Test 8/13 Questions
A 67 y/o man was seen in the ER complaining of cough, fever, and piercing right posterior chest pain. X-ray of the chest revealed consolidation of the right middle lobe of the lung. A sputum culture grew the bacteria species (mucoid, alpha hemolytic colonies on BAP). The gram stain was gram positive diplococci. What is the most likely cause of the pneumonia
- Streptococcus pneumoniae
A patient was admitted to the hospital recently with an obvious infection. A sputum specimen was submitted and the microbiologist inoculated it to sheep blood agar. Based on the colony morphology (large, mucoid) and the alpha hemolysis the mist likely identification is
- Streptococcus pneumoniae
What test is not used to quantify albumin?
- Sulfosalicylic acid precipitation - This is a semiquantitative method and not a quantitative method. It is not specific for albumin
When is testing for weak-D optional (not required)
- Testing for weak D on potential transfusion recipient samples - The AABB Standards requires testing for a weak D on donor cells that do not directly agglutinate with anti-D reagents. Weak D testing is also performed on prenatal evaluations and Rh immune globulin workups
The term affinity refers to
- The strength of attraction between a single antigenic determinant and a corresponding antigen binding site
Avidity is best described as
- The strength with which multivalent antigens and antibodies bind - The term avidity refers to the total strength of the attraction between an antibody and a multivalent antigen
What is a clinical finding that characterizes post-transfusion purpura (PTP)?
- Thrombocytopenia - Bleeding also, Platelet counts in PTP are usually less than 10,000uL
Pancytopenia is indicated in
- Transfusion associated graft vs. host disease (TA-GVHD) - Delayed transfusion reaction
Lipemia in a fasting serum sample is most likely caused by an increase in serum levels of
- Triglycerides - Lipemia is generally caused by an increase in VLDL which are primarily composed of triglycerides
Eosinophil
- Typically have a bilobed nucleus and cytoplasm filled with many large granules that appear bright orange-red in a Wright stain
Lymphocyte
- Typically have condensed chromatin and scant blue cytoplasm - Small numbers can be associated with viral infections, meningitis, and others
Acetest (confirmatory test for ketones) can be used to test for ketones in
- Urine, Serum, Whole blood
Enterococcus faecium is often resistant to this antibiotic
- Vancomycin
A reaction is in _____ kinetics when the reaction rate depends only on enzyme concentration
- Zero order - In this case the substrate concentration is high and the only limiting factor to the reaction and the formation of the enzyme-substrate complex is the enzyme concentration. Once all of the enzyme is bound to the substrate, no further complex concentration can occur and the maximum velocity of the reaction has been reached
If a patient has anti-c what donor unit should be used
- r'r^y - This blood type contains C (capital C), the patient has an antibody to little c, so as long as the type is homozygous for big C, it is acceptable
General Hospital is considering the addition of a new chemistry panel containing 12 tests. The lab is asked to calculate the total cost of quality control per new chemistry test panel. QC must be performed 3 times per day (every 8 hours). The labor cost per QC test for this panel is $2.63. A month's worth of QC reagent costs $354. What is the total QC cost per new chemistry test panel if 76,000 of these new panels are performed each year?
- $0.09 - If QC is run 3 times per day, a total of 1095 QC runs are performed each year. The direct labor cost of $2.63 multiplied by 1095 QC control runs equals $2879.85 per year in QC direct labor. the hospital pays $354 per month on QC consumables which equals $4248 per year. The total QC costs in a year are equal to $2879.85+ $4248.00= $7127.85. If 76,000 new chemistry test panels are performed each year, the total quality control cost per new chemistry test panel will be $0.09
A new chemistry analyzer costs $108,000 and will be expected to run specimens for 6 yrs in the lab. The maintenance costs are approximately $1,000 per year on this analyzer. The hospital lab expects to perform approximately 1200 tests per month on this analyzer. what is the equipment cost for each test performed during the 6 year period?
- $1.32 - The operating cost of the instrument over 6 yrs= $114,000 (analyzer cost+ maintenance fees). Amount of tests run in 6 yrs= 1200 tests*12 months*6 years= 86,400. SO $114,000/86,400 tests= $1.32 (equipment cost per test)
FFP that has been thawed at 30-37C and maintained at 1-6C must be transfused within ___ hours after it has been thawed
- 24 hours - After the initial 24 hours have elapsed, thawed FFP and PF24 nay be re-labeled as "Thawed Plasma" and stored at 1-6C for up to 4 more days (not to exceed 5 days)- contains stable coagulation factors but reduced amounts of factors V, VII, VIII, and X
A 56 y/o woman with a history of high blood pressure and cardiovascular disease is evaluated by her physician due to her recent loss of appetite. the doctor reviews the following test results: - Plasma creatinine= 2.4 mg/dL - Urine creatinine= 65 mg/dL - Urine volume (24 hours)= 1400mL What is the estimated glomerular filtration rate for this patient?
