Delia, a five-year-old, woke up one morning complaining that she had a sore thro

Question

Delia, a five-year-old, woke up one morning complaining that she had a sore throat, headache and stomachache. Her tonsils appeared swollen, and a tonsular exudate, appearing as a cream-colored pus, was evident upon examining the child’s oropharynx. Her mother also took Delia’s temperature and noted the girl was running a low-grade fever. Suspecting strep throat (streptococcal pharyngitis), her mother made an appointment with the pediatrician.

The doctor first performed a rapid strep test, which works by detecting certain cell surface proteins on group A streptococci (GAS). This test is inexpensive and can detect GAS in a matter of minutes. However, rapid strep tests that come back negative are not especially reliable; about five out of every 100 patients with streptococcal pharyngitis will have a negative rapid strep test result. Therefore, despite Delia’s rapid strep test being negative, the doctor went ahead and ordered a bacterial culture. This was a wise decision because Delia had signs and symptoms that pointed to a case of streptococcal pharyngitis caused by the Gram-positive, nonmotile, encapsulated prokaryote Streptococcus pyogenes.

When cultures to detect S. pyogenes are performed, the patient’s sample (in this case a swab of the throat) is streaked out onto a specialized nutrient-rich agar called blood agar. Actively growing S. pyogenes can break down red blood cells (a process called beta hemolysis), and, therefore, is readily detectable on blood agar plates because a clear zone develops around its colonies. Based on the microbiology data that came back, Delia was treated for streptococcal pharyngitis. After 48 hours on an antibiotic, Delia felt much better and returned to school.

QUESTION: Would you expect to find endospores if you conducted an endospore stain of the patient’s cultured infectious agent? Explain your reasoning. (Choose the single best answer.)

A. Endospores should be found within the patient’s culture since S. pyogenes makes endospores in response to antibacterial drugs treatments. B. Endospores should be found within the patient’s culture since S. pyogenes was grown in nutrient-limiting conditions. C. Endospores should not be detected in the patient’s culture since S. pyogenes is a non-endospore forming pathogen. D. Endospores should not be detected in the patient’s culture since S. pyogenes was grown under favorable conditions that promote germination. E. Endospores should not be detected in the patient’s culture since S. pyogenes is Gram-positive, and, therefore, doesn’t make endospores.

Explanation / Answer

answer: the answers could be D and E , but E cannot be the best answer as endospores are produced by gram positive bacteria and Endospore formation is usually triggered by a lack of nutrients. In endospore formation, the bacterium divides within its cell wall.

D. Endospores should not be detected in the patient’s culture since S. pyogenes was grown under favorable conditions that promote germination.

.Streptococcus pyogenes is a Gram-positive facultative anaerobic bacterium.  It is not motile, and does not produce spores

Streptococcus pyogenes is Beta-hemolytic streptococci produce a toxin which forms a clear zone of hemolysis on blood agar, signifies its ability to destroy red blood cells, it belongs to Lancefield serogroup A, also known as the group A streptococci (GAS), causes a wide variety of diseases in humans. most common bacterial cause of sore throat is Streptococcus pyogenes which is accompanied by swollen lymph nodes, fever, and headache

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