🦠microbiology review

Cross-resistance

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Cross-resistance occurs when a microorganism resistant to one antimicrobial drug also becomes resistant to another drug, often due to similar mechanisms of action or genetic factors. This phenomenon can complicate treatment options and contribute to the spread of multidrug-resistant infections.

5 Must Know Facts For Your Next Test

  1. Cross-resistance often arises from the use of antibiotics with similar structures or mechanisms.
  2. It can be caused by genetic mutations that confer resistance to multiple drugs.
  3. Efflux pumps in bacteria are common contributors to cross-resistance by expelling various drugs out of the cell.
  4. Horizontal gene transfer between bacteria can spread resistance genes, leading to cross-resistance.
  5. Cross-resistance poses significant challenges in treating infections, particularly in hospital settings where multidrug-resistant strains are prevalent.

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