- 26.32 mL/min - General GFR calculation: (Urine creatinine / Plasma creatinine)*(volume/minute)= GFR mL/min - 24 hours needs to be converted to minutes= 1440 SO: (65/2.4)*(1400/1440)= 26.32 mL/min
Approximately how many out of 1,000,000 Caucasians will have the following phenotype? Group O, K+, Jk(a+)
- 30,000 - Group O blood types comprise about 44% of the Caucasian population. Out of 1,000,000 people this leaves us with about 440,000 people. - Approximately 9% of Caucasians have the K antigen, leaving us with 39,600 individuals who are group O and K positive. Approximately 77% of Caucasians are positive for the Jk^a antigen. 77% of 39,600 individuals leaves us with 30,492 or approximately 30,000 individuals that are group O, K positive, and Jk(a+)
A serum sample is recieved in the clinical chemistry department of the lab. The first time the sample is assayed, the result is 600 mg/dL. to verify this result the tech makes 2 mL of a 1:2 dilution of the original sample. If only 1 mL of this sample is analyzed, what would the result be? Assume the original 600 mg/dL value was accurate and that the instrument did not automatically perform a dilution calculation
- 300 mg/dL - Dilution factor is 2, so divide 600 by 2
FFP prepared from whole blood must be frozen within ___ hours of collection
- 8 hours
PF24 must be frozen within ____ hours of collection
- 8-24 hours
Burr Cell (Echinocyte)
- Spiculated RBCs with short, equally spaced projections over the entire surface
You lab has 17,264 hours of total paid labor time. Of this amount 1458 hours are nonproductive hours. If your employees work 40 hour work weeks each year, what is the total number of FTEs (full time equivilents) needed to run the lab
- 8.3 - Divide the number of nonproductive and productive hours by 2080 (which is the total number of hours worked per year in a 40 hour workweek) SO 17,264 hours paid for labor/ 2080 hours per person= 8.3 FTEs
A CSF glucose value is 62 mg/dL. What would you estimate the serum glucose?
- 93 mg/dL -CSF glucose is roughly estimated to be about 2/3 of the serum glucose level in md/dL. Therefore: 62mg/dL= (2/3) x serum glucose serum glucose= 62 x(3/2)= 93 mg/dL
A unit of RBCs has been issued and returned to the blood bank. Under what conditions can it be returned to inventory and is acceptable to use?
- A unit of RBCs that was not transfused but stored in a temperature-controlled remote refrigerator in the operating room for 2 hours - Need to be stored in a temperature controlled remote refrigerator - If kept at room temperature for greater than 30 min- not acceptable, discard - Need to be kept between 1-6C in order to be acceptable
What genotypes are possible for a mating of an AB mother and an AB father
- AB, AA, BB
The direct antiglobulin test (DAT) is most unreliable when diagnosing hemolytic disease of the fetus and newborn due to which blood group system
- ABO - In ABO HDFN the DAT result is neither strongly nor consistently positive
Characteristics of yeast cells on a Gram stain as to size and staining
- About the same size as RBCs - Will stain purplish-blue - Distinguished from RBCs by observing budding - Yeasts are larger than bacteria on gram stain
Acanthocyte
- Acanthocytes have blunt spicules that are irregularly distributed around the cell
Given the following results, what is the immune status of the patient? - HbsAg: positive - HbeAg: positive - Anti-HBc IgM: positive - Anti-HBs: negative
- Acute infection - HbsAg is positive in acute and chronic HepB since the antigen is found on the actual surface of the virus - HbeAg is present in the blood when HepB virus is replicating indicating active infection - Anti-Hbc IgM is present due to the immune response to the presence of the hepatitis core antigen and indicates an acute infection - Anti-HBs is generally interpreted as indicating recovery and immunity from HepB virus infection
Pseudomonas aeruginosa is often used as a bacterial species for the QC of Kligler iron agar. What is the expected reaction?
- Alkaline slant/ Alkaline deep = P. aeruginosa is a non-fermenter so it cannot produce acid from glucose in a fermentative medium. Therefore, there is no change in the KIA tube and both the slant and the deep remain alkaline (red).
