Chapter 36: Clinical Microbiology And Immunology

1. Standard microbiological practices include all of the following EXCEPT A. work space should be disinfected only when contaminating spills occur. B. eating, drinking, manipulation of contact lenses, and the use of cosmetics, gum, and tobacco products are strictly prohibited in the lab. C. lab personnel should know how to use the emergency eyewash and shower stations. D. hair longer than shoulder length should be tied back.

2. Recommended guidelines for laboratory microbiological precautions should reflect the laboratory's ________ _________. biosafety level

3. Which of the following is not a guideline on selection, collection, and handling of clinical specimens? A. A small quantity of specimen should be obtained. B. The specimen selected should be representative of the infectious disease process. C. The specimen should be forwarded promptly to the clinical laboratory. D. Attention must be given to avoid contamination of the specimen.

4. Which of the following tests can be used to distinguish Escherichia from Enterobacter? A. IMVIC B. ONPG test C. Citrate utilization D. Starch hydrolysis

5. The clinical microbiology laboratory can provide preliminary identification of microorganisms based on A. microscopic examination of specimens. B. growth or biochemical characteristics. C. immunologic techniques that detect microbial antigens. D. All of the choices are correct.

6. Which of the following can be examined with an ordinary bright-field microscope? A. Wet mounts B. Heat-fixed specimens C. Chemical-fixed specimens D. All of the choices are correct.

7. Ten percent Calcofluor White stain is often used in wet mounts of _________. A. bacteria B. parasites C. molds D. protozoa

8. In the clinical laboratory, which of the following is (are) used as a rapid method of identification? A. Manual biochemical kit systems B. Mechanized/automated systems C. Immunologic systems D. All of the choices are correct.

9. An example of miniaturized commercial rapid bacterial identification system based on biochemical analysis is the A. API 20E system. B. Widal test. C. Kirby-Bauer test. D. All of the choices are correct.

10. Which of the following media will permit the growth of one group of bacteria while inhibiting the growth of some other groups? A. Differential B. Selective C. Enrichment D. Characteristic

11. The most common method used by clinical microbiology labs for identifying bacteria are _________. A. biochemical B. morphological C. PCR D. DNA fingerprinting

12. Which of the following is not used to culture viruses? A. Growth on artificial media B. Growth in cell cultures C. Growth in embryonated hen's eggs D. Growth in whole animals

13. Which of the following is useful in the identification of bacteria? A. Source of the culture specimen B. Growth patterns on selective and differential media C. Hemolytic, metabolic, and fermentative properties D. All of the choices are correct.

14. Which of the following is routinely used to detect spirochetes in skin lesions in early syphilis? A. Bright-field microscopy B. Phase-contrast microscopy C. Dark-field microscopy D. DNA fingerprinting

15. Which of the following is/are used to detect chlamydiae in tissues and cell scrapings? A. PCR methods B. Microscopy of Giemsa stained samples C. Immunofluorescence D. All of the choices are correct.

16. Fungal infections are often diagnosed by direct microscopic examination of specimens.

17. The major focus of the clinical microbiologist is to rapidly isolate and identify microorganisms from clinical specimens.

18. The purpose of the clinical microbiology laboratory is to maintain cultures of microorganisms.

19. A clinical specimen represents a portion or quantity of human material for testing, examination, or study in order to determine the presence or absence of specific microorganisms.

20. DNA probe technology identifies microorganisms by probing their genetic composition.

21. Restriction endonucleases are a class of enzymes produced by bacteria.

22. The principle of plasmid fingerprinting is that microbial isolates of the same strain contain the same plasmids.

23. Determining the susceptibility of a microorganism to specific chemotherapeutic agents is an important service performed in the clinical microbiology laboratory.

24. The Gram stain is used for bacteria that have cell walls while the acid-fast stain is used primarily for wall-less bacteria.

25. The use of rRNA gene sequences to identify bacterial strains is referred to as ___________.

26. Indirect immunofluorescence involves fixing the specimen onto a slide, adding fluorochrome-labeled antibodies and then incubating before examining on the microscope.

27. Identification and characterization of ova, trophozoites, and cysts of parasites is typically accomplished by direct microscopic evaluation of the clinical specimen.

28. PCR is considered more flexible and easier to modify than antibody-based identification technologies.

29. The immunologic technique involving the transfer of proteins separated by electrophoresis to nitrocellulose sheets is _________. A. complement fixation B. direct immunofluorescence C. immunoblotting D. immunoelectrophoresis

30. Which of the following uses red blood cells? A. Hemagglutination inhibition B. MIC C. ELISA D. RIA

31. Which of the following tests is an agglutination test for the bacterium causing typhoid fever? A. Quellung reaction B. API 20E system C. Widal test D. IMViC

32. The indirect immunosorbent assay detects antibodies rather than antigens.

33. An elevated IgM titer typically indicates an active infection while an elevated IgG titer does not distinguish between active and past infections.

