Diagnostic Methods (Voiler)

Question 1

Advice:

Answer 1

Work on pattern recognition

Question 2

Diagnostic tests ahead:

Answer 2

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

Question 3

Chest radiograph:

Answer 3

Pneumonia

Bacterial/Viral/Inflammatory

Pneumothorax

Pleural effusion

Rib fracture

Chest Mass

Lactic Acid

Procalcitonin

Question 4

Note:

Answer 4

Should not generally see stem cells in the blood stream

Question 5

CBC

Answer 5

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

emphasis on neutrophils aka left shift=acute infection

Question 6

Acute phase reactant

Answer 6

platelet count can rise in times of high stress

Question 7

WBC concepts

Answer 7

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

Question 8

ANC (absolute neutrophil count)

Answer 8

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

Question 9

Peripheral blood smear

Answer 9

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

Question 10

Immunoassay

Answer 10

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)

Question 11

Note

Answer 11

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?)

Question 12

urinalysis:

Answer 12

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)

Question 13

note:

Answer 13

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

Question 14

“Pearl, write this down”

Answer 14

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

Question 15

ELISA/EIA

Answer 15

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

Question 16

FEIA

Answer 16

Measures compounds, drugs, hormones, proteins

Identifies Ab, Ag quantification,-viral particles

Differs in read out from ELISA

common with allergy testing

Question 17

Western Blot/Immunoblot

Answer 17

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

Question 18

HIV testing

Answer 18

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

Question 19

HIV testing

Answer 19

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

Question 20

4th generation ELISA

Answer 20

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

Question 21

HIV testing

Answer 21

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

Question 22

Urinalysis

Answer 22

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

Question 22

Urinalysis

Answer 22

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

Question 23

Urinalysis Indications

Answer 23

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.

Question 24

Note

Answer 24

Urinalysis details slide 20

Question 25

Obtaining urinalysis technique:

Answer 25

Clean urethra with wipe clean catch (mid stream)

Question 26

UA: microscopic

Answer 26

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

Question 27

Urine obtained vis clean catch:

Answer 27

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

Question 28

Indications for Urinalysis

Answer 28

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

Question 29

Blood Culture and Sensitivity

Answer 29

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

Question 30

Note:

Answer 30

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

Question 31

Aseptic technique

Answer 31

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

Question 32

CSF analysis

Answer 32

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

Question 33

Lumbar Puncture

Answer 33

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

Question 34

Microscopy

Answer 34

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

Question 35

good note:

Answer 35

if you hear it a lot, it's important

Question 36

Microscopy: stool

Answer 36

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

Question 37

Microscopy Stool indications

Answer 37

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

Question 38

Microscopy stool

Answer 38

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

Question 39

Chest Radiograph

Answer 39

PA vs AP view Black= empty White=increased density

Question 40

Make sure to review this powerpoint rather than just notecards

Answer 40

the images are helpful plus extra info

Question 41

Viral pneumonia

Answer 41

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

Question 41

Viral pneumonia

Answer 41

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

Question 42

Lactic Acid: sepsis marker

Answer 42

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

Question 43

Procalcitonin

Answer 43

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