M5: Streptococcus

Question 1

Streptococcus shape

Answer 1

coccus, links to other bacteria in chain-like structures

Question 2

Streptococcus gram stain

Answer 2

positive

Question 3

Streptococcus catalase test

Answer 3

negative (can’t break down peroxides)

Question 4

best way to identify Strep

Answer 4

hemolysis (blood agar plate)

Question 5

Alpha-hemolytic Strep

Answer 5

• partial lysis of rbcs
• greenish brown discoloration surrounding colony on BAP
• characteristic of Streptococcus pneumonia

Question 6

Beta-hemolytic Strep

Answer 6

• complete lysis of rbcs
• distinct zone of clearing around colony
• characteristic of Streptococcus pyogenes and streptococcus aureus

Question 7

Lancefield groupings

Answer 7

• grouping system for beta hemolytic strep
• groups based on antigens in cell wall
• named by letter (group A, group B, etc)

Question 8

Gamma-hemolytic Strep

Answer 8

• no lysis of rbcs
• colonies are white/tan on red background
• characteristic of enterococcus faecalis

Question 9

Streptococcus pyogenes

Answer 9

• Group A

- responsible for 90% of human strep infections resulting in pharyngitis, scarlet fever, and rheumatic fever

Question 10

Key illnesses caused by strep (3)

Answer 10

• Streptococcal Pharyngitis (strep throat)
• Rheumatic fever
• Streptococcal septicemia

Question 11

Streptococcal Pharyngitis overview

Answer 11

• aka Strep throat
• group A disease
• untreated, progresses to rheumatic fever

Question 12

symptoms of strep throat (5)

Answer 12

• fever
• enlarged lymph nodes on neck
• reddening w/in lining of throat
• soreness and discomfort in throat
• can cause ear, lung, sinus issues

Question 13

Rheumatic fever overview

Answer 13

• progression of untreated Streptococcal pharyngitis
• occurs 2-3 weeks post Strep infection
• causes damage to heart valves due to inflammation of heart tissue
• treated via penicillin

Question 14

Rheumatic fever symptoms (4)

Answer 14

• joint inflammation
• involuntary jerking movements
• pea sized nodules under skin
• red, raised surfaces on skin

Question 15

Streptococcal Septicemia overview

Answer 15

• group B disease
• infection of blood that can secondarily infect surrounding tissues
• life threatening, worsens quickly (body’s response is as damaging as infection)
• can result from infection of lungs, abdomen, or urinary tract
• may precede or accompany meningitis or endocarditis
• treatment = antibiotics, oxygen, IV fluids

Question 16

Streptococcal Septicemia symptoms

Answer 16

• fever
• chills
• increased HR
• rapid breathing
• quick progression to shock and decreased BP