Antibacterials 1

Question 1

Examples of Broad Spectrum antibacterials

Answer 1

eg, tetracycline, chloramphenicol

Question 2

Examples of Narrow Spectrum antibacterials

Answer 2

isoniazid

Question 3

Examples of Extended spectrum antibacterials

Answer 3

ampicillin, amoxicillin

Question 4

List Cell wall synthesis inhibitors

Answer 4

Beta-lactam antibiotics,

vancomycin, daptomycin, bacitracin & fosfomycin

Question 5

List Protein synthesis inhibitors

Answer 5

tetracyclines,
glycylcyclines, aminoglycosides, macrolides,
chloramphenicol, clindamycin, streptogramins & linezolid

Question 6

List drugs that affect nucleic acid synthesis

Answer 6

(fluoroquinolones, sulfonamides & trimethoprim

Question 7

List Miscellaneous and urinary antiseptics

Answer 7

metronidazole,

nitrofurantoin, rifaximin, polymyxin B, lactulose

Question 8

Examples of Gram Negative

Answer 8

E.coli, Salmonella, Shigella, Pseudomonas, Helicobacter, Legionella, Enterobacter, Neisseria(meningitidis,gonorrhea)

Question 9

Examples of Gram Positive

Answer 9

Staphylococcus, streptococcus, clostridium, listeria, actinobacteria, mycoplasma, bacillus, enterococcus

Question 10

Penetration of blood brain barrier is influenced by

Answer 10

• lipid solubility of drug (eg, fluoroquinolones &
metronidazole are lipid soluble. Penicillin has low
lipid solubility)
• molecular weight
• protein binding of the drug

Question 11

Disadvantage of combination therapy

Answer 11

some agents only act on multiplying bacteria. If
combined with another agent that causes
bacteriostasis they will be less effective
eg, -lactams + tetracyclines
• can select for multi-drug resistant bacteria

Question 12

Mechanisms for synergism:

Answer 12

Sequential blockade (eg, trimethoprim +
sulfamethoxazole)
• Blockade of drug-inactivating enzymes (eg,
clavulanic acid + amoxicillin)
• Enhanced drug uptake (eg, increased
permeability to aminoglycosides after
beta- lactam
treatment)

Question 13

Broad Spectrum, definition uses and disadvantages?

Answer 13

Antimicrobial drugs which are effective against several
groups of microorganisms eg, Gram positive and Gram
negative bacteria
Uses
• Empiric therapy
• Mixed infections (multiple bacteria present)
Disadvantages
• Selection of multi-drug resistant bacteria
• Disruption of ‘normal’ flora

Question 14

Narrow Spectrum, definition uses and disadvantages?

Answer 14

Antimicrobial drugs which are effective against only a
specific group of bacteria
Uses
• Treating infections of known origin
Disadvantages
• Must know causative organism
• Not useful for empiric therapy

Question 15

Extended Spectrum definition, uses, and disadvantages

Answer 15

Antimicrobial drugs that are effective against Gram-positive
organisms and a significant number of Gram-negative
organisms due to chemical modifications
Uses
• Empiric therapy
• Mixed infections (multiple bacteria present)
Disadvantages
• Selection of multi-drug resistant bacteria
• Disruption of ‘normal’ flora

Question 16

The three major mechanisms of antibiotic resistance

are

Answer 16

Altered uptake of antibiotic eg, decrease in
permeability and/or uptake mechanisms. Increase in
multi-drug resistance pumps
2. Altered target eg, change in receptor site affinity,
modification of targeted metabolic pathway
3. Drug inactivation eg, bacterial production of enzymes
that inactivate drug