Bacteriology Flashcards
What is microscopy?
Direct visualization of bacteria through a microscope
What is in vitro culture?
Planting specimens on appropriate culture media and performing ID by MALDI
What are signs of inflammation?
Systemic: fever, lethargy and inappetence - bloodwork, leukocytosis, neutrophilia and left shift
Local signs: heat, swelling, pain, discharge and loss of function
How do you know if you need to culture?
- If the definitive diagnosis would change the treatment, control or prognosis
-If disease is very serious or life threatening
What is empirical therapy?
Administration of therapy based on previous experience (may be someone Elses)
When is empirical therapy indicated?
-High level of efficacy for proven treatment
-waiting for results for c/s
-cant afford c/s
What should you base your empirical treatment on?
-Likely bacteria to cause the disease
-Likely antimicrobial sensitivity pattern
-other factors like location of infection, cost antibiotics and ease of administration
What is a common pathogen that causes UTI in dogs?
E.coli (Rod) or staph pseudointemedius (Cocci)
What is a common empirical treatment for an uncomplicated UTI?
Amoxicillin or amoxicillin-clavulanic acid, Cefpodoxime, Trimethoprim-sulfonamides
If the dog returned and you know the owner had been Complient what is the next step?
Culture and sensitivity
When is a specific diagnosis needed?
-Animal is significantly compromised (young or old or co-morbidities)
-Superinfection suspected
-Suspected pathogens don’t have predictable susceptibility pattern
-poor response to earlier therapy
-outbreak of disease
-suspect disease is reportable
What are some suspect pathogens you would culture?
Staphs
Recurrent pyoderma
Strep Equi (strangles)
Reportable
What are some things to consider when collecting a sample that may be used for culture and sensitivity?
Specific location, is the site sterile or does it have normal flora, when should you sample, what technique should you use
What is the 4 point rule to make sure you collected sterily?
-Collected correctly
-inflammation was present
-organism present
-can it cause this disease
If the site has normal flora what should you be asking yourself?
-Is what I found normal flora
-is it in excess numbers
-can it cause disease
If you have a sample question what should you do?
Call the lab
Samples for microbiology testing need to be…
kept cold (except dermatophytes, blood culture, CSF, joint fluid and anaerobic culture)
If you have the choice between taking a tissue/fluid sample or a swab you should choose?
Tissue and fluid
If you are going to send a sample for culture it must stay ….
You should never put samples you want to culture in…
Moist
Formalin, alcohol, EDTA or Heparin
Why do microbiologist hate swabs?
-Dont get enough material (.5ml or % bacteria)
-Bacteria adhere to them and wont come off
-Dry out
-Exposed to air
-People thick them where they shouldn’t
If you have to use a swab, what type should you use?
Flocked, plastic shaft
-Dry PCR
-Correct media
-Guarded if uterine or nasopharyngeal
What do you use the following media for:
-Stuarts:
-Amies:
Stuart: aerobic or PCR
Amies: Aerobic, anaerobic or fungal
Where should you use a swab?
Mucous membranes, ears, uterus, cornea
What are 2 ways we evaluate samples?
Cytologically and culture
Cytology can give you a pretty good…
presumptive diagnosis (many respiratory fungi ID this way)
What are some pros and cons of fluid aspirations/centesis?
Pro: Preferred for all sample, easier for sterile technique, more material, cheap and easy
Neg: Bacteria dont like in them forever, like anaerobes
What can you take an aspirate sample of?
Joint, thoracic, abdominal, blood, CSF, tracheal wash, pustule, abscess
no swab in fluid
What are some pros and cons to tissue samples?
Pros: need to pass normal flora (draining tract), bacteria survive longer in tissues, tissue represent all path process
Cons: invasive, need sedation and anesthetic, expensive, need transport media, add sterile saline to keep specimen moist
Tell me about blood cultures:
-Need special bottle (aerobic and anaerobic)
-Must take aseptically (prep for venipuncture, alcohol top, ml blood per bottle
-3 separate samples in 24 hours
(before antimicrobial therapy, or right prior to next dose
-don’t refrigerate
What are some pros and cons of a free catch sample?
Pro: cheap, may be only way to collect
Con: contaminated with normal fora
What are the major goals of transportation?
-Prevent contamination
-maintain viability of all organisms present
-Maintain ratio of bacteria in sample if mixed
(urine room temp, biopsy on dry ice)
What are some major problems with transportation?
-sample drying (saline on all sides), this side up label
-exposure to noxious atmosphere
-Excess time delays
What are key points to transportation?
-Deliver ASAP
-Deliver in proper primary and secondary containers
-Keep cool (4C) - unless room temp
-In correct transport media
Results are only as good as the…
sample collected (bad sample = bad results)
What are some microbiology rules?
-Problem list with differentials
-Empirical only when appropriate - using knowledge of bugs and drugs
-collect correct sample from correct site
-correct rules to interpert results
-NO draining tracts
-Always evaluate for inflammation and bacteria
-Transport to lab ASAP in right media at temp with history
-consider host factors and pathogen virulence
-4 point rule
What are the steps to bacterial investigation:
- Is there inflammation
- Collect a sample for culture and susceptibility
- Transport to lab
If you have discospondlitis what are some of your differentials?
Fungal: aspergillus, blasto, histo, coccidia
Bacteria: staph, brucella, strep, pasturella
Non-infectious: congenital, healing and unstable fracture
Can we treat emperically?
difficult site
serious consequence
zoonotic pathogen on list
no normal flora here
-NO emperical
How would we sample for discospndlitis?
Aerobic, anaerobic, fungal blood and urine
-Blood if think hematogenous
-serology brucella
-CSF
(EDTA antimicrobial)
Even if it is a predictable pathogen, but it is zoonotic what should we do?
Culture and sensitivity
