Enter a player name to begin or load your saved progress.
Cross-resistance is characterized by an organism developing resistance to multiple substances that operate through distinct and unrelated mechanisms of action.
Answer: False
Explanation: Cross-resistance is defined by resistance to multiple substances that share a similar mechanism of action, not distinct and unrelated ones.
An efflux pump is a common mechanism of cross-resistance because it can actively transport various toxic substances out of a cell, maintaining low internal concentrations.
Answer: True
Explanation: Efflux pumps are a common mechanism of cross-resistance, as a single pump can expel multiple structurally diverse compounds, thereby reducing their intracellular concentration.
For microorganisms, cross-resistance is defined as a virus's resistance to a new drug due to prior exposure to the exact same drug.
Answer: False
Explanation: Cross-resistance in microorganisms is defined as resistance to a *new* drug as a consequence of prior exposure to a *different* drug, or more broadly, resistance to multiple distinct antimicrobial agents resulting from a single molecular mechanism.
Structural similarity between compounds is a strong and reliable predictor of cross-resistance, especially when considering aminoglycosides.
Answer: False
Explanation: Structural similarity is generally a weak predictor of cross-resistance, and its predictive power diminishes further when aminoglycosides are excluded from consideration.
The most common cause of cross-resistance is target similarity, where antimicrobial agents share the same biological target or pathway.
Answer: True
Explanation: Target similarity, where different agents affect the same biological target or pathway, is identified as the most common underlying cause of cross-resistance.
What is the defining characteristic of cross-resistance?
Answer: Resistance to multiple substances that share a similar mechanism of action.
Explanation: Cross-resistance is fundamentally defined by an organism developing resistance to multiple substances that operate through a similar, shared mechanism of action.
Which of the following is a common mechanism by which cross-resistance provides protection against multiple compounds?
Answer: Activation of a single efflux pump.
Explanation: A common mechanism of cross-resistance is the activation or increased expression of a single efflux pump, which can expel various toxic substances, including multiple antimicrobial compounds, from the cell.
In the context of microorganisms, particularly viruses, how is cross-resistance broadly defined?
Answer: Resistance to multiple distinct antimicrobial agents resulting from a single molecular mechanism.
Explanation: For microorganisms, cross-resistance is broadly defined as resistance to multiple distinct antimicrobial agents that results from a single underlying molecular mechanism.
To what extent does structural similarity predict cross-resistance between compounds?
Answer: It is generally a weak predictor, and does not predict it at all when aminoglycosides are excluded.
Explanation: Structural similarity is generally a weak predictor of cross-resistance, and its predictive value is further diminished when aminoglycosides are not considered.
What is identified as the most common cause of cross-resistance?
Answer: Target similarity.
Explanation: The most common cause of cross-resistance is identified as target similarity, where different antimicrobial agents share the same biological target or pathway.
In bacteria, resistance to ciprofloxacin can lead to cross-resistance to nalidixic acid because both are quinolone antibiotics that inhibit topoisomerase.
Answer: True
Explanation: The source explicitly states that resistance to ciprofloxacin can lead to cross-resistance to nalidixic acid due to their shared mechanism of inhibiting topoisomerase.
Cross-resistance is generally considered beneficial for antimicrobial treatments like phage therapy, as it enhances their long-term effectiveness.
Answer: False
Explanation: Cross-resistance is detrimental to antimicrobial treatments, as it can lead to a rapid loss of effectiveness, making it a critical factor to manage in evolutionary therapies.
Cross-resistance plays a significant role in the increasing development of multidrug resistance in bacteria, contributing to the broader problem of antibiotic resistance.
Answer: True
Explanation: Cross-resistance is a significant factor in the development of multidrug resistance in bacteria, exacerbating the global challenge of antibiotic resistance.
Antibiotic resistance always arises as a direct consequence of exposure to an antimicrobial compound.
Answer: False
Explanation: Antibiotic resistance can emerge through various pathways and is not exclusively a direct result of exposure to an antimicrobial compound.
