A DAMB 721 Microbiology Exam 2A 100 points September 28, 2005

Your name:

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Part I. Multiple Choice: Choose the ONE BEST answer. Mark the correct answer in Part 1 of your answer sheet.

1. Of the following, which conveys the highest risk of nosocomial infection to a hospitalized patient?

A. the hospital environment (rooms, floors, fomites) B. invasive medical devices (catheters, respirators, etc.) C. hospital personnel, including physicians

2. A strain of Vibrio cholerae is moved from seawater to a low salt, high pH environment where it begins to produce the cholera toxin that will cause profuse diarrhea as well as pili and outer membrane proteins that will allow the bacterium to adhere to the colon. This environmental regulation of a number of closely linked virulence genes is typical of a:

A. transposon B. specialized transduction C. phage conversion D. pathogenicity island

3. Primary characteristics that are used to classify bacteria include:

A. Gram stain, cell shape and cell size B. Colony morphology C. Cell surface antigens D. Nutritional requirements E. Resistance profiles

4. Bacteria are only susceptible to penicillin and other β-lactam antibiotics during this phase of their growth cyle.

A. lag phase B. logarithmic phase C. stationary phase D. death phase

5. Mannitol salt agar is selective and differential for ______. The selective component is ______; the differential component is ______.

A. Enterococcus faecalis; 7.5% sodium chloride; mannitol B. Staphylococcus aureus; 7.5% sodium chloride; mannitol C. Corynebacterium diphtheria; tellurite; mannitol D. Staphylococcus aureus; mannitol; 7.5% sodium chloride E. Streptococcus pneumoniae; optochin; α-hemolytic response

2 6. Protein A is:

A. Useful for serotyping strains of Streptococcus pyogenes. B. A protein that is a virulence determinant for Staphylococcus aureus and can activate fibrinogen to cause clot formation around the bacterial cell. C. A protein that is unique to the cell surface of Staphylococcus aureus and that contributes to the virulence of the bacterium by binding the Fc region of immunoglobulins D. Toxic for white blood cells. E. The unusual capsule of S. pneumoniae.

7. The anti-microbic action of the sulfonamides is due to their molecular:

A. resemblance to acyl-d-alanylalanine B. resemblance to penicillin binding proteins (PBPs) C. resemblance to para-aminobenzoic acid (PABA) D. resemblance to trimethoprim

8. Dental equipment that is reusable and that penetrates tissue, bone or pulp:

A. Is critical and should be disinfected with a high level disinfectant. B. Is semi-critical and should be disinfected with a low level disinfectant. C. Is critical and should be sterilized. D. Is semi-critical and should be disinfected with a high level disinfectant. E. Is semi-critical and should be sterilized.

9. OSHA regulates the following:

A. Hazardous waste disposal. B. Employee Exposure to blood borne pathogens. C. Employee Exposure to hazardous chemicals. D. Both A and B. E. Both B and C.

10. Infections caused by bacteria that develop resistance to this anti-microbic are untreatable unless new anti-microbics can be developed to take its place.

A. penicillin B. cephalosporin C. sulfonamide D. vancomycin

11. The following are the requirements for microbial pathogenicity: the ability to gain entry into and adhere to the host; the ability to cause damage, for example, by releasing toxins or LPS; the ability to avoid the host immune system; the ability to metabolize and replicate in the area of infection.

A. The list is complete. A bacterium that could do these things could cause disease. B. The list is incomplete. A bacterium could do all of these things and still not be able to cause disease. 3

12. Prevotella sp. is (are):

A. an asaccharolytic genus of periodontal pathogens B. endogenous pathogens C. a saccharolytic genus of periodontal pathogens D. resistant to most antibiotics E. pathogens for which there are special infection control requirements

13. The insoluble polysaccharide matrix of plaque is:

A. fructosyl transferase catalyzing levan B. glucosyl transferase catalyzing alpha-1,3-branched mutan C. fructosyl transferase catalyzing alpha-1,3-banched glucan D. glucosyl transferase catalyzing alpha-1,6-branched mutan

14. Porphyromonas gingivalis are:

A. collagenases B. invertases C. hydrolyases D. kinases

15. Which of the following statements is true of bacterial anaerobic respiration but not bacterial aerobic respiration?

A. oxygen is the terminal electron acceptor B. nitrate or sulfate may be the terminal electron acceptors C. electron transport occurs in the bacterial cell membrane instead of in the mitochondrion D. is less energetic, because the electron transport chain may have fewer cytochromes and therefore fewer ATP synthetase complexes E. Both B and D.

