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BMS 602 Exam #2 Questions And Correct Answers
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BMS 602 Exam #2 Questions AndCorrect Answers
LO (11&12): Know the disease states that S. pyogenes and S. pneuomniae can cause
and be able to discriminate between these disease states in a case study. - Answer
Streptococcus pyogenes:
-Lance group: A
-Hemolysis: Beta
-Habitat: Throat, and Skin
-Disease: Pharyngitis, Impetigo, Rheumatic fever, Glomerulonephritis
Streptococus pneumoniae:
-Lance group: None
-Hemolysis: Alpha
-Habitat: Throat (primarily nasopharynx)
-Disease: Pneumonia, Meningitis,and Bacteremia
What are some characteristics that allow Streptococci to be distinguished from other
bacteria? - Answer Streptococci grow in chains or pairs, and are catalase-negative
organisms. While these are their main distinguishing traits, Streptococci are also
facultative anaerobes, meaning that they can survive in both aerobic or anaerobic
conditions, and have complex nutritional requirements, meaning that they are not easily
grown. (Need Blood Agar medium or serum enriched media)
What are the three ways that species of Sreptococci are classified? - Answer The three
different overlapping classification schemes are:
1. Lancefield groupings: serological grouping by surface antigens - groups are A, B, C,
and G.
2. Hemolysis patterns: Complete (beta), partial (alpha), no hemolysis (gamma)
3. Biochemical properties
*ALL BETA HEMOLYTIC streptococci are put into lancefield groupings, however other
species with different hemolysis patterns are classified by their biochemical properties.
List the Lancefield grouping, hemolysis pattern, habitat, and common diseases caused
,by:
S. pyogenes - Answer Lancefield: A
Hemolysis: Beta
Habitat: Throat, skin
Common disease: pharyngitis, impetigo, rheumatic fever (can also cause necrotizing
fasciitis)
List the Lancefield grouping, hemolysis pattern, habitat, and common diseases caused
by:
S. pneumoniae - Answer Lancefield: NONE
Hemolysis: Alpha
Habitat: Throat
Common disease: pneumonia, meningitis, bactermia (S. pneumonia is the leading cause
of bacterial meningitis, which is bacterial infection of the blood)
What is the difference between epithelial and endothelial cells? - Answer Epithelial cells
are cells that line the hollow organs and glands, and make up the outer surface of the
body. These cells are EXPOSED to the outside world, and are generally coated in
mucous. Some epithelial cells contain cilia to remove foreign substances.
Endothelial cells are cells that line the INTERIOR surface of blood vessels and lymphatic
vessels. These cells are only exposed to blood or lymph, NOT the outside world. These
cells are not ciliated, and do not contain mucous.
** Main Differences:
Epithelial: EXTERIOR - ciliated, contain mucous
Endothelial: INTERIOR - non-ciliated, no mucous
What are the roles of the two functional domains of the respiratory system? - Answer
The two functional domains are:
Upper Respiratory (UR) Tract: intake of Oxygen and outtake of Carbon Dioxide
Lower Respiratory (LR) Tract: functions in the exchange of Oxygen for Carbon dioxide
Describe the disease progression of Streptococcus pyogenes. - Answer Pathogen:
gram positive cocci - HUMAN RESERVOIR
Encounter: S. pyogenes are normal flora of the skin and nasopharynx. The disease is
caused by acquiring new strains that are not normal flora, and by person to person
contract through contaminated respiratory droplets, skin to skin contact, or contact
, with a fomite.
Entry: wound infection of the skin, or inhalation for nasopharynx infection.
Spread: the organism produces a number of enzymes and toxins that destroy host tissue
Multiplication: extracellular growth on mucous membranes, in skin, or in deep tissue.
Damage: possible outcomes of infection are pharyngitis, scarlet fever, necrotizing
fasciitis, and rheumatic fever. (only the most relevant ones are listed).
Diagnosis: Throat or skin culture on blood agar - BETA hemolysis. An immunodetection
assay will also be run.
Treatment and Prevention: Penicillins/Cephalosporins. The primary treatment is
penicillin, which is the lowest level antibiotic. Treatment prevents local infection from
becoming invasive, potential rheumatic fever, and spread to other people.
What are the specific components of the S. pyogenes cell wall, and how do they
contribute to its virulence? - Answer The cell wall of S. pyogenes contains specific
antigens that are referred to as Lancefield group A antigens. - EXPLAIN
M protein: this protein is anchored in the cytoplasm and has two main roles:
1. contributes to adhesion by binding fibronectin - allowing bacteria to bind to cell
surfaces.
2. Prevents C3b (opsonin) binding, preventing complement activation and opsonization.
Fimbriae (pili): These extracellular structures allow attachment to host tissues, and in S.
pyogenes they are encoded by the FCT pathogenicity island.
F protein: this proteins binds fibronectin which allows adherence to respiratory cells.
** These adherence factors allow an organism to combat mucociliary clearance and
take up residence in the Upper Respiratory tract.
C5a peptidase: This is a protease that inactivates C5a, which prevents it from attracting
phagocytic cells to the site of infection. This halts or delays the immune response,
allowing S. pyogenes to establish an infection.
CAPSULE: described in other slides.
Describe how the capsule of S. pyogenes contributes to its virulence and pathogenicity.
- Answer The capsule of S. pyogenes is composed of hyaluronic acid. This is extremely
important, because hyaluronic acid is commonly found in connective tissue and
recognized as "self" by the immune system, so the bacteria is able to mask itself as a
normal component and avoid destruction by the immune system.
What are three different types of toxins that S. pyogenes secretes? Describe them
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