Question

Cross resistance is:

1) the deactivation of an antimicrobial agent by a bacterial enzyme
2) alteration of the resistant cells so that an antimicrobial agent cannot attach
3) the mutation of genes that affect the cell membrane channels so that antimicrobial agents cannot cross into the cell's interior
4) resistance to one antimicrobial agent because of its similarity to another antimicrobial agent

Answer 1

Cross resistance is when bacteria or other microbes are resistant to multiple drugs due to a shared mechanism, often making them resistant to similar drugs. It is significant clinically as it can make entire classes of antibiotics less effective against infections.

Step-by-step explanation:

Cross resistance refers to the phenomenon where a single resistance mechanism in a microbe provides resistance to multiple antimicrobial drugs. This happens for instance, when an efflux pump can expel multiple antimicrobial drugs out of the cell. Cross resistance is particularly concerning as it enables bacteria, and other microbes, to withstand various types of drugs not because they're resistant to each on an individual basis, but because a shared mechanism confers resistance to similar drugs.

For example, if bacteria are resistant to a ß-lactam antibiotic like penicillin because they produce ß-lactamase, which breaks down the antibiotic, they may also be resistant to other ß-lactam antibiotics like amoxicillin. Therefore, the correct definition of cross resistance is that it is resistance to one antimicrobial agent because of its similarity to another antimicrobial agent, option 4 in the student's question.