Which pair of antibiotics exemplifies cross-resistance in bacteria due to shared inhibition of topoisomerase?
Answer: Nalidixic acid and Ciprofloxacin
Explanation: The source identifies nalidixic acid and ciprofloxacin as an example of cross-resistance in bacteria, as both are quinolone antibiotics that inhibit topoisomerase.
How does cross-resistance primarily affect the effectiveness of antimicrobial treatments like phage therapy?
Answer: It leads to a rapid loss of effectiveness against bacteria.
Explanation: Cross-resistance can cause antimicrobial treatments, including phage therapy, to rapidly lose their effectiveness against target bacteria.
What is a significant consequence of cross-resistance in clinical medicine?
Answer: It contributes to the increasing development of multidrug resistance in bacteria.
Explanation: A significant consequence of cross-resistance in clinical medicine is its contribution to the increasing development of multidrug resistance in bacteria, complicating treatment options.
According to the source, is antibiotic resistance always a direct result of exposure to an antimicrobial compound?
Answer: No, it can emerge through multiple pathways.
Explanation: The source explicitly states that antibiotic resistance can emerge through multiple pathways and is not necessarily a direct result of exposure to an antimicrobial compound.
In pest management, cross-resistance specifically refers to resistance developed by pest populations to pesticides from different chemical families.
Answer: False
Explanation: In pest management, cross-resistance refers to resistance to multiple pesticides that belong to the *same* chemical family, often due to shared binding target sites.
Cadherin mutations in *Helicoverpa armigera* can result in cross-resistance to Cry1Aa and Cry1Ab proteins, which are insecticidal proteins from *Bacillus thuringiensis*.
Answer: True
Explanation: The source provides this as a specific example of cross-resistance in pest management, where cadherin mutations confer resistance to related insecticidal proteins.
Multiple resistance is distinct from cross-resistance because it involves resistance to several pesticides through different resistance mechanisms.
Answer: True
Explanation: Multiple resistance is characterized by resistance to several pesticides via *different* mechanisms, whereas cross-resistance involves resistance to multiple substances through a *single shared* mechanism.
In pest management, cross-resistance is defined by the development of resistance to multiple pesticides that share what characteristic?
Answer: They belong to the same chemical family.
Explanation: In pest management, cross-resistance is specifically defined as resistance to multiple pesticides that belong to the same chemical family, often due to shared target sites.
What specific genetic alteration in *Helicoverpa armigera* leads to cross-resistance to Cry1Aa and Cry1Ab proteins?
Answer: Cadherin mutations
Explanation: Cadherin mutations in *Helicoverpa armigera* are identified as the genetic alteration leading to cross-resistance against Cry1Aa and Cry1Ab proteins.
How does 'multiple resistance' fundamentally differ from 'cross-resistance' in the context of pesticides?
Answer: Multiple resistance develops through different resistance mechanisms, unlike cross-resistance which uses a single shared mechanism.
Explanation: Multiple resistance involves distinct resistance mechanisms for different pesticides, whereas cross-resistance arises from a single mechanism conferring resistance to multiple compounds.
Exposure to certain disinfectants can lead to antibiotic cross-resistance by increasing the expression of efflux pump genes.
Answer: True
Explanation: Exposure to disinfectants can induce the overexpression of efflux pump genes, leading to cross-resistance against both disinfectants and various antibiotics.
Cross-resistance between antibiotics and metals is impossible because their chemical structures are fundamentally different.
Answer: False
Explanation: Cross-resistance between antibiotics and metals is possible, even with dissimilar structures, if a shared cellular mechanism, such as an efflux transporter, is involved in their removal.
Experimental studies have shown that exposure to zinc can decrease bacterial resistance to antibiotics.
Answer: False
Explanation: Experimental studies have demonstrated that exposure to zinc can lead to *increased* bacterial resistance to antibiotics, not decreased.
The presence of heavy metals in the environment can contribute to the development of antibiotic resistance in microorganisms.
Answer: True
Explanation: Environmental factors, including exposure to heavy metals, can contribute to the development of antibiotic resistance in microorganisms through mechanisms like cross-resistance.
