LabCe Questions I
The red ring at the top of the media in this tube indicates a positive indole reaction. The precursor substance in the medium from which the indole is produced is: Tryptophan p-dimethylaminobenzaldehyde Pyruvic acid Peptone
Tryptophan
What is the lower reference limit for progressive motility of spermatozoa when performing a semen analysis? 12% 22% 32% 40%
32% The lower reference limit for progressive motility is 32%. The lower reference limit for total motility (progressive + non-progressive) is 40 %.
What is the expected M:E ratio in this slide? 3:1 5:1 1:3 1:5
3:1
Does the Levey-Jennings chart to the right show acceptable quality control results? No, because of Westgard Rule 13s No, because of Westgard Rule 22s No, because of Westgard Rule 41s Yes
Yes
The primary antibody response takes an average of how many days? 1-3 days 3-4 days 5-10 days 14-21 days
5-10 days The primary immune response takes approximately one week, or 5-10 days, to occur. The secondary immune response typically has a shorter lag period, which is approximately 1-3 days. The primary immune response typically does not begin as early as 3-4 days. A lag time of 14-21 days is exceptionally long and would lead to additional issues with the infection.
Which derivative of PCR testing uses short primers not specifically complementary to a particular sequence of a target DNA? Multiplex PCR Nested PCR Arbitrary primed PCR Quantitative PCR
Arbitrary primed PCR Arbitrary primed PCR testing uses short (random) primers not specifically complementary to a particular sequence of a target DNA. Multiplex PCR is a method by which more than one primer pair is included in the PCR mixture. Nested PCR involves the sequential use of two primer sets. Quantitative PCR is an approach that combines the power of PCR for the detection and identification of infectious agents with the ability to quantitate the actual number of targets originally in the clinical specimen.
Which of the following cells is characterized by a thin rim of cytoplasm around the nucleus? Small lymphocyte Large lymphocyte Monocyte Segmented neutrophil
Small lymphocyte Small lymphocytes are not actively dividing, and therefore the amount of cytoplasm is very small. They are in the "resting" stage, and once they become activated, the amount of cytoplasm increases. Small lymphocytes are the most accounted for when performing a manual differential.
Which of the following gastrointestinal pathogens has an incubation period of 1-8 hours? Salmonella spp. Listeria monocytogenes Staphylococcus aureus Vibrio spp.
Staphylococcus aureus Staphylococcus aureus causes nausea and vomiting, with an incubation period of 1-8 hours. Salmonella spp. and Vibrio spp. cause fever, abdominal cramps, and diarrhea, with an incubation period of 6-48 hours. Listeria monocytogenes causes abdominal cramps and watery diarrhea, with an incubation period of 16-72 hours.
All of the following CD markers are present on a normal mature T cell, EXCEPT? CD20 CD7 CD3 CD5
CD20 Normal mature T cells should express CD2, CD3, CD5 and CD7 markers. The CD20 marker is NOT present on mature T cells. CD20 is expressed by B cells.
What is another name used to designate a fully committed B-lymphocyte? T-lymphocyte Reactive lymphocyte Large lymphocyte Plasma cell
Plasma cell
From the IgG molecule illustration, which region is the heavy chain? A B C D
A A = Heavy chain B = Light chain C = Antigen binding site D = Variable region
A patient has a history of repeated spontaneous abortion. Coagulation studies reveal an elevated APTT, normal PT, normal platelet function, and normal thrombin time. Schistocytes were seen on the peripheral blood smear. Which test should be performed to determine if the patient has lupus anticoagulant? Factor VIII assay Mixing studies with factor-deficient plasmas Antinuclear antibody test Platelet neutralization test
Platelet neutralization test Platelet neutralization tests are one of the confirmatory tests that can be used to determine if a patient has a circulating lupus antibody, or lupus anticoagulant. The principle in this test involves the use of a freeze-thawed platelet suspension that, when mixed with the patient plasma, will neutralize the anti-phospholipid antibodies (lupus anticoagulant) present and allow for a corrected APTT result upon re-testing.
The type of hypersensitivity reaction associated with macrophage activation, cytokine-mediated inflammation is: Type I Anaphylactic (Immediate hypersensitivity) Type II Cytotoxic (Antibody mediated and antibody dependent, complement mediated hypersensitivity) Type III Immune complex mediated hypersensitivity Type IV Cell mediated hypersensitivity (T-cell dependent)
Type IV Cell mediated hypersensitivity (T-cell dependent)
Which of the following best describes Myelodysplastic syndromes? A myeloproliferative disorder An acute leukemia that is in remission A leukemia that typically progresses to thrombocytopenia and lymphocytic leukemia A qualitative disorder of erythroid, myeloid and/or megakaryocytic cell series
A qualitative disorder of erythroid, myeloid and/or megakaryocytic cell series In myelodysplastic syndromes, the bone marrow stem cells cannot effectively make erythroid, myeloid, or megakaryocytic cells due to a qualitative or quantitative defect. These syndromes can lead to AML or acute myelogenous leukemia.
Type I Immediate hypersensitivity
mast cell-derived mediators (vasoactive amines, lipid mediators, and cytokines). Cytokine-mediated inflammation involves eosinophils, neutrophils, and lymphocytes. Type I reactions can range from life-threatening anaphylactic reactions to milder manifestations associated with food allergies.
Which of the following organisms is Gram-positive? Pasteurella Erysipelothrix Aeromonas Fusobacterium.
Erysipelothrix
An aqueous 3.00 M KOH solution is prepared with a total volume of 0.650 L. The molecular weight of KOH is 56.1056 g/mol. What mass of KOH (in grams) is needed for the solution? 45.7 g 54.2 g 109.4 g 129.6 g
109.4 g Molar concentration is defined as moles (mol) of solute per liter (L) of solution. Molar concentration= mol solute / L solution Rearrange this equation to solve for the moles of solute. Input the molar concentration and volume will tell you the moles of HCl. mol solute= molar concentration X L solution =3.00 M X 0.650 L =1.95 mol The moles of HCl then need to be converted to grams using the molecular weight. g HCl = 1.95 mol X (56.1056 g/1 mol) =109.4 g The correct answer is 109.4 g.
