MLS Summative #20: EIA, Immunofluorescence, Toxicity, & Microbiology

MEDICAL LABORATORY SCIENCE 8. SUMMATIVE EXAM REVIEW QUESTIONS #20 + ANSWERS & RATIONALIZATIONS 1. 2. 3. 4. 5. 6. 7. In EIA, antigen or antibody is typically bound to: a. Liquid phase b. Semi-solid phase c. Solid-phase d. Any of these In EIA, which of the following can be used qualitatively to determine the presence of an antigen or antibody or quantitatively to determine the actual concentration of an analyte in an unknown specimen? a. Antibody b. Antigen c. Enzyme label d. Solid-phase Indirect immunofluorescence is similar to which type of enzyme immunoassay in terms of the performance of the assay? a. Competitive EIA b. Capture EIA c. ELISA d. Homogenous assay For immunofluorescence, the tissue should be: a. Fixed in formalin b. Fixed in alcohol c. Fixed in b-5 d. Unfixed Tissue for immunofluorescence must be: a. Fixed briefly in formalin and then frozen b. Frozen and then fixed in acetone c. Fixed in alcohol and paraffin processed d. Frozen and unfixed Pre-analytical phase: a. Patient identification b. Patient identification, test order accuracy c. Test order identification, blood culture contamination d. Test order accuracy, patient identification, blood culture contamination → Preanalytical (Preexamination) Phase ▪ Test order accuracy ▪ Patient identification ▪ Blood culture contamination ▪ Adequacy of specimen information → Analytical (Examination) Phase ▪ Accuracy of point-of-care-testing ▪ Cervical cytology/biopsy correlation ▪ Diabetes monitoring ▪ Hyperlipidemia screening → Postanalytical (Postexamination) Phase ▪ Critical value reporting ▪ Turnaround time ▪ Clinician satisfaction ▪ Clinician follow-up Formula weight: a. Molarity b. Normality c. Atomic weight d. Molecular weight 9. 10. 11. 12. 13. 14. 15. 16. 17. Serologic “to deliver” (TD) pipettes are identified by which of the following? a. Two etched bands near the top b. Self-draining capacity c. Dual-purpose pipette labels d. Blue graduation labels A highly sensitive laboratory instrument which can accurately measure mass in the sub-milligram range to a high degree of precision: a. Analytical balance b. Triple beam balance c. Graduated cylinder d. Volumetric flask All sealed centrifuge buckets should be loaded and unloaded in a/an: a. Incubator b. Dry heat oven c. Fume hood d. Biological safety cabinet Which monochromator specification is required in order to measure the true absorbance of a compound having a natural absorption bandwidth of 30 nm? a. 50-nm bandpass b. 25-nm bandpass c. 15-nm bandpass d. 5-nm bandpass → Bandpass refers to the range of wavelengths passing. through the sample. The narrower the bandpass, the greater the photometric resolution Nephelometry measures the light scatter of: a. Ions b. Macromolecules complexes c. Antibodies d. Soluble antigens Liebermann-Burchard test is used for chemical estimation of cholesterol. What is the function of acetic anhydride in the test? a. Reducing agent b. Alkalinizing agent c. Solvent and oxidizing agent d. Solvent and dehydrating agent Lipoprotein electrophoresis from origin to anode: a. HDL, LDL, VLDL, chylomicrons b. HDL, VLDL, LDL, chylomicrons c. Chylomicrons, LDL, VLDL, HDL d. Chylomicrons, VLDL, LDL, HDL True of hypernatremia: a. 135 mmol/L b. 140 mmol/L c. 145 mmol/L d. Vomiting Which of the following enhances calcium resorption from bone and renal tubular reabsorption? a. Parathyroid hormone b. Calcitonin c. Cortisol d. Aldosterone Which of the following stimulates calcium uptake by bone and causes decreased renal tubular reabsorption? a. Parathyroid hormone b. Calcitonin c. Cortisol d. Aldosterone 1 → Thyroid, Parathyroid Hormones, and other related substances: 18. Which of the following hormones involved in calcium regulation acts by decreasing both calcium and phosphorous? a. PTH b. Calcitonin c. Vitamin D d. Cortisol → Effects of thyroid and parathyroid hormones, and other related substances to certain electrolytes: 19. Of the following, which will most likely interfere with quantitation of thyroglobulin? a. Antithyroglobulin autoantibodies b. Thyroid-stimulating antibodies c. TSH receptor antibodies d. Thyroid peroxidase antibodies 20. Acute toxicity: a. Single exposure b. Short-term exposure c. Dose sufficient to cause immediate toxic effects d. All of these 21. All of the following refers to chronic toxicity, EXCEPT: a. Dose is sufficient to cause immediate toxic effects b. Repeated frequent exposure c. Exposure for extended periods for greater than 3 months and possibly years d. Doses are insufficient to cause an immediate response 22. Carbon monoxide expresses its toxic effects by causing a ______ shift in the oxygen–hemoglobin dissociation curve, resulting in: a. Right; increased amount of oxygen delivered to tissues b. Left; increased amount of oxygen delivered to tissues c. Right; decreased amount of oxygen delivered to tissues d. Left; decreased amount of oxygen delivered to tissues 23. Which substance has the longest detection time? a. Amphetamines b. Cocaine c. Benzodiazepines d. Marijuana 24. Classic approach to bacterial identification, and most identification strategies are still based on bacterial: a. Genotype b. Phenotype c. Both of these d. None of these 25. Function of iodine in Gram staining: a. Stains all bacteria purple b. Fixes crystal violet to cells c. Removes crystal violet from gram negative d. Stains gram negative pink 26. Addition of egg yolk to nutritive media: a. Basal medium b. Enriched medium c. Enrichment medium d. Selective medium 27. All of the following