Bacteriology - Diagnosis

Question 1

Step one of determining if you need to specifically diagnose a disease is to determine if the bacteria is in fact an infection. What are the clinical signs that can alert you on if it is a bacterial disease

Answer 1

purulent disease
fever
swelling
heat
pain
discharge

Question 2

Define pathognomic. Is inflammation often seen bacterial infections pathognomic?

Answer 2

Pathognomic means that a symptom is directly related to the disease it is causing. Inflammation is a common sign of bacterial infection but also many other diseases therefore it is NOT pathognomic

Question 3

What are clinicopathological changes that could alert you to a bacterial disease?

Answer 3

Neutrophilia
Leukocytosis
+/- left shift
+/- toxic change
hyperfibrogenemia
+/- hyperglobinemia

Question 4

What is disease in most bacterial infections caused by?

Answer 4

Inflammation

Question 5

To help you identify what the bacteria are most likely to be involved in and if you need to identify them, what should you always start your evaluation of a clinical case with?

Answer 5

Problem list and location of high yield problems
Differential diagnosis of most important problems starting with most likely
list the specific bacteria that could cause the problem

Question 6

What question should you ask if deciding if you want to make a presumptive or definitive diagnosis?

Answer 6

Will it change the outcome of the case?
i .e. will it change how i will treat or control this infection or the prognosis I will give the client

Question 7

What is a presumptive or clinical diagnosis?

Answer 7

diagnosis based on history and findings of physical examination

Question 8

When is it appropriate to use a presumptive diagnosis?

Answer 8

1. pathognomic signs and accepted therapy
2. empirical therapy

Question 9

Define empirical therapy

Answer 9

administration of therapy based on previous experience either yours or someone else

Question 10

When is empirical therapy appropriate?

Answer 10

high level of efficacy for recommended therapy
waiting for results of c/s
client cant afford c/s

Question 11

If you do treat empirically, what should you base it on?

Answer 11

The likely bacteria to cause the dx
The likely antimicrobial sensitivity pattern of the disease
Other factors such as site of infection, cost of antibiotic, ease of administration

Question 12

What is a definitive or aetiological diagnosis? When do you want to use this over a presumptive or clinical diagnosis?

Answer 12

in very old, young, or sick animals
suspected infection is in a difficult site or serious consequences
Not responding to earlier treatment
not predictable susceptibility pattern
notifiable dx such as in an outbreak
herd situation

Question 13

What are 4 ways in which we can make a specific diagnosis of bacterial infections?

Answer 13

1. culture/sensitivity
2. specific antibody (serology)
3. specific antigen
4. detection of DNA

Question 14

What are common issues/problems associated with sample collection in practice?

Answer 14

sample is taken from incorrect site or contaminate sample
sample is not collected in correct way - unsure of bacteria and how it grows
RUBBISH IN = RUBBISH OUT

Question 15

What do you need to consider before collecting a sample?

Answer 15

Determine the best time to collect a sample

Question 16

When are the 3 best times to collect a sample?

Answer 16

1. already started empirical therapy
2. acute stages of infection
3. within 4 hrs of death

Question 17

If empirical therapy has already been started, how long should you wait before collecting a sample?

Answer 17

until trough concentration (when next dose is due)
until after a wash out period - (2-5 days after last dose)

Question 18

Why is it important to collect a sample on a deceased patient within a 4 hour window?

Answer 18

Within this window you will only be collecting bacteria in the tissue - if wait too long, bacteria colonizing other areas such as the gut will have free reign due to no mechanisms in place to stop them so will lead to inaccurate results

Question 19

Why is it important to specifically localize the site of infection and directly collect the sample directly from that site?

Answer 19

CONTAMINATION

Question 20

What should you NEVER collect a sample from?

Answer 20

Draining tract

Question 21

Why is it important to determine whether the site you are sampling consists of normal flora or is sterile?

Answer 21

Determines how sample is collected - do not want to introduce bacteria into sterile site.
IF bacteria is found in a sterile site….bingo was his name-o

Question 22

Determining whether a strict anaerobes are involved in an infection will affect what 3 things?

Answer 22

how you collect the sample
how you transport it to a lab
how they culture the sample

Question 23

What are 4 different methods that can be used to collect a sample?

Answer 23

swabs
FNA
Biopsy
Free catch

Question 24

In what instances would you use swabs toto collect a sample?

Answer 24

mm, ears, uterine, conjunctiva, cornea

Question 25

What are 4 types of swabs

Answer 25

dry with transport media guarded anaerobic

Question 26

What are some issues associated with swabbing a sample?

Answer 26

dont get enough material bacteria can adhere to swab swab dries out and bacteria dies exposure to air can kill anaerobes people stick where they shouldnt

Question 27

When would you use a fine needle aspirate (FNA) to collect a sample?

Answer 27

joint fluid thoracic fluid blood CSF pustule tracheal abdominal fluid abscess

Question 28

Why is fine needle aspirate the preferred technique for sample collection if possible?

Answer 28

cheap and easy for sterile technique and to get more materia

Question 29

What is an issue associated with fine needle aspirate sample collection?

Answer 29

bacteria dont live in them forever especially anaerobes

Question 30

When would a tissue biopsy sample collection be appropriate?