All of the following are factors that will affect migration in gel electrophoresis, EXCEPT? Gel concentration (size of gel pores) Size of particle Voltage used Amount of light present
Amount of light present The amount of light present when the electrophoresis performed does not impact the migration of the particle in electrophoresis. Particle migration is affected by a number of factors, including the concentration of the gel (gel pore size), the size of the particle, and the voltage used.
Which of the following ketones is NOT detected in the Acetest® tablet method? Acetone Beta-hydroxybutyric acid Acetoacetic acid Beta-hydroxybutyric acid and acetone
Beta-hydroxybutyric acid
The optimum time to collect a urine sample to maximize recovery of the ovum illustrated in this iodine-stained mount of urine sediment is: Immediately upon rising Just before bedtime Between Noon and 3:00 P.M Between midnight and 2:00 A.M
Between Noon and 3:00 P.M
What is the nuclear appearance of an Endolimax nana trophozoite? Blot-like karyosome, no peripheral chromatin Central karyosome, even peripheral chromatin Large karyosome, no peripheral chromatin Eccentric karyosome, uneven peripheral chromatin
Blot-like karyosome, no peripheral chromatin The nuclear appearance of Endolimax nana trophozoite has a blot-like karyosome but lacks peripheral chromatin. As examples, an Entamoeba hartmanii cyst has a central karyosome with even peripheral chromatin; an Endolimax nana cyst possesses a large karyosome with no peripheral chromatin and Entamoeba coli trophozoites, is a parasite with eccentric karyosome and uneven peripheral chromatin.
Which of the following D variants has the best likelihood to receive D-positive RBCs without any adverse effects? Del Partial D Partial weak D C in Trans to RHD
C in Trans to RHD Individuals with C in Trans to RHD possess complete D antigen structures. The allele that carries C is in trans (or opposite position) from the allele carrying RHD. As a result, the position of the C antigen in relationship to the D antigen interferes with the expression of the D antigen. This can be a weakened expression of D antigen; however, D antigen is still present. These patients can receive D-positive RBCs without the implication of an Rh-mediated transfusion reaction.
In DNA sequencing, multiple fluorescence labeled nucleotides are commonly separated using what type of test? Serum protein electrophoresis (SPEP) Capillary electrophoresis (CE) Two-dimensional electrophoresis HPLC
Capillary electrophoresis (CE) Capillary electrophoresis is used in DNA sequencing and several other molecular diagnostic procedures to separate amplified products.
This parasite measures 8 µm and is found in the stool. It may easily be mistaken for fecal debris or reported incorrectly as a nonpathogenic fecal contaminant. Entamoeba coli cyst Endolimax nana trophozoite Dientamoeba fragilis cyst Dientamoeba fragilis trophozoite
Dientamoeba fragilis trophozoite Dientamoeba fragilis is a flagellated intestinal protozoan. The trophozoites of Dientamoeba fragilis measure from 5-15 µm and are the only trophozoites of protozoan flagellates that contain two nuclei with each made up of 4 to 8 chromatin dots, as is shown in the image. Most other trophozoites of the protozoan flagellates contain a single nucleus.
Ninety-nine percent of lead absorbed in the body is taken up by what after absorption? Lungs Gastrointestinal tract Heart Erythrocytes
Erythrocytes Ninety-nine percent of lead is taken up first by the erythrocytes which causes interference with heme synthesis. Lead is mostly absorbed through the lungs (respiration) and gastrointestinal tract but is not taken up by these organs, nor the heart. It is taken up by the erythrocytes before being distributed into soft tissue and bone.
All of the following represent a 2-week temporary deferral from donating blood or blood products EXCEPT: Measles (rubeola) vaccine German measles (rubella) vaccine Mumps vaccine Polio vaccine
German measles (rubella) vaccine A potential blood donor who has received a German measles (rubella) vaccine is deferred for 4 weeks following the vaccination.
Which of the following conditions will cause a positive reagent strip blood result due to hematuria? Hemolytic anemia Severe burns Glomerulonephritis Dehydration
Glomerulonephritis Hematuria may be caused by glomerulonephritis, renal calculi, and pyelonephritis. Hemoglobinuria, on the other hand, can be caused by hemolytic anemia and severe burns. Dehydration will not cause hematuria.
A spectrophotometric scan of amniotic fluid may be valuable in the determination of which of the following conditions: Neural tube defects Maternal hypertension Hemolytic disease of the newborn Maternal diabetes
Hemolytic disease of the newborn Amniotic fluid bilirubin is elevated in hemolytic disease of the newborn. It is determined by using the absorbance spectrum of amniotic fluid to determine the increase in absorbance at 450nm, which is the absorbance peak for bilirubin. This value, along with the gestational age, are used in Liley's three zone chart to determine the risk of severe fetal hemolysis.
Recombinant Factor IX is indicated for which of the following? Hemophilia A Hemophilia B Hemophiliacs with inhibitors Persons with acquired Factor VII deficiency
Hemophilia B Persons with hemophilia B are lacking Factor IX. Recombinant Factor IX is used to treat patients with hemophilia B. Factor VIII concentrates are indicated for persons with hemophilia A and persons with von Willebrand's disease. Factor VIIa concentrates are indicated for persons demonstrating inhibitors with hemophilia A or B and for persons with Factor VII deficiency.
The primary mechanism responsible for glomerular filtration is: Osmotic gradient Concentration of blood components Rate of blood flow through the kidneys Hydrostatic differential in glomerular tufts
Hydrostatic differential in glomerular tufts
What are Howell-Jolly bodies composed of? Hemoglobin DNA Iron RNA
Iron Howell-Jolly bodies are residual fragments of DNA within erythrocytes. They may be seen in pernicious anemia and thalassemias. RBC inclusions composed of precipitated hemoglobin are called Heinz bodies, seen on supravital stains. RBC inclusions composed of aggregates of iron are called Pappenheimer bodies. RBC inclusions composed of RNA are called basophilic stippling.
Proteolytic enzyme techniques may be useful in identifying which of the following antigen groups: Kell system Kidd system MNS system Duffy system
Kidd system
CD5 antigen is normally found on which of the following lymphocyte populations? Mature T cells Normal B cells Both mature T cells and normal B cells None of the above, CD5 is not a lymphoid marker
Mature T cells The cluster of differentiation or CD system was developed to identify antigens on the surface of blood cells using monoclonal antibodies in flow cytometry. CD5 is a lymphoid marker present on mature T cells but is not present on normal B cells.