are differential media EXCEPT: a. Blood agar b. Chocolate agar c. MacConkey’s agar d. Eosin methylene blue agar 28. Green or brown zone around the colonies: a. Alpha hemolysis b. Beta hemolysis c. Gamma hemolysis d. Alpha prime hemolysis 29. Colonies that are irregular in shape and/or have irregular margins are likely to be ______ organisms: a. Aerobe b. Anaerobe c. Motile d. Glucose fermenter 30. Spreading growth on semisolid medium: a. Fermenter b. Nonfermenter c. Motile d. Nonmotile 31. Transport media: a. Preserve the viability of microorganisms in the specimen b. Allow multiplication c. Prevent specimen from drying d. All of these 32. Components of transport media, EXCEPT: a. Buffers b. Peptones c. Salts d. Nitrogen → Transport media are solutions of buffers with carbohydrates, peptones, and other nutrients (excluding growth factors) designed to preserve the viability of bacteria during transport without allowing their multiplication. → Transport media contains only buffers and salt. They do not contain nutritional ingredients such as carbon, nitrogen, or organic growth factors to prevent microbial multiplication. Addition of antibiotics and other substances like glycerol may be added for transporting specimens for tissue culture. 33. Iodophor: a. Iodine and alcohol b. Iodine and detergent c. Iodine and saline d. Iodine and water 2 34. When cleansing the skin with alcohol and then iodine for the collection of a blood culture, the iodine (or iodophor) should remain intact on the skin for at least: a. 10 seconds b. 30 seconds c. 60 seconds d. 5 minutes 35. Which of the following is a disinfectant? a. Benzalkonium chloride b. Chlorhexidine gluconate c. Household bleach d. Hydrogen peroxide 36. Which one of the following specimen requests is acceptable? a. Feces submitted for anaerobic culture b. Foley catheter tip submitted for aerobic culture c. Rectal swab submitted for direct smear for gonococci d. Urine for culture of acid-fast bacilli 37. When setting up a urine culture, a calibrated loop is used that delivers a specific amount of urine to the media plate. What is that amount? a. 0.01 or 0.001 mL of urine b. 0.10 or 0.01 mL of urine c. 0.001 or 0.0001 mL of urine d. None of the above is correct 38. Flocked swab: a. Flocked with cotton b. Flocked with gauze c. Flocked with cotton and gauze d. Flocked with nylon 39. Respiratory specimens are best collected with what type of swabs? a. Calcium alginate swabs b. Dacron or polyester-tipped swabs c. Swabs with cotton tips or wooden shafts d. All of the above are acceptable 40. Container for stool culture: a. Stuart's medium b. Amies medium c. Sterile, screw capped container d. Clean, leakproof container 41. A liquid fecal specimen from a three-month-old infant is submitted for microbiological examination. In addition to culture on routine media for Salmonella and Shigella, this specimen should be routinely: a. Examined for the presence of Entamoeba hartmanni b. Examined for the presence of Camylobacter sp c. Screened for the detection of enterotoxigenic Escherichia coli d. Placed in thioglycollate broth to detect Clostridium botulinum 42. MIC is the concentration of the: a. First tube with growth b. Last tube with growth c. First tube with no growth d. Last tube with no growth 43. The minimum concentration of antimicrobial agent needed to prevent visually discernible growth of a bacterial or fungal suspension. a. Minimum bactericidal concentration (MBC) b. Minimum inhibitory concentration (MIC) c. Both of these d. None of these 44. The minimum concentration of antimicrobial agent needed to yield a 99.9% reduction in viable colonyforming units of a bacterial or fungal suspension. a. Minimum bactericidal concentration (MBC) b. Minimum inhibitory concentration (MIC) c. Both of these d. None of these 45. Inoculum size for disk diffusion susceptibility testing: a. 1 x 104 CFU/spot b. 1.5 x 105 CFU/mL c. 1.5 x 108 CFU/mL d. 5 x 105 CFU/mL 46. Inoculum size for agar dilution susceptibility testing: a. 1 x 104 CFU/spot b. 1.5 x 105 CFU/mL c. 1.5 x 108 CFU/mL d. 5 x 105 CFU/mL 47. Inoculum size for broth dilution susceptibility testing: a. 1 x 104 CFU/spot b. 1.5 x 105 CFU/mL c. 1.5 x 108 CFU/mL d. 5 x 105 CFU/mL 48. Which of the following factors would make an organism appear to be more resistant on a disk diffusion susceptibility test? a. Too little agar in the plate b. Too many organisms in the inoculum c. The presence of 0.5% NaCl in the medium d. A medium with a pH of 7.4 49. In the Kirby-Bauer disc diffusion susceptibility test, which variable is critical when testing Pseudomonas species for antibiotic susceptibility to aminoglycosides? a. Incubation temperature b. Duration of incubation c. Cation content of media → Ca, Mg d. Depth of agar → Increased concentrations in: ▪ Decreased activity of aminoglycosides against P. aeruginosa ▪ Decreased activity of tetracyclines against all organisms (decreased concentrations have opposite effect) 50. In a disk diffusion susceptibility test, which of the following can result if disks are placed on the inoculated media and left at room temperature for an hour before incubation? a. The antibiotic would not diffuse into the medium, resulting in no zone b. Zones of smaller diameter would result c. Zones of larger diameter would result d. There would be no effect on the final zone diameter → A delay of more than 15 minutes between placing the disks on an inoculated plate and incubation permits excess rediffusion of the antimicrobial agent from the disk. This would result in a larger than expected zone diameter. 3