Streptococcus pyogenes

Nadia, a 12 year old female presented to her pediatrician with a sore throat and cough. She was complaining of off and on throat pain. She had a very low grade fever between 98.9 to 99.4 degrees F. Her pediatrician advised a rapid strep test to test for Strep throat. Strep throat is caused by the bacterium Streptococcus pyogenes. It can also be caused by certain viruses. It is very hard to differentiate between bacterial and viral strep throat although a 48 hr culture is a good way of confirming whether it is a bacterial infection.

A rapid strep test involves exposing a throat swab to a stick that is coated with an antibody. If a person's culture has the Streptococcus pyogenes bacteria, the antibody on the stick will react to the antigen on the cell surface of the bacterium and produce a color change. A more effective method to confirm strep throat is by culturing the sputum from the infected person for at least 48hrs. If the bacteria grows on a blood agar plate then it is positive for Streptococcus pyogenes.

Nadia's doctor found that the rapid strep test came negative and she sent her sample for culture in order to confirm whether it is strep throat or not. In the meantime, her doctor called in a prescription for penicillin and left to the discretion of her parents whether or not to give her the antibiotics.

As of now, penicillin is an effective antibiotic against Streptococcus pyogenes. It attacks the NAM and NAG molecules on the cell wall of the bacterium and prevents them from cross linking. This damages the cell wall and the bacterium fails to survive.

One of the concerns is the possibility of the emergence of penicillin resistant Streptococcus pyogenes strains due to overuse or misuse of antibiotics.

• Comment on the cell wall structure of Streptococcus pyogenes and its gram stain reaction. Also, comment on how the cell wall composition makes it more susceptible to antibiotics.
• Discuss your thoughts on antibiotic resistance and the misuse of antibiotics as pertaining to the above case study. What could the pediatrician have done before prescribing the antibiotics?

In your comments address the following:

• What do you agree with in your classmate's initial post?
• What do you disagree with?
• Pose questions to encourage further discussion.
• Provide any insight you have about the topic along with references.