Which of the following medications is considered an antineoplastic drug? Cyclosporine Methotrexate Clozapine Tacrolimus
Methotrexate
Identify the nucleated cell in the image. Neutrophil Monocyte Lymphocyte Basophil
Monocyte Monocytes typically have a loose/lacy chromatin pattern in the nucleus with plenty of pale blue cytoplasm.
A tech is working with a small Gram-negative coccobacillus that may be Burkholderia pseudomallei. Which of the following tests could the tech use to rule out this organism? Growth on MacConkey agar Oxidase negative Indole negative Resistant to polymyxin B or colistin
Oxidase negative Burkholderia pseudomallei is an oxidase-positive organism, thus if the tech is working with an organism that is oxidase negative, they can rule out B. pseudomallei (and B. mallei) as identifications for the organism. Burkholderia pseudomallei is a Gram-negative coccobacillus that grows slowly at 24 hours but forms larger gray colonies at 48 hours. Other characteristics of the organism include growth on MacConkey agar, indole negative, and resistance to polymyxin B or colistin.
What is the BEST type of microscopy for performing manual platelet counts? The correct answer is highlighted below Electron Dark-field Light Phase contrast
Phase contrast Phase-contrast microscopy can help to better define the outline of the platelets over regular light microscopy, making them easier to count and allowing for more accurate results. Dark-field and electron microscopes are not used for platelet counting.
Which of the following viral families contains DNA as its nucleic acid? Paramyxoviridae Rhabdoviridae Poxviridae Orthomyxoviridae
Poxviridae The Poxviridae family viruses are the some of the largest viruses and contain dsDNA. Examples of viruses in this family are Variola virus and Monkeypox virus.
Which characteristic best describes IgG antibodies produced against red blood cells? Are naturally occurring Cannot be identified using the AHG test React best at room temperature React best at 37o Celsius
React best at 37 Celsius
Adult cestodes are able to attach to the human intestine by which structure? Strobila Integument Proglottids Scolex
Scolex The scolex serves as the mechanism by which adult cestodes attach to the human intestine. The strobila is the body of a tapeworm, excluding the head and neck region. The integument is the outer body covering that allows the adult worm to obtain nourishment from the host. The proglottids are the major portion of the body of the tapeworm that contains the reproductive organs and often eggs.
Which of the following conditions/findings is most likely associated with the peripheral blood picture in the photomicrograph? Hereditary spherocytosis Lead poisoning Transfusion dimorphism Folic acid deficiency
Transfusion dimorphism
Oliguria is usually correlated with: Acute glomerulonephritis Diabetes mellitus Hepatitis Tubular damage
Acute glomerulonephritis Acute glomerulonephritis is closely associated with oliguria (decreased urine output), and occasionally anuria (no urine output).
Red blood cells with a positive DAT cannot be tested accurately with blood typing reagents that require an indirect antiglobulin technique unless they have been treated with all of the following (to dissociate IgG from the RBC membrane) EXCEPT: Chloroquine diphosphate Ficin ZZAP Albumin
Albumin Albumin would not be an effective way to remove IgG bound to the RBC's so that further testing could be performed.
The serum of which of the following individuals may agglutinate group A1 cells? A2 individual A1B individual A1individual Newborn
A2 individual Approximately 4% of individuals with A2 blood type will have Anti-A1 antibodies in their serum. Individuals with some rarer A subgroups may also have Anti-A1 in their serum. Agglutination will occur if the serum from any of these individuals is mixed with A1 red cells.
What is the BEST technique for monitoring the severity of hemolytic disease of the fetus and newborn (HDFN)? Amniocentesis Doppler ultrasound Antibody titration Cordocentesis
Doppler ultrasound Doppler ultrasonography can measure blood flow velocity, which allows for the severity of fetal anemia to be determined without invasive methods. This creates a safer alternative than amniocentesis for fetal monitoring and has largely replaced serial amniocentesis for predicting the severity of HDFN.
Which of the following combination of globin chains comprise Hemoglobin H? Two alpha, two beta Two alpha, two gamma Four beta chains Four alpha chains
Four beta chains Hemoglobin H is a tetramer made of four beta-globin chains. Hemoglobin H occurs when there is very limited alpha chain availability used to make normal hemoglobin A. Hemoglobin H forms in those affected with alpha thalassemia major as well as in people with the combination of two-gene deletion alpha thalassemia and hemoglobin Constant Spring. Two alpha, two betas is normal adult Hgb A Two alpha, two gammas is fetal hemoglobin Hgb F Four alpha chains cannot form a tetrad because they are highly insoluble and precipitate within the cell.
Vitamin D is formed in the skin and hydroxylated in two places before it is in its active form of 1,25-dihydroxy vitamin D. Where does the second hydroxylation occur? Liver Kidneys Skin Intestines
Kidneys Vitamin D is first hydroxylated in the liver, forming 25-hydroxy vitamin D. The second hydroxylation occurs in the kidneys to form 1,25-dihydroxy vitamin D. The skin and intestines do not hydroxylate the hormone.
What is the first-line treatment for moderate to severe hemophilia A? Platelets Lyophilized Factor VIII concentrate Factor IX complex Cryoprecipitated AHF
Lyophilized Factor VIII concentrate
Illustrated in the photograph is a classic example of "ringworm" as may be observed in a young child, possibly contracted from the spores of an infected dog or cat. The microscopic morphology of the dermatophyte causing this infection is illustrated in the lactophenol blue-stained mount photomicrograph. Select the dermatophyte causing this type of infection. Microsporum gypseum Microsporum canis Trichophyton tonsurans Epidermophyton floccosum
Microsporum canis Microsporum canis is the correct response. Characteristic is the production of spindle-shaped (fusiform) multi-celled macroconidia that are pointed at the tip and may be slightly turned to one side. The outer wall is slightly thickened with a prickly(echinulate) surface. Not shown in this photomicrograph are background hyphae from the sides of which small, scattered microconidia are produced.
Hippurate hydrolysis is an important characteristic in the definitive laboratory identification of the beta-hemolytic streptococci. The positive ninhydrin reaction, seen in the left tube in the photograph, is produced by: Streptococcus agalactiae Streptococcus pyogenes Streptococcus pneumoniae Streptococcus dysgalactiae subsp. equisimilis
Streptococcus agalactiae Streptococcus agalactiae (group B beta-hemolytic streptococcus) is unique among the streptococci (except for occasional strains of Group G streptococci) in its ability to hydrolyze hippurate to benzoic acid and glycine. The positive blue reaction seen in the left tube in the photograph illustrates the presence of glycine, after the addition of ninhydrin reagent.