Salmonella typhimurium charachteristics on Kligler iron agar
- Alkaline slant/ black deep (H2S positive)
Pheochromocytoma is
- An adrenal or extraadrenal neoplasm that secretes catecholamines. - Patients with this often exhibit persistent and paroxysmal hypertension. Urinary free catecholamines, and vanillylmandelic acid are also elevated
What antibody is best described as common autoantibody that can be found in virtually all sera
- Anti-I
What is the most common antibody seen in the blood bank
- Anti-K - Usually made through antigen exposure through pregnancy and transfusion and can persist for years
Bordet- Gengou potato infusion agar has been the time-honored medium for the recovery of what organism
- Bordatella pertussis - Agar contains charcoal, blood, potato (starch) to absorb toxin substances in the agar
While serum elevations are not generally seen in early stages, what tumor markers are elevated in more advanced stages of breast cancer
- CA 15-3 and CA 549 - CA 15-3 is also known as CA-breast as it is specifically associated with breast cancer. - CA549 is a glycoprotein found in the serum of breast cancer patients
Which of the following CD markers is not present on a normal mature T cell?
- CD 20 (expressed by B cells) Ones that are: * CD7 * CD3 * CD5 * CD2
In HbSS blood, an increased amount of what surface antigens on young sickle cells (reticulocytes) may allow platelets to form a bridge between the reticulocytes and endothelial cells, ultimately leading to vaso- occlusion
- CD36
A decrease in which of the following in an AIDS patient are associated with increased susceptibility to infection
- CD4+ cells
High ferritin levels have been noted in
- Cases of iron overload - Delayed transfusion reaction
hsCRP is a marker of ______ _____ and measured to predict the risk of _____ _____
- Chronic inflammation - Cardiovascular disease - Low levels= <1 mg/L - Moderate levels= 1-3 mg/L - High levels= > 3 mg/L
CSF lymphocytosis is associated with
- Chronis tuberculous meningitis - Chronic fungal meningitis - Viral meningitis
Which amendment or act describes the quality standards that all laboratories must meet in order to ensure testing accuracy, reliability, and timeliness no matter where a patient sample is tested
- Clinical Laboratory Improvement Amendments
What fungal infections are endemic in the southwestern US desert region
- Coccidioidomycosis
An increase in CEA levels is most closely associated with what organ
- Colon - Carcinoembryonis antigen (CEA) is a widely used tumor marker for gastrointestinal cancer - Useful for following response to therapy and detecting recurrences
Capnocytophaga canimorsus characteristics
- Colonies are slow growing - Grow better with media supplemented with cysteine - Early colonies are pinpoint, developing into slightly larger smooth convex, non-hemolytic colonies - No growth on MAC - Thin, fusiform gram neg bacilli are seen on gram stain - Reactions for oxidase, catalase, indole, VP, arginine= negative - Associated with dog bites and scratches
Cardiobacterium hominis characteristics
- Colonies are slow growing, small, smooth, and entire on all blood culture media - Gram variable staining, short bacilli that often line up in rosette-like clusters - Positive reactions= Oxidase - Negative reactions= Catalase, nitrate, urease, and esculin Weak positive= indole (spot tests often neg) - Associated with endocarditis of individuals with damaged heart valves from rheumatoid arthritis or following heart valve replacement
Eikenella corrodens characteristics
- Colonies on blood and chocolate agars are relatively small and smooth, but distinctive for pitting of the agar ("corrodens") - Light yellow pigment may be detected on cotton swab - Slender gram negative bacilli or coccobacilli with round ends on gram stain - Positive reactions= oxidase, nitrate reduction, lysine, ornithine - Negative reactions= Catalase, esculin, carbohydrate utilization
What test is used in the assessment of glomerular filtration
- Creatinine clearance - Creatinine excretion is related to muscle mass and is fairly constant from day to day. - Based on the serum creatinine level and is used to measure glomerular filtration rate (GFR) - Creatinine is filtered by the glomerulus and is not reabsorbed- cannot be used to estimate GFR
A 64 y/o man lost 15 pounds, became weaker, and his face became fuller with a ruddy complexion. His lab tests revealed: Serum cortisol: 8am: 880 nmol/L (reference range= 138-635 nmol/L) 4pm: 828 nmol/L (reference range= 83-414 nmol/L) After these results, an O/N dexametasone suppression test gave a cortisol level of 773 nmol/L. The most probable diagnosis for this patient is
