Unit 7A

Question 1

Describe staphylococcus

Answer 1

Gram positive
Cocci in Grape like clusters
Facultative anaerobes (can grow with or without oxygen)
Produces capsules and slime layers
Catalase positive (has the enzyme that breaks down hydrogen peroxide)

Question 2

Examples of diseases of staphylococcus

Answer 2

S. aureus
MRSA
S. intermedius

Question 3

What are some exotoxins that staphylococcus produce

Answer 3

Hemolysin (damage RBCs and hemoglobin) (most have some degree of hemolysis)

Coagulase (binds to fibrin and causes clotting, helps bacteria to hide and resist phagocytosis. Also causes pus to thicken)

Question 4

Where is staphylococcus commonly found

Answer 4

In the nevironment and in hospital settings (nosocomial) and in normal flora

Question 5

The slime layer staphylococcus produce allow

Answer 5

Bacteria to form biofilms

Question 6

Where is staphylococcus commonly found on the body (normal flora)

Answer 6

Skin and mucus membranes (skin, eyes, ears, respiratory tract, urogenital tract, GI tract)

Question 7

Staphylococcus is primarily opprotunistic , this means

Answer 7

Disease only occurs when natural barriers are compromised (trauma to skin/mucosa, or inflammation)

Question 8

What is the number one cause of mastitis in dairy cows

Answer 8

Staphylococcus aureus

Can also be caused by S. intermedius or S. epidermidis

Question 9

Mastitis is an opprotunistic infection and occurs when there is

Answer 9

Poor herd management 
Poor hygiene 
Stress during 3rd trimester pregnancy, or gestation
Changes in diet
Lactation

Question 10

Describe chronic subclinical mastitis due to S. aureus

Answer 10

Difficult to identify and treat

Milk and cow is normal/healthy on PE

Decreased total milk yield

Increased somatic cell count in milk, or low levels of bacteria in milk

Can be infected for months or years

Question 11

Why can you not emilimate S. aureus mastitis

Answer 11

Ubiquitous

Part of normal flora

Resistant to drying -survuves weeks in environment

Resistant to extreme cold and pasteurization

Can survive in 12% NaCl or 1% phenol for up to 15 minutes

Some strains have antibiotic resistance

Question 12

How can you prevent mastitis

Answer 12

Maintain milk equipment 
Better milking practices (teat dripping)
Fly control
Nutritional management 
Calving management
Screening for chronically infected cows and removing the from the herd

Question 13

What is MRSA

methicillin Resistant Staphylococcus aureus

Answer 13

Resistant to methicillin (antibiotic)

Can be acquired from the community or hospitals depending on the strain

Question 14

What is methicillin

Answer 14

A semisynthetic derivative of penicillin used against bacteria that are resistant to penicillin but then bacterial resistance to methicillin developed

Question 15

Why is hospital acquired MRSA difficult to treat

Answer 15

Because it is resistant to a wide range if different antibiotic classes

Common in skin and ear infections in vet clinics

Patient must be isolated to prevent spread

Question 16

What is community acquired MRSA

Answer 16

Up to 2% of the human population carries MRSA in normal flora

Has limited antobiotic resistance (mostly to beta-lactam class)

Immunocompromised individuals develop a mild illness but is difficult to treat

Question 17

How do you prevent MRSA

Answer 17

Testing before using antibiotics and only use antibiotics when needed
Autoclave materials
Hand washing

Question 18

What is staphylococcus intermedius pyoderma

Answer 18

Common in dogs, part of their normal flora

Is an opprotunistic infection

Question 19

The opprotunistic infection of staphylococcus intermedius pyoderma occurs with

Answer 19

Allergies (food) (atopy - allergy materials)

Skin parasites

Immunosuppression

Question 20

Why do allergies cause Staph pyoderma

Answer 20

Primary inflammation causes a warm, moist environment, which danages skin barrier so bacteria can enter subcutis and allow overgrowth of normal flora

Question 21

How do you collect a sample for a culture

Answer 21

Clean AROUND the lesion with water and mild cleanser (not alcohol/disinfectant)

Use sterile culterette swab to collect a sample, rub gently over the lesion (brewk open pustules or lift crysts to reveal lesion) (avoid hair)

Place in transport media

Question 22

Describe streptococcus

Answer 22

Geam positive
Cocci in chains or pairs 
Non motile
Facultative anaerobes 
Pathogenic soecies ferment carbohydrates 
Catalase negative

Question 23

What does the catalase test do

Answer 23

Used to differentiate between staphylococcus and streptococcus (staphylococcus is catalase positive, streptococcus is negative)

Question 24

What are some pathogenica factors of streptococcus

Answer 24

Capsules
Exotoxins
Part of normal flora
Primaryily opprotunistic

Question 25

What do capsules help streptococcus with

Answer 25

Helps resist phagocytosis by WBCs More pathogenic strains have capsules

Question 26

What exotoxins do streptococcus make

Answer 26

Hemolysin Cardiotoxin Streptococcal pyrogenic exotoxins (cause toxic shock syndrome) Streptococcal group antigens (species grouped accoriding to group A and B antigens) (help in attaching to tissues)

