Microbiology Review PDF
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This document provides a review of microbiology, covering concepts like the differences between plasma and serum, arterial and venous blood; universal safety precautions; gram positive and negative bacteria. It further details pathogens, opportunistic pathogens, iatrogenic infections, and virulence factors.
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Clinical Specimen Review What are the differences between plasma and serum? o Plasma –liquid portion of centrifuged anticoagulated blood; makes up ~55% of sample o Serum –liquid portion of centrifuged coagul...
Clinical Specimen Review What are the differences between plasma and serum? o Plasma –liquid portion of centrifuged anticoagulated blood; makes up ~55% of sample o Serum –liquid portion of centrifuged coagulated blood; (serum = plasma - coagulation factors) List the differences between arterial and venous blood. Why use arterial blood to measure O2 partial pressure? o Arterial § Bright red blood; contains oxygenated hemoglobin § Higher O2 content, lower CO2 content § Used to measure O2 partial pressure;tells you how much O2 is being delivered - is oxygenated § Used for arteriol blood gas o Venous § Dark red blood; contains deoxygenated hemoglobin § Lower O2 content, higher CO2 content What is universal safety precaution? o Developed by the CDC in 1988 o Rules that all patients are assumed to be infectious for blood-borne pathogens - Primary blood pathogens HepBV, Hep CV, HIV, CoV o Requires proper safety precaution during phlebotomy procedures § Ex: gloves, protective clothing, no recapping needles, proper disposal of sharps § Doesn’t mandate face shields during routine phlebotomy Section Review of Microbiology If given a bacterium, such as Escherichia (E.) coli O157H7, which is genus, which is species and which is strain? o Genus = Escherichia/ E. o Species = coli o Strain = O157H7 Compare Gram positive with Gram negative bacteria, explain why they are stained different colors in Gram stain. o Gram + § Thick layer of peptidoglycan traps primary stain (Crystal violet); stains purple o Gram – § Thin layer of peptidoglycan susceptible to decolorizer and allows for uptake of counterstain (Safranin); stains pink Why isMycobacterium tuberculosisresistant to Gram stain? What kind of stain can be used to detect it? o Resistant to Gram stain due to high lipid and wax content in its cell walls o Use acid-fast stain (Carbolfuschsin) to detect it; acid fast stains dissolve lipids via heat (Ziehl Neelsen method) or detergent (Kinyoun method) What stain can be used to detectCryptococcusin the CSF? o India ink stain; negative stain used to visualize capsules around yeast What are the complications of empiric antibiotic treatment? o Selection of drug resistant bacteria o Normal flora is eliminated which leads to § C-diff colitis § Fungal infections § Coagulopathy – some normal flora produce vitamin K in the gut Define pathogen, opportunistic pathogen, iatrogenic infection, virulence. o Pathogen –can cause disease in asusceptiblehost when conditions for infection are met § True pathogen– can cause disease in healthy immunocompetent individuals o Opportunistic pathogen –usual/normal microbial or environment flora which don’t usually cause clinical infection § Lead to opportunistic infections when · Imbalance in the normal flora = one resident microorganism predominates o Ex: C-diff causes pseudomembranous colitis after wide-spectrum antibiotic usage · Environmental organism enters the body only when immune defense is compromised o Ex: candidiasis/cryptococcal meningitis in AIDs patients o Iatrogenic infection –result of medical treatment/procedure o Virulence –relative ability of microorganism to cause disease (degree of pathogenicity) § Measured by infectious/infective dose · Low infective dose = high virulence (ex: Shigella) · High infective dose = low virulence (ex: Salmonella) § Virulence factors = traits determining pathogenicity and virulence (capsules, toxins, adhesive fimbriae) List common virulence factors of bacteria and their functions (especially protein A, toxins, capsule). o Resisting phagocytosis § Phagocytosis = role in clearing bacterial infections § Mechanisms to inhibit phagocytosis · Capsule = inhibits engulfment · Prevent phagosome-lysosome fusion · Escape to cytoplasm of human cells · Leukocidins damage/kill leukocytes · Protein A o Adhesion to target cells (fimbriae, pili, surface polysaccharides); enables attachment to host = ^ ability to colonize o Increased survival and proliferation = promote invasion o Bacteria secretes enzymes breaking down matrix to promote invasion and dissemination: - Streptokinase: activate plasmin to degrade blood clot - DNAse: degrade dna - Hyalurinidase: break down tissue matrix - Proteinase o Toxins causing cell damage (endotoxin vs exotoxin) Describe how protein A help bacteria resist phagocytosis? o Antibody binds to pathogen (typically s. aureus) and marks it to be engulfed by macrophages o Bacteria secretes protein A which binds to C fragments of IgG § Prevents macrophages from binding to C fragments they won’t be able to fight off bacteria Compare endotoxin withexotoxin. o Endotoxins § Lipopolysaccharides: cell wall components in Gram – bacteria § Heat stable § No enzyme activity § Effects are similar in different bacteria (hypotension, fever, initiates coagulation) o Exotoxins:Proteins secreted by some bacteria into surrounding environments § Two units · Binding subunit = allows toxin to enter cell · Toxic subunit = disrupts/destroys cellular function § Heat labile; usually have enzyme activity § Effect is toxin specific § Ex: C-diff secretes toxin A and toxin B Definebacteremia and septicemia. o Bacteremia –viable bacteria in the blood; can be in blood transiently/temporaily so to increase detection take multiple sample o Septicemia –bacteremia with a clinical presentation of physical signs/symptoms of bacterial invasion and toxin production § Has high mortality; needs early diagnosis and intervention diagnose with blood culture § Ex: sepsis, severe sepsis, and septic shock Describe how to correctly collect sample for blood culture. o New venipuncture is required; do not draw from indwelling line/port o Clean skill well to avoid contamination from skin flora otherwise potential false positive o Collection volume = blood collected from 3 different puncture with 20 mL in each (60ml total) § per 20ml at each site, it is split into 2 bottles of 10ml (an aerobic and anaerobic bottle) List the specimen of choice for wound culture. o Wound biopsy Describe themost important treatment of wound infection o Surgical wound care and draining o Systemic antibiotic treatment is supplemental Define pseudomembranous colitis. o Occurs due to overgrowth of C-diff, usually following wide-spectrum antibiotic use o Produces toxin that causes cytotoxicity to epithelial cells (major virulence factor in C-diff) What is the most common cause of gastroenteritis in children in US? o Rotavirus Compare laboratory tests for diagnosis of GI infection caused by C-diff, helicobacter pylori and rotavirus o C-diff (clostridium difficile): § Stool cultures · Most sensitive · Labor intensive; time consuming (48-96 hours) · False positive with nontoxigenic strains § Toxin detection · Cytotoxic assay – culture human cell with toxin which causes cell death o Need to wait for cytopathic effect to happen; takes long time (24-48 hours) · Enzyme immunoassay (EIA) – detects toxins secreted by bacteria o Takes 3 hours to perform best test § C-diff antigen detection · Non-specific; rapid tests (< 1 hour) § Molecular tests · Tests for the genes encoding toxin – specific for toxin-producing C-diff · Rapid test (within 3 hours) · Too sensitive, can detect toxin producing C-diff at numbers way below what is needed to cause clinical symptoms o Helicobacter pylori § Endoscopic biopsy gram stain or culture § Non-invasive tests · Antibody detection · Urea breath test detects radioactive CO2 in patient’s breath o Rotavirus § Rapid testing · Immunoassay – latex agglutination, EIA, DFA, ELISA · Molecular methods such as RT-PCR Describe characteristic laboratory finings associated with bacterial meningitis. o Increased CSF protein (>100) o Decreased CSF glucose ( decreased cerebral perfusion, brain cell death, or herniation o Symptoms specific to infants/children: irritability, restlessness, poor feeding Do you have to wait for microbiology results to start antibiotic treatment if the patient has clinical presentation of meningitis? o Do not wait, start right away; empirical abx Define: meningitis, encephalitis and meningoencephalitis. o Meningitis –infection within the subarachnoid space § Present with non-focal neural signs o Encephalitis –inflammation limited to brain substance § Present with focal neural signs o Meningoencephalitis –infection of subarachnoid space and brain substance Describe tests used to diagnose Syphilis. o Serology (identify antibody) § Screening tests: detect antibodies against non-treponemal antigens (antibodies to substances released by cells that are damaged by treponema) · Ex: RPR (rapid plasma regain), VDRL (venereal disease research laboratory) § Confirmatory tests: detect antibodies against treponemal antigens (antibodies against treponema) · Ex: FTA-ABS, TP-PA, MHA-TP Differentiate non-treponemal (RPR, VDRL) and