What is the maximum recommended amount of time a specimen without additive or anticoagulant should be allowed to clot before centrifugation? Two hours 30 minutes Three hours 10 minutes
Two hours A specimen without additive or anticoagulant should not be held for more than two hours prior to centrifugation because some of the analyte levels (such as glucose) may be falsely decreased due to cellular consumption or falsely increased (such as potassium) due to hemolysis. It should be allowed to clot for at least 30 minutes prior to centrifugation. Incomplete clotting of the specimen will leave small fibrin residue in the serum, which would interfere with testing or clog the testing instrument probe or tubing.
The serum from a patient of African American descent is reactive with all screening and panel cells. Which antibody directed to a high incidence antigen is most likely to be present? Anti-Lub Anti-Jk3 Anti-U Anti-Ku
Anti-U The U antigen is located on glycophorin B, a glycoprotein that carries the S, s, and U antigens in the MNS blood group system. Individuals who are U-negative are also S-s- and are of black descent. This phenotype is never found in the white population. The U antigen is present in more than 99% of the population.
In which of the following cases should Rh Immune Globulin (RhIG) be given? Ectopic pregnancy Rh positive mother carrying an Rh-negative fetus Rh positive mother carrying an Rh-positive fetus Rh negative mother with anti-D formed from previous pregnancy
Ectopic pregnancy When an ectopic pregnancy occurs, the blood type of the fetus can usually not be determined but it is possible for fetal blood to enter maternal circulation. Therefore, RhIG is given to protect the mother from forming an anti-D which could pose a risk to future pregnancies. This is also done in cases of abortions and stillbirths when the blood type of the fetus cannot be determined.
All of the following factors are involved in the initial contact phase of the intrinsic pathway, EXCEPT: Factor XII Fitzgerald Factor (high-molecular weight kininogen) Fletcher Factor (prekallikrein) Factor X
Factor X Factor X is part of the common pathway and is activated by both intrinsic and extrinsic pathways (according to the in vitro model of coagulation). Fitzgerald and Fletcher Factors are required to complete activation of Factor XII during the contact phase, which initiates the intrinsic coagulation pathway.
A known sickle cell trait patient has a hemoglobin electrophoresis test performed. Which of the following hemoglobin percentage sets would most closely match this patient's diagnostic state? Hgb A = 90%, Hgb S = 8%, Hgb A2 = 2%, Hgb F = 0% Hgb A = 60%, Hgb S = 38%, Hgb A2 = 2%, Hgb F = 0% Hgb A = 40%, Hgb S = 58%, Hgb A2 = 2%, Hgb F = 0% Hgb A = 25%, Hgb S = 70%, Hgb A2 = 2%, Hgb F = 3%
Hgb A = 60%, Hgb S = 38%, Hgb A2 = 2%, Hgb F = 0% Patients with sickle cell trait commonly have Hgb A values between 40 and 60%, Hgb S values between 20 and 40%, and Hgb A2 values between 2 and 3%.
Which of the following methods may be employed to definitively identify Bence-Jones proteins? Immunoelectrophoresis Sulfosalicyclic acid precipitation Heat precipitation at 40-60 C Urine dipstick
Immunoelectrophoresis Bence-Jones protein is a protein that is excreted by persons with multiple myeloma, a myeloproliferative disorder of the immunoglobulin-producing plasma cells. The protein, which is markedly elevated in blood serum, is filtered through the kidneys in quantities that exceed the tubular reabsorption capacity. Consequently, it is excreted in the urine. All suspected cases should have protein and immunoelectrophoresis performed on both serum and urine.
Which of the following analytes would be decreased due to delay in centrifugation? Ionized Calcium Potassium ALT AST
Ionized Calcium The specimen should not be delayed for more than two hours prior to centrifugation because some of the analyte levels (such as glucose, ionized calcium, bicarbonate, folate, etc.) may be falsely decreased due to cellular consumption or falsely increased (such as potassium, ALT, AST, creatinine, etc.) because they are released over time from cells into serum or plasma.
The hematology laboratory is experiencing instrument downtime. The laboratory has a backup method for hemoglobin, and hematocrit testing that is being used until the instrument is repaired. The hematologist calls and asks if you can provide any of the red blood cell indices. Which of the indices, if any, can you provide for the hematologist? MCV and MCH MCH and MCHC MCH only MCHC only
MCHC only Hemoglobin and hematocrit are required to calculate the MCHC. Since both of these values are available from the backup instrument, MCHC can be calculated.
The end product of fermentative metabolism of the Escherichia, Salmonella, and Shigella genera is which of the following? CO2 Nitrogen gas Pyruvic acid Various mixed acids
Various mixed acids Although the fermentation of glucose passes through pyruvic acid as a pivotal compound, the end products of fermentative metabolism are the mixed acids such as acetic, formic, butyric, propionic, etc. for Escherichia, Salmonella, and Shigella genera
The most significant class of microbial targets for Natural Killer (NK) cells is: Bacteria Parasites Viruses Fungi
Viruses
In the antibody screening test, at what phase of reactivity is it most important to read the reactions for detection of clinically significant antibodies? 4°C Immediate spin 37°C AHG
AHG A reading must be done at the AHG phase in the antibody screen procedure. The purpose of this is to detect clinically significant antibodies (IgG) which are known to potentially cause hemolytic transfusion reactions or hemolytic disease of the newborn. Immediate spin (IS) reading would detect the presence of IgM antibodies, primarily. A 4°C reading may be performed to enhance reactivity of an IgM cold antibody. These antibodies are not considered clinically significant if the reaction occurs at the IS phase only. A positive reading at 37°C may indicate the presence of a clinically significant antibody that may cause hemolysis.
Which of the following analytes would be increased due to delay in centrifugation? Bicarbonate Folate Ionized Calcium ALT
ALT The specimen should not be delayed for more than two hours prior to centrifugation because some of the analyte levels (such as glucose, ionized calcium, bicarbonate, folate, etc.) may be falsely decreased due to cellular consumption or falsely increased (such as potassium, ALT, AST, creatinine, etc.) because they are released over time from cells into serum or plasma.
