Bacteria & viruses

Question 1

Linnaeus system of naming organisms

Answer 1

generic name (genus) specific name (species)

example:
Escherichia coli (can be abbreviated E. coli)

Question 2

what is the difference between gram-negative and gram-positive bacteria. How does that stain work?

Answer 2

gram-positive:
- thin layer of peptidoglycans in cell walls
- pink conunterstrain
(if stain comes out with alcohol)

gram-negative:
- thick layer of peptidoglycans in cell walls
- remains purple
- stain does not come out

all bacteria stain purple with crystal violet

Question 3

Aerobic

Answer 3

Can survive and grow with the present of oxygen

Question 4

Anaerobic

Answer 4

Does not require oxygen for growth (some will die in the presence of

• Obligate anaerobe: Die in the presence of oxygen

Question 5

Facultative anaerobe

Answer 5

Uses oxygen if available but has the ability to use anaerobic methods by energy production

Question 6

Microaerophilic

Answer 6

Require oxygen for growth but are harmed by atmospheric concentration of oxygen (21%)

Question 7

Aerotolerant

Answer 7

Do not require oxygen but not poisoned by it

Question 8

explain the two main divisions of gram-negative bacilli. Know what biochemical test and what agar we use to differentiate them?

Answer 8

1. enterics: bacteria that are facultative anaerobic rods that ferment sugars to produce acid and gas
2. non-enterics: primarily opportunist, causing infections in the severe illness of hosts. can be isolated from the environment

MacConkey agar to select and differentiate:
- If cannot ferment sugars, will not grow
- Turns pink if can ferment lactose
- Colorless if cannot ferment lactose

Question 9

Is E. coli gram-negative or positive? Is it a rod or cocci?

Answer 9

• gram-negative
• rods

a lactose-fermentor

Question 10

what are the three types of pathogenic strains of E. coli?

Answer 10

1.Enterotoxigenic (ETEC)
2. Enteropathogenic (EPEC)
3. Enterohemorrhagic (EHEC)

Question 11

Enterotoxigenic (ETEC)

Answer 11

• Heat-labile & heat-stable toxins
• example: Edema disease

Question 12

Enteropathogenic (EPEC)

Answer 12

• Attaching and effacing mechanism
• example: Neonatal calf diarrhea

Question 13

Enterohemorrhagic (EHEC)

Answer 13

• E. coli O157:H7 strain, uses bacterial fimbriae for attachment and has a Shiga-like toxin
• example: Hemolytic uremic syndrome

Question 14

what is endotoxin?

Answer 14

• Came out of Gram-negative bacteria
• All have lipopolysaccharide outer membrane of the cell wall

Question 15

What is the primary Salmonella species that we deal with in veterinary medicine? Is it gram negative or positive? Is it a rod or cocci?

Answer 15

2 salmonella species:
S. enterica (PRIMARY)
S. bongori

• gram-negative
• rods

Question 16

what antigen is used to group S. enterica?

Answer 16

Salmonella Typhimurium

S. enterica subsp. enterica serovar Typhimurium
Group B, 1,4,5,12:i:-

Question 17

Is Yersinia pestis gram negative or positive? Is it a rod or cocci? What is the common name of the disease that it causes?

Answer 17

• gram-negative
• rods
• common name, “plague” (bubonic plague)

Question 18

what are the three forms of Yersinia pestis disease that are seen in animals?

Answer 18

Bubonic form:
- Acute disease with lymph node abscessation

septicemic form:
- Necrosis of liver, spleen and lungs

Pulmonic form:
- Severe acute pneumonia

Affects the liver, spleen, and lungs

Question 19

Is Pseudomonas aeruginosa a primary pathogen? Or is it opportunistic? Is it gram-negative or positive? Is it a rod or cocci?

Answer 19

• opportunistic pathogen
• gram-negative
• rod

Question 20

Is Brucella gram negative or positive? Is it a rod or cocci?

Answer 20

• small gram-negative
• cocci

Question 21

Is Francisella tularensis gram negative or positive? Is it a rod or cocci? What is the common name of the disease that it causes?

Answer 21

• gram-negative
• rod
• Tularemia

Question 22

what are 3 forms of Francisella tularensis that are seen in animals?

Answer 22

1. Pneumonic form
2. typhoidal
3. ulceroglandular or oculoglandular

Question 23

what does Haemophlius require in order to grow on blood agar?

Answer 23

• Require hemin, NAD, or NADP in order to grow on blood agar (satellitosis)
• tiny gram-negative pleomorphic rods

one of the few gram-negative diseases that can be treated with PENICILLIN

Question 24

what are the three general groups of gram-positive bacilli?

Answer 24

Endospore formers: Bacillus, Clostridium

Non-endospore formers: Listeria, Erisipelothrix

Irregular-shaped and staining properties: Corynebacterium, Mycobacterium, Actinomyces, Nocardia

Question 25

how do we diagnose Bacillus anthracis? What group of animals is it most commonly seen in? How do we treat or control it? Is Bacillus anthracis gram negative or positive? Is it a rod or cocci?

Answer 25

how to diagnose: - Peripheral blood for smears and culture - Cotton swab dipped in blood and allowed to dry - DON’T OPEN SUSPECT ANIMALS!!! - Classic lesion is enlarged, necrotic spleen, dark red to black “currant jelly” with blood oozing from all orifices group of animals it is commonly seen in: - common in herbivores, can be seen in infected dogs, horses, & pigs how to treat & control it: - treat with antibiotics - bury/burn/dispose of dead animals quickly - remove the contaminated feed - vaccines - decontaminate soil? remove soil? - disinfectants - Gram-positive, endospore-forming - motile rods *zoonotic disease*

Question 26

are Clostridia gram negative or positive? Are they rods or cocci?

Answer 26

- gram-positive - spore-forming rods

Question 27

which bacteria makes toxic shock syndrome toxin? Which bacteria makes exfoliative toxin?

Answer 27

toxic shock syndrome -> Staphylococcus exfoliative toxin -> Staphylococci

Question 28

what are the two main gram positive cocci that we deal with in veterinary medicine? Which one tests to arrange themselves in long chains or pairs? Which one forms catalase?

Answer 28

2 main gram-positive cocci: Staphylococcus spp. - catalase positive - spherical bacteria & arranged in clusters Streptococcus sp. - noon-spore forming, non-motile - do not form catalase

Question 29

describe the two ways that Streptococci are classified

Answer 29

1. Hemolytic properties on blood Agar 2. serologic group

Question 30

what are the 8 groups that viruses can be divided based on the form of their genetic material?

Answer 30

DNA viruses 1. double-stranded - double-stranded circular 2. single-stranded RNA viruses 3. double-stranded 4. (+) single-stranded 5. (-) single-stranded 6. single-stranded RT virus 7. double-stranded RT virus

Question 31

what are the general steps a virus must complete to set up a systemic infection?

Answer 31

1. Virus undergoes primary replication at the site of entry and in regional lymph nodes 2. Progeny virus spreads to the blood (primary viremia) and lymphatics to other organs 3. Virus is disseminated to the other target organs via a secondary viremia 4. Multiplies further in these target organs where it causes cellular degeneration and/or necrosis, tissue injury, and clinical disease