treponemal tests (FTA-ABS, TP-PA). Which tests are used as confirmatory tests? o Non-treponemal § Antibodies to substances released by cells that are damaged by treponema § Ex: RPR, VRDL o Treponemal § Antibodies against treponema § Ex: FTA-ABS, TP-PA, MHA-TP (used as confirmatory tests) What is the preferred collection method for urine tests? o Midstream “clean catch” collection How many colony counts of pure culture can be considered positive? If it is considered positive culture, what are the next things to do? o 75,000 or higher pure culture colony count to be considered positive o Next step would be to send sample for ID and susceptibility on all types of specimens Section Review of UA Describe the three forces that determine glomerular filtration. o Hydrostatic pressure – determined by BP o Oncotic pressure – determined by protein concentration o Shield of negativity – basement membrane’s negative charge that repels protein that also has negative charge Define renal threshold of glucose, midstream clean catch. o Renal threshold of glucose –concentration of glucose in the plasma above which it will exceed transport maximum (TM) and be passed in the urine = 160-180 mg/dL - Positive urine glucose = hyperglycemia or tubular damage o Midstream clean-catch –best type of collection for routine testing/baterial cultures; cleanse before voiding and collect the midstream portion of urine Describe the two hormones regulating kidney function. o Aldosterone - in distal convoluted tubule § Increases Na and H2O reabsorption § Increases K excretion o ADH (Antidiuretic Hormone- aka Vasopressin) § Regulates/affects reabsorption of water at collection duct · Controls permeability of collection duct walls to water § Synthesized in hypothalamus; determined by body state of hydration · Increased hydration = decreased ADH = increased urine volume · Decreased hydration = increased ADH = decreased urine volume Describe differential diagnosis of hematuria and hemoglobinuria o Hematuria § Blood in urine (red and cloudy) § RBCs intact and can be seen under microscope § Related to disorders of renal/GU origin · Pathologic: renal calculi, glomerular disease, tumors, trauma, pyelonephritis, excessive anticoagulant therapy · Non-pathologic: strenuous exercise, menstruation o Hemoglobinuria: when free hbg exceeds haptoglobin capacity § Blood in urine from lysis of RBC (red and clear) that come from dilute, alkaline urine in the urinary tract § RBCs not intact and can’t be seen under microscope - Mild Hemolysi= doesnt produce hemoglobinuria - Moderate/severe hemolysis = hemoglobinuria - Intravascular hemolysis = CKD - transfusion reactions, hemolytic anemia, severe burns, brown recluse spider bites, infections List conditions with proteinuria (albumin filtration/reabsorption imbalance; assoiciated with early renal disease) o In Glomerular diseases (more albumin filtered into urine): - Glomerulonephritis, Nephrotic syndrome o In tubular proteinuria: tubular reabsorbtion impaired o In UTI and if blood in urine What can cause positive glucose in urine? - Positive glucose = plasma concentration > renal threshold or if tubular reabsorption is impaired (Fanconi syndrome) - Caused by: DM, Pancreatitis, Thyroid issues (hyperthyroidism), Cushing syndrome Interpret the following results: glucose + and clinitest-; glucose – and clinitest + - clinitest = detects reducing agents (glucose) in urine o Glucose + and clinitest – § Glucose dipstick is more sensitive, can detect low glucose conc. (75- 125 mg/dL) o Glucose – and clinitest + § Other reducing sugars present · Lactosuria: found in UA of nursing mothers · Pentosuria: from eating certain fruit · Frutosuria: eating fruit or taking fructose · Galactosuria: most important; represents inborn error of metabolism = galactosemia -lacking enzyme that breaks down galactose can result in failure to thrive, mental retardation, or death; in urine of newborns The chemical test of urine shows positive on RBCs, but microscopic exam didn’t find RBCs. How can you explain it? o Hemoglobinuria – RBCs present in urine test, but they are not intact and can’t be seen microscopically What kind of bilirubin can urinalysis detect? What diseases can cause conjugated bilirubinemia? o UA can only detect conjugated bilirubin (processed by liver) o Conjugated bilirubinemia can be caused by § Viral hepatitis § Cirrhosis § Bile duct obstruction § Pancreatic cancer What does the positive result indicate? - Positive = jaundice > liver disease, hemolytic disorder, bile duct obstruction - Intestinal bacteria > reduced conjugated bilirubin >urobilinogen - + bilirubin/ - urobilinogen = bile duct obstruction - + bilrubin/+ urobillinogen = liver damage - - bilirubin/ + urobilinogen = hemolytic disease - itrate > bacteriuria (bacteria in urine = UTI) N - Leukocyte esterase > leukocyturia (WBCs in urine = UTI or inflammation) Identify the following elements that may be found during microscopic examination of urine and clinical significance - Normal urine = cells (RBC, WBC, epithelial), crystals, hyaline sasts o Cells: WBC, RBC, epithelial cells, oval fat body, bacteria and yeast § RBCs · Increased presence in urine is associated with glomerular membrane damage or vascular injury · Number of cells present is indicative of damage · Macroscopic hematuria o Urine is cloudy and red/brown o Associated with advanced glomerular damage from urinary trauma, acute infection, inflammation, or coagulation disorders · Microscopic hematuria o Associated with glomerular disorders, malignancy, renal calculi § WBCs · High number of WBCs = pyuria · Increased neutrophils = bacterial infection · Increased eosinophils = drug-induced interstitial nephritis · Increased mononuclear cells = early stages of renal transplant rejection § Bacteria · Indicates UTI or specimen contamination o WBCs should also be present to confirm infection § Yeast · Most common species = Candida albicans o Seen in diabetics, immunocompromised, vaginal yeast infections § For yeast infection diagnosis, WBCs must also be present o Casts: RBC, WBC, fatty, waxy, broad cast (all casts are unique to the kidney) § RBC casts · =Hematuriawhich occurs from glomerular diseases § WBC casts · = UPPERUTI or non-infectious inflammation · = infection/inflammation is in the kidney · associated with pyelonephritis = WBC casts + bacteria - epithelial cast associated too (= tubular cell damage) · Cystitis = no WBC casts + bacteria · Acute interstitial nephritis (non infectious) = WBC casts + no bacteria §Waxy casts · Seen during extreme urine stasis and indicate renal failure (mostly chronic) - Looks dark pink with supravital stain § Broad casts/ renal failure casts - Caused by extreme urine stasis - = tubular wall destruction from widening of tubules - Look BROAD o Crystals: common in urine but rare for clinical significance - Can indicate liver disease, inborn error, renal damage, hyperuricemia UA, calcium oxalate, triple phosphate, cystine, cholesterol, bilirubin, leucine, tyrosine, sulfonamide § Uric acid crystals- Indicate chemotherapy for leukemia and gout § Calcium oxalate- Indicate renal calculi § Triple phosphate– indicates UTI (urea-splitting bacteria) § Cystine– indicates cystinuria (metabolic defect that prevents ability of reabsorbing cystine by PCT renal calculi) § Cholesterol– indicatesnephrotic syndromeor lipiduria specimens; has notched corners on structure - Seen with fatty cast and oval fat bodies § Bilirubin · Composed of conjugated bilirubin · Correlates positive bilirubin on reagent strip § Sulfonamide– indicates treatment of UTI with sulfonamide drugs · Can cause tubular damage if prolonged exposure Section Review of Body Fluids Where is CSF produced? o In the choroid plexuses of the subarachnoid space What is Xanthrochromic CSF? o Orange or yellow CSF which indicates presence of RBC degradation products old bleeding If you have bloody CSF, how can you determine if it is from traumatic collection or SAH? o Traumatic collection – 1st tube has the most blood and 4th has the least o SAH – all 4 tubes have blood evenly distributed Define albumin index and IgG index. o Albumin index– CSF albumin (mg/dL) / serum albumin (g/dL) § Value < 9 indicates intact BBB § Value increases with increased damage to BBB · BBB damage leads to cerebral edema o IgG index– CSF IgG (mg/dL) / serum IgG (g/dL) § Value > 0.7 indicates internal production of IgG suggests CNS disease Name the common laboratory tests used to evaluate the following body fluids o Cerebrospinal fluid– CSF glucose and lactate tests o Serous fluids– thoracentesis, pericardiocentesis, paracentesis Describe which tests are sent for tube 1-4 during a lumber puncture. o Lumbar puncture/spinal tap Differentiate different causes of a “red CSF” sample. o If 1st tube has most blood and 4th has least traumatic collection o If all 4 tubes have equal amount of blood SAH Differentiate bacterial, viral, tuberculous and fungal meningitis o Bacterial meningitis § Elevated WBC (neutrophil) count § Marked increased protein + decreased glucose § Lactate > 35 mg/dL § Positive gram stain and cultures o Viral meningitis § Elevated WBC (lymphocyte) count § Moderate protein elevation + normal glucose § Lactate < 25 mg/dL § Negative gram stain and culture o Tuberculous meningitis § Elevated WBC (lymphocyte + monocyte) count § Moderate to marked increased protein + decreased glucose § Lactate 25-35 mg/dL § Acid-fast