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Gram positive organisms resist decolorization by ethyl alcohol. The large crystal violet-iodine complex is not able to penetrate the peptidoglycan layer, and is trapped within the cell in gram-positive organisms. Conversely, the outer membrane of gram-negative organisms is degraded and the thinner peptidoglycan layer of gram-negative cells is unable to retain the crystal violet-iodine complex and the color is lost.
What is the purpose of using ethyl alcohol or acetone in the gram stain procedure:
Assuming an alpha hemolytic reaction (not well seen in the image), viridans streptococcus and S. pneumoniae are the two possible responses. However, these colonies are far too mucoid for viridans streptococci; therefore, S. pneumoniae is the most likely choice. Also, the colonies are much too large and the hemolytic reaction is wrong for S. pyogenes or S. agalactiae.
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 and the alpha hemolysis seen in the image to the right, the most likely identification is:
The results demonstrate compliance with diet and medication. A HbA1C result that is <7.0% indicates glycemic control for most adults with diabetes.
Chemistry
A HbA1C result for a diabetic patient is 6.0%. What conclusion can be made regarding this patient's carbohydrate management?
This type of laboratory professional is responsible for the technical aspects of managing the operation of the laboratory and is most likely an MLS with additional education in administration:
A test with high specificity accurately detects the absence of disease. The more specific a test is, the fewer false-positive results will occur. A test with high sensitivity accurately identifies the presence of disease. The more sensitive a test, the fewer false-negative results it produces. In the case stated in this question, the immunoassay has high specificity, so it has few false-positives and will accurately detect those individuals who do not have the disease or condition that is being tested for. However, the test has low sensitivity, so it may not identify all individuals who actually have the disease; it may produce many false-negative results.
The accuracy of an immunoassay is its ability to discriminate between results that are true positives and results that are true negatives. Two parameters of test accuracy are specificity and sensitivity. Which of these statements apply to an immunoassay with high specificity, but low sensitivity?
Coumarin derivatives inhibit the vitamin K dependent Factors (II, VII, X) which can be measured with the PT and monitored frequently with the INR assay.
Hematology
Warfarin-based (coumarin derivative) oral anti-coagulant therapy is commonly monitored with :
Normal pH of semen must be a value equal to or greater than which of the following?
The morphologic characteristic(s) associated with the Chediak-Higashi syndrome is (are):
FFP that has been thawed at 30 - 37oC and maintained at 1 - 6oC must be transfused within 24 hours. In contrast, "Thawed Plasma" can be used for up to 5 days as a replacement therapy for patients requiring stable clotting factors. Keep in mind that these are two different component types and you are asked about FFP.
Blood Bank
FFP that has been thawed at 30 - 37oC and maintained at 1 - 6oC must be transfused within ___________ after it has been thawed.
HbA1C is the recommended test for monitoring diabetic carbohydrate management. Microalbuminuria, low concentrations of urinary albumin, is measured to detect early renal impairment, at a stage where it is reversible with treatment.
What is the role of microalbuminuria testing?
Following an accidental needlestick, the person should be tested for all of the following except:
Most researchers believe that the small size and increased density of LDL molecules found in atherogenic dyslipidemia enable the molecules to more easily invade the endothelium and arterial wall of vessels.
Why are small dense LDL molecules more atherogenic?
Which of the procedures listed below will increase the platelet concentration in the preparation of Platelets?
Which area of the laboratory can analyze a patient sample and be able to predict their risk of developing a disease?
The DAT, or direct antiglobulin test, is used to detect antibodies coating RBC's in vivo.
The Direct Antiglobulin Test (DAT) is usually used to detect:
Skeletal deformations result from the increased erythropoiesis that occurs in beta thalassemia major. Children with beta thalassemia intermedia may demonstrate some facial bone deformity, however this is not common. Beta thalassemia minor rarely causes any physical signs or symptoms and beta thalassemia minima is completely asymptomatic.
Skeletal deformations are most commonly present in which of the following beta thalassemias?
An ultrarapid metabolizer (UM) would require a higher dose of a drug than an EM (a person with normal enzyme activity) since the UM eliminates the drug more quickly.
A CYP2D6 ultrarapid metabolizer (UM) would require ___________ dose of an active drug (non-prodrug) that is metabolized by CYP2D6 than a CYP2D6 extensive metabolizer (EM).
