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Germs that infect humans


Streptococcus pneumoniae

Streptococcus pneumoniae

© Dennis Kunkel Microscopy, Inc.

Microorganism: several microorganisms can cause pneumonia, among them the bacterium Streptococcus pneumoniae.

Disease: pneumonia

Occurrence of the disease

History: in industrialized countries, the mortality rate for pneumonia was between 20 and 40% for hospitalized patients.

Current situation: the mortality rate has decreased since the arrival of antibiotic treatments; it is now between five and ten per cent of cases. In developing countries, the mortality rate due to pneumonia caused by S. pneumoniae is often greater than ten per cent and can even reach 60% in children less than six months old.

Mechanism of action of the microorganism: the bacteria S. pneumoniae is naturally present in the respiratory tract of healthy individuals. Alcoholism, smoking, diabetes, injuries, and viral infections are factors that can favor the reproduction of the bacteria in the lungs, more specifically in the alveoli.

Symptoms of the disease: chills, fever, respiratory difficulty (dyspnea), rapid breathing, chest pains, cough, rust-colored sputum, i.e., containing blood.

Incubation period: possibly one to three days

Contagious period: as long as the secretions persist

Hosts: humans

Transmission: spread of the disease can occur by contact between an infected person and a healthy person. Transmission is also possible through objects contaminated by the infected person.

Discoverer of the microorganism: Fraenkel in 1886

Treatment: use of antibiotics such as penicillin

Geographical distribution of the microorganism: worldwide

Prevention: avoid crowds in enclosed spaces.

Vaccine: a vaccine composed of bacterial capsules of S. pneumoniae exists and is recommended for women 65 years and older and for people between two and 65 years of age suffering from chronic diseases.