STUDIES ON THE NASOPHARYNGEAL SECRETIONS FROM PATIENTS WITH COMMON COLDS

Area of Science:

• Virology and Bacteriology
• Infectious Diseases
• Respiratory Pathogens

Background:

• The common cold is a widespread respiratory illness with unclear etiology.
• Distinguishing common colds from other respiratory infections like epidemic influenza is clinically important.
• Previous research has attempted to identify the causative agent of the common cold.

Purpose of the Study:

• To investigate the transmissibility of common cold infections.
• To determine if a specific pathogenic agent can be isolated from common cold patients.
• To differentiate common colds from epidemic influenza based on experimental transmission and pathological findings.

Main Methods:

• Transmission experiments using filtered nasopharyngeal secretions from early common cold cases in humans.
• Intratracheal inoculation of rabbits with nasopharyngeal washings from common cold and influenza patients.
• Aerobic and anaerobic cultures of nasopharyngeal washings using various media, including Smith-Noguchi and Gates' dialysate medium.
• Microscopic examination and staining techniques (Gram, Giemsa, polychrome methylene blue) to identify microorganisms and differentiate from precipitate.

Main Results:

• Common cold-like illness was transmitted to humans using unheated secretions from early disease stages (3-18 hours), with incubation periods of 8-48 hours.
• Heated secretions failed to transmit the illness, and transmission was not achieved from secretions obtained later in the disease course (18-20 hours).
• Rabbit inoculations showed no distinct pathological changes with common cold material, unlike influenza material which caused lung and blood alterations.
• No constant pathogenic agent was recovered from common cold secretions, although anaerobic Gram-negative bacteria were found in some cases but lacked consistent pathogenicity.
• Bacterium pneumosintes was not detected in common cold cultures.
• Foster's globoid bodies were not definitively identified, with observed particles attributed to medium precipitate.

Conclusions:

• Infectious common colds and epidemic influenza are distinct diseases.
• The causative agent of the common cold was not identified in this study.
• Nasopharyngeal secretions are most infectious in the early hours of common cold illness.
• Rigorous microbiological techniques are necessary to differentiate true microbial growth from artifactual precipitate in cultures.