A nurse is caring for a client who has a severe infection and is receiving a combination of antibiotics. The nurse knows that some antibiotics have synergistic effects when used together. Which of the following are examples of antibiotic combinations that have synergistic effects? (Select all that apply.)
Ampicillin and gentamicin
Trimethoprim and sulfamethoxazole
Clindamycin and erythromycin
Metronidazole and ciprofloxacin
Vancomycin and rifampin.
Correct Answer : A,B
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.
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Related Questions
Correct Answer is C
Explanation
This means that antifungal drugs have to target specific components of the fungal cell that are different from the human cell, such as the cell membrane or the cell wall.However, this also increases the risk of toxicity to human cells, especially those that have high turnover rates, such as liver and kidney cells.
Choice A is wrong because fungi do not have cell walls that are difficult to penetrate.Fungi have cell walls that are composed of chitin, glucan, and mannoproteins, which are different from the peptidoglycan cell walls of bacteria.
Antifungal drugs can target these components and disrupt the integrity of the fungal cell wall.
Choice B is wrong because fungi are not more resistant to drug therapy than bacteria.Fungi can develop resistance to antifungal drugs, but this is not a common mechanism of antifungal drug failure.Bacteria can also develop resistance to antibacterial drugs through various mechanisms, such as producing enzymes that degrade or modify the drugs, altering the target sites of the drugs, or pumping out the drugs from the cell.
Choice D is wrong because fungi do not mutate rapidly and develop drug resistance.
Fungi have a slower rate of mutation than bacteria because they have a more complex genome and a more efficient DNA repair system
Correct Answer is B
Explanation
Antiviral drugs for influenza can reduce the duration and severity of symptoms by inhibiting the replication of the virus in the body.They are most effective when started within 48 hours of illness onset.
Choice A is wrong because antiviral drugs do not kill the influenza virus, but only prevent it from multiplying.
Choice C is wrong because antiviral drugs do not prevent the transmission of the virus to others, but only reduce the amount of virus shed by infected persons.People who take antiviral drugs should still practice good hygiene and avoid close contact with others.
Choice D is wrong because antiviral drugs do not stimulate the immune system to fight off the virus, but only interfere with the viral enzymes that are essential for viral replication.Antiviral drugs are not a substitute for vaccination, which can induce protective immunity against influenza.
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