Elevation in conjugated bilirubin is most likely to be found in which of the following conditions:
Which of the following is a selective media recommended for the isolation of Clostridium difficile?
Albumin is a "negative" acute phase protein since it is found in decreased levels during acute phase response. Alpha-1-antitrypsin, fibrinogen, and ceruloplasmin are all "positive" acute phase proteins that are found in increased levels during acute phase response.
Which one of the following usually shows a decrease during an acute phase response?
Which of the following tubes contains an anticoagulant that does not bind calcium?
Question options:
Blood Bank; Immunology
Which of the following best describes the primary function of antibodies:
Basophilic stippling is strongly associated with lead poisoning the lead toxicity can affect the bone marrow; causing this phenomenon.
Hematology
What is a prominent morphologic feature of lead poisoning:
Calculation:
Cells Counted (in this case the average of both sides) X dilution factor (in this case 100) / # of squares counted (in this case 9) X area of each square (1mm2) X 0.1mm (depth factor)
So, in this problem:
158 x 100 / 9 x 1 x 0.1mm = 17555.55/mm3 (can be converted to 17.5 x 109/L*)
*There are 1,000,000 mm3 in a liter (L). So 17555.55 X 1,000,000 = 17.5 x 109/L
A manual white blood cell count was performed by the hematology technologist. The cell counts for both sides were 152 and 164 respectively. All nine large squares were counted on each side. The dilution for this kit was pre-measured at 1:100. What should the technologist report as the white cell count?
The Westgard multi-rule 22S describes the scenario where two consecutive data points fall outside +2SD or -2SD. If this occurs, then the run must be rejected. This situation is most likely caused by a systematic error.
Which of the following describes the Westgard multi-rule 22S?
Convert the following temperature from Celsius to Fahrenheit
20 degrees C
Question options:
The division of Department of Health and Human Services (DHHS) responsible for protecting public health by ensuring the safety and efficacy of foods, drugs, biological products, medical devices, and cosmetics is:
Transfusion of red cells of any ABO type other than O to a group O patient is of course likely to cause a hemolytic transfusion reaction.
Which of the following types of packed RBCs could be transfused to a group O patient:
Twelve weeks after onset of the disease, patients with uncomplicated acute hepatitis B usually will demonstrate which of the following in their serum?
Which advancement in clinical science occurred during the second half of the twentieth century?
The FTA-ABS is used to confirm that a positive non-treponemal test like RPR is not the result of a biological false positive, which occur in about 1 to 10 percent of the population.
A positive RPR test and a negative FTA-ABS test is most likely the result of:
The term that is used to describe the color in these tubes of CSF is "xanthochromia." Xanthochromia is an abnormal color, usually yellow, orange, or pink, in the supernatant of the CSF sample. It may indicate that a subarachnoid hemorrhage (SAH) has occurred.
Jaundice and icterus both describe a yellowing of the skin, mucous membranes, and eyes. Blood plasma/serum that is deep yellow is also described as icteric.
What term is used to describe the color in these tubes of cerebrospinal fluid (CSF)?
AHG must be added to the cells immediately following washing. Antibodies may elute from the cells if the cells are allowed to sit in saline without the addition of AHG.
Which one of the following may cause a FALSE-NEGATIVE result with antiglobulin techniques?
The cells indicated by the arrows in the image are spherocytes. Spherocytes have a decreased surface to volume ratio and are therefore smaller with an increased MCHC. Spherocytes have lost their bi-concave shape and are spherical in shape, hence the name.
What are the cells that are indicated by the arrows in this peripheral blood smear image?
RAST tests, or Radioallergosorbent tests, are used to screen for an allergy to a specific substance or substances if a person presents with allergy-like symptoms.
The assay which is most helpful in identifying specific allergens is:
Serum ferritin is a good indicator of iron deficiency. However, it acts like an acute phase reactant, being elevated in a large number of conditions. Patients who have iron deficiency as well as another condition that elevates serum ferritin levels may therefore have normal or even elevated serum ferritin levels.
Which one of the following statements about serum ferritin are true:
Eosinophils do not have cytoplasm containing large purple/blue-staining granules. Instead, their granules are large but are orange/red in color. These granules are very distinctive for this type of cell, typically making their identification simple.
ll of the following statements describe an eosinophil EXCEPT:
Streptococcus pyogenes is the correct answer. Streptococcus pneumoniae is alpha-hemolytic which demonstrate a green area of partial hemolysis around the colonies. Staphylococcus aureus will produce complete hemolysis but is catalase positive. Streptococcus agalactiae is beta-hemolytic but only produces a partial clearing of the red blood cells in sheep blood agar.
