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Spring 2025 Therapeutics V > Exam 1 Intro to ID Lec 1 > Flashcards

Exam 1 Intro to ID Lec 1 Flashcards

1
Q

Before prescribing antibiotics we must first do what?

A

Determine if there is an infection present

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2
Q

What is the hallmark of infection?

A

Fever

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3
Q

What temperature indicates a fever?

A

> 38C (100.4F)

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4
Q

What is a normal body temperature?

A

36-37C (98-98.6F)

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5
Q

What are some of the non-infectious causes of fever?

A

Drug-induced
Malignancy
Blood transfusion
Auto-immune disorder

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6
Q

What drugs can cause drug-induced fever?

A

Beta-lactam antibiotics
Sulfonamides
Anticonvulsants

*fever coincides with administration and disappears when the agent is stopped

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7
Q

What can cause a fever to be detected falsely as negative?

A

*Antipyretics (acetaminophen, NSAIDs, aspirin)

Corticosteroids

Overwhelming infection (can cause hypothermia)

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8
Q

What are the systemic signs of infection?

A

BP: Hypotension (S <90 or MAP <70)

HR: Tachycardia (>90)

RR: Tachypnea (>20)

Fever

Increased/decreased WBC count (>12,000 or <4000)

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9
Q

What are the 4 criteria for systemic inflammatory response syndrome (SIRS) and how many criteria need to be met?

A

Tachycardia (>90)

Tachypnea (>20 rpm)

Fever

Increased/Decreased WBC (>12,000 or < 4000)

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10
Q

What is the systemic inflammatory response syndrome (SIRS) criteria used to determine?

A

If a patient is septic or not

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11
Q

What are the systemic symptoms of infection?

A

Chills
Rigors
Malaise
Mental status changes

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12
Q

What are the local symptoms of infection?

A

Symptoms that are referable to a specific body system

Pain and Inflammation
(swelling, erythema, tenderness, purulent or abnormal drainage)

*note that these may be absent in neutropenic patients

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13
Q

What are the non-infectious causes of elevated WBC counts?

A

Steroids
Leukemia
Stress
Rheumatoid Arthritis
Pregnancy

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14
Q

What are mature neutrophils?

A

The most common WBC

-Fight infections

AKA: PMNs, polys, segs

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15
Q

What are immature neutrophils?

A

Immature neutrophils released by the bone marrow into the blood

Increase during an infection= “left shift”

AKA: bands

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16
Q

What are eosinophils?

A

Involved in allergic reactions and immune responses to parasites

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17
Q

What are basophils?

A

Associated with hypersensitivity reactions

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18
Q

What are lymphocytes?

A

Humoral (B cell) immunity
+
Cell-mediated (T cell) immunity

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19
Q

What are monocytes?

A

Mature into macrophages

-serve as scavengers for foreign substances

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20
Q

What is leukocytosis?

A

Elevated neutrophils + bands

ASSOCIATED WITH BACTERIAL INFECTIONS

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21
Q

What is lymphocytosis?

A

Increase in B and T lymphocytes

Associated with: viral, fungal, or tuberculosis infections

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22
Q

What is the role of B-lymphocytes?

A

Proliferate into plasma cells and produce antibodies + memory B cells

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23
Q

What is the role of T-helper (CD4) cells?

A

Regulate the immune system

Help with antibody production

Secrete lymphokines to help protect against infection and tumors

*Depleted in HIV infection

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24
Q

What is the role of T-suppressor (CD8) cells?

A

Bind and kill tumor cells directly

Help regulate humoral and cell-mediated immunity

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25
Q

What is the absolute neutrophil count (ANC)?

A

Total number of circulating segs + bands

26
Q

What ANC indicated neutropenia?

A

ANC < 500 cells/mm3
or
ANC expected to decrease to < 500 in the next 48 hours

*ANC < 100 is termed “profound neutropenia”

27
Q

How do ANC and infection risk correlate?

A

Infection risk increases as ANC decreases

28
Q

What are ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein)?

A

Biomarkers that are elevated in the presence of an inflammatory process

**these do not confirm an infection but are often elevated

29
Q

What is procalcitonin and what do its levels tell us?

A

Precursor to calcitonin

*More specific for bacterial infections than ESR or CRP

Normal: <0.05

Increases 3-12 hrs after stimulation and declines over 24-72 hrs
*can get serial measurements while on therapy to determine if weaning is appropriate

30
Q

How often can we take serial measurements of procalcitonin?

A

Every 1-2 days

31
Q

For osteomyelitis, where would we take a culture collection?

A

bone biopsy

32
Q

For meningitis, where would we take a culture collection?

A

CSF

33
Q

For endocarditis, where would we take a culture collection?

A

blood cultures, heart valve tissue

34
Q

Who should blood cultures be taken in and how?

A

-Acutely ill, febrile patients

Obtain from two different peripheral sites as two sets
*1 set= 1 aerobic and 1 anerobic bottle

*Take 1hr apart, with one from each arm

35
Q

What is colonization?