How can exposure to disinfectants lead to cross-resistance to antibiotics?
Answer: By increasing the expression of genes coding for efflux pumps.
Explanation: Exposure to certain disinfectants can induce the increased expression of efflux pump genes, which then confer cross-resistance to both disinfectants and various antibiotics.
Which of the following statements is true regarding cross-resistance between antibiotics and metals?
Answer: It can occur if the same cellular mechanism is used to remove both types of compounds.
Explanation: Cross-resistance between antibiotics and metals can occur if a shared cellular mechanism, such as a multi-drug efflux transporter, is utilized to remove both types of compounds from the cell.
What experimental evidence supports the link between metal exposure and antibiotic resistance?
Answer: Research reporting cross-resistance to various metals and antibiotics through efflux systems.
Explanation: Experimental studies have reported cross-resistance to various metals and antibiotics, often mediated by mechanisms like drug efflux systems, supporting a link between metal exposure and antibiotic resistance.
What broader implication does cross-resistance between metals and antibiotics have for antibiotic resistance?
Answer: It indicates that environmental factors like heavy metal exposure can contribute to resistance.
Explanation: The cross-resistance between metals and antibiotics implies that environmental factors, such as heavy metal exposure, can significantly contribute to the development and spread of antibiotic resistance in microorganisms.
Collateral sensitivity is a phenomenon where resistance to one drug leads to increased resistance to another different drug.
Answer: False
Explanation: Collateral sensitivity is defined as the development of resistance to one drug leading to *increased susceptibility* (sensitivity) to a different drug, not increased resistance.
Collateral sensitivity has only been observed and studied in bacterial pathogens.
Answer: False
Explanation: Collateral sensitivity has been studied in both bacterial and pathogenic fungal organisms, indicating its broader relevance in microbial resistance.
Collateral sensitivity-based treatments have shown effectiveness against resistant populations in laboratory settings, offering promise for combating cross-resistance.
Answer: True
Explanation: Collateral sensitivity-based treatments have demonstrated effectiveness against resistant populations in *in vitro* studies, suggesting a promising strategy for managing drug resistance.
The individual mechanisms for collateral sensitivity are fully understood and involve a direct enhancement of organism fitness.
Answer: False
Explanation: The specific individual mechanisms underlying collateral sensitivity are not yet fully understood, and it is theorized to involve a trade-off where resistance benefits might be balanced by reduced organism fitness.
Collateral sensitivity-based treatments are being explored for multidrug-resistant pathogens like *Staphylococcus aureus* and *Candida auris*.
Answer: True
Explanation: Collateral sensitivity-based treatments are being investigated for their potential application against multidrug-resistant pathogens such as methicillin-resistant *Staphylococcus aureus* and *Candida auris*.
What is collateral sensitivity in the context of drug resistance?
Answer: The development of resistance to one drug leading to increased susceptibility to another different drug.
Explanation: Collateral sensitivity is a phenomenon where the acquisition of resistance to one drug results in an increased susceptibility to a different drug.
In which types of organisms has collateral sensitivity been studied?
Answer: In both bacteria and pathogenic fungi.
Explanation: Collateral sensitivity has been investigated and observed in both bacterial and pathogenic fungal organisms.
What is theorized about the relationship between collateral sensitivity and antimicrobial resistance regarding organism fitness?
Answer: They exist as a trade-off, where resistance benefits might be balanced by risks like reduced organism fitness.
Explanation: It is theorized that collateral sensitivity and antimicrobial resistance represent a trade-off, where the benefits of resistance may be counterbalanced by potential reductions in overall organism fitness.
For which of the following multidrug-resistant pathogens could collateral sensitivity-based treatments potentially be utilized in the future?
Answer: Methicillin-resistant Staphylococcus aureus and Candida auris.
Explanation: Collateral sensitivity-based treatments are being explored for future application against significant multidrug-resistant pathogens, including methicillin-resistant *Staphylococcus aureus* and *Candida auris*.