16. Bacteria as a group produce a variety of acids, gasses, aldehydes and alcohols through fermentation reactions. The most common intermediate in these bacterial fermentation reactions is:

A. pyruvate B. lactate C. ethanol D. citrate E. format

17. A form of gene transfer that requires a bacteriophage is:

A. conjugation B. transduction C. transformation D. locomotion

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18. What are Molecular Koch's Postulates trying to determine?

A. the bacterium or other microorganism that is the etiologic (causative) agent of a disease B. the virulence determinant (gene) that encodes the major virulence factor of a pathogenic microorganism C. an appropriate animal model for a disease D. both A and B E. both B and C

19. What are Koch's Postulates trying to determine?

A. the bacterium or other microorganism that is the etiologic (causative) agent of a disease B. the virulence determinant (gene) that encodes the major virulence factor of a pathogenic microorganism C. an appropriate animal model for a disease D. both A and B E. both B and C

20. A bacterium that undergoes a chromosomal mutation that results in the loss of the major surface antigen has undergone:

A. a phage conversion B. an antigenic variation C. a phase variation D. generalized transduction

21. Some bacteria may gain a selective advantage if they have chromosomes with: 1. multiple structural genes that encode an antigen that is required for virulence; and 2. molecular mechanisms that allow them to change the structural gene that is adjacent to the promoter. This mechanism for gaining selective advantage is:

A. antigenic variation B. lysogeny C. specialized transduction D. conjugation E. phage conversion

22. A form of gene transfer that requires a competent bacterial cell is:

A. conjugation B. transduction C. transformation D. locomotion

5 23. The clonality of pathogenic bacteria refers to:

A. the environmental regulation of genes encoding virulence factors B. the acquisition of virulence determinants encoded on extrachromosomal elements C. the infective dose of a specific species of bacteria D. opportunistic pathogens E. among a number of strains in a given bacterial species only a few will be associated with disease

24. Which of the following statements describes the way in which genes are transferred in bacterial conjugation?

A. In a viral capsid B. On the plasmid carried by the male (+) donor cell. C. In specific bacteria the male (+) plasmid can integrate into the host chromosome and initiate transfer of the host chromosome to a recipient cell. D. B and C both describe ways in which genes may be transferred in bacterial conjugation.

25. The botulinum, scarlet fever and diphtheria toxins are encoded by a gene carried on a temperate bacteriophage. This type of phage conversion is also known as:

A. Transformation B. Conjugation C. Specialized transduction. D. Generalized transduction.

26. The bacterium ______is the most frequent cause of nosocomial infections while ______is the second most frequent cause.

A. Staphylococcus aureus; Escherichia coli B. Escherichia coli; Enterococcus faecalis C. Enterococcus faecalis; Staphylococcus aureus D. Escherichia coli; Staphylococcus aureus

27. Which of the following anti-microbics disrupts membrane function by binding ergosterol in fungal membranes?

A. chloramphenicol B. streptomycin C. the polyene, amphoteracin B D. clindamycin E. polymyxin B

28. An example of a biological vector is:

A. a mosquito which harbors a pathogen during part of its life cycle. B. a medicine bottle covered with the pathogen Staph. aureus. C. a disease transmitted by an animal bite. D. a fly whose legs are covered with pathogenic bacteria 6

29. If the portal of exit and portal of entry of a disease is on the same person:

A. this is an endogenous infection. B. this is evidence that the disease is spread by a fomite. C. this is evidence of spread by a biological vector. D. the individual must be immunocompromised.

30. A common portal of exit for diseases such as cholera that are spread by contaminated food and water is:

A. Blood. B. Skin scales or flakes. C. Respiratory secretions. D. Fecal wastes.

31. Areas of the human body that are colonized by high levels of microorganisms (107 to 1011 per gram, cc or ml) are the:

A. skin, stomach and esophagus B. kidneys, middle ear, bladder and dental pulp C. colon, dental plaque and saliva D. skin and nasopharynx

32. The kidneys, middle ear, bladder and dental pulp are areas of the human body that:

A. have low levels of microorganisms, approximately103 per gram, cc or ml. B. are not colonized by normal flora and, therefore, are usually sterile C. have high levels of microorganisms, approximately >107 to 1011 per gram, cc or ml D. have medium levels of microorganisms, 104 to 107 per gram, cc or ml

33. Statement A: An endotoxin is likely to be phage or plasmid encoded. Statement B: An exotoxin is usually not heat stable.