Complete hemolysis of sheep blood agar as demonstrated by the image below would be seen in which of the following catalase-negative isolates?
Which of the following organizations now provides the certification exam for laboratory professionals?
The increase in inflammatory cytokines and the abnormal lipids and lipid levels often present in metabolic syndrome increase the risk of cardiovascular disease. Adiponectin is decreased and increases in angiotensinogen lead to hypertension.
Chemistry
Which of the following statements is true regarding cardiovascular disease and adipose tissue? Please select all correct answers
Which of the following legislation was developed to protect the privacy of all patient information in the health care?
Blood plasma will contain coagulation proteins, but not in a clotted tube where serum is present.
Blood serum contains each of the following substances except:
Incompatiblity involving the ABO blood group system can cause the most severe type of transfusion reaction.
The cause of the most severe life-threatening hemolytic transfusion reactions is:
A monoclonal B-cell population (Kappa or Lambda predominant) with expression of CD19, CD20, CD23, and co-expression of CD5 is consistent with which of the following?
Patients who develop severe sepsis or septic shock commonly have increased plasma lactic acid values.
Patients who develop severe sepsis or septic shock commonly have __________ plasma lactic acid values.
G6PD deficiency causes an increased suseptibility to the oxidation of hemoglobin, which in turn, causes the precipitation of hemoglobin inside of the red blood cell.
Which one of the following conditions is associated with glucose-6-phosphate dehydrogenase (G6PD) deficiency?
Which of the following is NOT part of the magnification system of the microscope?
Valine substitutes for glutamic acid in the Beta 6 position to produce HbS.
To produce hemoglobin S, glutamic acid that is normally present in the sixth position on the beta globin chain is substituted with which of the following?
1+ reaction has numerous small clumps and cloudy red supernatant
2+ has many medium-sized clumps and clear supernatant.
3+ has several large clumps and clear supernatant
4+ has one solid clump, no free cells, and clear supernatant
BB
Tube-based agglutination reactions in blood bank are graded from negative (0) to 4+. A reaction that has numerous small clumps in a cloudy, red background is:
Leptin signals the hypothalamus that there are changes in fat stores.
Resistin increases insulin resistance and enhances adhesion molecules present on endothelial cells.
IL-6 responds to tissue injury. IL-6 increases insulin resistance by inhibiting insulin receptor signal transduction in liver cells. It also increases other inflammatory cytokines, interleukin-1 (IL-1) and TNF-a, and stimulates the liver to produce C-reactive protein (CRP).
Adipose tissue and liver cells produce angiotensinogen, a precursor of angiotensin II. Besides increasing blood pressure, angiotensin II may stimulate adipose cell formation and thus increase adipose mass.
Which one of the following adipocyte products is an important messenger in metabolism, signaling the hypothalamus that there are changes in fat stores?
In DIC, or disseminated intravascular coagulation, the prothrombin time is increased due to the consumption of the coagulation factors due to the tiny clots forming throughout the vasculature. This is also the reason that the fibrinogen levels and platelet levels are decreased. Finally FDP, or fibrin degredation products, are increased due to the formation and subsequent dissolving of many tiny clots in the vasculature. The FDPs are the pieces of fibrin that are left after the fibrinolytic processes take place.
Which of the following laboratory results would be seen in a patient with acute Disseminated Intravascular Coagulation (DIC)?
PCT usually rises within 3-6 hours of infection. CRP also increases rapidly following infection, but is not as specific for infection as PCT. A rise in CRP could also occur with SIRS. Lactic acid is usually used to detect and monitor impaired circulation and tissue oxygenation in critically ill patients.
Chemistry
Of the three laboratory tests that are listed, which has proven to be most effective for early differentiation of systemic inflammatory response syndrome (SIRS) from sepsis due to its increase following infection and higher specificity?
The mandatory waiting period between blood donations is 56 days, or eight weeks.
