Lecture 1: Diagnostic and Therapeutic Techniques Flashcards

1
Q

What is step 1 of diagnosing?

A

Recognizing the S/S of an infection.

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2
Q

What are some general symptoms of infection?

A

Fatigue
Fever
Chills

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3
Q

What are some skin/wound symptoms of infection?

A

Redness
Swelling
Tenderness
Discharge

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4
Q

What are some lower respiratory tract symptoms of infection?

A

Productive cough
SOB
Pleuritic chest pain

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5
Q

What are some upper respiratory tract symptoms of infection?

A

Congestion
Discharge/drainage
HA/pain/pressure

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6
Q

What are some abdominal symptoms of infection?

A

Abd pain
N/V/D

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7
Q

What are some GU symptoms of infection?

A

Pain/burning upon urination
Vaginal/urethral discharge

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8
Q

What are some neuro symptoms of infection?

A

HA
Confusion
AMS

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9
Q

What are some MSK symptoms of infection?

A

Arthralgia
Edema
Erythema
Warmth

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10
Q

What are some general signs of infection?

A

Fever
Tachycardia

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11
Q

What are some skin/wound signs of infection?

A

Erythema
Edema
Discharge
Lesions

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12
Q

What are some lower respiratory tract signs of infection?

A

Wheezing/rhonchi/rales
Dullness to percussion
Hypoxia

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13
Q

What are some upper respiratory tract signs of infection?

A

Ears: bulging, erythematous TMs

Nose: Edematous, eythematous nasal mucosa/turbinates, sinus tenderness.

Throat: Erythematous oropharyngeal mucosa, tonsillar hypertrophy, exudates.

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14
Q

What are some GI signs of infection?

A

Abd tenderness
Increased bowel sounds

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15
Q

What are some GU signs of infection?

A

Cloudy/dark urine
Vaginal/urethral discharge
Lesions/sores

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16
Q

What are some neuro signs of infection?

A

Papilledema
Meningeal signs
Focal neurologic deficits

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17
Q

What are some MSK signs of infection?

A

Tenderness
Joint effusion
Decreased ROM

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18
Q

What is step 2 of diagnosing an infection?

A

Confirming the presence of an infection.

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19
Q

What is the category we are concerned with in a CBC regarding infection?

A

Leukocytes, which are typically ELEVATED in the presence of an infection.

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20
Q

What are the granulocytes and agranulocytes?

A

Granulocytes: Neutrophils, Eosinophils, Basophils

Agranulocytes: Lymphocytes, monocytes

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21
Q

What is the general proportion of leukocytes in the blood?

A

Neutrophils: 60-70%
Lymphocytes: 20-30%
Monocytes: 1-6%
Eosinophils: 1-3%
Basophils: <1%

Never Let Monkeys Eat Bananas

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22
Q

When are neutrophils typically elevated?

A

Bacterial infections

Sometimes fungal infections and general physiological stress.

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23
Q

What is a left shift and what does it indicate?

A

Increased presence of IMMATURE neutrophils.

Suggests Acute/early bacterial infection.

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24
Q

When do I see lymphocytosis?

A

Mainly in viral infections.

Leukemias and lymphomas as well.

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25
Q

What is the most common WBC in lymph?

A

Lymphocytes

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26
Q

What is the largest WBC?

A

Monocytes

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27
Q

When are monocytes typically elevated?

A

Late/chronic infection.

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28
Q

When are eosinophil counts elevated?

A

Allergic
Parasitic
Chronic skin conditions

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29
Q

When are basophil counts elevated?

A

Hypersensitivity reactions

Note:
Least common cause of leukocytosis.

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30
Q

What is a clean catch?

A

Collecting a clean urine sample that has typically only been in the bladder for 2-3 hours max.

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31
Q

What does getting a clean catch require?

A

Women must clean the labia.
Men must clean the head of the penis.

Children must be potty trained. If not, catherization will be used.

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32
Q

Describe the clean catch process.

A

Clean GU area.
Pee a little into the toilet.
Stop and then pee the cup to the marker.
Close the cup with the lid, never touching the inside of the cup.

Note:
If at home, refrigerate in a plastic bag afterwards.

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33
Q

What does a cloudy/turbid urine suggest?

A

Pyuria. (color)

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34
Q

What does a strong/fishy odor urine suggest?