A false-positive result can be observed in a rheumatoid factor latex agglutination procedure reaction due to: Poor specimen quality Antigen excess Excessive complement levels Juvenile idiopathic arthritis
Antigen excess Technical false-positive results may be obtained if a patient's serum is lipemic, hemolyzed, or heavily contaminated with bacteria or if the test result is read after the specified time.
This 20 µm in diameter cyst was seen in a trichrome stained mount of a stool specimen from a patient with low-grade, intermittent diarrhea. What is the presumptive identification? Entamoeba histolytica Entamoeba coli Entamoeba hartmanni Iodamoeba bütschii
Entamoeba coli Entamoeba coli is the correct response. Note that there are 5 nuclei, each with a distinctly eccentrically placed karyosome and a chromatin ring that is irregular in width and blotchy in distribution. The usual size range is 15-25 µm.
An eleven-year-old girl was seen in the emergency room with sudden onset of sore throat, fever, and dysphagia, the latter accompanied by an intermittent sensation of choking. The bacterial species shown in the upper photograph of a chocolate agar plate was recovered from a throat culture. The most likely bacterial species based on the test shown in the lower photograph is: Corynebacterium diphtheriae Haemophilus influenzae Haemophilus parainfluenzae Abiotrophia (nutritionally variant streptococci)
Haemophilus influenzae Acute epiglottitis, both in the pediatric and the adult population, may present a life-threatening emergency from airway obstruction. Haemophilus influenzae type b is the cause of this acute infection.
What changes in potassium and sodium serum results may occur with diuretic use? Decrease in both. Increase in both. Increase in potassium and decrease in sodium. Decrease in potassium and increase in sodium.
Increase in potassium and decrease in sodium. Drugs can affect various analytes. For example, diuretics can cause hypokalemia (decreased potassium in the blood) and hyponatremia (decreased sodium in the blood) in patients through renal loss. Sometimes diuretics are used to dilute the specimen to try to cheat on drug testing.
Which of the following is correct regarding C-reactive protein (CRP)? Is a highly specific test Corresponds to serum complement levels Is usually elevated in pediatric bacterial infections Does not react with pneumococcal C-polysaccharide
Is usually elevated in pediatric bacterial infections C-reactive protein was first found to precipitate pneumococcal C-polysaccharide in patients who had recovered from pneumococcal pneumonia. It was subsequently found to be elevated in numerous other conditions. It is often elevated in pediatric bacterial infections, and usually not elevated in pediatric viral infections, and thus may help the pediatrician to differentiate these entities. It can also be used to follow the disease activity in autoimmune conditions.
A sputum specimen submitted for culture is brick red in color. The organism causing this sputum color also has a distinct polysaccharide capsule and is non-motile. What organism can be associated with this sputum? Yersinia Pasteurella Salmonella Klebsiella
Klebsiella Klebsiella is the bacterial species that causes necrotizing pneumonia characterized by the production of brick-red sputum and offers a distinct polysaccharide capsule.
Which one of the following blood group systems may show a cell typing change during pregnancy? Rh MNS Lewis Duffy
Lewis The Lewis group antigens are not intrinsic to the red blood cell membrane and can be shed from red blood cells. A distinguishing feature about these blood group antigens is that during pregnancy their expression is diminished on the mother's red blood cells. This can result in the formation of antibodies that are not clinically significant (IgM in nature).
What causes the hemolysis associated with malarial infections? Multiplication of merozoites within erythrocytes Invasion of erythrocytes by sporozoites Host's immunologic response to damaged erythrocytes Toxins produced by the malarial organisms
Multiplication of merozoites within erythrocytes
Donation of which apheresis blood product more than once every four weeks requires monitoring of total plasma protein and antibody levels? Red cell apheresis Plateletpheresis Plasmapheresis Leukapheresis
Plasmapheresis Plasma levels of total protein, IgG, and IgM levels must be monitored every four months in plasmapheresis donors because levels of these and other proteins present in plasma decrease following plasmapheresis.
This antinuclear antibody (ANA) pattern is characterized by granular staining in the nuclei of the interphase cells (a). There is also an absence of staining in the chromosomal area of the metaphase mitotic cells (b). The slide is viewed using fluorescent microscopy. Which pattern is this? Homogeneous Speckled Nucleolar Centromere
Speckled The image shown displays the features of a speckled ANA pattern: granular/speckled staining in the nuclei of the interphase cells (a) and absence of staining in the chromosomal area of the metaphase mitotic cells
This isolate is a catalase negative, gram positive coccus on sheep blood agar. The P disk has 5µg of optochin and the zone around it is 16 mm. It has been streaked perpendicular to a beta-lysin producing strain of Staphylococcus aureus. The presumptive identification is: Streptococcus pneumoniae Streptococcus agalactiae Streptococcus pyogenes Viridans Streptococcus
Streptococcus pneumoniae
The body of an adult tapeworm is known as the: Proglottid Scolex Strobila Rostellum
Strobila Strobila is the correct answer because the body or strobila of a tapeworm is made up of segments known as proglottids. Proglottid is incorrect because proglottids are a chain of egg-producing units. Scolex is incorrect because the scolex is a specialized structure for attachment that is found at the anterior end of the worm. Rostellum is incorrect because this allows the organism to attach to the human intestines. The rostellum (found at the crown of the scolex) may be smooth or armed with hooks.
Cytomegalovirus (CMV) appears to suppress cell-mediated immune functions. Which of the following is a characteristic finding in persons infected with CMV? Increased CD4+ cells; decreased CD8+ cells Increased CD4+ cells; increased CD8+ cells Decreased CD4+ cells; increased CD8+ cells Decreased CD4+ cells; decreased CD8+ cells
Decreased CD4+ cells; increased CD8+ cells The correct answer is 'decreased CD4+ cells; increased CD8+ cells'. Cytomegalovirus infects neutrophils, which transport the virus to other areas of the body. The virus is known to suppress cell-mediated immunity and cause the production of autoantibodies that are cytotoxic toward lymphocytes. CD4+ cells represent T helper lymphocytes, while CD8+ cells represent T suppressor lymphocytes. Thus, what is commonly seen in CMV infections are a decrease in T helper cells and an increase in T suppressor cells.
