Gram Positive Cocci

Question 1

What is catalase?

Answer 1

Enzyme that breaks hydrogen peroxide into water and oxygen.
Gram + cocci in clusters contain catalase
Gram + cocci in chains don’t contain catalse

Question 2

What common gram + cocci in clusters produces coagulase?

Answer 2

Staphylococcus aureus

Question 3

Name a coagulase negative staphylococci

Answer 3

Staphylococcus epidermidis

Question 4

Describe staphylococcus epidermidis

Answer 4

Gram-positive cocci in clusters (stains purple)
Coagulase negative
Catalase positive (contains catalase enzyme)
Facultative Anaerobe (can live with or w/o O2)
Part of the normal skin flora & mucosal flora

Question 5

Describe Staphylococcus aureus

Answer 5

Gram-positive cocci in clusters (stains purple)
Catalase & coagulase positive
Most common and serious pathogen
Facultative Anaerobe (can live with or w/o O2)
Typically lives in nose

Question 6

Illnesses caused by staphylococcus epidermidis infection & common treatments

Answer 6

Cellulitis

Bacteremia (e.g. IV insertion)

Question 7

Name the 4 most common infections caused by Staphylococcus aureus

Answer 7

Wounds
Skin (cellulitis)
Heart valves (endocarditis)
Bone (osteomyelitis)

BoWSH

Question 8

Which class of antibiotics is MRSA resistant to?

Answer 8

Beta-lactam

Question 9

When ‘coagulase negative staphylococci’ appears on a lab result, what does this typically indicate?

Answer 9

contamination or colonization

Question 10

Which infection is often caused by staphylococcus saprophyticus?

Answer 10

UTI in women of reproductive age

Treated with nitrofurantoin (Macrobid)

Question 11

What are the 3 possible hemolytic patterns?

Answer 11

Alpha - green
Beta - clear
Gamma - non-hemolytic

Question 12

Characteristics of gram positive cocci in chains

Answer 12

Catalase negative
Categorized by hemolytic pattern (alpha - green; beta - clear; gamma - non-hemolytic)
NO coagulase

Question 13

Two examples of Gram-positive cocci in chains that are alpha hemolytic

Answer 13

Streptococcus pneumonia

Viridans streptococci

Question 14

What is an example of gram positive cocci in chains that is beta hemolytic?

Answer 14

Streptococcus pyogenes (Group A streptococcus)
NO catalase

Question 15

What is an example of gram positive cocci in chains that is gamma hemolytic?

Answer 15

Enterococcus spp (species)
NO catalase

Question 16

This alpha hemolytic streptococci is responsible for most community acquired pneumonias and meningitis

Answer 16

Streptococcus pneumoniae (pneumococci)

Question 17

What are the viridans streptococci?

Answer 17

Grouping of all other alpha hemolytic gram positive cocci.
Part of normal oral and gastrointestinal flora
Can cause endocarditis (heart valve infection)

Question 18

This is a sub-group of the viridans group that is notorious for forming abscesses throughout the body

Answer 18

streptococcus angionosus group

Question 19

What is a Lancefield group?

Answer 19

How beta hemolytic gram positive cocci in chains are categorized.
A,B,C,F,G

Question 20

What are some infections that can be caused by Group A streptococci?

Answer 20

Group A Streptococci can cause

• strep throat (pharyngitis)
• skin infections (cellulitis)
• necrotizing fasciitis (flesh-eating disease)
• bacteremia
• rheumatic fever
• glomerulonephritis (inflammation of small blood vessels in kidneys)

GAS for ToNS BaRG

Question 21

What part of the body is typically colonized with enterococcus?

Answer 21

Gastrointestinal tract
Often isolated as part of mixed infection with other bowel flora
Can cause UTIs

Question 22

What are the two most important species of enterococci?

Answer 22

Enterococcus faecalis

Enterococcus faecium

Question 23

What is the hemolytic pattern of the enterococcus species?

Answer 23

Gamma (non-hemolytic)

Question 24

What is VRE?

Answer 24

vancomycin resistant enterococci

Question 25

Peptococcus and peptostreptococcus are...

Answer 25

Anaerobic gram-positive cocci in chains Part of normal flora in most mucous membranes Most often isolated as part of mixed infection (e.g. abscesses in mouth, lung, vulva, brain)

Question 26

Name the 3 multi-drug resistant gram-positive cocci

Answer 26

Vancomycin resistant enterococci Methicillin resistant streptococcus aureus Streptococcus pneumoniae

Question 27

MRSA is typically susceptible to which antibiotic?

Answer 27

Vancomycin

Question 28

What is a VISA?

Answer 28

Vancomycin intermediate streptococcus aureus (MRSA's that also show reduced sensitivity to vancomycin)

Question 29

What is the mecA test?

Answer 29

Molecular testing for the methicillin resistance gene (test for MRSA)

Question 30

Which parts of the body are typically colonized with MRSA?

Answer 30

nose and skin

Question 31

Common types of infections caused by hospital acquired (HA) MRSA?

Answer 31

Bacteremia Wound infections Respiratory infections

Question 32

Common types of infections caused by community acquired (CA) MRSA?

Answer 32

Mainly skin and soft tissue infections (cellulitis, abscesses, furuncles)

Question 33

Risk factors for HA - MRSA?

Answer 33

Indwelling devices, catheters, lines, etc

Question 34

Modes of transmission for MRSA

Answer 34

person-to-person environmental (hospital equipment, sports equipment) Animal-to-patient Shared facilities (washrooms, changerooms)

Question 35

Community acquired MRSA tends to be more susceptible to antibiotics, which are:

Answer 35

TMP/SMX doxycycline clindamycin TDC

Question 36

What is VRE?

Answer 36

Vancomycin resistant enterococci | Prolific in hospitals

Question 37

What is the 'van' gene?

Answer 37

Vancomycin resistance gene. | Transferred by plasmids between organisms

Question 38

What are the 3 most common types of 'van' genes?

Answer 38

A, B and C

Question 39

Ways to control VRE:

Answer 39

Prevent resistance development (decrease vancomycin use) Carrier and case detection (admission and lab isolate screening) Containment of clinical cases (isolation practices, investigation of contacts, education programs, hand hygiene) LID

Question 40

What antibiotic can Streptococcus pneumoniae be resistant to?

Answer 40

Penicillin

Question 41

What are the three subtypes of penicillin resistance in Streptococcus pneumoniae?

Answer 41

``` Susceptible (MIC of 0.06 mg/ml or less) Intermediate Resistance (MIC of 0.1-1 mg/ml) High level (MIC of > 1 mg/ml) ```