Bacteriology - Diagnosis Flashcards
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
purulent disease
fever
swelling
heat
pain
discharge
Define pathognomic. Is inflammation often seen bacterial infections pathognomic?
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
What are clinicopathological changes that could alert you to a bacterial disease?
Neutrophilia
Leukocytosis
+/- left shift
+/- toxic change
hyperfibrogenemia
+/- hyperglobinemia
What is disease in most bacterial infections caused by?
Inflammation
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?
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
What question should you ask if deciding if you want to make a presumptive or definitive diagnosis?
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
What is a presumptive or clinical diagnosis?
diagnosis based on history and findings of physical examination
When is it appropriate to use a presumptive diagnosis?
- pathognomic signs and accepted therapy
- empirical therapy
Define empirical therapy
administration of therapy based on previous experience either yours or someone else
When is empirical therapy appropriate?
high level of efficacy for recommended therapy
waiting for results of c/s
client cant afford c/s
If you do treat empirically, what should you base it on?
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
What is a definitive or aetiological diagnosis? When do you want to use this over a presumptive or clinical diagnosis?
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
What are 4 ways in which we can make a specific diagnosis of bacterial infections?
- culture/sensitivity
- specific antibody (serology)
- specific antigen
- detection of DNA
What are common issues/problems associated with sample collection in practice?
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
What do you need to consider before collecting a sample?
Determine the best time to collect a sample
When are the 3 best times to collect a sample?
- already started empirical therapy
- acute stages of infection
- within 4 hrs of death
If empirical therapy has already been started, how long should you wait before collecting a sample?
until trough concentration (when next dose is due)
until after a wash out period - (2-5 days after last dose)
Why is it important to collect a sample on a deceased patient within a 4 hour window?
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
Why is it important to specifically localize the site of infection and directly collect the sample directly from that site?
CONTAMINATION
What should you NEVER collect a sample from?
Draining tract
Why is it important to determine whether the site you are sampling consists of normal flora or is sterile?
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
Determining whether a strict anaerobes are involved in an infection will affect what 3 things?
how you collect the sample
how you transport it to a lab
how they culture the sample
What are 4 different methods that can be used to collect a sample?
swabs
FNA
Biopsy
Free catch
In what instances would you use swabs toto collect a sample?
mm, ears, uterine, conjunctiva, cornea