- Cushing's syndrome - This is a hormonal disorder caused by the effects of an individual having high levels of cortisol. - Signs: skin becomes fragile and thin, rounding/full face - Cortisol production is normally suppressed at night, but in this, the suppression doesn't occur. - Dexamethasone suppression test- cortisol signals the pituitary to release less ACTH so the normal response after taking dexamethasone is decrease in blood and urine cortisol levels- in cushing's the decrease doesn't happen
What agar would you use to isolate Francisella tularensis
- Cysteine-blood agar - Will also grow on Thayer-Martin and CAP that have been enriched with supplemental nutrients
___ media contains certain factors that allow colonies of specific organisms to appear different that other colonies
- Differential
____ media encourages the growth of specific types of organisms
- Enrichment
Treatment of "sequestration crisis" often seen in infants and young children with sickle cell disease, involves what treatments
- Exchange transfusions and/or splenectomy
True or False: The 5' end of a DNA strand ends with an -OH group
- False - The 5' end is distinguished with a phosphate while the 3' end is distinguished by an -OH group
What is the most likely cause of a patient who developed a severe hemolytic episode after taking anti-malarial drugs, and red cell inclusions caused by denatured hemoglobin were seen on the differential smear
- G-6PD deficiency - Individuals with this deficiency develop a nonimmune hemolytic anemia in response to antimalarial drugs. The red cell inclusions are Heinz bodies (precipitated, denatured hemoglobin)
Characteristics of Enterococcus faecium
- Gram positive cocci - Lancefield antigen group D - Alpha-hemolytic (or non-hemolytic) - Vanco resistant - Resistant to aminoglycosides - arabinose positive - Non-motile
In acute HBV infection what antigens would be present
- HBsAg - HBeAg
In chronic HBV infections what antigens would be present
- HBsAg - HBeAg - Total Anti-HBc
The absence of what clotting factor causes no bleeding tendency
- Hageman factor (XII) - This may cause prolonged clotting the the specimen tubes but does not cuase abnormal coagulation symptoms or complications in vitro
Reactions that associated with immediate hypersensitivity
- Hay fever - Anaphylactic shock
The most likely cause of an elevated serum potassium level in an apparently normal individual is
- Hemolysis - When RBCs hemolyze the increased levels of potassium found within the RBCs is released in the plasma
Factor VIII, IX, or XI deficiencies are all types of
- Hemophilia - inherited hemorrhagic disorders caused by a genetic mutation of the gene coding for the coagulation factor
A completely sickled cell (drepanocyte) is most commonly seen in what condition
- Homozygous HbSS - Truly sickled cells are a result of a homozygous HbSS state
In examining a Wright's stained blood smear of a patient who has had a splenectomy one would most likely also find
- Howell-Jolly bodies - These are composed of small, round, RBC inclusion DNA - Can also be seen in megaloblastic anemia
What antibody is chiefly seen in the secondary immune response
- IgG
What class of antibody is able to agglutinate RBCs after anti-human globulin is added
- IgG - Binds at the Fc portion of the antibodies - AHG binds to both unbound and bound IgG antibodies- when bound to RBCs= visible agglutination
What solution is an RBC that lacks Kidd blood group system resistant to
- Jk(a-b-) RBCs are resistant to lysis in 2 M urea - Kidd antigens are located on the RBCs urea transporter - Ab to Kidd are enhanced with ficin treatment - Kidd prefers AHG phase (IgG) - Can drop in titer in vivo but detection is aided by the use of potentiators (LISS and PEG)
E. coli characteristics on Kligler iron agar
- Lactose fermenter - Acid slant/ acid deep
Scopulariopsis brumptii conidia characteristics
- Lemon shaped and have a flat, truncated base
Exophiala jeanselmei phialide characteristics
- Long, slender, tapered phialide that may appear roughened at the tip where the rings or annellides have formed
During the 'staining' process prior to flow cytometry analysis of WBCs, how are the erythrocytes treated?
- Lysed - Unless RBCs are the population of interest they should be lysed, if not, they lead to false analytic results
An automated CBC produced the following blood cell parameters: - WBC = 5.6x10^9/L (reference= 4-10x10^9) - RBC= 3.4x10^12/L (reference= 4.2-5.9x10^12) - Hb= 11.1 g/dL (reference= 12-16 g/dL) - HCT= 31% (reference= 37-48%) - MCV= 92fL (reference= 80-100 fL) - MCHC= 38 g/dL (reference= 30-37 g/dL) A specimen for a repeat CBC is received in the lab 6 hrs later. The sample visually appears to be much lighter in color than the original sample. The tech questions whether both samples are from the same patient. What parameter is least likely to change between samples, if from the same patient, and would be most useful to determine if there is a discrepancy that may be the result of a preanalytical error in sample collection?