A

Infection. (odor)

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35
Q

What main things are we testing for in a dipstick test of urine?

A

Leukocyte esterase
Nitrites
Blood

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36
Q

What are we looking for in a microscopic examination of urine?

A

WBCs
RBCs
Microorganisms
Casts

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37
Q

What does elevated leukocyte esterase suggest?

A

Increased WBC count and therefore infection.

Note:
Enzyme made by WBCs.

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38
Q

What does elevated nitrites suggest?

A

Presence of G- bacteria.

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39
Q

What does presence of casts indicate?

A

Kidney infection

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40
Q

When is a wet mount/KOH prep used?

A

Primary indication for vaginal/cervical/urethral discharge.

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41
Q

What is a wet mount used to observe?

A

Looking for microorganisms.

Clue cells indicate bacterial vaginosis.
Protozoans indicate Trichomonas

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42
Q

What is a KOH prep used to observe?

A

Fungal cells.

Note:
KOH degrades skin cells.

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43
Q

Can a wet mount be used to identify bacteria?

A

NO.

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44
Q

What does a clue cell look like?

A

Stippled appearance, covered in bacteria.

See slide 32 for visual

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45
Q

What is the purpose of an LP?

A

Obtain CSF for analysis

Therapeutic:
Relieve ICP
Administer intrathecal medications.

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46
Q

When are LPs indicated?

A

Sudden/severe HA and/or stiff neck.
Fever
Confusion, hallucinations, seizures, difficulty with speech, light sensitivity, dizziness, lethargy, and muscle weakness.

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47
Q

What positions are used for an LP?

A

Lateral decubitus is used when opening pressure is needed.

Upright, hunched over position is used when opening pressure is not needed.

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48
Q

What are the two pops I will feel on an LP?

A

Pop 1 will be the ligamentum flavum.
Pop 2 will be the dura mater.

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49
Q

Where is an LP performed?

A

Around L4-L5 vertebral level.

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50
Q

How many tubes do I get when collecting CSF? Why?

A

4

  1. Cell count and Diff
  2. Glucose and protein levels
  3. Gram stain, C&S
  4. Other
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51
Q

If my CSF looks yellowy, what is that called and what is it indicative of?

A

Xanthochromic.

Bleeding!!

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52
Q

What is the normal viscosity of CSF?

A

Same as water.

Thicker would imply an infection or malignancy.

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53
Q

What does presence of RBCs in tube 1 indicate?

A

CNS bleed

OR

Traumatic tap

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54
Q

How does an adult and neonate WBC range differ for tube 1?

A

Neonates can go up to 30 WBCs before being considered abnormal.

55
Q

What kind of glucose abnormality indicates infection or malignancy in tube 2?

A

Low glucose.

56
Q

What does elevated protein in tube 2 suggest?

A

Infection
Malignancy
Autoimmune disease

57
Q

What is the purpose of tube 4?

A

So we can do other specific tests if needed.

58
Q

Which type of meningitis causes extremely high opening pressure?

A

Bacterial

59
Q

What is the main complication that occurs with LPs?

A

HA

60
Q

Why are LPs relatively contraindicated in patients with increased bleed risk or increased ICP?

A

Hemorrhage may occur with increased bleed risk.

Cerebral herniation may occur with increased ICP.

61
Q

How is pleural fluid obtained?

A

Thoracentesis

62
Q

When is a thoracentesis for pleural fluid indicated?

A

Pleural effusion

63
Q

What is measured on a microscopic fluid analysis of pleural fluid?

A

Total cell counts
Cytology

64
Q

Define transudate.

A

Imbalance between the pressure within blood vessels and the amount of protein in blood, resulting in the abnormal accumulation of fluid.

65
Q

What is the most common cause of transudate?

A

CHF

66
Q

What does transudate look like?

A

A clear fluid with low protein/albumin/LDH and low cell count.

67
Q

Define exudate.

A

Caused by injury or inflammation of the pleura, resulting in a pleural effusion.

68
Q

What are the etiologies of an exudate?

A

Infectious diseases
Bleeding
Inflammation
Malignancies

69
Q

What does exudate usually look like?

A

Cloudy fluid with a high protein/albumin/LDH and high cell count.

70
Q

What is Light’s criteria? When do I use it?

