Lecture 14: Diagnosing Infections Flashcards
True or False: When doing specimen collection, sufficient quantity is required
True
Swabs should be used for specimen collection from ___ and ____ _____ only
skin; mucous membrane
True or False: Decontamination procedures and appropriate handling should occur during specimen collection
True
True or False: Gram and acid-fast stains are an example of macroscopic direct testing
False - MICROSCOPIC, direct testing
____ ____ are both a culture/isolation test and direct test
A. AF Stain
B. Gram Stain
C. Gene probes
C. Gene probes
True or False: Antimicrobic sensitivity is an example of direct testing
False - culture/isolation
Gram stain, acid-fast stain, capsule stain, Fluorescent Ab stain, and gene probes are examples of:
A. Microscopic Direct Testing
B. Macroscopic Direct Testing
A. Microscopic Direct Testing
(example: syphilis)
Serological methods (agglutination) and PCR are examples of:
A. Microscopic Direct Testing
B. Macroscopic Direct Testing
B. Macroscopic Direct Testing
Advantage of Culture/Isolation specimen analysis?
Once you culture microorganism, you could do all kinds of testing (including direct!)
What are the 4 phenotypic methods of identification?
- Macroscopic
- Microscopic
- Biochemical
- Chemical Analysis
Strep tests, PPD, and western blots are example of ____ methods for identification while PCR, sequencing, and DNA hybridization are ____ methods
immunological; molecular
Which phenotypic method allows for the appearance of colonies, pigmentation, and phage typing?
A. Macroscopic
B. Microscopic
C. Biochemical
D. Chemical Analysis
A. Macroscopic
Label
Which types of cultures are best for determining number of bacteria in specimens?
Quantitative vs. semi-quantitative
Which phenotypic method could you use to see structural features of pathogens?
Electron microscope
Which phenotypic method uses enzymes, sensitivity to abx, or gas?
A. Biochemical
B. Chemical Analysis
A. Biochemical
True or False: Chemical Analysis allows for detect of chemical composition
True
What are the three types of selective media for isolation?
Thioglycolate
Chocolate agar
Charcoal agar
Which of the following selective media is best for growing B. pertussis (fastidious organism)?
A. Thioglycolate
B. Chocolate agar
C. Charcoal agar
C. Charcoal agar
Which media is best for Haemophilis (fastidious organism)?
A. Thioglycolate
B. Chocolate agar
C. Charcoal agar
B. Chocolate agar
If you add an abx to chocolate agar, you create Thayer-Martin media, which is selective for which pathogen?
Neisseria
Which media would be best for anaerobic bacteria (e.g Clostridium or Bacteroides)?
A. Thioglycolate
B. Chocolate agar
C. Charcoal agar
A. Thioglycolate
When one is using a Thioglycolate media, broad spectrum ___ that acts against many ___ and ___ organisms is preferred.
abx; facultative/aerobic
Why is selective media important with anaerobes?
Polymicrobic
Which agar is the ONLY differential agar and is useful for differentiating between alpha or beta or gamma hemolysis group of bacteria?
A. Eosin Methylene Blue
B. MacConkey
C. Blood Agar
C. Blood Agar
Which agar is best to determine the type of hemolysis of S. pyogenes and Streptococcus?
A. Eosin Methylene Blue
B. MacConkey
C. Blood Agar
C. Blood Agar
True or False: Blood Agar can be used to differentiate between alpha, beta, and gamma hemolysis
True
Label
True or False: Eosin Methylene Blue and MacConkey are both selective and differential agars
True
Which agar is best for differentiating between pink/red colonies for lactose fermenter, white/colorless for Gram (-) non, lactose fermenters?
A. Eosin Methylene Blue
B. MacConkey
C. Differential (Blood Agar)
A. Eosin Methylene Blue
B. MacConkey
True or False: Only the blood agar selectively supports the growth of gram negative while inhibiting growth of gram positive
False - both EMB (Eosin Methylene Blue) and MacConkey do
Label the EMB Agar
Label the MacConkey Agar
What is the best method for identification of species during outbreak?
Phage typing
True or False: Different strains of bacteria differ in their susceptibility to different phages
True
In vitro serological immunological methods involves in vitro diagnostic testing of serum, which allows for detection of…
- antibody from patient (qual/quan)
- microorganism’s antigen (qual)
What is one of the cons of serology (immunological methods)?
Serological identification of an antibody to the infecting agent can only be successful several WEEKS after infection has occurred
ELISA, RIA, Western blot, precipitation, agglutination are examples of which type of tests?
A. Molecular
B. Serological (Immunological)
C. Direct Test
B.
B. Serological (Immunological)
Agglutination helps diagnose _____
A. Tetanus
B. Rosacea
C. Rubella
D. Tb
C. Rubella
- detection of rubella virus antibodies in patient’s serum against solubilized rubella virus
In a tube precipitation test, an ___ is put on the bottom and an ___ is on the top.
A. Antigen; Antibody
B. Antibody; Antigen
C. Anti-anti body; anti-antigen
What suggest a positive test?
B. antibody; antigen
- Positive if there’s a band
In the complement fixation test, no color change and no hemolysis suggests?
A. Negative reaction
B. Positive reaction
B. Positive reaction
- Complement fixes Ab and RBC do not lyse
In the complement fixation test, color change due to hemolysis suggets?
A. Negative reaction
B. Positive reaction
A. Negative reaction
- Complement fixes RBC’s and hemolysis occurs
Which test is good for screening, since it has HIGH sensitivity, but LOW specificity (can cause FALSE POSITIVE)?
ELISA
- example: HIV dx
True or False: Both indirect and direct ELISA detect Ab
False
- Direct ELISA: detect Ag
- Indirect ELISA: detect Ab
Which tests can be initially used to dx HIV? Test used to confirm?
Initial - ELISA
Confirmation - Western Blot
How is the western blot unlike the ELISA?
ELISA has low specificity while Western has high specificity
Which test can be used to detect disorders in antibody production?
Immunoelectrophoresis
True or False: PPD is an in vivo skin test while rapid tests are throat swabs (detect S. pyrogens antigen)
True
True or False: Molecular methods of diagnostics (PCR, hybridization) are more rapid than phenotypic methods AND culturing not always needed
True
Which test allows you to distinguish between different strains of a bacterial species AND used to determine source of outbreaks?
A. Hybridization
B. PCR
C. Culturing
B. PCR
What test is useful for hybridizing LARGE NUMBER of DNA samples against LARGE NUMBER of DNA probes on a simple support membrane?
Checkerboard hybridization
True or False: Checkerboard hybridization can be used to identify bacterial species contained in sample w/ many species
True
____ ____ is the only media that is Differential
A. Chocolate Agar
B. Blood Agar
C. MacConkey or EMB
B. Blood Agar
