MLSCI340 Superficial Wounds/ Mycology

Question 1

Skin infections only occurs when __.

Answer 1

Skin infections only occurs when THE SKIN BARRIER IS BROKEN BY TRAUMA

Question 2

Provide an example of how the skin inhibit pathogens

Answer 2

• acid pH produced by fatty acids of the sebaceous gland
• gram positive bacteria (skin flora) convert fatty acids/ lipids to unsaturated fatty acids = INHIBIT GRAM NEG BACTERIA and FUNGI

Question 3

Mixed skin flora consists of TWO OR MORE of these organisms:

Answer 3

• CNS
• Non-hemolytic Streptococci
• Viridans group Streptococci
• Anaerobes
• Diphtheroids/ coryneforms
• Enterococcus sp.
• Bacillus sp.

Question 4

List obligate skin pathogens

Answer 4

• S. aureus
• Candida sp.
• Enterobacteriaceae
• Beta hemolytic Streptococci
• Pseudomonas aeruginosa

Question 5

These potential pathogens may cause infections in surface wound specimens when found in HIGH NUMBERS and when SIGNIFICANT IN THE DIRECT SMEAR (INTRACELLULAR, PREDOMINANT)

Answer 5

• Anaerobes
• Enterococcus sp.
• Bacillus CEREUS
• other NFB

Question 6

Define boils/ furuncles

Answer 6

Caused by S. aureus; often forms when hair follicle/ sebaceous gland becomes blocked

Question 7

Define carbuncles

Answer 7

• more extensive invasion of S. aureus
• comprised of multiple draining sinuses (often on back/ neck)

Question 8

Define impetigo

Answer 8

• form of pyoderma/ purulent skin disease
• associated with S. pyogenes or S. aureus
• almost inclusively in children during warm weather

Question 9

Define erysipelas

Answer 9

• acute inflammation of superficial layers
• caused by S. pyogenes
• sharply defined lesions

Question 10

Define pyoderma

Answer 10

Pyogenic lesion of the skin

Question 11

S. aureus colony morph

Answer 11

BAP: wop(h), gop(h)

Question 12

Which of the following is described as a filament composed of fungal cells?

a.
Arthroconidia

b.
Hyphae

c.
Fimbriae

d.
Pilus

Answer 12

b.
Hyphae

Question 13

Which of the following microscopes is used for examination of calcofluor white stained slides?

a.
Bright field

b.
Fluorescent

c.
Polarizing

d.
Inverted

Answer 13

b.
Fluorescent

Question 14

The following results are recorded from a cat bite swab:
Direct Smear:

3+WBC
3+ RBC
1+EPI
4+GNB
1+GPCCL
Culture:
BAP: 4+ small grey non-hemolytic
1+ small white opaque
CAPCO2: 4+ small grey non-hemolytic
1+ small white opaque
MAC: no growth

Which of the following organisms is the most likely pathogen?

a.
Staphylococcus aureus

b.
Toxoplasma gondii

c.
Pseudomonas aeruginosa

d.
Pasteurella multocida

Answer 14

d.
Pasteurella multocida

Question 15

Which of the following organisms produces an oxidative reaction in the O-F test?

a.
Serratia marscesens

b.
Pseudomonas aeruginosa

c.
Staphylococcus epidermidis

d.
Morganella morganii

Answer 15

b.
Pseudomonas aeruginosa

Question 16

Which of the following organisms is / are fastidious gram negative bacilli? Select all that apply:

a.
Legionella sp

b.
Francisella sp

c.
Haemophilus sp

d.
Brucella sp

Answer 16

b.
Francisella sp

c.
Haemophilus sp

Question 17

Which of the following antimicrobials identifies MRSA?

a.
Cefoxitin

b.
Cefazolin

c.
Oxacillin

d.
Methicillin

Answer 17

a.
Cefoxitin

Question 18

Organism with “ASB” colonial morph

Answer 18

Bacillus sp.

Question 19

Organism with “pyo” colonial morph

Answer 19

Pseudomonas aeruginosa

Question 20

Organism transmitted by ticks

Answer 20

Borrelia burgdorferi

Question 21

Organism associated with cat bites

Answer 21

Pasteurella multocida

Question 22

Organism that smells like bleach

Answer 22

Eiknella corrodens

Question 23

Francisella tularensis is a level __ organism.

Answer 23

Francisella tularensis is a level THREE organism.

Question 24

Typical results for Pseudomonas aeruginosa (TSI, motility, 42C growth, oxidase)

Answer 24

TSI: K/K
Motility: pos
Growth at 42C: pos
Oxidase: pos

Question 25

Which fungi exists in the mold phase in the saprophytic environment and tissue or parasitic phase in the host?

a.
Cryptococcus sp

b.
Mucor sp

c.
Histoplasma sp

d.
Aspergillus sp

Answer 25

c.
Histoplasma sp

Question 26

Which of the following results require immediate attention when working with Bacillus spp?

a.
Catalase positive

b.
Non-hemolytic

c.
Lecithinase positive

d.
Lipase negative

Answer 26

b.
Non-hemolytic

Question 27

Which of the following techniques is most useful for direct examination of skin, hair or nails for fungal infection?

a.
Gram stain

b.
Ziehl-Neelsen stain

c.
10% KOH

d.
India ink

Answer 27

c.
10% KOH

Question 28

Which of the following antimicrobials is the best option for an MRSA wound infection?

a.
Vancomycin

b.
Metronidazole

c.
Colistin

d.
Penicillin

Answer 28

a.
Vancomycin

Question 29

test results to ID S. pyo

Answer 29

cat -
PYR +
latex A
CAMP -
Taxos A S

Question 30

test results to ID P. aeruginosa

Answer 30

TSI = K/K
OF = oxidative
Wet mount motil = pos
Ox = pos
Nitrate = pos
TSB 42°C = pos
UV = pos

Question 31

What is the nitrate reduction test ?

Answer 31

add reagent A+B turns red = pos (nitrATES -> nitRITES)

if neg add zinc

red w zinc = neg (no nitrites)
white w zinc = pos (reduced further)

Question 32

Media plates for wound swab

Answer 32

CAC
MAC
SAS
CAP
CNA
BAP

Question 33

tests to ID yeast

Answer 33

• direct smear
• CAC
• germ tube
• MALDI TOF

Question 34

how to ID filamentous fungi

Answer 34

• microscopic special stain
• culture using tape
• growth rate
• microslide culture mount

Question 35

how to ID molds

Answer 35

shape/ arrangement of hyphae/ conidia

Question 36

Test results to ID Pasteurella multocida

Answer 36

%= gncb
Ox= pos
CAT= pos
TSI= A/A
Spot indole= pos

NOTE: animal bites

Question 37

What can happen if the germ tube test is incubated for >2.5 hrs ?

Answer 37

• Candida sp. produces pseudohyphae= FALSE POS

Question 38

2 organisms that cause cellulitis

Answer 38

• S. aureus
• S. pyogenes