7.6 STAPHYLOCOCCUS SP

Question 1

2 family and 3 species

Answer 1

Micrococcaceae
Staphylococcaceae

• S. aureus: white opaque
• Coagulase negative : just white
  Staphylococcus
• S. saprophyticus

Question 2

reminder of what media is usd for urine one m,ore in her slide

Answer 2

BA
CLED
MAC
PEA
Chromogenic

Question 3

GROWTH OF STAPHYLOCOCCUS

Answer 3

 BA: small white (opaque), gold; beta- or gamma-hemolytic
 CLED: can be LF or NLF
 MAC: no growth: inhibits gram +
 PEA: small white (opaque), gold, inhibits gram -

 All species will demonstrate good growth after 18-24 hours
 All species are facultative anaerobes and mesophilic

Question 4

how can you distinguish the opaque white and plain white

Answer 4

in the well opaque will look chalky while white jsut look whote

Question 5

staph is never what color

Answer 5

grey

Question 6

what kind of unique hemolyiss can happen

Answer 6

double zone beta hemolosysi

Question 7

IDENTIFICATION OF STAPHYLOCOCCACEAE

gram and shape

Answer 7

 Gram stain: Gram positive cocci in
clusters
 Cocci are very round (divide via many axes)

Question 8

IDENTIFICATION OF MICROCOCCACEAE

shape and gram

Answer 8

 Gram stain: Gram positive cocci in
tetrads
 Cocci are very round (divide via many axes)

Question 9

STAPHYLOCOCCUS AUREUS

Answer 9

 Normal flora of nose, nasopharynx, skin, perineum
 Endogenous and person-to-person transmission
 Nosocomial and community-acquired antimicrobial resistance
 i.e. MRSA (Methicillin-resistant Staphylococcus aureus)
 Causes infection due to many virulence factors: dont need to know which
 Localized skin infections:
 Impetigo, folliculitis, furuncles, and carbuncles

Question 10

STAPHYLOCOCCUS AUREUS

wound vs deep infection

Answer 10

wound
* Can be community or
nosocomially acquired
* Can be extremely dangerous
and lead to necrosis or
intense suppuration
* Often found with S. pyogenes

deep
* Bacteremia, endocarditis,
osteomyelitis, joints, deep
organs, lungs, tissues (invasive)
* Scalded skin syndrome in
neonates
* Food poisoning
* TSS

Question 11

STAPHYLOCOCCUS AUREUS color and hemo

Answer 11

WHITE OP BH

Question 12

MICROCOCCUS SP.

Answer 12

 Normal flora of human skin, mucosa,
and oropharynx
 Rarely associated with infection
 Typical lemon-yellow coloration

Question 13

STAPHYLOCOCCUS SAPROPHYTICUS

Answer 13

 Normal flora of skin and GUT
 Only associated with UTI in young, sexually active females
 Community-acquired (not nosocomial like most other coagulasenegative Staphylococcus infections

Question 14

STAPHYLOCOCCUS SAPROPHYTICUS

color and hemo

Answer 14

WHITE NH

Question 15

COAGULASE-NEGATIVE STAPHYLOCOCCUS

Answer 15

 Includes a group of bacteria with the same genus but several different
species
 We only determine species under specific circumstances (i.e. CSF)
 Normal flora of skin and mucous membranes
 Less virulent than S. aureus
 Opportunistic, endogenous, and person-to-person transmission
 Most infections are nosocomial and associated with implanted medical
devices
 Invasive procedures provide opportunity
 Common contaminants of specimens because they are “ubiquitous
colonizers”

Question 16

COAGULASE-NEG STAPHYLOCOCCUS

colorn and hemo

Answer 16

sm white NH

Question 17

BIOCHEMICAL TESTS FOR STAPHYLOCOCCACEAE
5

Answer 17

catalase
Staphaurex
Tube Coagulase
Novobiocin Susceptibility

Question 18

catalase test is the same as in previous / buble deue to catalse enzyme

Question 19

microdase was FYI

Question 20

coagulase test

Answer 20

 Looking for the enzyme coagulase possessed by certain organisms
 Staphylococcus aureus possesses coagulase in two forms..

Bound coagulase (clumping factor)
Free coagulase

Question 21

LATEX AGGLUTINATION (STAPHAUREX®)

bound coagulase

Answer 21

 Tests for clumping factor and protein A (found in 95% of all S. aureus)
 Latex beads coated with fibrinogen and the Fc portion of IgG that specifically
binds to protein A
 Fibrinogen will bind with the clumping factor on the bacterial cell wall and IgG will
bind with protein A

latex particle has fibrinogen and IgG attached and from the bacteria get the Protein A and Clumping factor if present

 Positive: Staphylococcus aureus
 Negative: All other Staphylococcus sp.
 Note: Always confirm with a tube coagulase

black background

Question 22

FREE (TUBE) COAGULASE

Answer 22

 An extracellular protein enzyme possessed by S. aureus
 Coagulase-reacting factor (CRF – a modified or derived thrombin molecule) in
plasma is activated and forms a CRF-coagulase complex
 The complex reacts with fibrinogen to produce a fibrin clot
 Positive: Staphylococcus aureus
 Negative: Coagulase negative Staphylococcus
 Must check at 3 hours because clot can form and then be dissolved by staphylokinase (would be false negative at 24 hours)

Question 23

NOVOBIOCIN SUSCEPTIBILITY

Answer 23

 Testing an organisms susceptibility to the antibiotic, novobiocin
 Can visualize sensitivity to antibiotic by a zone of inhibition of bacteria growing
around a filter paper disc that has been impregnated with the antibiotic
 Used to identify Staphylococcus saprophyticus from urine specimens ONLY

use of an MH and BA plate, QC cloudiness

 Resistant: Staphylococcus saprophyticus
 Susceptible: Other Staphylococcus sp.
greater than 16mm
have to streak in 3 planes

Question 24

very nice summary at the end of the slides PRINT before the pathway