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Immunology & ID > Diagnostic Methods (Voiler) > Flashcards

Diagnostic Methods (Voiler) Flashcards

1
Q

Advice:

A

Work on pattern recognition

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2
Q

Diagnostic tests ahead:

A

CBC, ELISA, Western blot, urinalysis, blood culture, CSF, microscopy

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3
Q

Chest radiograph:

A

Pneumonia

Bacterial/Viral/Inflammatory

Pneumothorax

Pleural effusion

Rib fracture

Chest Mass

Lactic Acid

Procalcitonin

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4
Q

Note:

A

Should not generally see stem cells in the blood stream

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5
Q

CBC

A

WBC (4.5-11)
Differential:
Basophils, Eosinophils, lymphocytes, monocytes, neutrophils, hemoglobin, hematocrit, MCV, Platelets

emphasis on neutrophils aka left shift=acute infection

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6
Q

Acute phase reactant

A

platelet count can rise in times of high stress

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7
Q

WBC concepts

A

Elevation in WBC (Leukocytosis):

-Bacterial Infection
-Leukemia/ blood cancers
-Steroid effect
-Clostridium Diff Infection (taking antibiotics, good bacteria are killed, Cdiff spore releases toxins causing severe diarrhea)
-Recent stressors- surgery/major illness/ MI (myocardial infarction)

Low WBC:(Leukopenia)
-Immunomodulator drugs
-Chemotherapy
-Bone marrow failure

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8
Q

ANC (absolute neutrophil count)

A

Follow in immunocompromised (ex. myelosuppressive chemo patient, treatment prevent RBC production in bone marrow)

Neutropenia = ANC<1500
-mild 1000-1500
-mod 500-999
-severe<500

opportunistic infection risk

neutropenic fever: life threatening, high mortality

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9
Q

Peripheral blood smear

A

RBC size/shape
-Hypochromic/normochromic- MCHC -> IDA
-Megaloblastic -> defective DNA-> folate/b12 deficiency

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10
Q

Immunoassay

A

ELISA most common kind
FIA another common

Add Reagent Antibody (Ab)#enzyme combo specific for target Antigen (Ag) under investigation

Can test for food contamination, environmental, HIV, various uses (not that clinically relevant except for HIV)

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11
Q

Note

A

Don’t worry too much about how and why this stuff works, mostly focus on diagnostic relevance (when to test people? why? what are you looking for?)

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12
Q

urinalysis:

A

bacteria showing up might not mean infection, just colonization, in which case you may not need to use antibiotics!

UTI: nitrite in urine is a metabolic product of bacteria (nitrate converted to nitrite)

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13
Q

note:

A

Sometimes she will start with a broad spectrum “big gun” antibiotic and then get more narrow as results come in so she doesn’t kill off good bacteria

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14
Q

“Pearl, write this down”

A

When you see someone breathing very quickly, think sepsis as a possibility! This happens when turning into sepsis

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15
Q

ELISA/EIA

A

Antibody linked enzyme specific for Antigen

Detects Antigen (viral/bacteria) or antibody in blood

Sensitivity usually high,

Used for screening

Enzyme triggered color change

HIV, Lyme disease, COVID, pernicious anemia, RMSF, Syphilis, Allergies, Drugs, Pregnancy

Not great for determining acute vs chronic

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16
Q

FEIA

A

Measures compounds, drugs, hormones, proteins

Identifies Ab, Ag quantification,-viral particles

Differs in read out from ELISA

common with allergy testing

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17
Q

Western Blot/Immunoblot

A

Detects microbial Ab to organism (or proteins) in serum/body fluids w/ target antigens (viral)

Detects IgM (1-2week)/IgG (2-6 week) antibodies

Good sensitivity, less than ELISA
Helps exclude false positive ELISA’s as Highly specific

