Infectious Disease Intro Pt.2

Question 1

What are the three ways of diagnosing an infection?

Answer 1

1. History
2. Physical Examination
3. Laboratory Testing

Question 2

In diagnosing an infection, patient history includes…

What does each tell us in regards to the infection?

Answer 2

a) Signs and symptoms - severity and potentially location
b) source of infection - trauma, contact with another person, etc.
c) try and determine which organism is most likely the cause (if not severely ill, tests not done and go with best guess0

Question 3

In diagnosing an infection, physical examination includes…

Examples and presentation

Answer 3

• Will be different for each infection, but the GOAL is to localize the infection

a) Measles - characteristic rash
b) Meningitis - neck stiffness
c) pneumonia - cough and sputum production; chest sounds

Question 4

In diagnosing an infection, laboratory testing may include…. (examples)

Answer 4

• WBC and Differential (differential means with percentages)
• ESR and CRP
• Renal and Hepatic Function –> Need to know to choose an antibiotic. Some antibiotics may cause renal damage and/or decreased hepatic function
• Others - such as electrolytes
• Microbiology

Question 5

What is the goal of laboratory microbiology testing? What are some examples?

Answer 5

• Goal is to determine invading pathogen(s), so that the proper antibiotic can be used

a) Gram stain
b) Culture
c) Sensitivity testing

Question 6

What is a gram stain? Purpose?

Answer 6

Quick and easy way to gain an idea of the organism

is it gram + or - ?

cocci vs bacillus

presence of WBC –> they do stain. If no WBC, need to start wondering if just colonization rather than infection

is it even a bacteria?

Not all organisms stain well – Ex. TB

Question 7

Positive Cocci Clusters

Answer 7

Staphylococci

Coagulase Positive

Coagulase Negative

Question 8

Coagulase Positive Example

Answer 8

Staphylococcus Aureus

Question 9

Coagulase Negative Examples

Answer 9

Staphylococcus epidermidis
Staphylococcus saprophyticus
Staphylococcus hominis
Staphylococcus hemolyticus
Staphylococcus warneri

Question 10

Positive Cocci Pairs (Diplococci)

Answer 10

• Pneumoncocci

e.g. streptococcus pneumoniae

Question 11

Positive Cocci Chains

Answer 11

Streptococci

a) Beta-hemolytic
- Streptococcus pyogenes
- Streptococcus agalactiae
- Groups C, F, G

b) Alpha-hemolytic
- Viridians streptococci
- Streptococcus pneumoniae

Question 12

Positive Bacilli Small

Answer 12

• Listeria
• Cutibacterium
• Corynebacterium
• Gardnerella

Question 13

Positive Bacilli Large

Answer 13

a) Spore forming
- Clostridium
- Bacillus

b) Nonspore-forming
- Lactobacillus

Question 14

Positive Bacilli Branching or Non-filamentous

Answer 14

• Nocardia
• Actinomyces
• Erysipelothrix

Question 15

Negative Cocci

Answer 15

• Neisseria Meningitis
• Neisseria Gonnorhea
• Veillonella

Question 16

Negative Bacilli Lactose-Fermenter

Answer 16

a) Oxidase Positive
- Aeromonas
- Pasturella
- Vibrio

b) Oxidase-negative
- Escheria coli
-Klebsiella spp.
- Enterobacteur spp.
- Citrobacter spp.

Question 17

Negative Bacilli Non-lactose Fermenter

Answer 17

a) Oxidase-Positive
- Pseudomonas spp.
- Flavobacterium spp.
- Alcaligenes spp.
- Achromobacteur spp.
- Moraxella spp.

b) Oxidase negative
- Proteus spp.
- Proficendia spp.
- Seratia spp.
- Morganella spp.
- Salmonella spp.
- Shigella spp.
- Stenotrophomonas
- Acinebacteur spp. (coccobacilli)

Question 18

Gram-negative coccobacilli

Answer 18

• Haemophilus influenzae
• Moraxella catarrhalis

Question 19

Negative Bacilli are commonly found in…

Answer 19

• The G.I. Tract

Question 20

What is the best method for revealing an organism?
What is determined?
Are all organisms shown?

Answer 20

Laboratory - Culture

• Biochemical profile determined
  –> Coagulase + or -
  –> Oxidase + or -
• Not all organisms grow well

Question 21

MALDI- TOF MS

Answer 21

Matrix-assisted laser desorption/ionization time of flight mass spectrometry

Vaporizes bacterial samples with laser. This ionizes proteins and other macromolecules. The ‘cloud’ of ionized analyte is separated by mass and charge. This influences the time of flight to a detector which creates a ‘fingerprint’”. The fingerprint is compared to a data base to identify the microorganism

Question 22

What type of testing determines what type of antibiotics an organism is susceptible to?

Answer 22

• Sensitivity Testing

Question 23

Define Sensitivity Testing. What is based on?

Answer 23

• Determines which antibiotics the organism is susceptible to
• Based on the minimal inhibitory conc. (MIC)
• The lowest antimicrobial concentration that prevents growth after 24 hours of incubation

Question 24

What other information should be considered along with sensitivity testing?

Answer 24

Site of Infection and subsequently the penetration of the antibiotic

Question 25

When a sensitivity analysis is conducted what do the letters S, R, and I mean?

Answer 25

S = Sensitive R = Resistant I = Intermediate

Question 26

In regards to the degree of susceptibility from a sensitivity test, what is actually susceptible?

Answer 26

- Shows the susceptibility of an organism, not the person, to an antibiotic

Question 27

T/F: Choosing an antibiotic with an S is sufficient for a microbial condition

Answer 27

No - Need to take into account the site of infection and the penetration of the antibiotic

Question 28

How is the MIC calculated?

Answer 28

-Minimum Inhibitory Concentration - Test tube of antibiotics - Introduce a standard amount of organism and allow for a standard amount of time - if clear (no turbidity) than antibiotic is working - If not clear (turbidity) than organism growing - Disk with an antibiotic on an agar plate - Antibiotic diffuses out, antibiotic is inhibiting that organism growth - Sample of organism must come from patient - Measure the zone of inhibition and that is correlated The best antibiotic choice is not always the one with the largest zone of inhibition as may need a large dose to reach that amount in the blood stream

Question 29

What is an E-test?

Answer 29

- The test has a single antibiotic with a gradient of antibiotic dosage Cloudy Parts = Antibiotic Growing Clear = Organism not growing - Not absolute. Can see some growth in the clear.

Question 30

Immunologic testing is useful when....

Answer 30

When the organism cannot be cultured or treatment has already begun

Question 31

What is antibody testing? Does it provide a diagnosis?

Answer 31

- Detects the presence of antibodies directed against the pathogen - Can not tell you when the infection happened, but can help solidify a diagnosis

Question 32

What does antigen testing detect? What can it detect?

Answer 32

- Detects presence of an antigen in the serum, urine, CSF, etc. - Bacterial, Fungal or Viral - Various methods used - Would tell you if the infection is current

Question 33

What does PCR detect?

Answer 33

- Polymerase Chain Reaction - Detects very low amounts of specific DNA in clinical specimens

Question 34

What can be used to see viruses?

Answer 34

Electron Microscopy

Question 35

What is the difference between empiric and direct antibiotic therapy? As pharmacists we want to move from..... to......

Answer 35

Direct --> Antibiotic chosen due to knowing the exact causative organism and susceptibility Empiric --> An educated guess antibiotic --> DO not know the causative organism As pharmacists we want to move from empiric to direct when we have information we need.