A deficiency in which of the following vitamins is associated with "rickets"? Thiamine Vitamin C Vitamin A Vitamin D
Vitamin D Vitamin D deficiency can cause rickets. Vitamin A deficiency can cause night blindness. Thiamine (vitamin B1) deficiency can cause Beriberi. Vitamin C deficiency can cause Scurvy.
Red blood cell units that contain CPD (citrate-phosphate-dextrose) can be stored for up to how many days? 21 days 28 days 35 days 42 days
21 days Red blood cell units that contain CPD or CP2D may be stored for up to 21 days. Irradiated red cell units may be stored for up to 28 days or the original expiration date, whichever occurs first. Red cell units that contain CPDA-1 may be stored for up to 35 days. Red cell units that contain an additive solution may be stored up to 42 days.
Troponin I is used frequently to assess acute myocardial infarctions (AMI). If a patient has experienced an AMI, at what point (approximately) will the troponin I begin to increase and how long will it stay increased? 12-24 hours, 5-10 days 6-10 hours, 1-2 days 3-12 hours, 7-14 days 3-6 hours, 1-2 days
3-12 hours, 7-14 days
Identify the urine sediment element shown by the arrow. Mucus thread Cylindroid Fiber Amorphous urates
Cylindroid The correct answer is cylindroid. Cylindroid is a type of varied morphology of hyaline casts. Hyaline casts consist of normal parallel sides and rounded ends. On the other hand, cylindroid forms have one tapered end and convoluted shapes that indicate the aging of the cast matrix. Mucus appears as single or clumped threads with a low refractive index. Fiber in a urine specimen from clothing and diapers can be confused with casts by inexperienced techs. To differentiate fiber artifacts from most casts, the specimen can be examined under polarized light. Fibers polarize while most casts other than fatty casts do not. Amorphous urates appear as yellow-brown granules. They could be in clusters that resemble granular casts. Upon refrigeration of urine sample, amorphous urates produce pink sediment.
This photograph shows a positive reaction in each of the tubes with the tube on the left containing esculin medium and the tube on the right containing heart infusion broth with 6.5% sodium chloride. The bacterial species that characteristically produces these reactions is: Staphylococcus aureus Streptococcus bovis Enterococcus faecalis Listeria monocytogenes
Enterococcus faecalis Of the bacterial species listed, only Enterococcus faecalis hydrolyzes esculin (black color in the medium) and can grow in a culture medium containing 6.5% sodium chloride (turbid broth and yellow color).
A unit of leukocyte-reduced red blood cells must retain at least what percentage of red blood cells following leukoreduction? 65% 75% 85% 95%
85% The American Association of Blood Banks (AABB) standards state that a unit of leukocyte-reduced red blood cells must contain at least 85% of the red cells as the original unit.
Although it is actually non-motile, which Gram-positive, catalase-negative organism produces "bottle brush" growth from the stab inoculation in a gelatin agar tube at 22° C, along with hydrogen sulfide production in TSI agar? Eikenella corrodens Moraxella catarrhalis Listeria monocytogenes Erysipelothrix rhusiopathiae
Erysipelothrix rhusiopathiae Erysipelothrix rhusiopathiae may be differentiated from other Gram-positive, catalase-negative bacilli by H2S production *********** of TSI. It produces a characteristic "bottle brush" appearance from the stab in a gelatin agar tube, as the growth is perpendicular to the stab lines, appearing as bristles.
These adult nematodes are round, elongated, typically look like an earthworm and can be found in decaying vegetation or moist soil. Of the following organisms listed, which one is a nematode? Ascaris lumbricoides Diphyllobothrium latum Taenia solium Hymenolepis diminuta
Ascaris lumbricoides Ascaris lumbricoides or roundworms are a common parasite found worldwide. Ascaris eggs remain viable and infective more often than eggs of any other helminth species. Diphyllobothrium latum, Taenia solium, and Hymenolepis diminuta are all cestodes. Cestodes are also known as tapeworms and are capable of self-fertilization.
All of the following fungi are listed with their appropriate morphology, EXCEPT: Syncephalastrum sp. produce merosporangia Fusarium sp. produce macroconidia Coccidioides immitis produces arthroconidia Aspergillus sp. produce ascospores
Aspergillus sp. produce ascospores Aspergillus sp. produce chains of conidia on the end of phialides. Ascospores, sexual spores, are produced by Pseudallescheria boydii. Syncephalastrum sp. produce merosporangia which appear as "daisy petals" around a columella. Fusarium sp. produce macroconidia that are canoe-shaped and microconidia that are elliptical shaped arranged in a "Chinese-letter" pattern. Coccidioides immitis produces arthroconidia which are hyphae that have vegetative cells or disjunctor cells between each arthroconidia which gives an alternating staining pattern that is typical of arthroconidia and helps to distinguish them from septate hyphae.
All of the following are Lancefield carbohydrate antigens found on beta-hemolytic Streptococcus species. All of the following antigens are found on organisms from the Streptococcus anginosus group EXCEPT? A B F G
B Group B is the correct answer because the group B Lancefield carbohydrate antigen is found on Streptococcus agalactiae. Group A is the incorrect answer because this Lancefield carbohydrate antigen is commonly found on Streptococcus pyogenes; however, it can also be found on Streptococcus anginosus, which is found in the Streptococcus anginosus group. Streptococcus anginosus can be separated from Streptococcus pyogenes by its small colony size on blood agar and the detection of Group A, C, F, and G carbohydrate group antigens. Group F is the incorrect answer, but this carbohydrate antigen is the most common Lancefield antigen detected in the Streptococcus anginosus group. Streptococcus anginosus and Streptococcus constellatus can both have Group F antigens. Group G is incorrect because it is found on organisms in the Streptococcus anginosus group, specifically Streptococcus anginosus and Streptococcus dysgalactiae. Streptococcus dysgalactiae has a large colony size whereas Streptococcus anginosus has a small colony size.