staining positive o Fungal meningitis § Elevated WBC (lymphocyte + monocyte) count § Moderate to marked protein elevation + normal to decreased glucose § Lactate 25-35 mg/dL § Positive India Ink test with positive immunologic test for Cryptococcus neoformans Describe 3 factors controlling formation of serous fluid. o Hydrostatic pressure – drives fluid to enter between the membranes o Colloidal (oncotic) pressure – draws seroud fluid back into blood/lymphatic vessels o Permeability of blood vessels – more fluid enters between membranes with increased permeability Name the procedures to obtain effusion from different body cavities. o Thoracentesis (pleural cavity), pericardiocentesis (heart cavity), paracentesis (peritoneal cavity) Differentiate transudate from exudate based on causes, physical examination, microscopic examination and chemical examination of serous fluid. o Transudate § Results from filtration of blood serum across a physically intact vascular wall due to systemic disease (CHF or low protein) § Causes · Increased hydrostatic pressure · Decreased oncotic pressure § Clear, pale yellow, no clots § Microscopic exam · < 1000 cells (pleural), < 300 cells (peritoneal) · Differential: mononuclear cells § Chemical exam · Glucose = serum level · TP: < 50% of serum · LDH: < 60% of serum o Exudate § Active accumulation of fluid within body cavities in association with vascular wall damage caused by inflammation, malignancies, infections § Causes · Increased capillary permeability § Cloudy, variable color, clots § Microscopic exam · > 1000 cells (pleural), > 500 cells (peritoneal) · Differential: segs and mononuclear § Chemical exam · Glucose < or equal to serum level · TP: > 50% of serum · LDH: > 60% of serum Hematology Section Review o Compare plasma and serum. o Plasma § Liquid part of the blood obtained after centrifuging anticoagulated blood § Contains proteins, electrolytes, hormones, waste o Serum § Liquid part found after blood is clotted obtained by centrifuging coagulated blood § Components are like plasma but without coagulation factors o Define “Buffy coat” and hematocrit. o Buffy coat– middle layer between plasma and RBCs; contains WBCs and platelets o Hematocrit– ratio of the volume of blood cells to the total volume of blood § HCT = RBC + buffy coat / total volume o List cellular components of blood o RBCs, WBCs, and platelets o List major lineages of hematopoiesis in the BM o Lymphoid progenitor cells – give rise to T and B lymphocytes o Common myeloid progenitor cells § Myeloid progenitor cells – give rise to granulocytes (neutrophils, eosinophils, basophils) and monocytes § Erythroid progenitor cells – give rise to RBCs § Megakaryocyte progenitor cells – give rise to platelets o Describe how RBC production is regulated. o Regulated by the release of EPO from the kidneys § EPO is stimulated by tissue hypoxia (decreased blood volume, altitude, anemia, etc) o Explain why kidney failure is usually associated with anemia. o Kidney failure causes decreased EPO production which leads to anemia o Define reticulocyte. List clinical significance of increased or decreased reticulocyte count. o Reticulocyte – immature RBCs that have no nucleus but have RNA (last stage of immaturity); only present in blood for 24 hours § Increased reticulocytes BM is hyperactive in making RBCs § Decreased reticulocytes BM is hypoactive in making RBCs o Describe major changes expected in CBC of a patient with severe bacterial infection. o Increase in neutrophils (60-75% differential); specifically band neutrophil (bandemia) o List major function(s) of each blood cells including RBC, neutrophils, lymphocytes and platelets. o RBCs:transport oxygen o WBCs:inflammation/immunity § Neutrophils:fight bacterial infections § Lymphocytes:adaptive immunity including antibody production and cytotoxic killing § Monocytes:phagocytosis (largest cell in circulating blood) § Eosinophils:fight parasites § Basophils:release histamine during anaphylactic reactions o Platelets:active in plasma hemostasis and blood coagulation o Compare life span of RBC and platelet in peripheral blood. o RBC = 120 days o Platelets = 8-10 days o List major components of CBC. o Cell count (WBC, RBC, platelets) o Hematocrit + hemoglobin concentration o RBC indices (MCV, MCH, MCHC, RDW) o WBC differential o Define: MCV, MCH. MCHC, RDW, WBC Diff. o MCV– volume (size) of RBC § High MCV = macrocytosis § Low MCV = microcytosis o MCH/MCHC– how much hemoglobin the RBC has o RDW– variation of RBC sizes o WBC diff– percentage of different WBCs; evaluated by flow cytometry efine anemia. Describe our body’s adaptions to anemia. Summarize causes of anemia and lab findings (including the morphology