Intro to ID Part 1

Question 1

Temperature for fever

Answer 1

> 38C or >100.4

Question 2

Non-infectious causes of fever (false-positives)

Answer 2

-Drug-induced fevers
-Malignancies
-Blood transfusions
-Auto-immune disorders

Question 3

False-negatives (absence of fever in patients with signs/symptoms consistent with infection)

Answer 3

-Antipyretics (acetaminophen, NSAIDs, aspirin)
-Corticosteroids
-Overwhelming infection (may be hypothermic (<36C or 96.8F)

Question 4

Systemic signs of infection

Answer 4

-Hypotension (SBP <90 or MAP <70)
-Tachycardia (BP >90)
-Tachypnea (>20 RPM)
-Fever (>38C or 36C)
-Increased/decreased WBC count (>12000 or <4000 or >10% immature forms (bands))

Question 5

Systemic symptoms of infection

Answer 5

-Chills
-Rigors
-Malaise
-Mental status changes

Question 6

Local signs and symptoms of infection

Answer 6

-Symptoms referable to specific body systems (ex: local pain)
-Pain and inflammation
-Inflammation in deep-seated infections (pneumonia, meningitis, UTIs)
-May be absent in neutropenic patients (main sign is fever)

Question 7

Function of white blood cells

Answer 7

Defend the body against invading organisms

Question 8

Types of white blood cells

Answer 8

-Neutrophils
-Lymphocytes
-Monocytes
-Eosinophils
-Basophils

Question 9

Potential non-infectious causes for elevated white blood cell count

Answer 9

-Steroids
-Leukemia
-Stress
-Rheumatoid arthritis
-Pregnancy

Question 10

Mature neutrophils (PMNs, polys, segs) description

Answer 10

-Most common WBC
-Fight infections

Question 11

Immature neutrophils (bands) description

Answer 11

-Increased during infection = left shift
-Released by bone marrow into blood during infection

Question 12

Eosinophil description

Answer 12

Involved in allergic reaction and immune response to parasites

Question 13

Basophil description

Answer 13

Associated with hypersensitivity reactions

Question 14

Lymphocyte description

Answer 14

Humoral (B-cell) and cell-mediated (T-cell) immunity

Question 15

Monocyte description

Answer 15

-Mature into macrophages
-Serve as scavengers for foreign substances

Question 16

What is leukocytosis?

Answer 16

-Increased neutrophils +/- bands associated with bacterial infections
-Presence of bands indicates increased bone marrow response to infection (left shift)
-May be elevated due to non-infectious diseases (leukemia, stress) or drugs (steroids)
-Leukopenia (abnormally low WBC) may be a sign of overwhelming infection; poor prognostic sign

Question 17

What is lymphocytosis?

Answer 17

-Associated with viral, fungal or tuberculosis infections
-B-lymphocytes: proliferate into plasma cells -> produce antibodies and memory B-cells
-T-lymphocytes: HIV type infections

Question 18

What is an absolute neutrophil count?

Answer 18

Total number of circulating segs and bands

Question 19

What is neutropenia?

Answer 19

-ANC <500
-ANC expected to decrease to <500 in the next 48 hours
-ANC less than 100 is termed profound neutropenia
-Start getting worried when ANC <1000

Question 20

What are the acute phase reactants?

Answer 20

-ESR
-CRP
-Procalcitonin (more specific for bacterial infections)
-Does NOT confirm infection

Question 21

Normal ESR levels

Answer 21

-0-15 for males
-0-20 for females

Question 22

Normal CRP levels

Answer 22

0-0.05

Question 23

Normal procalcitonin

Answer 23

-<0.5
-Increase 3-12 hours after stimulation; decline over 24-72 hours
-Magnitude of elevation provides useful diagnostic information

Question 24

How often should procalcitonin levels be taken?

Answer 24

Serial measurements every 1-2 days useful to assess response to therapy and when to discontinue antibiotics

Question 25

Radiographic tests for infections

Answer 25

-X-rays -Computed tomography (CT) -Magnetic resonance imaging (MRI) -Nuclear imaging (bone scans, WBC-related scans) -Echocardiography (transthoracic echocardiogram (TTE) or transesophageal echocardiogram (TEE))

Question 26

What type of culture would be collected for osteomyelitis?

Answer 26

Bone biopsy

Question 27

What type of culture would be collected for meningitis?

Answer 27

CSF

Question 28

What type of culture would be collected for endocarditis?

Answer 28

Blood cultures, heart valve tissues

Question 29

When should blood cultures be obtained?

Answer 29

Should be performed in acutely ill febrile patients

Question 30

How should blood cultures be obtained?

Answer 30

Two sets from two different sites

Question 31

What is one set in a blood culture?

Answer 31

One aerobic and one anaerobic bottle

Question 32

What is a colonization?

Answer 32

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

Question 33

What is an infection?

Answer 33

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