|
Title: A throat swab is taken from a patient with a respiratory infection. After 24 hou Post by: colleen on Apr 17, 2012 A throat swab is taken from a patient with a respiratory infection. After 24 hours, 1- to 3-mm colonies develop, which are round, mucoid, nonpigmented, and dimpled in the middle. What is the most likely pathogen, and how could you confirm the diagnosis on the culture?
Title: Re: A throat swab is taken from a patient with a respiratory infection. After 24 hou Post by: lewis on Apr 22, 2012 The colonies described are characteristic of Streptococcus pneumoniae. Diagnosis of this pathogen is confirmed if they are alpha-hemolytic on blood agar when grown aerobically and beta-hemolytic when grown anaerobically. Pneumococcal colonies can be differentiated from other colonies of alpha-hemolytic strains by adding a drop of bile to a colony. The bile triggers chemicals in S. pneumoniae that lyse the cells. The colony dissolves in a few minutes, confirming that they are pneumococcal colonies.
|