Answer 30

sx sequestrum (dead bone) deep skin infections

Question 31

When should a sterile vial be used with tissue biopsy?

Answer 31

milk feces urine (midstream voided)

Question 32

What are issues related to tissue biopsy?

Answer 32

invasive and expensive

Question 33

What is an issue associated with sterile vials?

Answer 33

difficult to collect a sample without contaminated it so often inappropriate for sterile sites

Question 34

What are some advantages of using tissue biopsy?

Answer 34

bacteria can survive longer in tissue can represent entire pathological process

Question 35

Where are normal flora located on the skin? What type of bacteria does this consist of?

Answer 35

all over the skin especially in moist areas or ones that are in contact with more environmental contamination Gram + and yeast

Question 36

Explain the normal skin structure and where there is normal flora vs where is sterile

Answer 36

surface - normal flora present superficial epidermis -sterile deep epidermis - sterile

Question 37

If collecting a sample for surface pyoderma, what technique would you use? What would you look for?

Answer 37

Not a sterile site - can use a sticky tape test Would be looking an increase in # of normal flora or looking for gram negative bacteria which wouldnt typically be seen on the skin

Question 38

What type of bacteria inhabits the skin as normal flora?

Answer 38

gram positive cocci and yeast

Question 39

If collecting a sample for superficial pyoderma, what technique would you use?

Answer 39

sterile site so use a sterile technique to sample a pustule 1. pick intact pustule 2. clean skin surface over pustule with alcohol and allow to dry 3. open pustule with fine needle 4. use swab to collect pus 5. place in transport media and send to lab

Question 40

If collecting a sample for deep pyoderma, what technique would you use?

Answer 40

sterile site so FNA or biopsy

Question 41

Where is normal flora on the ear? Where are sterile sites?

Answer 41

Norrmal flora is on the ear flap (pinna), the vertical canal (fewer), horizontal canal (fewer) sterile is after the tympanic membrane (ear drum)

Question 42

What type of bacteria predominately inhabit the ear?

Answer 42

gram postive and yeast

Question 43

When collecting a sample from the ear where do you want to collect from?

Answer 43

Horizontal canal

Question 44

Where are normal flora on the udder? How would you collect a sample?

Answer 44

skin outside of udder and the streak canal has normal flora but sterile are in the udder tissue and on teat cistern

Question 45

What type of bacteria is predominately on the udder?

Answer 45

gram positive

Question 46

How would you collect a sample from a cow with suspected mastitis

Answer 46

1. label tubes 2. clean and dry teats 3. clean teat end and everted streak canal with alcohol 4. Strip out couple of streams 5. collect sample carefully by holding horizontally 6. use teat dip 7. store and transport appropriately

Question 47

Where are the normal flora in the respiratory tract? Where is it sterile?

Answer 47

normal flora cranial to the larynx in the URT sterile in the LRT

Question 48

What type of bacteria is predominately in the respiratory tract?

Answer 48

Gram + and -

Question 49

How would you sample the LRT of a horse vs dogs and cats

Answer 49

in horses would do a tracheal aspirate but not bronchiolar lavage (BAL) in dogs/cats would do blind technique for BAL or tracheal aspirate

Question 50

Where is normal flora in the urinary tract and where are sterile sites?

Answer 50

nf in distal urethra but sterile in proximal urethra and bladder

Question 51

What type of bacteria is predominately in the urinary tract?

Answer 51

Gram + and -

Question 52

What are 3 ways to collect a sample for lower urinary tract infections in a dog?

Answer 52

cytocentesis - sterile free catch - not sterile catheterization - not sterile

Question 53

Why are females more prone to UTIs?

Answer 53

urethra is shorter so less area for bacteria

Question 54

When interpreting colony counts what will influence whether or not you determine the bacteria to be significant or not?

Answer 54

sample collection and technique the more sterile, a smaller amount of bacteria will be more significant

Question 55

Where in the genital tract is normal flora? Where are sterile sites?

Answer 55

nf = vagina posterior to cervix sterile in uterus anterior to cervix

Question 56

What type of bacteria is present in the genital tract?

Answer 56

gram + and -

Question 57

How would you collect a sample in mares vs in bitches?

Answer 57

in mares would use guarded swab up vagina in bitches FNA of surgical sample with pyometra or swab anterior vagina

Question 58

Microscopic examination is a simple and cost effective way to determine what?

Answer 58

1. presence of inflammation 2. presence of pathogens 3. predominant pathogen if there is mixed infection 4. suitability of specimen for culture

Question 59

What are your goals of transporting a sample?

Answer 59

get the sample to the lab in the same state as when it was collected

Question 60

What are important principles to follow for transportation?

Answer 60

use transportation media that supports survival but not growth of bacteria use appropriate media depending on suspected pathogen transport as quickly as possible transport cool

Question 61

Name a few of the ways of cultivation and identification of bacteria

Answer 61

performing gram stains primary culture on blood agar using differential media to help identify bacteria oxidase test indole test catalase test

Question 62

Explain the 4 point rule for sterile sites

Answer 62

1. sample must be collected appropriately from actual site of infection 2. must be evidence of inflammation in the sample 3. good (but not essential) if also evidence of bacteria in sample 4. bacteria isolated must have opportunity to and be capable of causing disease