A

Classifying pleural fluid as transudative or exudative.

Likely exudative if at least one of these conditions exist:

Pleural fluid protein:serum protein ratio > 0.65
Pleural fluid LDH: serum LDH ratio > 0.6
Pleural fluid LDH > 0.6 or >2/3 times the normal upper limit for serum LDH

71
Q

What does a milky pleural fluid suggest?

A

Lymphatic system involvement

72
Q

What does a reddish pleural fluid suggest?

A

Presence of blood.

73
Q

What does a cloudy/thick pleural fluid suggest?

A

Presence of microorganisms and/or WBC.

74
Q

If I have decreased glucose in my pleural fluid, what does that suggest?

A

Infection.

Decreased pH on top of that would indicate malignancy.

75
Q

How does infectious pleuritis affect lactate levels in pleural fluid?

A

Increases it.

76
Q

What does increased amylase in my pleural fluid suggest?

A

Pancreatitis
Esophageal rupture
Malignancy

77
Q

What does increased TG in my pleural fluid suggest?

A

Lymphatic system involvement.

78
Q

What is the purpose of a pericardiocentesis?

A

Obtain pericardial fluid to diagnose the cause of pericarditis or a pericardial effusion.

79
Q

What is a key PE finding that suggests pericarditis?

A

CP that is relieved by bending forward.

80
Q

Where is a pericardiocentesis performed?

A

Subxiphoid process with a 40deg angle towards the left shoulder.

Inserted between the xiphoid and left costal margin

81
Q

What is a water bottle sign?

A

Shape of a cardiac silhouette on CXR, caused by pts who have very large pericardial effusions.

See slide 57 for visual.

82
Q

What is the purpose of a paracentesis?

A

Diagnose the cause of peritonitis or ascites.

83
Q

What is the purpose of an arthrocentesis?

A

Diagnose the cause of a joint effusion.

84
Q

What is the purpose of a diagnostic CXR?

A

To help diagnose a pulmonary infection when S/S are present.

85
Q

What is the purpose of a screening CXR?

A

Screening for pulmonary infections, masses, trauma, and other pathologies.

86
Q

What does lobar consolidation look like on CXR?

A

Thickened lobes.

See slide 68 for visual.

87
Q

What does patchy nodular infiltrate look like on CXR?

A

Patches of sparse, white everywhere.

See slide 68 for visual.

88
Q

What does a CXR ultimately offer?

A

A diagnosis, but not the underlying cause.

89
Q

What are CTs good for?

A

Quick scans that give great bone detail and can use contrast to highlight certain structures.

90
Q

What are MRIs good for?

A

High-res of soft tissue and the ability to use contrast to highlight certain structures.

91
Q

What are the cons of CTs and MRIs?

A

CT cons:
Radiation exposure is a lot.

MRI cons:
Long scan time
Safety issues with indwelling metal
Small imaging space

92
Q

What is step 3 of diagnosing a patient?

A

Determining the actual source/pathogen causing the infection via gram stain and cultures.

93
Q

What do G- bacteria have that G+ don’t?

A

An outer lipopolysaccharide wall and outer membrane.

94
Q

Describe the process of a gram stain.

A

Slide stained with crystal violet dye.
Gram’s iodine solution added to improve adherence.
Decolorization with ethyl alcohol and acetone.

G+ with thick cell walls will retain the dye, so they look purple.

G- with thin cell walls decolorize.

Counterstain with safranin red turns G- pinkish red and G+ stay purple.

95
Q

What color do atypicals stain?

A

None.

They are atypical because they do not stain either color.

96
Q

What are the two main types of G+ cocci?

A

Strep (alpha, beta, and gamma hemolytics)
Staphylo (S. aureus mainly)

97
Q

What are the two main shapes of G- bacteria?

A

Cocci
Rods (Majority)

98
Q

What happens if a culture comes up positive? Negative?

A

Positive is highly suggestive of cause of infection.

Negative does not rule out.
Could be due to insufficient bacteria quantity
Viral infection
Previous ABX use by pt.

99
Q

If I want to treat a patient empirically, do I collect samples prior or post?

A

PRIOR to beginning ABX!

100
Q

How long does it take for culture results?

A

Bacteria can take 24-72 hours.
Fungal and mycobacterial can take even longer.

101
Q

When are blood cultures ordered?