34. Detection of single or multiple microorganisms based on their cytometric parameters is known as _________. A. flow cytometry B. complement fixation C. agglutination D. serotyping

35. The immunological reaction that occurs when there is an optimal ratio of antigen and antibody, producing a lattice at the zone of equivalence is known _________. A. immunoblotting B. immunoelectrophoresis C. immunodiffusion D. immunoprecipitation

36. ________ can also be used to differentiate strains of microorganisms that differ in the antigenic composition of a structure or product.

37. A colorless substrate acted on by the enzyme portion of the ligand to produce a colored product is known as a/an _________. A. antibody B. chromogen C. antigen D. serotype

38. Of the scientific disciplines listed, which is the least directly relevant to the study of clinical microbiology? A. Physiology B. Microscopy C. Ecology D. Biochemistry E. Immunology

39. Clinical microbiologists diagnose some diseases by detecting and measuring the specific host response to the infection. What subdiscipline encompasses these methods? A. Immunology B. Microscopy C. Physiology D. Genetics E. Ecology

40. All of the following methods are employed to identify pathogens in clinical specimens EXCEPT A. special stains and microscopy. B. culture on a variety of all-purpose, selective, and/or differential media. C. biochemical tests. D. molecular testing for nucleic acids. E. immunoassays. F. There are no exceptions here. All of these methods are used to identify pathogens.

41. A test which uses specific monoclonal antibodies to detect the presence of a pathogen (such as an indirect ELISA) is classified as a molecular genomic technique.

43. Which infectious agent risk group would Mycobacterium tuberculosis be placed in? A. Risk group 1 B. Risk group 2 C. Risk group 3 D. Risk group 4

45. What biosafety level is required when working with Staphylococcus aureus and Streptococcus pyogenes? A. 1 B. 2 C. 3 D. 4

46. All of the following would be appropriate for handling routine patient specimens (urines, sputums, wound swabs) for microscopy and culture EXCEPT A. gloves. B. lab coat. C. full-body positive pressure suit with air supply. D. biological safety cabinet. E. appropriate waste decontamination.

48. Patients are instructed to collect sputum specimens in such a way as to minimize contamination with normal microbiota from the mouth. A sputum specimen has arrived in the clinical laboratory and a Gram-stained smear of the specimen reveals a mixture of Gram-positive cocci, Gram-negative cocci, and Gram-positive bacilli as well as numerous squamous epithelial cells. This result indicates A. a poor quality specimen of primarily saliva and oropharyngeal microbiota. B. that the specimen has been properly collected and is representative of sputum. C. that the patient has a pneumonia caused by a mixture of different bacteria. D. that the patient has bacterial pneumonia rather than viral pneumonia.

49. A growth medium used for the recovery of fungal isolates from patient specimens contains antibiotics to prevent the overgrowth of bacteria and cycloheximide to prevent the growth of saprophytic fungi. This medium would be categorized as _________. A. differential B. selective C. enriched D. enrichment E. both selective and differential.

50. A patient specimen was Gram-stained upon arrival in the clinical laboratory and revealed both Gram-positive cocci and Gram-negative bacilli. The specimen was cultured on sheep blood agar and chocolate agar, and after incubation, the culture grew only the Gram-negative bacilli. Which of the following is/are a likely explanation(s) for the failure of the Gram-positive cocci to grow? A. The Gram-negative bacilli may have grown very quickly and overgrew the slower growing Gram-positive cocci. B. The media used may not support the growth of the Gram-positive cocci. C. The growth temperature may have enabled the growth of the Gram-negative bacilli but not the growth of the Gram-positive cocci. D. The Gram-positive cocci may be an obligate anaerobe and was unable to grow in an ambient air incubator. E. All of the choices are possible explanations.

51. What is the first piece of information that is used in the identification of an unknown bacterial isolate? A. The ability of the bacterial isolate to ferment glucose B. The ability of the bacterial isolate to ferment lactose C. The presence of catalase enzyme D. The Gram stain morphology

52. An ELISA test to detect antibodies to the Rubella virus would include/use all of the following EXCEPT A. microtiter wells coated with rubella antigen. B. enzyme-labeled rabbit antihuman IgG antibodies. C. a chromogenic enzyme substrate. D. the patient serum specimen. E. There are no exceptions here. Each of these items would be used.