The accepted interval between blood donations is:
A regional laboratory that performs high volume, highly complex or infrequently ordered testing is a:
Estriol levels in conjunction with hCG and AFP can be obtained during pregnancy to:
The ApoB/ApoA1 ratio has a positive risk marker (ApoB-100) and a negative risk marker (ApoA1). Risk diminishes as ApoA1 goes up (a negative marker) and risk increases in proportion to ApoB concentrations (a positive risk marker). This 'double-edged sword' provides good risk prediction. The other risk markers in question do not have this dual-advantage.
Which risk marker has both positive and negative cardiovascular risk integrated into its measurement?
The MCV is indicative of microcytosis with MCV=<80fL. The RDW is within normal limits and indicative of a homogenous cell population.
If the MCV was >100 fL, this would be indicative of macrocytosis. An RDW that was outside of normal limits would be indicative of a heterogenous cell population.
An 18 year old female has a CBC as part of a routine physical exam. The following results were obtained and the physician determines she is anemic. After reviewing her CBC results shown below, which of the following would be an appropriate description of the anemia?
White blood cells (WBC): 5.6 x 10^9/L (RR:4.0-10.0 x 10^9/L)
Red blood cells (RBC): 3.7 x 10^12/L (RR: 4.2-5.9 x 10^12/L)
Hemoglobin: 9.9 g/dL (RR:12-16 g/dL)
Hematocrit: 28% (RR: 37-48%)
MCV: 75 fL (80-100 fL)
RDW-CV: 14% (RR: 11.0-15.0%)
In the laboratory, surfaces must be disinfected for blood spills. What is the most common disinfectant used?
The thrombin time (TT) involves the addition thrombin to platelet poor plasma to stimulate the clotting process. It reflects ability of the patient to convert fibrinogen to fibrin but is also sensitive to the presence of inhibitors that may be present in the plasma, like heparin. Therefore, it can be used to measure the effects of heparin on a coagulation sample.
This assay would be used to help rule-out heparin contamination in a coagulation sample:
Blood collected in CPDA-1 may be stored at 1 - 6 oC for up to 35 days.
How long may blood be stored using CPDA-1 preservative prior to transfusion?
Myoglobin rises typically within 2-4 hours after a myocardial infarction and stay elevated for days, with a peak at the 6-9-hour mark post-MI. After myoglobin, troponin is the next fastest to rise afer a mycardial infarction and can rise within 3-4 hours with a peak around 12 hours post-MI. LD (8-12 hours, 24-48 hour peak) and CK (4-6 hours with peak at 24-36 hours) will also rise after MI, but are not as fast to rise as myoglobin and troponin.
Chemistry
A patient is admitted to the hospital with acute chest pain, but which of the following cardiac markers will be elevated FIRST if the patient had an MI?
Match each of the following:
1. Ratio of cellular area to total area in the bone marrow section.
2. Number of myeloid cells compared to nucleated erythroid cells.
3. Use low power to estimate their quantity and appearance.
4. Use Perls' Prussian blue stain.
Though automated extraction machines have many benefits over manual methods the costs are high and generally require a high throughput of samples in order to justify the costs.
Automated extraction has many benefits over the traditional manual methods. The most important benefit is that the nucleic acid isolated is constantly consistent. There is a reduced amount of manipulation with dramatically decreases the chance of cross contamination. Also, automated extraction machines are considered moderate complexity and can be performed by a wider variety of laboratory professionals.
All of the following are considered benefits of automated isolation and extraction equipment EXCEPT:
The production of long, tapered phialides is one of the key identifying features of Trichoderma species. In contrast, Penicillium species, produce phialides with blunt ends.
The phialides of Beauveria species are geniculate, forming a zig-zag pattern.
The arrows in the image on the right point to single, long, tapered phialides that extend laterally from either side of the hyphae. This is an identifying feature of which of the fungi listed below?
The indole (modified Kovacs' reagent) is used to assess the ability of certain bacteria to produce indole by the deamination of tryptophan. Indole reacts with aldehyde in the Kovac's reagent to produce a red color. An alcoholic layer holds the red color as a ring at the top of the tube used for the idole test.
If a bacteria produces the enzyme tryptophanase to break down the amino acid tryptophan, which of the following tests will be positive with Kovac's reagent?
Oxalate, EDTA, and citrate are anticoagulants that inhibit clot formation.
Which of the following blood additives is most useful for serum collection:
The correct answer which best fits the characteristics in this question is Mycobacterium tuberculosis.
