A drug that intercalates into DNA has the following eects.

Why dont penicillins aect the human cell?

Why do antibiotics that inhibit protein synthesis aect bacteria and not human cells?

Many antifungal drugs combine with sterols in the plasma membrane. Why dont they combine with sterols in human cell membranes?

What does semisynthetic mean?

How does a low concentration of penicillin G select for penicillin-resistant bacteria?

What is penicillinase?

Would a _-lactamase eective against penicillin G be likely to aect cephalosporins?

What eect does the binding of chloramphenicol to the 50S portion of the ribosomes have on a cell?

How do tetracyclines aect bacteria?

How do macrolides aect bacteria?

Dene synergism.

Why do polyenes injure fungal plasma membranes and not bacterial membranes?

How do azoles aect fungi?

Why are viral infections generally dicult to treat with chemotherapeutic agents?

Which agent is the most eective against the bacterium being tested?

What is the MIC of the E test on the left?

What is MIC?

This test used streptomycin and a gram-negative bacterium. What would the lines have looked like if penicillin G had been the antibiotic?

How does this practice lead to development of resistant strains of pathogens?

What would the plate look like if the two antibiotics had been antagonistic?

Which of the following will not aect eukaryotic cells?a. inhibition of the mitotic spindleb. binding with sterolsc. binding to 80S ribosomesd. binding to DNAe. All of the above will aect them

Cell membrane damage causes death becausea. the cell undergoes osmotic lysis.b. cell contents leak out.c. the cell plasmolyzes.d. the cell lacks a wall.e. none of the above

A drug that intercalates into DNA has the following eects. Which one leads to the others?a. It disrupts transcription.b. It disrupts translation.c. It interferes with DNA replication.d. It causes mutations.e. It alters proteins

Chloramphenicol binds to the 50S portion of a ribosome, which will interfere witha. transcription in prokaryotic cells.b. transcription in eukaryotic cells.c. translation in prokaryotic cells.d. translation in eukaryotic cells.e. DNA synthesis

Te following data were obtained from a disk-diffusion test

Why do you suppose Streptomyces griseus produces an enzyme that inactivates streptomycin? Why is this enzyme produced early in metabolism?

. Te following results were obtained from a broth dilution test for microbial susceptibility

Vancomycin-resistant Enterococcus faecalis was isolated from a foot infection of a 40-year-old man. e patient had a chronic diabetes-related foot ulcer and underwent amputation of a gangrenous toe. He subsequently developed methicillin-resistant Staphylococcus aureus bacteremia. e infection was treated with vancomycin. One week later, he developed a vancomycin-resistant S. aureus (VRSA) infection. is is the rst case of VRSA in the United States. What is the most likely source of the VRSA?

A patient with a urinary bladder infection took nalidixic acid, but her condition did not improve. Explain why her infection disappeared when she switched to a sulfonamide

A patient with streptococcal sore throat takes penicillin for 2 days of a prescribed 10-day regimen. Because he feels better, he then saves the remaining penicillin for some other time. Aer 3 more days, he suers a relapse of the sore throat. Discuss the probable cause of the relapse