A nurse is administering an antifungal medication to a client who has a systemic fungal infection.
The nurse understands that antifungal drugs have a higher risk of toxicity than antibacterial drugs because:

This is because antibiotics that inhibit cell wall synthesis are most effective against bacteria that have a thick peptidoglycan layer in their cell wall, which is characteristic of gram-positive bacteria.Peptidoglycan is a polymer of glycan and peptides that gives the cell wall its strength and rigidity.Antibiotics that inhibit cell wall synthesis, such as β-lactams and glycopeptides, prevent the formation or cross-linking of the peptidoglycan layer, resulting in cell wall defects and bacterial lysis.

Choice B is wrong becauseGram-negative bacteria is wrong because gram-negative bacteria have a thin peptidoglycan layer and an outer membrane that protects them from antibiotics that target cell wall synthesis.Some gram-negative bacteria also have efflux pumps or β-lactamases that can expel or degrade these antibiotics.

Choice C is wrong becauseAnaerobic bacteria is wrong because anaerobic bacteria can be either gram-positive or gram-negative, and their susceptibility to antibiotics that inhibit cell wall synthesis depends on their cell wall structure and resistance mechanisms.

Choice D is wrong becauseAtypical bacteria is wrong because atypical bacteria are bacteria that lack a cell wall, such as Mycoplasma and Chlamydia.These bacteria are naturally resistant to antibiotics that inhibit cell wall synthesis, as they do not have a peptidoglycan layer to target.

These are examples of antibiotic combinations that have synergistic effects, meaning they enhance each other’s bacterial killing when used together.

Choice A is correct because ampicillin and gentamicin are synergistic against enterococcal infections.

Ampicillin inhibits the cell wall synthesis of enterococci, while gentamicin damages their ribosomes and interferes with protein synthesis.

Choice B is correct because trimethoprim and sulfamethoxazole are synergistic against many gram-negative and gram-positive bacteria.

Trimethoprim inhibits the enzyme dihydrofolate reductase, while sulfamethoxazole inhibits the enzyme dihydropteroate synthase.

Both enzymes are involved in the synthesis of folic acid, which is essential for bacterial DNA replication.

Choice C is wrong because clindamycin and erythromycin are antagonistic, meaning they interfere with each other’s activity when used together.

Both antibiotics bind to the same site on the bacterial ribosome and block protein synthesis, but clindamycin has a higher affinity and displaces erythromycin.

Choice D is wrong because metronidazole and ciprofloxacin are not synergistic, but additive, meaning they have independent effects when used together.

Metronidazole damages the bacterial DNA by generating reactive oxygen species, while ciprofloxacin inhibits the enzyme DNA gyrase that unwinds the DNA for replication.

Choice E is wrong because vancomycin and rifampin are not synergistic, but indifferent, meaning they have no effect on each other’s activity when used together.

Vancomycin inhibits the cell wall synthesis of gram-positive bacteria by binding to the peptidoglycan precursors, while rifampin inhibits the bacterial RNA polymerase that transcribes DNA into RNA.