What is the Difference Between Multidrug Resistance and Cross Resistance

The key difference between multidrug resistance and cross resistance is that multiple drug resistance is a phenomenon where a pathogen develops resistance to at least one antimicrobial drug in three or more antimicrobial categories, while cross resistance is a phenomenon where pathogen develops resistance to several antimicrobial drugs that have a similar mechanism of action.

Antimicrobial resistance develops when microbes evolve mechanisms that protect them from the effects of antimicrobial drugs. Currently, it specifically applies to bacteria that become resistant to antibiotics. Moreover, infections due to antimicrobial resistance cause millions of deaths per year worldwide. All classes of microbes can evolve resistance, including bacteria, fungi, viruses, and protozoa. The main cause of antimicrobial resistance is the misuse of antimicrobials. There are different types of antimicrobial resistance. Multidrug resistance and cross resistance are two types of antimicrobial resistance.

CONTENTS

1. Overview and Key Difference
2. What is Multidrug Resistance  
3. What is Cross Resistance
4. Similarities – Multidrug Resistance and Cross Resistance
5. Multidrug Resistance vs Cross Resistance in Tabular Form
6. Summary – Multidrug Resistance vs Cross Resistance

What is Multidrug Resistance?

Multiple drug resistance (MDR) is a phenomenon where a pathogen develops resistance to at least one antimicrobial drug in three or more antimicrobial categories. Antimicrobial categories are a classification of antimicrobial agents based on the mode of action of antimicrobials and their specificity to target organisms. Multiple drug resistance types that most threaten public health include MDR bacteria resistant to multiple antibiotics, MDR viruses resistant to antivirals, MDR fungi resistant to antifungals, and other parasites such as MDR protozoa, resistant to antiparasitic drugs.

Figure 01: Multidrug Resistance

The common multidrug resistance bacteria are vancomycin-resistant Enterococci, methicillin-resistant Staphylococcus aureus, extended-spectrum β lactamase producing gram-negative bacteria, Klebsiella pneumoniae carbapenemase-producing gram negatives, multidrug-resistant gram-negative rods (Enterobacter species), and multidrug resistant tuberculosis. The multidrug resistance in bacteria is mainly due to several mechanisms: no longer relying on a glycoprotein cell wall, enzymatic deactivation of antibiotics, decreased cell wall permeability to antibiotics, altered target sites of antibiotics, efflux methods to remove antibiotics, and increased mutation rate as a stress response. An example of antifungal resistance is yeast species that become resistant to azoles preparations. Furthermore, viruses such as influenza, cytomegalovirus, and herpes simplex virus are good examples of MDR viruses. Influenza can become resistant to amantadines & oseltamivir, and cytomegalovirus can become resistant to ganciclovir & foscarnet, while herpes simplex virus can become resistant to acyclovir preparations. The prime example for MDR protozoa is Plasmodium vivax which causes malaria. It has become resistant to antiparasitic agents such as chloroquine and sulfadoxine-pyrimethamine a few decades ago.

What is Cross Resistance?

Cross resistance is a phenomenon where pathogen develops resistance to several antimicrobial drugs that have a similar mechanism of action. For example, if a bacterium develops resistance to one antibiotic, in cross resistance, that bacterium can also develop resistance to other antibiotics that target the same protein in bacteria or use the same route to get into bacteria. One prime example is when bacteria develop resistance to ciprofloxacin; they also develop resistance to nalidixic acid because both drugs work by inhibiting the viral DNA replication enzyme topoisomerase.

Figure 02: Cross Resistance

Cross resistance can occur between structurally similar and dissimilar compounds. An example is cross resistance between antibiotics and disinfectants in bacteria. Exposure to certain disinfectants can lead to the increased expression of efflux pumps that can clear antibiotics as well. Another example is cross resistance between antibiotics and metals. In the bacteria Listeria monocytogenes, a multidrug efflux transporter can export both metals such as Zn and antibiotics out of the cell.

What are the Similarities Between Multidrug Resistance and Cross Resistance?

  • Multidrug resistance and cross resistance are two types of antimicrobial resistance.
  • Both phenomena can be shown by microbes such as bacteria, fungi, viruses, and protozoa.
  • These phenomena mainly occur due to unnecessary exposure to antimicrobials.
  • Both phenomena can cause millions of deaths per year worldwide.

What is the Difference Between Multidrug Resistance and Cross Resistance?

Multiple drug resistance is a phenomenon where a pathogen develops resistance to at least one antimicrobial drug in three or more antimicrobial categories, while cross resistance is a phenomenon where the pathogen develops resistance to several antimicrobial drugs that have a similar mechanism of action. Thus, this is the key difference between multidrug resistance and cross resistance. Furthermore, multidrug resistance is more fatal compared to cross resistance.

The below infographic presents the differences between multidrug resistance and cross resistance in tabular form for side by side comparison.

Summary – Multidrug Resistance vs Cross Resistance

Multidrug resistance and cross resistance are two types of antimicrobial resistance. Multiple drug resistance is a phenomenon where a pathogen develops resistance to at least one antimicrobial drug in three or more antimicrobial categories, while cross resistance is a phenomenon where the pathogen develops resistance to several antimicrobial drugs that have a similar mechanism of action. So, this summarizes the difference between multidrug resistance and cross resistance.