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Published on: February 23, 2014
THE OCCURRENCE OF CARRIERS OF DISEASE-PRODUCING TYPES OF PNEUMOCOCCUS
1Hospital of The Rockefeller Institute for Medical Research.
Abstract:
Lobar pneumonia in 75 per cent of instances is due to specific types of pneumococci possessed of a high degree of pathogenicity. Although pneumococci occur in the mouths of 60 per cent of normal individuals, such organisms are readily distinguishable from the highly parasitic types of pneumococcus responsible for the severe forms of lobar pneumonia, a convincing proof that infection in this disease is, in the majority of instances, not autogenic in nature, but is derived from some extraneous source. In a high percentage of instances healthy persons intimately associated with cases of lobar pneumonia harbor the disease-producing types of pneumococcus. In every such instance the pneumococcus isolated has corresponded in type with that of the infected individual. Convalescents from pneumonia carry for a considerable length of time the type of pneumococcus with which they have been infected. The existence of the carrier state among healthy persons and among those recently recovered from pneumonia establishes a basis for understanding the mechanism by means of which lobar pneumonia spreads and maintains its high incidence from year to year.
Insights
Pneumonia is often caused by highly pathogenic pneumococci from external sources, not self-infection. Healthy contacts and recovered patients can carry and spread these disease-causing bacteria.
Area of Science:
- Microbiology
- Infectious Diseases
- Epidemiology
Background:
- Lobar pneumonia is frequently caused by specific, highly pathogenic pneumococcal serotypes.
- Pneumococci are common in the oral flora, but disease-causing strains are distinct from commensal types.
- Infection is typically exogenous, not autogenic, in most lobar pneumonia cases.
Purpose of the Study:
- To investigate the source and transmission of pathogenic pneumococci causing lobar pneumonia.
- To determine the role of healthy carriers and convalescents in pneumococcal transmission.
Main Methods:
- Bacteriological analysis of pneumococci from pneumonia patients and their contacts.
- Serotyping of isolated pneumococcal strains.
- Epidemiological investigation of disease spread.
Main Results:
- 75% of lobar pneumonia cases are linked to specific, highly pathogenic pneumococcal types.
- Healthy individuals associated with pneumonia patients frequently harbor disease-producing pneumococci of the same type.
- Pneumococci isolated from infected individuals matched the types found in their close contacts.
- Pneumonia convalescents remain carriers of the infecting pneumococcal type for extended periods.
Conclusions:
- The carrier state in healthy individuals and recent convalescents is crucial for the spread and sustained incidence of lobar pneumonia.
- Understanding pneumococcal carriage is key to controlling pneumonia transmission.
- Exogenous infection from carriers is the primary mode of transmission for severe lobar pneumonia.
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