Central Tolerance in the human immune defense system operates by: Clonal deletion of T cells and clonal editing of B cells Cellular inactivation by weak signaling without a co-stimulus Clearance of apoptotic bodies Antigen segregation
Clonal deletion of T cells and clonal editing of B cells Central tolerance is characterized by the elimination of immature lymphocytes in primary lymph organs. It is controlled by a mechanism of clonal deletion of T cells and clonal editing of B cells. There are layers of self-tolerance in the human immune system influenced by cellular activity and soluble mediators. The bone marrow and thymus are the sites of action of central tolerance. Central tolerance is initiated during fetal development by the elimination of cells with the potential to react strongly with self-antigens. Cellular inactivation by weak signaling without a co-stimulus describes the mechanism of the layer of the human immune system, peripheral tolerance. Peripheral tolerance is characterized by the elimination of mature lymphocyte clones that occurs in peripheral lymph tissues or clonal anergy. Negative selection is called peripheral tolerance. T cells in the thymus that lack any affinity for self-peptide-self MHC complexes are eliminated in a process called negative selection. B cells undergo negative selection before achieving immunocompetence. Clearance of apoptotic bodies occurs in secondary lymphoid tissue and sites of inflammation. It is characterized by the removal of self-antigen and induction of a negative signal. The layer of tolerance, antigen segregation, takes place in the peripheral organs such as the thyroid and pancreas. The mechanism of action is a physical barrier to self-antigen and induction of a negative signal.
The dimorphic molds exist in both mold and yeast forms depending on the temperature of incubation. In the laboratory, when cultures are incubated at 30o C, all of the dimorphic fungi will produce mold colonies, usually within 10 - 14 days. When cultures are incubated at 35o - 37o C, yeast colonies develop usually within 3 - 5 days, with the exception of one of the dimorphic species. From the options shown below, select the genus that does not produce yeast colonies when cultures are incubated at a higher temperature. Blastomyces dermatitidis Coccidioides immitis Histoplasma capsulatum Sporothrix schenckii
Coccidioides immitis Coccidioides immitis is the correct response. Coccidioides immitis is unable to convert from the mold phase to the yeast phase because the yeast form only develops within the infected tissues of the human or animal host. The yeast form can be seen as a spherule, which varies in size and contains endospores that are released into the surrounding area. Yeast colonies cannot be produced directly or from the subculture of a mold colony.
Which of the following cells would be increased if the cerebrospinal fluid (CSF) of a patient suspected of having multiple sclerosis? Neutrophils Lymphocytes Macrophages Monocytes
Lymphocytes Increased lymphocytes are typically associated with viral infections. There are also noninfectious causes for increased lymphocytes, such as multiple sclerosis. Infectious causes for increased lymphocytes include viral meningoencephalitis, aseptic meningitis syndrome, fungal meningitis, and syphilitic meningoencephalitis. Neutrophils in the CSF are indicative of a bacterial infection. Several infectious disorders result in an increase in neutrophils, such as untreated bacterial meningitis, viral meningoencephalitis, early tuberculosis, and mycotic meningitis. Macrophages can be seen in cases of meningitis or meningeal inflammation, infectious diseases, CNS leukemia, lymphoma, and malignant melanoma. Increased monocytes can be seen in tuberculous meningitis, syphilis, subarachnoid hemorrhage, and viral encephalitis.
A 41-year-old man is admitted to the hospital complaining of a decreased frequency of urination, a constant bloated feeling, weight gain, and mild edema of the ankles and eyes. Urinalysis results are as follows: Color: pale yellow Microscopic Results: Clarity: clear RBCs 0-2pH: 5.0 WBCs 0-2 Sp. Gravity 1.010 Casts: 2-5 hyaline, 0 - 3 fatty casts, 0 - 2 waxy casts Glucose: 2+ Few transitional epithelial cells Ketones: negative Few oval fat bodies Protein- 3+Blood: moderate Bilirubin: negative Bacteria: negative Urobilinogen: normal Nitrate: negative**A large amount of white foam was noted. Based on the urinalysis report above, the MOST probable diagnosis is: Acute pyelonephritis Nephrotic syndrome Acute glomerulonephritis Lipiduria of unknown etiology
Nephrotic syndrome Nephrotic syndrome would best match the clinical symptoms and laboratory findings. Nephrotic syndrome is caused by damage to the kidneys, especially the basement membrane of the glomerulus, which causes abnormal excretion of protein and red blood cells in the urine. Fats are also present in the urine in most cases. A foamy appearance of the urine is a key characteristic of this condition. Clinical symptoms include: Swelling Weight gain from fluid retention Poor appetite High blood pressure
The following steps were used in a procedure to identify M. kansasii: 1 - Extraction 2 - Denaturization 3 - Hybridization 4 - Hydrolysis of excess reagent 5 - Detection of acridinium ester Which of the following methods has been described? Polymerase chain reaction Indirect fluorescent microscopy Nucleic acid probes Lysis-centrifugation
Nucleic acid probes The correct response is nucleic acid probes. The steps listed are included within the nucleic acid probes procedure for M. kansasii. The correct sequence for nucleic acid probes is extraction, denaturization, hybridization, hydrolysis of excess reagent, and detection of acridinium ester. In polymerase chain reaction, a small segment of DNA is expanded by binding DNA primers to segments at the ends of the DNA to be expanded. Thermal cycling creates single stranded DNA followed by cooling that enables the primers to anneal to the target DNA. This is followed by primer extension, where DNA synthesis occurs by forming a copy of the template DNA by adding nucleotides to the hybridized probe. Indirect fluorescent microscopy is used to detect antigens or antibodies. To detect antigen, the specimen is fixed onto a slide and an unlabeled antibody directed against the microorganism to be detected is added to the slide and permitted to react. After incubation, unbound antibody is washed away, and a second fluorescein-labeled antibody is added which will complex with the first antibody that has bound to the antigen. To detect antibody, antigens of the microorganism are fixed onto a microscope slide and the specimen added to the slide. After incubation, excess antibody is washed away and a fluorescein labeled conjugate added. Fluorescence indicates a positive reaction. Lysis centrifugation is used in some blood culture systems to enhance the recovery of bacteria and some fungi from blood cultures. Saponin is used to lyse the red cells and then the blood is centrifuged. The sediment is vortexed, and the entire sediment is plated onto agar. Lysis centrifugation can provide more rapid recovery and isolation from blood cultures.
Donated red cell units contain which substance to stabilize the pH of the unit during storage? Dextrose Adenine Citrate Sodium biphosphate
Sodium biphosphate Sodium biphosphate helps to stabilize the pH of the red cell unit during storage by preventing the pH from excessively becoming more acidic. Dextrose is used in ATP generation. Adenine supports ATP synthesis. Citrate chelates calcium to prevent coagulation.
