Ch. 20 Microbiology Lecture - Crider
In table 20.1, the minimal inhibitory concentration of antibiotic X is
10 ug/ml
In Table 20.1, the minimal bactericidal concentration of antibiotic X is
15 ug/ml
Which of the following antibiotics are used to treat fungal infections? 1. Aminoglycosides 2. Cephalosporins 3. Griseofulvin 4. Polyenes 5. Bacitracin
3 and 4
Which of the following antibiotics causes misreading of mRNA?
Aminoglycoside - changes shape of 30S units
Which of the following antimicrobial agents is recommended for use against fungal infections?
Amphotericin B
Lamisil is an allylamine used to treat dermatomycoses. Lamisil's method of action is similar to that of
Azole antibiotics
Mebendazole is used to treat cestode infections. It interferes with microtubule formation, therefore, it would NOT affect
Bacteria
Most of the available antimicrobial agents are effective against
Bacteria
In what way are semisynthetic penicilllins and natural penicillins alike?
Both are based on B-lactam
In table 20.2, the antibiotic that exhibited bactericidal action was
Can't tell
In table 20.2, which antibiotic would be most useful for treating a Salmonella infection?
Can't tell
The antibiotic streptomycin binds to the 30S subunit of the ribosome as shown in Figure 20.4. The effect is to
Cause misreading of mRNA in 70S ribosomes
The structures of the influenza drug Tamiflu and sialic acid, the substrate for influenza virus's neuramidase are shown in Figure 20.6. What is the method of action of Tamiflu?
Competitive inhibition
In Table 20.2. the most effective antibiotic tested was
D.
The data in Table 20.3 show that these bacteria
Developed resistance to antibiotics.
Which of the following would be selective against the tubercle bacillus?
Ethambutol - inhibits mycolic acid synthesis
Which compound would be the most useful to treat candidiasis?
Flucytosine
A drug that inhibits mitosis, such as griseofulvin, would be more effective against
Fungi
Niclosamide prevents ATP generation in mitochondria. You would expect this drug to be effective against
Helminths.
Which of the following methods of action would be bacteriostatic?
Inhibition of RNA synthesis
Which of the following statements is false? -Fluoroquinolone inhibits DNA synthesis. -Acyclovir inhibits DNA synthesis. -Amantadine inhibits release of viral nucleic acid. -Interferon inhibits glycolysis. -Azoles inhibit plasma membrane synthesis.
Interferon inhibits glycolysis
Which of the following statements about drug resistance is false?
It is found only in gram-negative bacteria
In the presence of penicillin, a cell dies because
It undergoes osmotic lysis
Penicillin was considered a "miracle drug" for all of the following reasons, EXCEPT
It was the first antibiotic
Which of the following antibiotics does NOT interfere with cell wall synthesis?
Macrolides
Which of these antimicrobial agents has the fewest side effects? -Streptomycin -Tetracycline -Penicillin -Erythromycin -Chloramphenicol
Penicillin
Which of the following antibiotics is NOT bactericidal? -Aminoglycosides -Cephalosporins -Polyenes -Rifampins -Penicillin
Polyenes
Which of the following antibiotics is recommended for use against gram-negative bacteria?
Polymyxin
The antibiotic chloramphenicol binds to the 50S subunit of the ribosome as shown in Figure 20.3. The effect is to
Prevent attachment of tRNA
The antibiotic tetracycline binds to the 30S subunit of the ribosome as shown in Figure 20.1. The effect is to
Prevent attachment of tRNA and mRNA
The antibiotic cycloheximide binds to the 60S subunit of the ribosomes as shown in Figure 20.2. The effect is to
Prevent polypeptide elongation in eukaryotes
More than half of our antibiotics are
Produced by bacteria
Which of the following does NOT affect eukaryotic cells? -Antiprotozoan drugs -Antihelminthic drugs -Antifungal drugs -Nucleotide analogs -Semisynthetic penicillins
Semisynthetic penicillins
Which of the following organisms would most likely be sensitive to natural penicillin?
Streptococcus pyogenes
Which of the following does NOT belong with the others? -Bacitracin -Cephalosporin -Monobactam -Penicillin -Streptomycin
Streptomycin
Which of the following drugs does NOT act by competitive inhibition?
Streptomycin
The antimicrobial drugs with the broadest spectrum of activity are
Tetracyclines
Use of antibiotics in animal feed leads to antibiotic-resistant bacteria because
The antibiotics kill susceptible bacteria, but the few that are naturally resistant, live and reproduce, and their progeny repopulate the host animal
Protozoan and helminthic diseases are difficult to treat because
Their cells are structurally and functionally similar to human cells
Which of the following statements about drugs that competitively inhibit DNA polymerase or RNA polymerase is false?
They are too dangerous to use
The antibiotic actinomycin D binds between adjacent G-C pairs, thus interfering with
Transcription
Which of the following does NOT constitute an advantage of using two antibiotics together?
Two are always twice as effective as one
Drug resistance occurs
When antibiotics are used indiscriminately
The substrate for transpeptidase used to synthesize peptidoglycan is shown in Figure 20.5. Which of the drugs shown would inhibit peptidoglycan synthesis?
d
Antimicrobial peptides work by
disrupting the plasma membrane
