Question

in 2015, doctors in the united states identified a strain of escherichia coli (e. coli) that carried a gene called mcr - 1, which makes the bacteria resistant to colistin, an antibiotic considered a last resort when other drugs fail. the patient carrying this strain had not traveled abroad, showing that the resistant bacteria were already spreading within u.s. communities. colistin resistance is especially concerning because colistin is one of the few antibiotics effective against certain multi - drug resistant infections. scientists warn that if genes like mcr - 1 spread widely, we could enter a post - antibiotic era where even common infections are much harder to treat. which of the following best describes the concerns scientists have about genes like mcr - 1? they will only affect laboratory experiments they may improve antibiotic effectiveness they could make common infections much harder to treat they prevent bacteria from reproducing

Explanation:

The text states that if genes like mcr - 1 spread widely, we could enter a "post - antibiotic era" where even common infections are much harder to treat. This is the main concern scientists have about such genes.

Answer:

They could make common infections much harder to treat.