Antibiotics and Antimicrobial Agents > Pharmacology
Exam Review
Antimicrobial resistance
Total Questions : 4
Showing 4 questions, Sign in for moreA nurse is caring for a client with a urinary tract infection caused by Escherichia coli. The client is prescribed ciprofloxacin, a fluoroquinolone antibiotic.
The nurse understands that this antibiotic works by which mechanism?
Explanation
Ciprofloxacin works by inhibiting DNA gyrase, a type II topoisomerase, and topoisomerase IV, enzymes necessary to separate bacterial DNA, thereby inhibiting cell division.
Choice A is wrong because ciprofloxacin does not inhibit cell wall synthesis.
That is the mechanism of action of beta-lactam antibiotics, such as penicillins and cephalosporins.
Choice B is wrong because ciprofloxacin does not inhibit protein synthesis.
That is the mechanism of action of macrolides, such as erythromycin and azithromycin.
Choice D is wrong because ciprofloxacin does not inhibit folic acid synthesis.
That is the mechanism of action of sulfonamides, such as sulfamethoxazole and trimethoprim.
A nurse is educating a client with tuberculosis about the importance of adhering to the prescribed regimen of rifampin, isoniazid, pyrazinamide, and ethambutol for six months.
The nurse should explain that this combination of drugs is necessary to:
Explanation
This means that the combination of drugs reduces the chances of the bacteria becoming resistant to one or more of the drugs, which would make the treatment ineffective.
Choice B is wrong because “enhance the selective toxicity of each drug” means that the drugs would target only the bacteria and not harm the host cells, which is not the main reason for using a combination of drugs.
Choice C is wrong because “increase the penetration of drugs into the lungs” means that the drugs would reach the site of infection more easily, which is not the main reason for using a combination of drugs.
Choice D is wrong because “reduce the adverse effects of each drug” means that the drugs would have less side effects when used together, which is not the main reason for using a combination of drugs.In fact, some of these drugs can have serious side effects such as liver damage, vision loss, or nerve damage.
Normal ranges for rifampin are 8-24 mcg/mL, for isoniazid are 1-6 mcg/mL, for pyrazinamide are 20-60 mcg/mL, and for ethambutol are 2-6 mcg/mL.
A client with a wound infection caused by methicillin-resistant Staphylococcus aureus (MRSA) asks the nurse how the bacteria became resistant to methicillin.
The nurse should respond by saying:
Explanation
The bacteria have an altered target site that methicillin cannot bind to.This means that the bacteria have changed their structure so that the antibiotic cannot attach to them and kill them.
Choice A is wrong because methicillin does not work by being broken down by an enzyme.Some other antibiotics, such as penicillin, can be inactivated by bacterial enzymes, but not methicillin.
Choice C is wrong because methicillin does not work by entering the bacterial cell.Some other antibiotics, such as tetracycline, can be expelled by bacterial membrane pumps, but not methicillin.
Choice D is wrong because methicillin does not work by blocking an alternative pathway.Some other antibiotics, such as sulfonamides, can be bypassed by bacterial alternative pathways, but not methicillin.
A nurse is administering gentamicin, an aminoglycoside antibiotic, to a client with a severe gram-negative infection. The nurse should monitor the client for signs of nephrotoxicity and ototoxicity, which are potential adverse effects of this antibiotic.
The nurse should also be aware that these adverse effects are:
Explanation
This means that the higher the dose and the longer the duration of aminoglycoside therapy, the greater the risk of nephrotoxicity and ototoxicity, which are damage to the kidneys and ears respectively.These adverse effects are irreversible because they cause permanent damage to the cells of these organs.
Choice A is wrong because dose-dependent and reversible implies that the adverse effects can be reversed by lowering the dose or stopping the therapy, which is not true for aminoglycosides.
Choice C is wrong because time-dependent and reversible implies that the adverse effects are related to the length of exposure and can be reversed by shortening the therapy, which is also not true for aminoglycosides.
Choice D is wrong because time-dependent and irreversible implies that the adverse effects are related to the length of exposure and cannot be reversed by shortening the therapy, which is partly true but not as accurate as choice B.
Normal ranges for BUN are 7 to 20 mg/dL and for creatinine are 0.6 to 1.2 mg/dL for men and 0.5 to 1.1 mg/dL for women.Signs of nephrotoxicity include increased BUN and creatinine levels, decreased urine output, proteinuria, hematuria, and casts in urine.Signs of ototoxicity include tinnitus, hearing loss, dizziness, vertigo, and headache
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