Shiga toxin, HIV, HSV2, Hep B

Cryptococcus, Lyme disease

Influenza

Can have false positives

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18
Q

HIV testing

A

Subtype 1- common in US
Subtype 2-Western Africa

Indication: Clinical signs (mono or flu like symptoms) / and or high risk exposure

Consideration- if no risk factors- consider screening all 13-75 y/o at least once, all pregnant women

Takes 2 weeks- 6 months to develop antibodies

Sensitivity ~99% >12 weeks post infection

ELISA then if + Western blot to confirm

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19
Q

HIV testing

A

Subtype 1- common in US
Subtype 2-Western Africa

Indication: Clinical signs (mono or flu like symptoms) / and or high risk exposure

Consideration- if no risk factors- consider screening all 13-75 y/o at least once, all pregnant women

Takes 2 weeks- 6 months to develop antibodies

Sensitivity ~99% >12 weeks post infection

ELISA then if + Western blot to confirm

20
Q

4th generation ELISA

A

Combination Ag and Ab testing better detecting acute/early infection, compared w/ Ab only test

21
Q

HIV testing

A

CD4 (Helper T cells)-
800-1050 c/mL- normal
<200c/ml = AIDS
Helps staging/risk analysis
CD4 cell count, CD4 count %, HIV RNA, HIV genotype testing

Prophylactic therapy- prevent opportunistic infection (Pneumocystis)- CD4 <200c/mL

22
Q

Urinalysis

A

Infection symptoms
-Dysuria/frequency/urgency/bladder pain/lower abdominal pain/
-Flank pain/fevers- kidney infection sx
-Elderly confusion

UTI 2nd most common dx infection
Eval for:
-Hematuria bloody urine)
-Kidney failure
-Diabetes damage- protein

22
Q

Urinalysis

A

Infection symptoms
-Dysuria/frequency/urgency/bladder pain/lower abdominal pain/
-Flank pain/fevers- kidney infection sx
-Elderly confusion

UTI 2nd most common dx infection
Eval for:
-Hematuria bloody urine)
-Kidney failure
-Diabetes damage- protein

23
Q

Urinalysis Indications

A

hematuria or pyuria
renal disease
abnormalities of ureter
TB in urinary tract
prior to urinary tract surgery
flank pain
in children: polycystic kidney diseases
etc.

24
Q

Note

A

Urinalysis details slide 20

25
Q

Obtaining urinalysis technique:

A

Clean urethra with wipe
clean catch (mid stream)

26
Q

UA: microscopic

A

Eval for
Wbc
Rbc
Bacteria
Crystals
casts (?)
Casts- renal origin, stress, damage, hyaline sometimes normal, glomerulonephritis, kidney injury, nephrotic syndrome

27
Q

Urine obtained vis clean catch:

A

incubated on a petri dish, reveals bacterial infection growth if present

28
Q

Indications for Urinalysis

A

Pregnant women (doesn’t need sx)
Post menopausal women
Men
Prepubertal children
Urinary tract abnormality
Immunosuppressed
Concern for pyelonephritis
Recurrent UTI’s

29
Q

Blood Culture and Sensitivity

A

Indication: Concern for Blood infection
Fevers >100.4
Risk factors for blood infection
Kidney infection
Rigor Chills- very sensitive for blood infection
Signs: tachycardia, Confusion, low bp,
Immunocompromised
IV drug abuser
Prosthetic heart valves
Concern for localized infection spread
Sepsis
Hypotension
Rapid breathing/ heart rate
Indwelling central lines
Foreign bodies

30
Q

Note:

A

many helpful resources on this powerpoint, maybe worth saving? (ex. imaging slide)

31
Q

Aseptic technique

A

prep skin, vein or line draw, obtain at separate sites, petri dish

32
Q

CSF analysis

A

Indication: Concern for Meningitis/Encephalitis , Inflammatory Condition
Infection concern- Headache/Fever/Meningismus- stiff neck

