BSC 431 Lecture Notes - Lecture 9: Hyaluronidase, Streptolysin, Pus

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graysardine594

22 Mar 2016

School

University of Alabama

Department

Biological Sciences

Course

BSC 431

Professor

Julie Olson

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Document Summary

Streptococcus & enterococcus (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) Gram positive cocci: typically arranged in pairs or chains. Fastidious- complex nutritional requirements- blood agar plates required for growth (cid:1) (cid:1) Numerous species are human pathogens and differentiation between species is difficult (cid:1) (cid:1) (cid:1) Based on 3 characteristics: hemolysis on blood agar, beta, alpha, gamma, lancefield groups, serologic, based on antigenic properties of the cell wall carbohydrates, used only for a few species today, biochemical (physiological) properties. Streptococcal pharyngitis- swollen, red tonsils and pharynx, purulent exudate, high temperature (cid:1) Scarlet fever- sore throat progresses to include scarlet red rash- scars face, spreads all over body. Cellulitis, erysipelas (cid:1) (cid:1) (cid:1) (cid:1) (cid:1) Toxic shock syndrome- spe superantigen as seen w/ staph. Infection of the deeper layers of skin and subcutaneous tissue. Break in skin painful area swollen violet colored tissue w/ blisters necrosis. Influx of huge numbers of macrophages which release o2 radicals that kill tissue.

Related Questions

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 childâs oropharynx. Her mother also took Deliaâs 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 Deliaâs 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 patientâs 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: Assuming that Delia is not allergic to penicillin-based drugs, would a penicillin-family drug (amoxicillin, for example) typically be effective against S. pyogenes?

A. Penicillin-based drugs would effectively target the thick peptidoglycan layer within the pathogenâs cell wall.

B. Penicillin-based drugs would be ineffective since the cell wall of S. pyogenes does not contain peptidoglycan.

The porins within the pathogenâs outer membrane would exclude penicillin-based drugs, rendering these antimicrobials C. ineffective.

D. Penicillin-based drugs would effectively target the mycolic acids present in the pathogenâs cell wall.

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

A. Endospores should be found within the patientâs culture since S. pyogenes makes endospores in response to antibacterial drugs treatments.

B. Endospores should be found within the patientâs culture since S. pyogenes was grown in nutrient-limiting conditions.

C. Endospores should not be detected in the patientâs culture since S. pyogenes is a non-endospore forming pathogen.

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

E. Endospores should not be detected in the patientâs culture since S. pyogenes is Gram-positive, and, therefore, doesnât make endospores.

BSC 431 Lecture Notes - Lecture 9: Hyaluronidase, Streptolysin, Pus

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