of RBCs). Describe D algorithm to reach a diagnosis of IDA. o Anemia: decrease in competence of blood to carry oxygen to tissue (functionally) + impaired RBC production, blood loss, or accelerated RBC destruction (physiologically) § < 13 gm/dL HgB in males § < 12 gm/dL HgB in females o Body compensates by § Increasing RBC production in BM by releasing more EPO from kidneys § Increasing cardiac output § Increasing uptake of oxygen in the tissue o Causes § Decreased RBC/hemoglobin production · BM destruction via chemicals, toxins, radiation · Iron deficiency · Megaloblastic anemia – lack of vitamin B12 or folate · Chronic inflammation § Blood loss (chronic/acute) § Hemolysis (RBC destruction) o Lab findings § MCV/MCHC normal normocytic normochromic · From acute blood loss, aplastic anemia § MCV increased, MCHC normal macrocytic normochromic · From megaloblastic anemia § MCV decreased, MCHC normal microcytic normochromic · From chronic inflammation § MCV/MCHC decreased microcytic hyperchromic · From IDA and high RDW o What is the most sensitive test for iron deficiency? o Serum iron study § Serum iron = decreased § Ferritin values = decreased (earliest indicator of IDA) o If a patient with IDA receives iron therapy, and the physician wants to know if therapy is effective as soon as possible, what is the preferred test to order? o Reticulocyte count o Summarize changes on CBC and WBC morphology on a blood smear when a patient has bacterial infection o Granulocytosis o Left shift o Increased immature neutrophils (bandemia) o Morphological changes § Toxic granulation § Vacuolization § Dohle body o What are the clinical indications of lymphocytosis and eosinophilia? o Increased lymphocytes = lymphocytosis § Consistent with viral infection o Increased eosinophils = eosinophilia § Consistent with parasitic infection Hemostasis Section Review o What coagulation factors are inhibited by coumadin? What is the mechanism? o Vitamin K-dependent factors (II, VII, IX, X) o Mechanism: antagonize vitamin K to inhibit coagulation bleeding o Compare initiation of intrinsic and extrinsic pathway. o Initiation of intrinsic pathway § Damage of endothelium but no penetrating injury § Exposes negatively charged subendothelial tissue activation of XII § Factors involved: XII, XI, IX, VIII, Ca, platelets § Test: APTT § Result of pathway: activation of factor X o Initiation of extrinsic pathway § Penetrating injury to blood vessel § Tissue factor/factor III is initiator § Test: PT § Result of pathway: activation of factor X o What factor deficiencies can result in prolonged APTT or PT respectively? o Prolonged APTT – intrinsic and common pathway deficiencies (Factors XII, XI, IX, VIII, X, II, I) o Prolonged PT – extrinsic and common pathway deficiencies (Factors VII, X, II, I) o Which pathway is deficient if: o APTT normal, PT prolonged § Extrinsic pathway (Factor VII deficiency) o PT normal APTT prolonged § Factors XIII, IX, XI, XII deficiencies (intrinsic pathway) o Both prolonged § Factors I, II, V, X deficiencies (common pathway) § Multiple factor deficiency in intrinsic and extrinsic pathways o What is the value of normal INR? o < 1.1 o What is the ideal range of INR if a patient with A-fib is taking coumadin? What if the patient has a mechanical heart valve? o A-Fib: 2.0 – 3.0 o Heart valve: 2.5 – 3.5 o How is d-dimer formed? Factor XIII initiates cross-linking between fibrin monomers leading to firm mesh of fibrin with blood cells trapped inside firm clot o is formed § Covalent bonds are formed between D domains of fibrin molecules o What does a positive d-dimer test indicate? o Clot o What does a prolonged TT indicate (3 possible causes)? o Fibrinogen disorders o Heparin administration o Increased fibrin degradation products o Compare heparin with coumadin. o Heparin § Only SQ or IV (inpatient) § Inhibits common pathway § Monitor with APTT test o Coumadin (Warfarin) § Oral (outpatient) § Inhibits II, VII, IX, X § Inactive in vitro anticoagulant, only therapeutic in vivo oral form § Monitor with PT and INR tests o What is indicated by the following lab profiles: 1. FDP+ and d-dimer+ a. There is a clot formed (DIC) 2. FDP+ and d-dimer- a. No clot formed, plasmin is cleaving fibrinogen (secondary fibrinolysis) i. Plasmin is activated without clot formation o Why urokinase and streptokinase can be used to treat stroke and myocardial infarction? o They can dissolve the clot by working like tPA o Plasminogen + fibrin + tissue plasminogen activator (tPA) = plasmin o Plasmin breaks down fibrin o Describe the causes, pathophysiology and lab profiles of DIC o Causes: sepsis, tumors, immune disorders, snake/insect bites, drugs o Pathological activation of coagulation