- MCV - Delta checks help identify potential errors before they are reported to clinicians. this compares the current result with a previous result, if they differ by a percentage determined by the lab then an investigation of the reason for the change occurs
Bence-Jones proteins
- Markedly elevated in blood serum - Filtered through kidneys in quantities that exceed the tubular reabsorption capacity - Excreted in the urine - If dipstick negative and sulfosalycilic acid test is positive then these are suspected, the next step would be perform heat precipitation test to test for their presence
What assay, using 24-hour urine, is considered the best single screening test for pheochromacytoma
- Metanephrines - The most reliable screening tests for diagnosis of pheochromocytoma is measurement of plasma free fractioned metanephrines and urinary fractionated metanephrines
Characteristics of Thalassemia major (Cooley's anemia)
- Microcytic, hypochromic RBCs - Traget cells - Polychromasia - nRBCs
Bence-Jones protein is a protein that is excreted by persons with
- Multiple myeloma (produces plasma cells and Waldenstrom's macroglobulinemia)
Does genotyping for genetype screening in pharmacogenomics take into accound drug interactions that can affect metabolism
- No - cannot factor in environmental or health variable that could affect drug metabolism
Shigella flexneri characteristics on Kligler iron agar
- Non-lactose fermenter - Alkaline slant/ acid deep
Characteristics of Pyruvate kinase deficiency
- Normochromic, normocytic RBCs - Reticulocytosis
What best describes the relationship between dietary iron and iron absorption in a healthy individual?
- Only a small percentage of dietary iron is absorbed and used - the majority of iron is in the ferric form which is less easily absorbed than ferrous iron
Sample recovered from a cat bite, and colonies reveal good growth of entire, convex, grey-white, smooth colonies on BAP and CAP. non-hemolytic growth on BAP, and no growth on MAC was observed. Coccoid to rod-shaped gram neg bacilli observed in gram stain. Positive tube tests= indole, VP, ornithine, arginine, esculin, cytochrome oxidase, oxidase, catalase. What is the identification of this isolate
- Pasteurella multocida - Decarboxylation of ornithine and arginine provides a definitive ID - Associated with cat bites and scratches
You observe several background dematiacious hyphae with long, flask-shaped, tapered phialide that has a flat saucer-like terminus. This feature is most characteristic of
- Phialophora richardsiae
What temperature does Bence-Jones proteins precipitate at and redissolve at when performing the heat precipitation test
- Precipitates between 40-60C - Redissolves at 100C
In order to avoid repeating pretransfusion testing on a neonate during one hospital admission, what must be true
- Received only ABO compatible blood - Received only Rh- compatible blood - No unexpected Ab in serum or plasma
The disappearance of HBsAg and HBeAg, the persistence of total anti-HBc, the appearance of anti-HBs, and often the presence of anti-HBe indicates what type of hepatitis infection
- Recovery phase HBV infection - Recovery phase of HepB infections show the actual viral antigens disappearing while the body produces an antibody to the virus's core, surface, and e antigens
Plasma concentrations of creatinine are used to assess
- Renal function
This gram-positive coccus is catalase positive. The tests done so far were tube coagulase, MRSA screen plate containing 4% NaCl and 6ug/mL oxacillin. Then, a 0.5 McFarland standardized inoculum of the isolate was plated. What should the next step you take be
- Report the isolate as methicillin resistant Staphylococcus aureus - Since the coagulase plasma is clotted indicating it is coagulase positive, and the organisms is growing in 4% NaCl and 6ug/mL oxacillin MRSA screen plate (so organism demonstrates resistance to oxacillin, methicillin, and nafcillin), the ID of this organism is MRSA
The prozone effect can be described by
- Results in a false negative reaction - The result of antibody excess - Dilution of antibody can help prevent this occurance
An acid-fast bacillus is isolated and produces an orange pigment when grown in either the light of the dark. Which type of organism has most likely been isolated
- Scotochromogen
____ media contains agents that inhibit all but one specific organism
- Selective
What tests are quantitative methods for the determination of albumin?
- Serum protein electrophoresis - Nephelometry - Colorimetric spectrophotometry
Reactions that are not associated with immediate hypersensitivity
- Serum sickness (Type III hypersensitivity involving the formation of immune complexes) - Arthrus reaction (Type III hypersensitivity involving the formation of immune complexes) - Tuberculin reaction (delayed hypersensitivity reaction that appears 48-72 hrs after antigen exposure)
Characteristics of Paroxysmal nocturnal hemoglobinura
- Severe hemolytic anemia - Intermittent sleep associated hemoglobinuria - Microcytic, hypochromic
What type of fat (LDL, HDL, VLDL, etc.) is most likely to interact with arterial walls leading to deposition of cholesterol and initiating or worsening artherosclerosis
- Small dense LDL
What is a detergent added to gel media that enhances separation of solutes during electrophoresis?
- Sodium dodecyl sulfate (SDS)