A. Statement A is true. B. Statement B is true. C. Both statements are true. D. Neither statement is true.

34. To diagnose a patient’s disease by isolating the causative agent (pathogenic microorganism) responsible, specimens are collected from the:

A. portal of entry B. portal of exit C. biological vector D. mechanical vector

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35. This acute phase protein will opsonize bacteria:

A. muramyl-dipeptide B. flagella C. C5a D. interleukin 1 E. C reactive protein

36. Use of this medical device/procedure involves substantial risk of transmission of blood-borne pathogens (hepatitis and HIV), both to patients and hospital personnel.

A. urinary catheter B. hemodialysis C. respirator D. vascular catheters

37. The normal flora will be distributed in various body sites that support their specific growth requirements. The specific genera that occupy each body site may have all except the following characteristics:

A. resistance to natural antibiotics, such as penicillin or colicin, that may be released by other bacteria occupying the body site B. resistance to host defense factors, such as lysozyme C. presence only when the host is suffering from disease D. adhesins specific to that body site E. pathogenesis

38. A chemical disinfectant should have a number on the container that assures the disinfectant has been tested and its effectiveness is scientifically supported. This number is issued by the:

A. Centers for Disease Control (CDC) B. Food and Drug Administration (FDA) C. Occupational Health and Safety Administration (OSHA) D. Environmental Protection Agency (EPA)

39. A dental clinic treats more than six patients with active tuberculosis in a period of one year, but there is no evidence of TB transmission in the facility. The risk category for this facility is:

A. High B. Intermediate C. Low D. Very Low E. Minimal

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40. Use of the dental dam, pre-procedure mouth rinsing and high volume evacuation are infection control methods designed to:

A. Prevent endogenous infections. B. Eliminate the need for barrier protection for the dental staff. C. Block the formation of bacterial biofilms in dental unit waterlines. D. Prevent transmission of microorganisms from patient to patient by packaging one set of sterile instruments per patient. E. Reduce the number of microorganisms present in aerosols created by high-speed hand pieces, ultrasonic scalers and air/water syringes.

41. Viruses that may not be killed by an intermediate level disinfectant are:

A. hydrophobic viruses B. hydrophilic viruses C. all viruses D. blood borne viruses

42. A method of epidemiologic investigation that is useful for determining the source of nosocomial infections caused by S. aureus is:

A. serotyping B. pyocin typing C. phage (bacteriophage) typing D. cell wall composition

43. The bacteria that cause human caries are:

A. Streptococcus sobrinus and Streptococcus mutans B. Streptococcus sobrinus and Streptococcus maccaccae C. Streptococcus cricetus and Streptococcus rattus D. Streptococcus mutans and Streptococcus rattus E. Streptococcus ferus and Streptococcus rattus

44. A Staphylococcus aureus that cannot produce this enzyme is avirulent.

A. catalase B. lipase C. coagulase D. hyaluronidase E. staphylokinase

45. Bacterial virulence factor(s) that specialize(s) in obtaining sequestered iron from the host and delivering it to the bacterial cell:

A. lysozyme B. siderophores C. transferrin and lactoferrin D. bacteriocins and antibiotics 9

46. Molecule(s) in the human defense system that deprive(s) bacteria and other microorganisms of iron are (is):

A. lysozyme B. siderophores C. transferrin and lactoferrin D. bacteriocins and antibiotics

47. Bacteria that alter anti-microbic binding sites on enzymes such as DNA dependent RNA polymerase and DNA gyrase may develop resistance to:

A. polymyxin B B. sulfonamides C. penicillin and vancomycin D. rifampin and quinolones E. erythromycin and clindamycin

48. Chloramphenicol, clindamycin and erythromyicn have the following in common:

A. They bind the 30S subunit of the ribosome. B. They bind the 50S subunit of the ribosome. C. They inhibit peptidyl transferase. D. They inhibit protein synthesis. E. They have all but A in common.

49. These anti-microbics bind to the 30S subunit of the bacterial ribosome and inhibit protein synthesis by preventing binding of amino-acid charged tRNAs:

A. chloramphenicol, erythromycin and clindamycin B. tetracycline and streptomycin C. polymyxin B and amphoteracin B

50. The exfoliative toxin is produced by ______and it causes the symptoms of ______.

A. Enterococcus faecalis; scalded skin syndrome B. Streptococcus pyogenes; scarlet fever C. Staphylococcus aureus; scalded skin syndrome D. Streptococcus pneumoniae; meningitis E. Staphylococcus aureus; impetigo

51. A bacterium found in dental plaque that may actually kill other bacteria and raise the pH of plaque through metabolic production of hydrogen peroxide and ammonia is:

A. Streptococcus mutans B. S. gordonii C. S. salivarius D. S. sanguis (sanguinis) E. S. mitis 10

52. The M protein is:

A. Useful for serotyping strains of Staphylococcus aureus. B. A protein that is a virulence determinant for Staphylococcus aureus and can activate fibrinogen to cause clot formation around the bacterial cell. C. A protein that is unique to the cell surface of Staphylococcus aureus and that contributes to the virulence of the bacterium by binding the Fc region of immunoglobulins. D. Is coiled around the pili of Streptococcus pyogenes; acts as an adhesin by binding the bacteria to keratinocytes and epithelial cells; activates fibrinogen to form a fibrin clot that protects the bacterium from opsonization and phagocytosis. E. The unusual capsule of S. pneumoniae

53. The antigen used to subdivide the Streptococci into species is:

A. the Lancefield carbohydrate B. the β hemolysin C. the M protein D. the teichoic acid E. A, C, and D.

54. Bacteria with the ability to survive, metabolize and reproduce at pH 5.5 and below are:

A. acidogenic B. have glucosyl transferases C. asaccharolytic D. aciduric E. inhibitors of acid diffusion

55. The cell component of S. pneumoniae that is a virulence determinant and is used to serotype the species.

A. teichoic acid B. alpha hemolysin C. carbohydrate capsule D. M protein E. fimbriae

56. An elderly patient develops meningitis 3 days after being admitted to the hospital. Upon culture of the patient’s cerebrospinal fluid, a Gram + diplococcus is isolated that is α- hemolytic on blood agar and sensitive to the bile salt, optochin. This is a presumptive diagnosis for:

A. Staphylococcus aureus B. Escherichia coli C. Streptococcus pyogenes D. Streptococcus pneumoniae E. Streptococcus agalactiae

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57. A streptococcus is isolated from a patient with a suppurative pharyngitis. When grown on blood agar, it is beta hemolytic and sensitive to a bacitracin disc. This is a presumptive positive test for:

A. Streptococcus pneumoniae B. Viridans streptococci C. Streptococcus agalactiae D. Enterococcus faecalis E. Streptococcus pyogenes

58. The antigen used to subdivide S. pyogenes into serotypes is:

A. the Lancefield carbohydrate B. the β hemolysin C. the M protein D. the teichoic acid E. A, C, and D.

59. These streptococci do not have the Lancefield group-specific carbohydrate:

A. Viridans streptococci and Streptococcus pneumoniae B. Most beta hemolytic streptococci C. Enterococcus faecalis and Streptococcus bovis D. S. anginosus and S. milleri E. Streptococcus agalactiae and Streptococcus pyogenes

60. A child that suffers from a pyogenic cellulitis is predisposed to these sequelae of S. pyogenes infections.

A. toxic shock syndrome B. acute glomerulonephritis C. rheumatic fever D. rheumatoid arthritis

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Part II. Matching: The questions below consist of headings followed by a list of phrases. For each phrase select the ONE heading that best describes that phrase. Mark the answer in Part 2, numbers 1 through 11, of your answer sheet.

1. necrotizing fasciitis 8. Lactobacillus casei 2. hyaluronidase 9. osteomyelitis 3. puerperal fever 10. enterotoxin 4. cellulitis 11. viridans streptococci 5. coagulase 12. catalase 6. toxic shock syndrome 7. pandemic

1. inflammation caused by bacterial invasion of the lymphatics and connective tissues under the skin

2. “spreading factor” produced by pathogenic bacteria including the streptococci and staphylococci

3. etiologic in more than 80% of subacute bacterial endocarditis infections

4. describes the incidence of a disease that causes a world-wide (global) epidemic

5. infection of uterus after delivery

6. secondary invader of carious lesions

7. blood vessel

8. rapid biochemical test that will distinguish streptococci from staphylococci

9. a form of gangrene caused by Streptococcus pyogenes

10. heat stable toxin produced by Staphylococcus aureus

11. pyrogenic exotoxins produced by S. aureus or S. pyogenes cause multiple organ failure

13 Part III. Matching: The questions below consist of headings followed by a list of phrases. For each phrase select the ONE heading that best describes that phrase. Mark the answer in Part 2, numbers 12 through 18, of your answer sheet.

1. sonication 6. ADA 2. CDC 7. 1% available iodine 3. 2% glutaraldehyde 8. 121o C, 15 psi, 15 to 20 minutes 4. spore test 9. 160o C, 2 hrs 5. M. tuberculosis 10. autoclave tape

12. killed by intermediate and high level disinfectants

13. safest way to clean sharp instruments

14. chemical sterilant

15. conditions for autoclaving

16. agency responsible for development of the new infection control guidelines

17. assurance that the autoclave is working

18. assurance that a set of instruments has been subjected to a heat sterilization procedure

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