Penicillin was considered a "miracle drug" for all of the following reasons except

A) It was the first antibiotic

B) It doesn't affect eukaryotic cells

C) It inhibits gram-positive cell wall synthesis

D) It has selective toxicity

E) None of the above

A

The first antibiotic discovered was

A) Quinine

B) Salvarsan

C) Streptomycin

D) Sulfa drugs

E) Penicillin

E

Most of the available antimicrobial agents are effective against

A) Viruses

B) Bacteria

C) Fungi

D) Protozoa

E) All of the above

B

Antimicrobial peptides work by

A) Inhibiting protein synthesis

B) Disrupting the plasma membrane

C) Complementary base-pairing with DNA

D) Inhibiting cell-wall synthesis

E) Hydrolyzing peptidoglycan

B

Semisynthetic penicillins differ from natural penicillins in all of the following respects except

A) Broad spectrum

B) Resistant to penicillinase

C) Resistant to stomach acids

D) Bactericidal

E) None of the above

D

Which of the following antibiotics is not bactericidal?

A) Aminoglycosides

B) Cephalosporins

C) Polyenes

D) Rifampins

E) Penicillin

C

Which one of the following does not belong with the others?

A) Bacitracin

B) Cephalosporin

C) Monobactam

D) Penicillin

E) Streptomycin

E

The antibiotic tetracycline binds to the 30S subunit of the ribosome as shown in Figure 20.1. The effect is to

A) Prevent attachment of tRNA

B) Prevent peptide bond formation

C) Prevent transcription

D) Stop the ribosome from moving along the mRNA

E) Prevent attachment of tRNA and mRNA

B

The antibiotic cycloheximide binds to the 60S subunit of the ribosome as shown in Figure 20.2. The effect is to

A) Prevent mRNA-ribosome binding in eukaryotes

B) Prevent peptide bond formation in prokaryotes

C) Prevent polypeptide elongation in eukaryotes

D) Prevent transcription in prokaryotes

E) None of the above

C

Which of these antimicrobial agents has the fewest side effects?

A) Streptomycin

B) Tetracycline

C) Penicillin

D) Erythromycin

E) Chloramphenicol

C

All of the following act by competitive inhibition except

A) Ethambutol

B) Isoniazid

C) Streptomycin

D) Sulfonamide

E) None of the above

C

Which of the following methods of action would be bacteriostatic?

A) Competitive inhibition with folic acid synthesis

B) Inhibition of RNA synthesis

C) Injury to plasma membrane

D) Inhibition of cell wall synthesis

E) None of the above

B

Which of the following antibiotics is recommended for use against gram-negative bacteria?

A) Polyenes

B) Bacitracin

C) Cephalosporin

D) Penicillin

E) Polymyxin

E

Which of the following antimicrobial agents is recommended for use against fungal infections?

A) Amphotericin B

B) Bacitracin

C) Cephalosporin

D) Penicillin

E) Polymyxin

A

In Table 20.1, the minimal bactericidal concentration of antibiotic X is

A) 2 mg/ml

B) 10 mg/ml

C) 15 mg/ml

D) 25 mg/ml

E) Can't tell

C

In Table 20.1, the minimal inhibitory concentration of antibiotic X is

A) 2 mg/ml

B) 10 mg/ml

C) 15 mg/ml

D) 25 mg/ml

E) Can't tell

B

More than half of our antibiotics are

A) Produced by fungi

B) Produced by bacteria

C) Synthesized in laboratories

D) Produced by Flemins

E) None of the above

B

The antibiotic erythromycin binds to the 50S subunit of the ribosome as shown in Figure 20.3. The effect is to

A) Prevent attachment of tRNA

B) Prevent peptide bone formation

C) Prevent transcription

D) Stop the ribosome from moving alone the mRNA

E) None of the above

D

The antibiotic streptomycin binds to the 30S subunit of the ribosome as shown in Figure 20.4. The effect is to

A) Cause misreading of mRNA in 70S ribosomes

B) Prevent binding of tRNA in eukaryotes

C) Prevent polypeptide elongation in eukaryotes

D) Prevent peptide bond formation in prokaryotes

E) None of the above

A

Which compound would be the most useful to treat candidiasis?

