MCQ Microbiology Answer 2

• The optochin test is a presumptive test that is used to identify strains of Streptococcus pneumoniae.
• Optochin (ethyl hydrocupreine) disks are placed on inoculated blood agar plates. Because S. pneumoniae is not optochin resistant, a zone of inhibition will develop around the disk where the bacteria have been lysed. This zone is typically 14mm from the disk or greater.
• Streptococcus pneumoniae is a gram-positive coccus that in clinical specimens often appears in pairs with tapered ends (lancet shaped), although it grows in short chains on nutrient broth media.
• It is a relatively fastidious facultative anaerobe and requires increased carbon dioxide for optimum recovery from clinical specimens .
  
• Susceptibility to ethyl hydrocupriene hydrochloride (Optochin) distinguishes pneumococci from other streptococci in the clinical microbiology laboratory.

Category: Microbiology MCQs