A

Bacteremia/septicemia.

102
Q

How do I order blood cultures?

A

2 samples from 2 or more locations.

103
Q

How do I interpret blood cultures?

A

Both positive for same organism = positive culture.
1 positive, 1 negative = retest, possible contamination.
Both negative = negative culture.

104
Q

When are wound cultures ordered?

A

Draining of fluid or pus
Heat, redness, swelling, tenderness at site
Wound that is slow to heal

105
Q

When are stool cultures ordered?

A

Suspected GI infections.

It is only for extended diarrhea, ingestion of suspected contaminated food, or recent travel outside of US.

DO NOT ORDER on everyone with GI symptoms.

106
Q

What are stool cultures usually evaluating for?

A

Common intestinal bacterial pathogens like E. coli, Salmonella, Shigella, or Campylobacter.

107
Q

How do you evaluate for parasites in stool?

A

Stool for Ova and parasites must be added onto order.

108
Q

What is the most common source of a UTI and how is it treated?

A

E. Coli
Treated empirically.

109
Q

What indicates a positive urine culture?

A

> = 100,000 colonies of a SINGLE bacteria.

110
Q

What is a sputum culture indicated for?

A

Bacterial infection in the lungs, usually pneumonia.

111
Q

What does rust colored sputum suggest?

A

Strep Pneumoniae

112
Q

What does yellowish/green sputum suggest?

A

Haemophilus influenzae

113
Q

What does green sputum suggest?

A

Pseudomonas

114
Q

What does Red, currant-jelly sputum indicate?

A

Klebsiella

115
Q

What does bloody sputum indicate?

A

TB

116
Q

What does a foul-smelling/bad tasting sputum indicate?

A

Anaerobes

117
Q

What does thin/scant sticky sputum indicate?

A

Atypicals:
Mycoplasma pneumoniae
Chlamydia pneumoniae

118
Q

How is TB diagnosed via a sputum culture?

A

Acid Fast testing + culture specific testing + 3 separate samples and 12 weeks…

119
Q

What does NOT grow on typical sputum culture media?

A

Atypical bacteria
Mycobacterium (TB)
Fungus

120
Q

How are fungal infections in the lungs diagnosed?

A

Serum or biopsy testing.

121
Q

What is a rapid strep test for?

A

Check if someone with pharyngitis has group A strep

122
Q

What does a positive and negative rapid strep indicate?

A

Positive = no further testing.
Negative = throat culture.

Note:
Confirmatory testing is not needed on adults unless you are suspicious of something else.

123
Q

Who should not be strep throat tested?

A

Children under 3 yo unless at HIGH RISK

Avoid routine screening of asymptomatic people, even if they came in close contact.

Also do not test if symptoms match a viral infection more closely.

124
Q

What symptoms suggest an infection is more likely to be viral than strep?

A

Cough
Runny Nose
Mouth sores

125
Q

What are the criteria for a throat culture called? How is it measured?

A

Centor criteria 0-4.

History of fever = +1
Tonsillar exudate = +1
Tender anterior cervical adenopathy = +1
Absence of cough = +1

<15 = +1
>44 = -1

126
Q

What Centor criteria levels require treatment?

A

0-1 = no tx.
2-3 = Throat culture. If positive, treat with ABX.

4-5 = Empirical ABX tx

127
Q

What is the most common cause of a viral sore throat?

A

Adenovirus. Will usually appear as a negative rapid strep and negative throat culture.

128
Q

When is sensitivity testing indicated?

A

Unknown or mixed pathogens
Known resistance
Severe infection
Infection not responding to first-line tx.

129
Q

How do I order sensitivity testing?

A

C&S
Culture and Sensitivity testing

130
Q

What is the process of sensitivity testing?

A

Disk diffusion.

Disks of ABX are plated along the border of an agar plate.

If the ABX is effective against a bacteria, aka bacteria is SENSITIVE to the ABX, a clear ring will appear around the abx disk.

If not effective, no change in growth.

131
Q

What is the alternative to disk diffusion?

A

Broth dilution.

Tests for the MIC.

132
Q

How long does C&S take?

A

24-48 hours AFTER organisms have been identified on culture.

133
Q

When should abx treatment begin relative to C&S results?

A

PRIOR to C&S results.

Start with broad spectrum and adjust once results are obtained.