A) Uracil

B) Thymine

C) Flucytosine

D) Guanine

E) None of the above

C

Which of the following antibiotics are used to treat fungal infections?

1. Aminoglycosides

2. Cephalosporins

3. Griseofulvin

4. Polyenes

5. Bacitracin

A) 1, 2, and 3

B) 3 and 4

C) 3, 4, and 5

D) 4 and 5

E) All of the antibiotics

B

All of the following antibiotics interfere with cell wall synthesis except

A) Cephalosporins

B) Macrolides

C) Natural penicillins

D) Semisynthetic penicillins

E) Vancomycin

B

The antimicrobial drug with the broadest spectrum of activity are

A) Aminoglysosides

B) Chloramphenicol

C) Lincomycin

D) Macrolides

E) Tetracyclines

E

Which of the following statements is false?

A) Fluoroquinolone inhibits DNA synthesis

B) Acyclovir inhibits DNA synthesis

C) Amantadine inhibits glycolysis

D) Interferon inhibits glycolysis

E) None of the above

D

Protozoan and helminthic diseases are difficult to treat because

A) Their cells are structurally and functionally similar to human cells

B) The replicate inside human cells

C) They don't have ribosomes

D) They don't reproduce

E) None of the above

A

Which of the following organisms would most likely be sensitive to natural penicillin?

A) L forms

B) Streptococcus pyogenes

C) Penicillinase-producing Neisseria gonorrhoeae

D) Penicillium

E) Mycoplasma

B

All of the following statements about drug resistance are true except

A) It may be carried on a plasmid

B) It may be transferred from one bacterium to another during conjugation

C) It may be due to enzymes that degrade some antibiotics

D) It is found only in gram-negative bacteria

E) It may be due to increased uptake of a drug

D

All of the following are advantages of using two antibiotics together except

A) Prevention of drug resistance

B) Lessening the toxicity of individual drugs

C) Two are always twice as effective as one

D) Providing treatment prior to diagnosis

E) None of the above

C

Drug resistance occurs

A) Because bacteria are normal microbiota

B) When antibiotics are used indiscriminately

C) Against antibiotics and not against synthetic chemotherapeutic agents

D) When antibiotics are taken after the symptoms disappear

E) All of the above

B

The following results were obtained from a disk-diffusion test for microbial susceptibility to antibiotics. S aureus was the test organism.

Antibiotic and Zone of Inhibition

A - 3mm

B - 7mm

C - 0mm

D - 10mm

Which was the the most effective antibiotic?

A) A

B) B

C) C

D) D

E) Can't tell

D

The following results were obtained from a disk-diffusion test for microbial susceptibility to antibiotics. S aureus was the test organism.

Antibiotic and Zone of Inhibition

A - 3mm

B - 7mm

C - 0mm

D - 10mm

The antibiotic that exhibited bactericidal action was

A) A

B) B

C) C

D) D

E) Can't tell

E

The following results were obtained from a disk-diffusion test for microbial susceptibility to antibiotics. S aureus was the test organism.

Antibiotic and Zone of Inhibition

A - 3mm

B - 7mm

C - 0mm

D - 10mm

Which antibiotic would be most useful for treating a Salmonella infection?

A) A

B) B

C) C

D) D

E) Can't tell

E

Which of the following would be selective against the tubercle bacillus?