pathways resulting in § Deposition of large amount of fibrin and platelet aggregates throughout microcirculation § Consumption of coagulation factors § Activation of fibrinolysis system § 2 and 3 lead to coagulopathy (perfused bleeding) o Lab findings § Prolonged APTT, PT and TT § Decreased fibrinogen + platelet count § Increased FDP and D-dimer o List treatment plans of DIC o Treat underlying disease o Treat hyperactive coagulation § Heparin § Recombinant protein C (anti-coagulation factor) § Stop activation of coagulation cascade to stop stimulation of fibrinolysis system o Replace consumed coagulation factors § Plasma § Platelets o Treat hyperactive fibrinolysis system to stop production of FDPs § Antifibrolytic agents o Describe pathophysiology and lab findings of hemophilia A and products that can be used to treat it. o Hemophilia A: inherited deficiency of dysfunction of VIII o Lab findings § Prolonged APTT § Normal PT and TT o Treatment § Cryoprecipitate: rich in factor VIII and high risk of infection; induces anti-VIII antibody § Recombinant factor VIII concentrate: no risk of infection; induces anti-VIII antibody § Hemlibra (emicizumab): lab produced humanized antibody mimicking factor VIII; doesn’t induce anti-VIII antibody § Desmopressin: releases VWF from endothelium and promotes stability of circulating factor VIII § Fibrin sealants § Supporting therapy o What are the clinical consequences of VWF deficiency? o Increased breakdown of factor VIII factor VIII deficiency o Impaired platelet function (like taking aspirin) o Lab findings like hemophilia A § Prolonged APTT, normal PT and TT § Decreased factor VIII o Lab findings unique – increased bleeding time o What does prolonged bleeding time indicate? o VWF deficiency Blood Bank Review Questions What is the specific therapeutic purpose to use each type of blood product? o Packed RBCs (PRBCs):increase O2 carrying capacity o Plasma:restores volume and hemostasis (has coagulation factors) o Platelets:hemostasis o Granulocytes:increase neutrophil count to prevent severe infection o Cryoprecipitate:treats severe fibrinogen deficiency, VWD, Hemophilia A (especially in DIC patients, liver failure, massive transfusion, rare congenital fibrinogen deficiency) One packed RBC is expected to increase Hgb by? o 1 g/dL Hgb and 3% Hct What are the indications of using washed RBCs? o Reduce anaphylactic reactions in patients with IgA deficiency o Remove excess K (prevent post-transfusion hyperkalemia) in pediatric patients Define massive transfusion. o When the patient has at least 10 units of blood product or equivalent to patient’s total blood volume has been exchanged within a 24-hour range o For patients who are actively bleeding When an Rh- patient with anti-D antibody in serum is receiving massive transfusion due to active bleeding, how do you manage? o Provide Rh- PRBCs o If active bleeding is occurring, incompatible products may not even have enough time to cause a transfusion reaction What is the specific bleeding pattern for platelet disorders? o Petechiae, ecchymosis, purpura, mucosal bleeding How is platelet product stored? o Only in room temperature; never frozen/refrigerated Describe the pathophysiology, clinical presentation and treatment strategy of TTP. o Pathophysiology § Excess activation of platelets § Deposits of platelets aggregate in small vessels (especially renal/cerebral vessels) believed to be caused by vascular wall dysfunction, leading to abnormal platelet activation o Clinical presentation § Thrombocytopenia, microangiopathic hemolytic anemia (leads to schistocytes – RBCs are physically destroyed), neural/renal damage (due to platelet plugs) o Treatment § Don’t give platelets – treat cause of platelet activation Explain the purpose of the following tests: o Type and hold– only perform ABO/Rh type, no crossmatch o Type and screen– perform ABO/Rh and perform Ab screen (IAT), no crossmatch unless blood products needed o Type and crossmatch– perform ABO/Rh, Ab screen, and crossmatch; blood is ready for transfusion o IAT– determines if there are antibodies in recipient’s blood against certain RBC antigens (AKA “antibody screen”) o DAT– test for antibodies that are bound directly on RBCs in vivo (AKA “crossmatch”) · List two diseases that can be treated with immunoglobulin injection. o ITP, myasthenia gravis, congenital hypogammaglobulinemia escribe the ABO blood groups and ABO natural occurring antibodies. Compare ABO blood type phenotype and genotype. Describe ABO inheritance D pattern. Select the compatible blood groups based on ABO/Rh for packed RBC, FFP, platelets for patients with different blood types. In what patient population, Rh negative patient should only