Which of the following conditions is most likely when an oligoclonal band is seen in CSF electrophoresis without a corresponding serum peak? Lymphoproliferative disorder Viral meningitis Multiple sclerosis Traumatic lumbar puncture
Multiple sclerosis Oligoclonal bands are found in the gamma region of CSF electrophoresis of most patients with multiple sclerosis. These bands are not seen in the serum electrophoresis of the same patients and are caused by increased levels of IgG in the CSF. Other conditions that may show oligoclonal bands in CSF electrophoresis include, inflammatory conditions, Guillain-Barre syndrome, bacterial meningitis, viral encephalitis, neurosyphilis, and subacute sclerosing panencephalitis.
Contact dermatitis is mediated by: B lymphocytes Mast cells Polymorphonuclear cells T lymphocytes
T lymphocytes Contact dermatitis is an example of a cell-mediated (type IV) hypersensitivity reaction that involves macrophages and T lymphocytes. When an antigen comes in contact with the skin, the antigen is processed by cells in the epidermis and comes in contact with T lymphocytes. T lymphocytes recognize the antigen as foreign and circulate through the bloodstream back to the epidermis. There, they release cytokines that produce an inflammatory response, causing a characteristic rash in the skin called contact dermatitis.
The purified protein derivative (PPD) test is also known as: Targeted tuberculin testing RPR QuantiFERON® assay SPOT TB® assay
Targeted tuberculin testing The purified protein derivative skin test is also known as a targeted tuberculin testing. This form of skin testing for Mycobacterium tuberculosis. It is performed by injecting 0.1 ml of tuberculin purified protein derivative (PPD) into the inner surface of the forearm.
The colonies seen in the upper frame, grown after 48 hours of incubation aerobically at 35°C, and the accompanying Gram stain in the lower frame are of an organism uncommonly associated with human disease; however, this organism has been associated with septicemia, bronchopneumonia, osteomyelitis and other infections, particularly in intravenous drug users. What is the most likely identification of the organism? Clostridium septicum Bacillus circulans Listeria monocytogenes Lactobacillus species
Bacillus circulans This isolate was identified as Bacillus circulans, which is consistent with the colony and Gram stain morphologies. The clue to the identification of the colony seen in the upper frame is the Gram stain in the lower frame, in which are seen short, rounded, gram positive bacilli, many of which possess distinct spores. Since the colonies grew aerobically, the presence of spores indicates Bacillus species. The colonies are spreading, smooth, yellow-white and non-hemolytic. The lack of hemolysis and the small size of the bacterial cells suggests a species other than Bacillus cereus, the species causing most human infections. Although B. circulans is most often considered a contaminant when isolated from clinical specimens, the patient's overall health status and history must be taken into consideration to determine if it is a cause of disease.
A swab is submitted for an influenza screen. The swab used is a cotton swab with a wooden shaft that was placed in a moist transport container. What is the most appropriate next step in this scenario? Call the RN or physician to confirm that the site of collection was the nasopharyngeal area. Call the RN or physician to let them know that the specimen is unacceptable, and it should be recollected. Proceed with processing the specimen in the LIS and begin testing. Do not proceed, the specimen is unacceptable, and you should throw the swab in the trash.
Call the RN or physician to let them know that the specimen is unacceptable, and it should be recollected. The specimen submitted is inappropriate for viral testing. Wood shafted swabs should not be used to collect samples for viral testing. The moist transport container is not appropriate for viral testing; only viral transport media should be used as a source of transport.
What would be the next step when an EDTA specimen had an automated platelet count of 61,000/mm3 and the platelets were surrounding the neutrophils on the differential? Report the automated platelet count since it is more accurate than a platelet estimate Warm the EDTA tube and repeat the automated platelet count Rerun the original specimen since the platelet count and blood smear estimate do not match Recollect a specimen for a platelet count without using EDTA
Recollect a specimen for a platelet count without using EDTA Occasionally platelet satellitosis can occur in some patient samples when collected in EDTA. The solution for this problem is to recollect in a different type of anticoagulated tube, usually a sodium citrate tube, to prevent the platelets from adhering to the neutrophils. The platelet count would be multiplied by 1.11 to account for the dilution of the blood sample with sodium citrate (9:1).
Type II Antibody-mediated hypersensitivity
associated with complement and Fc receptor-mediated recruitment and activation of leukocytes (neutrophils and macrophages). Opsonization and phagocytosis of cells. Abnormalities in cellular function, e.g., hormone or neurotransmitter receptor signaling. Types II and III are initiated by the interaction between antibodies, except IgE and antigen. Three different mechanisms of antibody-mediated injury exist in type II reactions: (1) Antibody-dependent, complement-mediated cytotoxic reactions characterized by the interaction of IgG or IgM antibody with the cell-bound antigen. (2) Antibody-dependent, cell-mediated cytotoxicity that depends on the initial binding of specific antibodies to target cell surface antigens. (3) Antireceptor antibodies that disturb the functioning of receptors. Transfusion reactions are an example of an antibody-dependent, complement-mediated cytotoxic reaction. Hyperacute graft rejection is also an example of a Type II hypersensitivity reaction.
Type III Immune complex-mediated hypersensitivity
associated with complement and Fc receptor-mediated recruitment and activation of leukocytes and tissue damage secondary to impaired blood flow. Type III reactions are caused by IgG, IgM, and possibly other antibody types. Immune complexes can cover a spectrum of biological activities, including suppression or augmentation of the immune response by interacting with T and B cells; inhibition of tumor cell destruction; and deposition in blood vessel walls, glomerular membranes, and other sites. These deposits interrupt normal physiologic processes because of tissue damage secondary to the activation of complement and resulting activities.
Type IV Cell-mediated hypersensitivity
associated with macrophage activation. Type IV is characterized by direct target cell lysis and cytokine-mediate inflammation. There are three defining characteristics of type IV hypersensitivity reactions: (1) Type IV delayed-type hypersensitivity involving antigen-sensitized T cells or particles that remain phagocytized in a macrophage and are encountered by previously activated T cells for a second or subsequent time. Delayed hypersensitivity is a major defense mechanism again various intracellular pathogens, including mycobacteria, fungi, and certain parasites. (2) Rejection of foreign tissue grafts, elimination of tumor cells bearing neoantigens. (3) Formation of chronic granulomas.