Obtained via lumbar puncture (LP):
Evaluate for intracranial pressure prior
Get CT head first

Contraindicated if:
Infected skin at puncture site
Bleeding issues, csf blockage concern like tumor

Normal values: clear/colorless- yellow tinged think infectio

33
Q

Lumbar Puncture

A

Infection patterns

Bacterial Meningitis-
H.Flu kids, Neisseria Meningititis/Strep Pneumonia Adults
Leukocytes/PMN’s elevated
Protein elevated
Glucose low
Gram stain >10^5 CFU

Viral meningitis
Mixed PMN’s/Lymphocytes
Protein elevated
Glucose normal
Check enterovirus/herpes/west nile PCR’s

TB meningitis
Mixed wbc’s,
Protein elevated
Glucose low
AFB staining +
Mycobacterium cx elevated

Fungal Meningitis
Elevated lymphocytes, decreased glucose, elevated protein

34
Q

Microscopy

A

Wet prep/mount-microscopic eval
Vaginitis symptoms-itching/burning/rash/odor/discharge
Evals for Yeast, trichomonas, bacterial vaginosis
Tested by:
Wet mount- visual
Potassium hydroxide (KOH) slide-
Evals yeast
Whiff test
KOH, strong fishy odor= bacterial vaginosis
Caveat - Does not eval for all STI’s

35
Q

good note:

A

if you hear it a lot, it’s important

36
Q

Microscopy: stool

A

Protozoa:
Developing countries
Cyclical sheading- need multiple samples
Microscopy not as reliable as ELISA

Sx: abdominal pain, diarrhea, fever, anorexia, nausea
Recent travel out of country/hiking
Giardia- flagella, Cryptosporidium-small acid fast stain, Entamoeba histolytica

37
Q

Microscopy Stool indications

A

Indications: eosinophilia, known exposure, malabsorption, rectal pruitis, most asymptomatic
abdominal pain/nausea/vomiting rare- if large worm burden
Diarrhea/Colitis- more common bacterial/viral/ protozoa infections
Enterotoxic ecoli, Yersenia, Camppylobacter, Shigella, Samonella, Protazoa infection

Helminthic Infections- usually don’t cause diarrhea

Common- Enterobius pin worm (most common US)/ whip worm- mostly asymptomatic
Pin worm- scotch tape test
wet mount, stain

38
Q

Microscopy stool

A

Ova &Parasite Eval
Most acute diarrhea causes are infectious-likely viral
Diarrhea usually transient

Indication: Fever, bloody or mucousy stool, profuse watery diarrhea, HIV, enteric bacteremia

Exposure- food, occupation, travel, camping, pets, close contact w/ sick person
Rapid antigen testing-bacterial infections

39
Q

Chest Radiograph

A

PA vs AP view
Black= empty
White=increased density

40
Q

Make sure to review this powerpoint rather than just notecards

A

the images are helpful plus extra info

41
Q

Viral pneumonia

A

Viruses are estimated to cause 30 to 50 percent of CAP cases

41
Q

Viral pneumonia

A

Viruses are estimated to cause 30 to 50 percent of CAP cases

42
Q

Lactic Acid: sepsis marker

A

represents the anaerobic breakdown of glucose

Big player in Early goal directed therapy w/ Sepsis

Trend mirrors response to treatments

Most common cause of Metabolic Acidosis

Production exceeds clearance

Primary cleared by liver, alittle kidneys, tiny from muscles

Indication: Consider if hypotensive, severe infection, metabolic acidosis w/o obvious cause

43
Q

Procalcitonin

A

Biomarker helps distinguish bacterial infections from other infections/inflammation

Goal- reduce antibiotic use

Use as a tool but not your only data point
Not all bacterial infection cause procal to rise
-Atypical not as likely to rise
-Has False positive/false negatives

Guides early antibiotic discontinuation

Chronic kidney have higher baseline levels

Immunology & ID (15 decks)

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