Question 27

Where is streptococcus found in normal flora

Answer 27

``` Mucous membranes Upper respiratory tract Lower urogenital tract Skin GI tract ```

Question 28

Describe how streptococcus is opportunistic

Answer 28

It is in some areas of normal flora, if it is present in urine ir internal tissues it is pathogenic Can be secondary in diseased tissues (have hugher than normal numbers but did not cause disease)

Question 29

Life cycle of a sporulation

Answer 29

Sporulation: spore forms inside cytoplasm (6-12 hours) Free spore (thick shell, resistant, dominant, metabolically inactive) -return of H2O and nutrients in hospital environment- Germination: return to metabolically active form (1-1.5 hours) Vegetative form: growing, metabolically active -lack of nutrients- Sporulation

Question 30

Describe gram positive rods

Answer 30

Spore forming: Bacillus anthracis and clostridium Non spore forming: histeria monocytogenes (zoonotic, neurological symptoms) and Rhodococcus equi (foal pneumonia)

Question 31

What are bacterial endospores

Answer 31

The hibernation stage of some bacteria (Bacillus spp. and Clostridium spp.) Different than persister cells, sporulation is triggered by starvation: spore genes are turned on and the genes for metabolism, growth and repair are turn off (vise versa during growth)

Question 32

What are the physical changes that occur with endospores

Answer 32

Thick protein coat develops around the nucleoid Chromosomal DNA condenses Water is removed from the cytoplasm

Question 33

What is germination and when is it triggered

Answer 33

When a bacteria breaks out of the protein coat and it can start replicating again Triggered by the return of water and nutrients Genes for growth, replication and repair are turned on Bacteria becomes metabolically active

Question 34

True or false Endospores are easy to see when being stained because they do not takenup the stain, then are clear spots in the center of the rod

Answer 34

True

Question 35

Two important spore forming bacteria in vet med

Answer 35

Bacillus antracis (Anthrax) C. perfeimgens: clostridial diarrhea

Question 36

Describe Bacillus anthracis

Answer 36

Gram positive Long chain rods Strict anaerobe Spore forming

Question 37

Describe transmission and exposure of antrax

Answer 37

Horizontal transmission: most commonly ingestion if contaminated soil (gastrointestinal anthrax) Zoonotic Most common in cows and sheep

Question 38

Describe anthrax Epidemiology

Answer 38

Endemic in saskatchewan Environmental reservoir (soil, water, dried organic matter, aerosolized in air/wind, fludding causes spores in the ground to reach the surface)

Question 39

Describe pathology of anthrax

Answer 39

Ingestion, inhalation ot absorption through skin of spore enters the small intestine (triggers germination) Incubation period: few hours to 3 weeks depending on dose) Absorption of exotoxins

Question 40

What are the 2 exotoxins produced by vegetative B. anthracis

Answer 40

1) causes severe edema and tissue necrosis (causes decreased oxygen to advance spread) 2) kills WBCs so host camnot fight the infection

Question 41

What are the clinical signs of anthrax

Answer 41

Related to tissue necrosis and edema Death (24-48 hours of the start of clinical signs) Severe damage to cessel walls due to edema toxin causes fatal hemorrhage

Question 42

What is the treatment, prevention and control of anthrax

Answer 42

Vegetative form of anthrax: antibiotics Vaccines Control the spread of spores in environment

Question 43

How do you control the spread of spores of anthrax in the environment

Answer 43

Very hard to destroy spores ``` Prevent air exposure Plug all openings of carcasses Secure head in a plastic bag tied around neck Protect carcass from scavengers Burn carcass ```

Question 44

True or false | Anthrax is a reportable disease and must be reported to the CFIA

Answer 44

True

Question 45

What is the purpose of tracking reportable diseases

Answer 45

To identify source of infection To prevent spread To track rate of spread To ensure there is no risk of it entering canada

Question 46

What are characteristics of reportable diseases

Answer 46

``` High mortality and/or morbidity Often no treatment High risk of transmission Economic importance Zoonosis Not currently in canada Emerging diseases ```

Question 47

Describe Clostridium perfringens

Answer 47

Widespread in nature Part of normal GI flora in most species NOT a strict anaerobe (different from other clostridia strains) Most common cause of small animla diarrhea (mild but can be fatal) (scowers in calces, lambs, piglets, foals) Can cause fatal diarrhea in adult livestock Associated with antibiotic triggered diarrhea in pocket pets Zoonotic

Question 48

Describe diagnosing C. perfringens diarrhea

Answer 48

Fecal smears , Swab of rectum or fecal sample Diagnosis is by increased levels of typical large gram positive rods with or without spores