receive Rh negative pRBCs? o Females of childbearing age Compare regular transfusion with emergency transfusions and massive transfusions. o Emergency transfusion § Only typing is performed or use O-/O+ if not enough time to blood type § No time for antibody screen/crossmatch § Unit must have tie bag/label indicating compatibility test wasn’t performed § Physician signs release and accepts responsibility for using incompletely tested products § Compatibility testing to be completed ASAP o Massive transfusion § Patient has at least 10 units of blood products or equivalent to patient’s total body volume has been exchanged within 24 hours § Patient is actively bleeding § Patient has significant antibodies all units should be antigen negative Describe the D antigen. o Determines if a person is Rh- or Rh+ o Responsible for hemolytic reactions in newborns when mom is Rh- and baby is Rh+ Who are candidates for RhIG (RhoGAM)? o Rh- mothers with unknown fetuses at 28 weeks and 72 hours after birth if baby is Rh+ o Rh- male patients younger than 16-years old who are given Rh+ products How RhIG (RhoGAM) work? o Destroys fetal RBCs in mother’s circulation before antibody synthesis can occur o Contraindicative to IgA deficient patients Explain pretransfusion testing and identify the proper ordering schemes. o Type and hold § Draw blood sample, ABO/Rh type § No antibody screen/crossmatch o Type and screen § Draw blood sample, ABO/Rh type, antibody screen § No crossmatch § If transfusion needed, must find donor RBC and crossmatch before giving o Type and crossmatch § Draw blood sample, ABO/Rh type, antibody screen, and crossmatch with donor blood Explain the principles and uses of the direct and indirect antiglobulin tests. o DAT § Checks for antibody-coated RBCs § Detect in vivo sensation of RBCs with IgG/complement/both § Positive DAT there are antibodies or C3 bound to RBC · Hemolytic disease of the newborn (HDN) · Hemolytic transfusion reaction (HTR) · Autoimmune and drug-induced hemolytic anemia (AIHA) o IAT § Determines if there are antibodies in recipient blood against RBC antigen of potential donor RBCs If the antibodies can fix C3 on RBCs, is this a good sign or bad sign? o Bad sign; C3 will destroy RBCs directly which will cause severe intravascular hemolysis In intrauterine transfusion, what is used to perform compatibility test (crossmatch) of the pRBCs? What are the requirements of the RBC product? o Crossmatch performed by: cordocentesis, unit blood type compatible to baby o Requirements: < 7 days old, sickle cell negative, CMV negative, O = best Describe pathophysiology and principle of management of HDN. o Erythroblastosis fetalis § Hemolytic anemia found in babies as a result of maternal antibodies binding to baby’s RBCs causing RBC destruction/jaundice § Enlarged spleen/liver § Increased retic value, nRBCs, indirect bilirubin o Hydrops fetalis § Increased hematopoiesis can’t keep up with loss of RBCs § Severe anemia leads to development of cardiac failure, generalized edema, effusions, ascites o Kernicterus § Build-up of unconjugated bilirubin in brain § Can cause death or severe mental retardation o Management § Prevent production of anti-D antibody by mom = key § RhIG (RhoGAM) · Anti-D antibody · Given during and after first pregnancy with Rh+ baby · Destroys fetal Rh+ RBCs in mom’s circulation before they induce antibody production against D · No anti-D antibody produced second baby safe Describe test used to detect fetomaternal hemorrhage. o Kleihauer-Berke (KB) staining § Detects fetal RBCs in mom’s circulation § Severity of FMH can be quantified by % § Dose of RhoGAM based on % of fetal RBCs Who are the candidates for Rh Immune Globulin injection? o Mothers o Females of childbearing age that are D negative o Males under 16 years that are Rh- Who will develop anaphylactic reaction after IVIG infusion? o Patients who are IgA deficient Describe the plans to monitor pregnancy if the mom is Rh negative, fetus is not first pregnancy and there are anti-D antibodies in mom’s serum. Amniotic fluid analysis to elevate bilirubin levels o o Color doppler middle cerebral artery peak to look for hemodynamic changes from anemia o Cordocentesis – blood drawn out of umbilical cord and tested for H&H, bilirubin, blood type, DAT, and antigen phenotype If there are evidence that the fetus is developing hemolysis and anemia, what are the treatment plans? o IVIG § Protects fetal RBCs from destruction § Competes against mother’s antibodies for Fc receptor on macrophages in infant spleen o Intrauterine transfusion § Treats severe anemia o Phototherapy § Blue light changes unconjugated bilirubin to lipophilic isomers that are less toxic to the brain
