An 8-year-old boy presented to his pediatrician with a low-grade fever and a diffuse erythematous rash over his chest, which developed 2 days after he complained of a painful sore throat. An exudate was present over the tonsillar area of the throat and covered his tongue. The clinical diagnosis of scarlet fever was confirmed by positive antigen test for group A Streptococcus from a throat specimen. The genera Streptococcus and Enterococcus include a large number of species capable of causing a wide spectrum of diseases.
1. What sites of the human body are normally colonized with Streptococcus pyogenes, Streptococcus agalactiae, and Streptococcus pneumoniae? How does this relate to infections caused by these bacteria?
2. The viridans streptococci (i.e., α-hemolytic and nonhemolytic streptococci) are subdivided into five groups. What are the groups and the specific diseases associated with each group?
3. Enterococci, like many other bacteria, can cause urinary tract infections but primarily in hospitalized patients. What characteristics of this bacterium are responsible for the predilection for disease in this population?
4. What biochemical properties are used to separate enterococci from the staphylococci and streptococci?
Answers
Answer:
An 8-year-old boy presented to his pediatrician with a low-grade fever and a diffuse erythematous rash over his chest, which developed 2 days after he complained of a painful sore throat. An exudate was present over the tonsillar area of the throat and covered his tongue. The clinical diagnosis of scarlet fever was confirmed by positive antigen test for group A Streptococcus from a throat specimen. The genera Streptococcus and Enterococcus include a large number of species capable of causing a wide spectrum of diseases.
1. What sites of the human body are normally colonized with Streptococcus pyogenes, Streptococcus agalactiae, and Streptococcus pneumoniae? How does this relate to infections caused by these bacteria?
2. The viridans streptococci (i.e., α-hemolytic and nonhemolytic streptococci) are subdivided into five groups. What are the groups and the specific diseases associated with each group?
3. Enterococci, like many other bacteria, can cause urinary tract infections but primarily in hospitalized patients. What characteristics of this bacterium are responsible for the predilection for disease in this population?
4. What biochemical properties are used to separate enterococci from the staphylococci and streptococci?
Explanation: