If a quellung test was done on the following bacterial isolates, which one would you expect to be positive?
Correct Answer: S. pneumoniae
Description: The quellung test determines the presence of bacterial capsules. Specific antibody is mixed with the bacterial suspension or with clinical material. The polysaccharide capsule-antibody complex is visible microscopically. The test is also termed capsular swelling. The capsules of S. pneumoniae as well as N. meningitidis, H. influenzae, and K. pneumoniae play a role in the pathogenicity of the organisms. These surface structures inhibit phagocytosis, perhaps by preventing attachment of the leukocyte pseudopod. C. diphtheriae, Enterobacter, and H. parainfluenzae are nonencapsulated.
Category:
Microbiology
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