What is the MOST likely identity of an acid-fast bacilli that showed buff colored, dry, heaped colonies; niacin, nitrate, and urease positive; and took 23 days at 35ºC to grow?
In primary responses, the major class of antibody produced is IgM whereas in the secondary response, as mentioned in this question, it is IgG. IgG is present in the highest quantities compared to all other antibody classes and is the only antibody able to cross the placental barrier.
Which of the following antibody types is chiefly seen in the secondary immune response:
Intravascular hemolysis is typically associated with increased levels of serum (plasma) LDH and bilirubin, and an increased number of reticulocytes. Serum LDH is found in higher levels during intravascular hemolysis due to fact that high levels of LDH are normally found within the red cells, but is now being spilled into the bloodstream via red cell lysis. Bilirubin is a breakdown product of hemoglobin, which has also been spilled into the bloodstream from broken red blood cells via hemolysis. Reticulocytosis is a reflection of the release of an increased number of immature red blood cells from the marrow to account for the red blood cells that are lost through hemolysis. This is a normal response. Failure to show an increased reticulocyte count with hemolytic episodes or hemorrhage would indicate an ineffective erythropoiesis (possible bone marrow function problem).
Which of these blood levels will increase during intravascular hemolysis?
On the red cell membrane, there is a bicarbonate / chloride exchanger. This exchanger allows for bicarbonate to leave the red cells while chloride is allowed inside.
In blood, bicarbonate leaves the red blood cell and enters the plasma through an exchange mechanism with:
Mrs. Jones, a diabetic, is admitted to the hospital on November 25th. It appears that she has had an AMI but did not feel the severe chest pain because of diabetic neuropathy. She has not felt well since November 20th and her physician believes she possibly had an AMI on November 20th.
Assuming that the infarct was uncomplicated, which of the following cardiac biomarkers would most likely still be elevated and would assist in an AMI diagnosis?
A positive spot test shows agglutination of horse erythrocytes when added to patient serum previously absorbed with guinea pig kidney, but not when added to patient serum previously absorbed with beef erythrocyte stroma. The test is generally simple, sensitive, and specific, but false negative are common in young children with mononucleosis.
The most common rapid slide test (MONOSPOT©) for infectious mononucleosis employs:
Rule-out is a process by which antibodies are identified as being unlikely in a given sample because of the absence of an expected antigen-antibody reaction. In other words, the absence of a reaction is noted with a cell that is positive for the corresponding antigen.
Although rule-out procedures may vary somewhat from institution to institution, the following general principles apply:
Non-reactive cells are selected for rule-out. To be classified as non-reactive, a cell must NOT have reacted at any phase of testing in a given panel or screen.
Using the logic that if the rule-out cell is positive for a given antigen, it should have reacted with the corresponding antibody, you can rule-out antibodies that correspond to antigen positive cells.
To increase the probability that rule-out will not mistakenly eliminate a weakly-reacting antibody that exhibits dosage*, use only cells that are homozygous for the corresponding antigen for those systems that generally show dosage. Generally these include: C, c, E, e, Fya, Fyb, Jka, Jkb, M, N, S, and s.
In this case, it is only possible to rule out on screening cell 2 since it demonstrates a negative reaction with the patient serum. Anti-C cannot be ruled out since the C antigen is heterozygous on screening cell 2 with c. Anti-Fya cannot be ruled out since this antigen is not present on screening cell 2. Anti-M and anti-Jka can be ruled out since the antigens are homozyous while demonstrating a negative reaction on screening cell 2.
Rule-out, while very useful, can lead to error. Ruling out an antibody should be combined with other supporting data to increase confidence in the solution; the more data collected, the higher the probability that the final solution is correct.
*Dosage means that there are two "doses" of the same antigen present on the red cells . Antibodies that exhibit dosage react more strongly with homozygous cells (e.g., Jka Jka) than with heterozygous cells (e.g., Jka Jkb) .
Based on the phenotype of the RBC screening cells, and patient results shown on the right, which of the following antibodies CANNOT be ruled out?
Laboratories performing which of the following types of tests need to be enrolled in a CLIA-approved proficiency testing program?
Kell, Kidd, and Duffy are usually warm reacting IgG antibodies. The most common P system antibody is anti-P1, which is a frequently naturally occurring low titer IgM antibody, seen in most P2 individuals.
Blood bank
Which of the following blood groups is most frequently associated with cold agglutinins:
TESTED 23 Apr 2024