A

A potentially pathogenic organism is present at the body site but is not invading host tissue or eliciting an immune response

36
Q

What is infection?

A

A pathogenic organism is present at the body site and is damaging host tissue + eliciting host responses and symptoms consistent with infection

37
Q

What is the only rapid diagnostic for bloodstream infections that can tell you susceptibility of the organism?

A

PhenoTest BC Kit

38
Q

What is Minimum Inhibitory Concentration (MIC)?

A

The lowest antimicrobial concentration that prevents visible growth

Concentration of first vial with no growth in it

39
Q

In susceptibility testing, what is the breakpoint?

A

MIC or zone diameter value used to categorize an organism as: susceptible, susceptible dose-dependent, intermediate, resistant, or non-susceptible

40
Q

In susceptibility testing, what is “susceptible”? (S)

A

Isolates with an MIC at or below, or a zone diameter at or below the (S) breakpoint are considered inhibited by the usually achievable concentrations of antimicrobial agent when the normal dosing regimens are used

-this results in likely clinical efficacy

41
Q

In susceptibility testing, what is “susceptible-dose dependent”? (S-DD)

A

Implies susceptibility is dependent on the dosing regimen used

*need to use higher doses than standard to adequately treat

42
Q

In susceptibility testing, what is “Intermediate”? (I)

A

Isolates with MICs approach achievable blood or tissue concentrations and response rates may be lower than for susceptible isolates

43
Q

In susceptibility testing, what is “Resistant”? (R)

A

Isolates not inhibited by usually achievable concentrations of agent with normal dosage schedules
-clinical efficacy has not been reliably demonstrated

44
Q

In susceptibility testing, what is “non-susceptible”? (NS)

A

If MIC is above or zone diameter is below the susceptible breakpoint, the isolate is categorized as NS

45
Q

What test is the gold standard for identifying a pathogen?

A

Broth dilution

46
Q

What is the Kirby-Bauer method of pathogen identification?

A

AKA Disk Diffusion Assay

-put antibiotic impregnated disks on agar streaked with bacteria
-the drugs in the disks diffuse out into the agar
-there is visual bacterial growth only in areas where drug concentrations fall below those required for growth
-zone diameters are measured and compared with standard size ranges

47
Q

What can you not determine from the Kirby-Bauer method?

A

Cannot derive MIC

*can only determine if susceptible, intermediate, or resistant

48
Q

What is the Epsilometer test/ E test for pathogen susceptibility?

A

Gradient strip test

-Plastic strip is impregnated with known prefixed antibiotic concentration gradient placed on agar streaked with known bacteria

*MIC= concentration on strip where inhibition ellipse intersects the scale of the strip

*More precise than standard methods

*Expensive

*Used for newer agents with no other means of testing or for agents that are not in standard panels

49
Q

What is the Vitek-2 System for determining MIC?

A

-Uses small reagent cards that test predetermined bug/drug combinations

-Growth curves are calculated for all wells compared to growth control curves

49
Q

True or False: MICs are unique for each bug/drug combo

A

TRUE

-cannot compare different drugs based on MIC

50
Q

What is Empiric Therapy?

A

Initial anti-infective therapy administered before identification and susceptibility results are known

*The selective anti-infective should cover most common pathogens

51
Q

What is Directed (targeted) Therapy?

A

Therapy selected after the organism is identified and/or susceptibility is known

52
Q

What is De-escalation?

A

Selecting an anti-infective with the narrowest spectrum of activity

-either stepwise or all at once

53
Q

What is Spectrum of Activity?

A

What anti-microbials the drug covers

54
Q

If a patient has pneumonia, what drug can be used as empiric therapy?

A

Cefepime
-covers a lot of bugs

55
Q

If a patient has preliminary cultures that grow e.coli, what de-escalation drug can be used?

A

Ceftriaxone
-more specific for e.coli

56
Q

If a patient is found to have pan-susceptible e.coli, what de-escalation targeted therapy can be used?

A

Amoxicillin

-the most targeted therapy

57
Q

What is an Antibiogram?

A

Annual summary of institution-specific anti-infective susceptibility

**Want at least 80% susceptibility!!!

58
Q

What can happen with a G6PG genetic deficiency?

A

Causes hemolytic anemia when given certain antibiotics

59
Q

Which antibiotics have therapeutic drug monitoring available?

A

Vancomycin

Aminoglycosides

60
Q

Which of the following is an example of an antimicrobial stewardship strategy?

◦ a) Switch to broad spectrum antimicrobials to better treat infections
◦ b) Require ID pharmacist approval before ordering broad spectrum antibiotic
◦ c) Continuing empiric antibiotics for 96 hours prior to reassessment
◦ d) Developing polices aimed at increasing antimicrobial resistance

A

b) Require ID pharmacist approval before ordering broad spectrum antibiotic

Spring 2025 Therapeutics V (13 decks)

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