A) Bacitracin - inhibits peptidoglycan synthesis

B) Ethambutol - inhibits mycolic acid synthesis

C) Streptogramin - inhibits protein synthesis

D) Streptomycin - inhibits protein synthesis

E) Vancomycin - inhibits peptoglycan synthesis

B

In the presence of penicillin a cell dies because

A) It lacks a cell wall

B) It plasmolyzes

C) It undergoes osmotic lysis

D) It lacks a cell membrane

E) None of the above

C

Lamisil is an allylamine used to treat dermatomycoses. Lamisil's method of action is similar to

A) Polymyxin B

B) Azole antibiotics

C) Echinocandins

D) Griseofulvin

E) Bacitracin

B

Niclosamide prevents ATP generation in mitochondria. You would expect this drug to be effective against

A) Gram-negative bacteria

B) Gram-positive bacteria

C) Helminths

D) Mycobacterium tuberculosis

E) Viruses

C

The following data were obtained from a broth dilution test:

Concentration of Antibiotic X and Growth

2.0 mg/ml (-)

1.0 mg/ml (-)

0.5 mg/ml (-)

0.25 mg/ml (+)

0.125 mg/ml (+)

0 (+)

The data in the Table show that these bacteria

A) Can be subcultured

B) Developed resistance to antibiotics

C) Were killed by 0.125 mg/ml of antibiotic X

D) Were killed by 0.5 mg/ml of antibiotic X

E) Were resistant to 1.0 mg/ml at the start of the experiment

B

Which of the following statements about drugs that competitively inhibit DNA polymerase or RNA polymerase is not true?

A) They cause mutations

B) They are used against viral infections

C) They affect host cell DNA

D) They are too dangerous to be used

E) None of the above

D

If the compound shown in Figure 20.5 is the substance for a particular enzyme, which of the drugs would be the most effective competitive inhibitor?

A) a

B) b

C) c

D) d

E) None of the above

D

Which of the following is not bactericidal?

A) Tetracycline

B) Natural penicillin

C) Streptomycin

D) Bacitracin

E) Semisynthetic penicillin

A

Which of the following foes not affect eukaryotic cells?

A) Antiprotozoan drugs

B) Antihelminthic drugs

C) Antifungal drugs

D) Nucleotide analogs

E) None of the above

E

Mebendazole is used to treat cestode infections. It interferes with mucrotubule formation; therefore, it would not affect

A) Bacteria

B) Fungi

C) Helminths

D) Human cells

E) Protozoa

A

Which of the following antibiotics causes misreading of mRNA?

A) Aminoglycoside - changes shape of 30S units

B) Chloramphenicol - inhibits peptide bonds at 50S subunit

C) Oxazolidinone - prevents formation of 70S ribosome

D) Streptogamin - prevents release of peptide from 70S ribosome

E) Tetracyclines - bind with 30S subunit

A

The antibiotic actinomycin D binds between adjacent G-C pairs, thus interfering with

A) Transcription

B) Translation

C) Cellular respiration

D) Plasma membrane function

E) Peptide bond formation

A

Use of antibiotics in animal feed leads to antibiotic-resistant bacteria because

A) Bacteria from other animals replace those killed by the antibiotics

B) The few surviving bacteria that are affected by the antibiotics develop immunity to the antibiotics, which they pass on to their progeny

C) The antibiotics cause new mutations to occur in the surviving bacteria, which results in resistance to antibiotics

D) The antibiotics kill susceptible bacteria, but the few that are naturally resistant live and reproduce, and their progeny repopulate the host animal

E) The antibiotics persist in soil and water

D

An antibiotic that attacks the LPS layer would be expected to have a narrow spectrum of activity.

True/False

True

PABA serves as the competitive inhibitor in the action of sulfanilamides.

True/False

False

Undergrowth of fungi after antibiotic use is commonly referred to as a superinfection.

True/False

False

Due to its target, rifamycins can be effective over a broad spectrum.

True/False

True

Both trimethoprim and sulfamethoxazole inhibit reactions along the same metabolic pathway.

True/False

True

Penicillin and streptomycin are commonly used in synergism because they display the same mode of action.

True/False

False

Only microbes produce antimicrobial peptides.

True/False

False

Community-acquired MRSA is typically more virulent than health care-associated MRSA.

True/False

True

Antiviral drugs target viral processes that occur during viral infection.

True/False

True

Phage therapy has been used in the past as an antiviral treatment.

True/False

False