Section 2: Gram positive cocci (clinical bacteriology)

Question 1

Where is Staphylococci found?

Answer 1

normal flora of skin, upper respiratory tract, and GI

Question 2

What is the morphology of staphylococci?

Answer 2

spherical-cocci
grapelike clusters
G+
non motile
non spore forming

Question 3

What are the metabolic characteristics of staphylococci?

Answer 3

faculative anaerobes
catalase positive
ferment sugars

Question 4

What is the morphology of Streptococci?

Answer 4

spherical-cocci
in chains
G+
non-motile
non-endospore forming

Question 5

What are the metabolic characteristics of streptococci?

Answer 5

require rich media for growth
blood provides necessary enzymes
aerotolerant, no need for catalase enzyme

Question 6

What are the two ways to classify streptococci?

Answer 6

hemolysins and lancefield groups and the 4 groupings

Question 7

What defines alpha-hemolysis streptococci?

Answer 7

partial hemolysis with greenish cast around colonies

Question 8

What defines beta-hemolysis streptococci?

Answer 8

complete hemolysis of blood cells, creates clear area around colonies

Question 9

What defines gamma-hemolysis streptococci?

Answer 9

no lysis of blood cells

Question 10

What is are the four groupings of streptococci that includes all streptococci?

Answer 10

1. lactic streptococci
2. endterococci
3. non-beta hemolytic streptococci
4. beta hemolytic streptococci

Question 11

What are the features of lactic streptococci?

Answer 11

non pathogenic
no hemolysis (gamma)
found in milk products

Question 12

What are the features of enterococci?

Answer 12

lancefield group D
normal flora of GI 
different hemolysis patterns
commonly cause UTIs
opportunistic pathogens

Question 13

What are the features of non-beta hemolytic streptococci?

Answer 13

viridans streptococci
large heterogenous gourp, no lancefield antigen, alpha hemolysis
formal flora of mouth and respiratory tract
may cause tooth decay
may cause bacterial endocarditis

Question 14

What are the features of beta hemolytic streptococci?

Answer 14

lancefield group A-streptococcus pyogenes

lancefield group B-streptococcus agalactiae

Question 15

What are the characteristics of the family neisseriaceae?

Answer 15

contains both pathogenic and non-pathogenic genera and species
pathogenic species=fastidious
oxidase positive

Question 16

Which of the staphylococci are coagulase negative?

Answer 16

staphylococcus epidermis
staphylococcus saprolyticus
(staph. aureus is coagulase positive)

Question 17

What can staph. aureus cause (pathogenesis) ?

Answer 17

furuncles and carbuncles
impetigo
folliculitis
scalded skin syndrome
TSS
pneumonia
osteomyelitis
catheter and shunt infections
wound infections
enteritis
MRSA

Question 18

What situations are likely to cause staph. epidermis infections?

Answer 18

catheters, prosthetic joints, artificial heart valves

and blood draws are frequently contaminated, so re-test to confirm infection

Question 19

What is a leading cause of UTIs in sexually active females?

Answer 19

staphylococcus saprolyticus (second only to E. coli)

Question 20

What can streptococci pyogenes cause (pathogenesis)?

Answer 20

strep. pharyngitis
strep. impetigo
cellulitis
erysipelase (St.Anthony’s fire)
scarlet fever
post strep diseases: rheumatic fever, glomerulonephritis

Question 21

What bacteria can cause neonatal meningitis, pneumonia, and sepsis?

Answer 21

streptococci agalactiae

Question 22

What can streptococcus pneumoniae cause?

Answer 22

pneumonia
ottis media and sinusitis
meningitis
osteomyelitis