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Correlation between Congo red binding and contact haemolysin production in Shigella species
K Sharma1, P Rishi, J S Grewal
1Department of Microbiology, Panjab University, Chandigarh, India.
Abstract:
Haemolytic strains of Shigella dysenteriae type 1, Shigella flexneri, Shigella boydii and Shigella sonnei cultured on Congo red agar produced pigmented colonies (Pcr+) whereas nonhaemolytic strains produced white colonies and did not bind Congo red (Pcr-). S. flexneri-1 haemolysin negative mutant (lacking plasmid) of haemolysin positive prototroph also did not bind Congo red and produced nonpigmented colonies. Among the twelve strains of Shigella included in this study, the characteristics of Congo red binding, plasmid profile and haemolytic activity appeared to be correlated. Congo red binding occurred comparatively more by haemolysin-producing strains. Congo red binding can be used as a quick and reliable method for virulence traits of pathogens, including haemolysin activity.
Insights
Shigella bacteria strains that produce haemolysin also bind to Congo red dye, forming pigmented colonies. This binding ability correlates with virulence and can be a quick indicator of haemolysin activity in pathogens.
Area of Science:
- Microbiology
- Bacteriology
- Pathogen Virulence
Background:
- Shigella species are significant human pathogens responsible for bacillary dysentery.
- Virulence factors, such as haemolysin, are crucial for Shigella pathogenesis.
- Assessing virulence traits aids in understanding and combating bacterial infections.
Purpose of the Study:
- To investigate the correlation between Congo red binding and haemolytic activity in Shigella strains.
- To determine if Congo red binding can serve as a reliable indicator of virulence factors like haemolysin.
Main Methods:
- Culturing various Shigella species (S. dysenteriae type 1, S. flexneri, S. boydii, S. sonnei) on Congo red agar.
- Observing colony pigmentation (Congo red binding, Pcr+) versus non-pigmentation (Pcr-).
- Analyzing haemolytic activity and plasmid profiles of both wild-type and mutant strains.
Main Results:
- Haemolytic Shigella strains produced pigmented colonies (Pcr+) on Congo red agar, while non-haemolytic strains produced white colonies (Pcr-).
- A haemolysin-negative mutant of S. flexneri lacked Congo red binding and pigmentation.
- Congo red binding, plasmid profile, and haemolytic activity were found to be correlated in the studied Shigella strains.
Conclusions:
- Congo red binding is strongly associated with haemolysin production in Shigella.
- Congo red binding serves as a rapid and dependable method for identifying virulence traits, specifically haemolysin activity, in pathogenic bacteria.