Bacterial Diagnostics

Question 1

Sample types(7)

Answer 1

Sample types

• blood
• swabs
• transudates/exudates (other fluids)
• urine
• feces
• vomitus
• tissues

Question 2

Blood samples

sites

tests

Answer 2

Blood samples

*maintain sterility*

• veinpuncture sites
  
  • jugular
  • femoral
  • cephalic
  • caudal vein (cattle)
  • ear veins (rabbits+pigs)
• Bloos can be used for:
  
  • culture
  • serology
  • diagnostics

Question 3

Vacutainer Colors(6)

Answer 3

Vacutainer Colors

• Red- no additive or clot activator (for serum)
• Tiger top- cloct activator/serum separator (also for serum)
• Purple top- KEDTA anticoagulant (CBC)
• Green- lithium heparin anticoagulant (chemistries)
• Green tiger- lithium heparin and plasma separator
• Light blue- sodium citrate anticoagulant

Question 4

Swabs(6) and Scrapes(2): Locations

Answer 4

Swab and Scrape: locations

Swabs

• ears
• wounds
• abscesses
• conjunctiva
• joint
• genitourinary areas

Scrapes

• skin
  
  • ** for mycology and parasitology
    *

Question 5

Transudates/Exudates (7)

Answer 5

Transudates/Exudates= Misc. fluids

• abscess
• abdominal fluids
• oral fluid
• nasal fluid
• CSF
• joint fluid
• TTW

Question 6

Urine: collection methods (4)

Answer 6

Urine: collection methods (4)

***very important in practice*** (exam)

There is a order of preference for urine collection methods:

1. cystocentesis- with needle
2. catheter
3. free catch
4. environmental

Question 7

Feces (3) and Vomitus (2): collection methods

Answer 7

Feces (3) and Vomitus (2): collection methods

Feces- usually for parasite diagnostics

• fecal loop
• fecal swab
• environmental

Vomitus

• same/similar
• uncommon to collect vomit

Question 8

Tissue collection (2)

Answer 8

Tissue collection (2)

• biopsy
• necropsy

Question 9

Methods for direct examination of sample

Answer 9

Methods for direct examination of sample

• Stain!!!
• Culture- identification and antibiotic susceptibility

Question 10

Stains (4)

Answer 10

Stains

• Histopathology (h&e)
  
  • shape
  • cellular association(intra or extra)
• Romanowsky/Wright (diff-quik)
  
  • everything will be purple
  • shows shape
• Gram Stain- bacteria
  
  • shape
  • surface characteristice (+/-)
• Acid Fast Stain
  
  • mycobacterium
  • nocardia
  • cryptosporidium

Question 11

Gram stain

Answer 11

Gram stain

Remember:

• stains peptidoglycan layer in gram + cells (blue)
• gram - cells dont hold the crystal violet stain becuase less peptidoglycan. dye red with follow up stain.

** shapes and groupings can help with diagnostics

• staph- grapes
• strep- chains

Question 12

Making the decision to culture

Answer 12

Things to consider…

• time
• cost
• supplies
• expertise

DIAGNOSTIC LABS MAKE MORE SENSE THESE DAYS

Question 13

Bacterial Nutrition

Answer 13

Bacterial Nutrition-for cultures

• lots of carbon and nitrogen
• peptones (amino acids and peptides)
• some vitamines

Question 14

Bacterial environmrntal conditions

Answer 14

Bacterial environmrntal conditions

• temperature
  
  • mesophiles-body temp
  • thermophiles
  • psychrophiles- cold
  • psychrotropes
• ph
  
  • acidophiles
  • neutrophiles
  • alkaliphiles
• humidity
• atmospheric composition

Question 15

Oxygen requirements

6 types

different location in culture based on requirements

Answer 15

Oxygen requirements

• obligate aerobes (1)
• obligate anerobes (2)
• faculative either (3)
• microaerophiles (4)- killed by high o2 but like some
• aerotolerant anaerobes (5)
• capnophiles - like co2 (not shown)

***grow differently based on preferences see diagram

Question 16

Culture (3)

Answer 16

Culture (3)

• Agar
  
  • nutrient media
  • selective media
  • diffferential media
• Broth
  
  • nutrient broth
  • enrichment broth
• Biochemical Testing
  
  • enzymes
  • fermentation

Question 17

Agar- specifics

Answer 17

Review agar slides in powerpoint for specific examples

• basic nutrient media- food
• enriched nutrient media- food to grow extra good
• selective media- only allows growth of target
• differential media- results in different behavior of different organisms

Question 18

ID test strips

Answer 18

ID test strips

• save space and resources and time
• lots of tests in one strip
• gives you diagnostic bacterial info!

Question 19

Molecular diagnostics (4 specifics)

Answer 19

Molecular diagnostics

• 16s ribosomal RNA PCR = GOLD STANDARD
• real-time PCR
• MALDI-TOF- based on molecular weights of component proteins
• Snap tests
  
  • ELISA- looks for antibodies or antigens

Question 20

antibiotic sensativity vs. resistance

Answer 20

TESTS

• Kirby-baur disk diffusion
  
  • there are antibiotics in a place, see to what degree it deters batcherial growth
• Microdilution
  
  • different concentrations of antibiotics in different wells. determine at what dilution bacteria ceases to grow

Question 21

Sample Results

Answer 21

Sample Results

• S: senative
• R: resistant
• I: intermediate
• NI: no interpretation

Question 22

Diagnostics for parisitology

Answer 22

Diagnostics for parasitology

• based on fecal sedemintation. FLOAT eggs
• send samples to lab
• blood samples can be used sometimes too

WONT ASK ANY QUESTIONS ABOUT PARASITOLOGY