Clinical Microbiology Flashcards
List 7 specimen types?
Blood Tissues Scraps/Swabs Transudate Urine Feces Vomit
What is the first and most critical step in diagnostic testing?
Proper specimen collection
Should specimens be collected before antibiotics/ treatment?
Yes
How can one eliminate the possibility of having normal flora in a specimen in dog pyoderma?
Remove fluid from intact pustule
How can one eliminate normal flora from a urine sample?
Remove urine directly from bladder with sterile syringe
Cystocentesis
Does the specimen type depend on suspected viral infection and patient symptoms?
Yes
What are two phenotypic methods of diagnostic testing?
Microscopic examination
Culture/biochemical tests
What are two immunochemical and serological methods of diagnostic testing?
Blood
Binding of specific antibodies or antigens
Success of parasite diagnosis by phenotypic techniques depends on what?
Stage of infection
Animal age and species
Special technique procedure
Severity of infection/parasite type
What are some disadvantages to cytology?
Mild/chronic infection may not be detected
Not all samples are appropriate
Can viruses cause specific changes in tissues, resulting in different cell structure, organization and morphology?
Yes
What is Ramanowksy stain?
Diff-quik/ Wrights stain
Can identify sample abnormatlies, bacterial and parasite infections
Are viral infections cultured?
No
Should you culture if a organism is slow to grow in culture?
No
Name three different culture options?
Agar (solid)
Broth (liquid)
Biochemical testing
What are three types of agar culture options ?
Nutrient media
Selective media
Differential media
What are two types of broth culture options?
Nutrient broth
Enrichment broth
What agar would you use for gram negative organisms?
Espinosa methylene blue agar
What is an example of differential media?
Blood agar
Antigens from pathogens can be what?
The whole pathogen itself
A molecule produced by the pathogen
Pathogen molecules presented on surface of host cell
What are two common specimens for antibodies?
IgG: Blood, tissue fluids
IgM: Blood
In what phase of disease should you collect specimen?
Acute phase
What is ELISA?
Enzyme linked immunosorbent assay
Superficial antigen or antibody detection
What is agglutination?
Where particles clump together
A antibody and antigen interaction
What is molecular diagnostics ?
Identification of markers in genome or proteome
What is MALDI-TOF?
Type of mass spectrometry that detects pathogens by their mass and charge
What are some advantages of molecular diagnostics ?
Faster than culture based methods
Highly sensitive
Accurate
High volume testing
What are consequences of incorrect specimen collection and mishandling?
Infection of other patients/public/workers
Are culture based methods good for detecting parasites and viruses ?
No
What do biochemical tests help?
Identify differences in enzyme production, carbon source usage, carbohydrate fermentation
What do SNAP tests do?
Antigen to antibody detection
Can measure several infectious diseases in 1 test
Bacteria can require resistance by what three things?
Mutation
Horizontal gene transfer
Conjugation
What are consequences of antimicrobal resistance?
Increased patient mortality
Risks of zoonotic transmission
What are economic consequences of antimicrobal resistance?
More visits, lab tests, therapies
Prolonged hospitalization
Costs for surveillance and intervention programs
What are three superbugs of antimicrobal resistance?
ESBL producing E. Coli
MRSA
MRSP
What are two clinically relevant resistant bacteria in food borne zoonotic bacteria?
Salmonella ( resistance to cephalosporins)
Campylobacter (resistance to macrolides)
What are two reasons antimicrobal resistance is a problem?
Food animal use has public health consequences
Companion animal use has animal health consequences
What is MRSA? Why is it a problem?
Methcillain resitance staphylococcus aureus
It has acquired a resistance gene called mecA that encodes for penicillin binding protein (PBP2A) that has low affinity to B-lactams
What is ESBL? Why is it a problem?
Extended spectrum beta lactamase
It is an enzyme that inactivated most B-lactams (except carbapenems)
It is produced by gram negative bacteria
What are true ESBL’s susceptible to?
B-lactamase inhibits such as clavulanic acid
Is antimicrobial resistance a quantitative property?
Yes
What are two methods of antimicrobial susceptibility testing?
Dilution methods (broth and agar) Diffusion methods (agar, E-test, disk diffusion test)
What are dilution methods of AST?
Enable quantification of antimicrobial susceptibility by determining minimum inhibitory concentration and minimum bactericidal concentration
What are diffusion methods for AST?
Use antimicrobial fished strips/disks to measure inhibition
What is a breakpoint of AST?
Drug specific value to interpret the results of susceptivity testing and determine if an antibacterial is potentially useful in treatment
What does one need to due to set a breakpoint for AST?
Minimum inhibitory concentration
PD/PK index
Clinical trails
What is a wild-type bacteria?
Species that does not have any acquired resistance genes and or mutations increasing the MIC of the antimicrobial agent
What two drugs are used for detection of MRSA/MRSP because mecA is poorly expressed in lab media?
Oxacillin
Cefoxitin
Strains resistant to these should be regarded as resistant to all B-lactams
How would you select a drug?
Pathogen involved
Drug properties
Host specific
Build up of resistance
Should you minimize use of broad spectrum antibiotics?
Yes
When should you culture?
When there is no response to therapy, there was previous antibiotic treatment, history of relapse
What should every clinic have?
A formal infection control program, a written manual, and an infection control practitioner
