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					Microbiology & Immunology P201 – SP 5 2008

Week 9 – Quiz

Q1: The MIC procedure in antibiotic sensitivity testing involves
   a) antibiotic dilution
   b) culture dilution
   c) antibiotic and culture dilutions
   d) none of the above

Q2: In the Kirby-Bauer method of antibiotic sensitivity testing
   a) zone sizes obtained are measured and diameter compared with those in standard
        tables
   b) a zone of inhibition of growth around a disc is always indicative of sensitivity of
        that organism to the antibiotic
   c) a narrow zone of inhibition of growth around the disc is always indicative of
        resistance to the antibiotic
   d) all of the above

Q3: The E-test method of antibiotic sensitivity testing
   a) is an agar diffusion method that provides a direct assessment of the MIC
   b) can only be used for anaerobes
   c) allows determination of MBC (mean bactericidal concentration)
   d) all of the above

Q4: Based on biological breakpoints an organism is considered resistant if
   a) the MIC is lower than the normal distribution of MICs for populations of that
      organism
   b) the MIC is higher than the normal distribution of MICs for populations of that
      organism
   c) biological breakpoints cannot be determined from MIC data
   d) the patient fails to respond to treatment

Q5: Antibiotic assays are used for
   a) therapeutic monitoring
   b) pharmacokinetic studies
   c) detection of residues in meat
   d) all of the above

Q6: Combined antimicrobial therapy:
   a) is used to achieve antagonism in disease therapy
   b) is demonstrated in the combination of sulphonamide and ketoconazole to form co-
      trimoxazole
   c) is used in the treatment of herpes virus infections to make sure resistance strains
      are not selected




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   d) is important in reducing the emergence of resistance in Mycobacterium
      tuberculosis

Q7: Antibiotic resistance
   a) is caused by treating bacteria with antibiotics
   b) occurs when antibiotic use selects for strains of bacteria carrying resistance genes
      encoding resistance to that antibiotic
   c) is only a problem with a few bacteria
   d) is not as big a problem now as it was in the 1960s

Q8: Which of the following are examples of natural or intrinsic resistance?
   a) ampC cephalosporinases in Klebsiella spp
   b) AcrE or MexB multidrug efflux pumps
   c) Aminoglycoside resistance in strict anaerobes
   d) All of the above

Q9: Acquired resistance
   a) can be caused by mutations
   b) is only important in enteric bacteria
   c) is caused by treating bacteria with antibiotics
   d) none of the above

Q10: Horizontal gene transfer
   a) is a rare phenomenon in bacteria
   b) is an important mechanism for dissemination of antibiotic resistance genes
   c) is most commonly seen in viruses
   d) is caused by treating bacteria with antibiotics

Q11: Which reactions describe mechanisms used by bacteria to inactivate
sulphonamides?
    a) target site modification
    b) metabolic by-pass
    c) efflux systems
    d) enzyme inactivation

Q12: Which of the following describe mechanisms that can be used by bacteria resistant
to -lactam antibiotics?
    a) amylase enzymes
    b) alterations in the 50S subunit of the bacterial ribosome
    c) reduced transport of the antibiotic into the periplasmic space
    d) changes in cell membrane permeability




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Q13: Which of the following describe mechanisms used by bacteria resistant to
glycopeptides?
    a) modification of the precursor
    b) alterations in the 30S subunit of the ribosome
    c) efflux enzymes
    d) none of the above

Q14: Which of the follow describe mechanisms used by bacteria resistant to
aminoglycosides?
   a) cell wall permeability
   b) inactivation by acetyl transferases
   c) alterations in the 50S subunit of the ribosome
   d) all of the above

Q15: Methylation of rRNA is an important resistance mechanism used by bacteria
resistant to
    a) tetracyclines
    b) macrolides
    c) quinolones
    d) polymixins

Q16: Which of the following is NOT a recognised method of horizontal transfer of
antibiotic resistance genes?
    a) transposons
    b) class 1 integrons
    c) chemiosmosis
    d) R-plasmids

Q17: Resistance to antiviral drugs can be determined by
   a) plaque reduction assays
   b) detection of specific mutations in the viral genome
   c) detection and quantification of the viral load in a patient
   d) all of the above

Q18: Resistance to antifungal drugs
   a) only occurs in moulds
   b) is only a problem with Candida spp
   c) at this stage can be overcome by using newer generation azoles
   d) in particular to amphotericin B, is caused by changes in cell wall sterols

Q19: Resistance to antimalarial drugs
   a) means that you need to use one drug at a time to treat malaria cases
   b) can be influenced by the type of mosquito involved in the spread of the disease
   c) is a particular problem with Plasmodium falciparum
   d) is only a problem in SE Asia




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Q20: List the 5 main targets for antibiotic action in bacteria
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Q21: Give an example of each of the following:
   i.     a bacteriostatic antibiotic
   ii.    a bactericidal antibiotic
   iii.   two antibiotics that act synergistically

    iv.      two antibiotics that demonstrate an antagonistic interaction

Q22: Give 3 examples of situations where combination therapy is used
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Q23: Give an example of an antibiotic in each of the following classes
   i.     glycopeptide
   ii.    -lactam
   iii.   Aminoglycoside
   iv.    Macrolide
   v.     Fluoroquinolone
   vi.    Streptogrammin
   vii.   Tetracycline




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Q24: Match the following antimicrobial with its mode of action
   i.    Chloramphenicol                           a. transpeptidation in cell-wall
                                               synthesis
   ii.   Penicillin                                        b. interference with the
                                                              activity of bactoprenol
   iii.   Enrofloxacin                                     c. inhibits glucan synthesis
                                                              in the cell wall
   iv.   Colistin                                          d. nicotinamide growth
                                                              factor inhibitor
   v.    Isoniazid                                         e. damages DNA
                                                           f. inhibit bacterial DNA
   vi.   Ketoconazole                                         gyrase
                                                           g. inhibit synthesis of
   vii.  Caspofungin                                          ergosterol in the cell
                                                              membrane
   viii. Sulphonamide                                      h. structural analogue of p-
                                                              aminobenzoic acid
   ix.   Bacitracin                                        i. inhibit peptidyl
                                                              transferase – stops protein
   x.    Metronidazole                                        synthesis
                                                           j. alters cell membrane
                                                              permeability




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