There are fewer antifungal, antiprotozoan, and antihelminth drugs compared to antibacterial drugs because these organisms
do not cause many human infections.
have fewer target sites compared to bacteria.
are so similar to human cells that selective drug toxicity is difficult to achieve.
are parasites found inside human cells.
are not affected by antimicrobics.
The Correct Answer is C
A. do not cause many human infections: While some fungi, protozoa, and helminths cause fewer infections compared to bacteria, the main limitation in drug development is not the frequency of infections. Even common infections like candidiasis or malaria require treatment, so infection prevalence alone does not explain the scarcity of effective drugs.
B. have fewer target sites compared to bacteria: These organisms do possess cellular structures that could be targeted, such as cell membranes, enzymes, or nucleic acids. The issue is not the number of potential targets but the similarity of those targets to human cells, which complicates drug design.
C. are so similar to human cells that selective drug toxicity is difficult to achieve: Fungi, protozoa, and helminths are eukaryotic, like human cells, meaning their cellular structures and metabolic pathways closely resemble those of the host. This similarity makes it challenging to develop drugs that are toxic to the pathogen but safe for human cells, limiting the number of available therapeutic options.
D. are parasites found inside human cells: While intracellular parasites pose delivery challenges for drugs, this is not the primary reason for the overall scarcity of antifungal, antiprotozoan, and antihelminth medications. Drug development is limited mainly by eukaryotic similarity rather than intracellular location alone.
E. are not affected by antimicrobics: This is incorrect because antifungal, antiprotozoan, and antihelminth drugs do exist and can be effective. The challenge is creating agents that selectively target these organisms without harming human cells, not an inherent resistance to all antimicrobial agents.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is E
Explanation
A. allergic reactions: Allergic reactions occur when the immune system responds abnormally to a drug, often due to hypersensitivity to certain antimicrobial agents such as penicillins or sulfonamides. While these reactions can occur with antimicrobial therapy, they are related to immune responses rather than disruption of the body’s normal microbiota.
B. nephrotoxicity: Nephrotoxicity refers to kidney damage caused by certain medications, particularly drugs such as aminoglycosides or vancomycin that may accumulate in renal tissues. Although some antimicrobials can cause kidney injury, this effect is due to the drug’s toxic properties rather than the elimination of normal microbial flora.
C. drug toxicity: Drug toxicity occurs when a medication reaches harmful concentrations in body tissues, often due to excessive dosage, impaired metabolism, or prolonged use. While antimicrobial agents can produce toxic effects, these are pharmacologic complications related to the drug itself rather than the loss of beneficial microorganisms in the body.
D. All of these choices are correct: Although allergic reactions, nephrotoxicity, and drug toxicity are potential adverse effects of antimicrobial therapy, they do not directly result from the disruption of normal microbiota. The question specifically refers to the effects of disturbing the body’s normal microbial balance, therefore this is not accurate.
E. superinfections: Broad-spectrum antimicrobials can eliminate beneficial microorganisms that normally compete with opportunistic pathogens for nutrients and space. When the protective normal microbiota are suppressed, resistant organisms such as Clostridioides difficile or certain yeasts can overgrow. This imbalance often leads to secondary infections known as superinfections.
Correct Answer is D
Explanation
A. saprobic: A saprobic relationship refers to organisms that obtain nutrients by decomposing dead or decaying organic matter. Saprobes, such as many fungi and bacteria, play an important role in environmental nutrient cycling. The E. coli in the human intestine are not primarily decomposing dead tissue but instead living within a host and interacting with host physiology.
B. commensal: In a commensal relationship, one organism benefits while the other is neither significantly helped nor harmed. Although many normal microbiota are considered commensal, intestinal E. coli provide a measurable benefit to the host by synthesizing vitamin K and certain B vitamins. The host receives a physiological benefit, this interaction is more than commensal.
C. parasitic: A parasitic relationship occurs when one organism benefits at the expense of the host, often causing harm or disease. Pathogenic bacteria demonstrate parasitism by damaging tissues, stealing nutrients, or producing toxins. E. coli that reside in the colon as part of the normal microbiota do not harm the host and instead contribute to normal metabolic functions.
D. mutualistic: Mutualism describes a symbiotic relationship in which both organisms benefit. In the human colon, E. coli receive nutrients and a stable environment for growth, while the host benefits from bacterial synthesis of vitamin K, which is essential for blood clotting processes. This reciprocal exchange of benefits characterizes a mutualistic relationship.
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