneumococci bacteria can attack different parts of the body. When the bacteria
attack the lungs, they cause pneumonia. When the bacteria invade the
bloodstream, they cause bacteremia. Infection of the covering of the brain causes
meningitis. Pneumococci may also cause middle-ear infection
(otitis
media) and sinusitis.

In adults, symptoms of pneumonia include chills, fever, shortness of breath or rapid breathing, chest pain that is worsened by breathing deeply, and a productive cough. Symptoms of meningitis include stiff neck, fever, mental confusion, and photophobia (visual sensitivity to light). Symptoms of bacteremia can include some of the symptoms of pneumonia and meningitis.

In children, symptoms of pneumonia include fever, cough, rapid breathing, and grunting. The symptoms of meningitis vary with age, but include diarrhea, vomiting, and fever. In older children, meningitis symptoms include headache, sensitivity to light, and a stiff neck. Bacteremia typically causes nonspecific symptoms, such as fever and irritability. Otitis media typically causes a painful ear and also may cause sleeplessness, fever, and irritability.

Screening and Diagnosis

If pneumococcal disease is suspected, Gram’s stain and cultures are performed. Chest X rays are done if pneumonia is suspected. Additional tests include a complete blood cell count, erythrocyte sedimentation rate, and C-reactive protein.

Treatment and Therapy

Penicillin
antibiotics are used to treat pneumococcal disease. However,
pneumococcal strains have emerged that are resistant to these antibiotics. These
resistant forms of pneumococcus are difficult to treat.

Prevention and Outcomes

Vaccination is the best prevention strategy. There are two types of
pneumococcal
vaccine available: a polysaccharide vaccine and a conjugate
vaccine. The pneumococcal polysaccharide vaccine protects against the twenty-three
types of S. pneumoniae that are responsible for more than 90
percent of all cases of pneumococcal disease in adults. In children, the
pneumococcal conjugate vaccine protects against 86 percent of the bacteria types
that cause blood infections and 83 percent of those that cause meningitis.

Bibliography

French, Neil. “Pneumococcal Diseases.” In Manson’s Tropical Diseases, edited by Gordon C. Cook and Alimuddin I. Zumla. 22d ed. Philadelphia: Saunders/Elsevier, 2009.

Hoffman-Roberts, H. L., E. Babcock, and I. F. Mitropoulos. “Investigational New Drugs for the Treatment of Resistant Pneumococcal Infections. Expert Opinion in Investigational Drugs 14 (2005): 973-995.

Surhone, L. M., M. T. Tennoe, and S. F. Henssonow, eds. Pneumococcal Infection. Saarbrücken, Germany: VDM, Mueller, 2010.