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Studies on gonococcus infection. 3. Correlation of gonococcal colony morphology with infectivity for the chick embryo
Abstract:
Comparable numbers of types 1, 2, 3, and 4 gonococci were placed on the intact chorioallantoic membrane of 236, 10-day old chick embryos. Types 1 and 2 organisms produced infection and could be cultured from chorioallantoic fluid 2 days later significantly more often (69%) than types 3 and 4 organisms (12%, P < 0.001). This confirms in an animal model the same correlation between colony types and infectivity observed in human volunteers and suggests that types 1 and 2 gonococci possess a fundamental virulence characteristic which is absent from types 3 and 4 organisms. Gonococcal infection of the chick embryo chorioallantoic cavity remains a useful model somewhat analogous to localized gonococcal infection in man.
Insights
Types 1 and 2 gonococci were more infectious in chick embryos than types 3 and 4. This animal model confirms gonococcal virulence correlates with colony type, similar to human studies.
Area of Science:
- Microbiology
- Infectious Diseases
- Animal Models
Background:
- Neisseria gonorrhoeae exhibits different colony types.
- Previous studies in human volunteers suggested a correlation between gonococcal colony type and infectivity.
Purpose of the Study:
- To investigate the infectivity of different gonococcal colony types (1, 2, 3, and 4) in a chick embryo model.
- To determine if the chick embryo model recapitulates findings from human studies regarding gonococcal virulence.
Main Methods:
- 236, 10-day old chick embryos were inoculated on the chorioallantoic membrane with comparable numbers of gonococcal types 1, 2, 3, and 4.
- Infection was assessed by culturing gonococci from chorioallantoic fluid 2 days post-inoculation.
Main Results:
- Types 1 and 2 gonococci caused infection and were cultured significantly more often (69%) compared to types 3 and 4 (12%, P < 0.001).
- This demonstrates a clear difference in infectivity between gonococcal colony types in this model.
Conclusions:
- The chick embryo chorioallantoic membrane serves as a valid animal model for studying localized gonococcal infection.
- The findings confirm that gonococcal colony types 1 and 2 possess inherent virulence factors absent in types 3 and 4, consistent with human observations.