The Ultimate Guide to Antimicrobial Resistance

Take a look under the microscope

According to the World Health Organization, antimicrobial resistance is one of the top 10 global public health and development risks, which also carries considerable economic costs. In this comprehensive article, we examine what causes antimicrobial resistance as well as how to prevent it.

What is antimicrobial resistance?

Antimicrobial resistance (AMR) refers to the process that allow germs like bacteria and fungi to vanquish what they consider their enemies, i.e., drugs aimed to kill them. When the first antibiotic was used clinically in 1910, the common belief in the healthcare industry was that the battle against microorganisms was finally won. Unfortunately, scientists quickly found out that bacteria and fungi can develop resistance to antibiotics or antifungal treatments. When they are exposed to drugs, they still continue to grow.

What causes antimicrobial resistance? 

AMR can involve a change in a microorganism’s genetics by acquisition of genetic material from other organisms via transformation, transposition, or conjugation that can confer resistance to antimicrobials. Their survival strategies are defined as resistance mechanisms.

AMR mechanisms can be classified by their targets of bacterial metabolism:
1.    Inhibition of cell wall synthesis: A process that inhibits both growth and multiplication of the cell
2.    Depolarization of the cell membrane: A shift in the electric charge of the membrane, resulting in less negative charge inside vs. outside
3.    Inhibition of protein synthesis: The disruption of the process that creates new proteins
4.    Inhibition of the nucleic acid synthesis: The disruption of the production of nucleic acids: DNA and RNA
5.    Inhibition of metabolic pathways: The disruption of several chemical reactions such as glycolysis

There are four main categories of AMR which can be classified as natural or intrinsic resistance or acquired resistance:
1.    Modification of drug target : Several components in the bacterial cell may be targets of antimicrobial therapeutic substances used to prevent or treat infections
2.    Inactivation of a drug: Bacteria inactivate drugs by degrading the drug or transferring a chemical group to it
3.    Limiting uptake of a drug: The ability of bacteria to limit the uptake of antimicrobial therapeutic substances used to prevent or treat infections
4.    Efflux pump: A process used to remove an antimicrobial from a cell

Of course, the mechanisms used depend on the type of microorganisms. For example, Gram-negative bacteria could use all the mechanisms mentioned above, while Gram-positive bacteria cannot perform specific drug efflux mechanisms due to their structure. 

Preventative measures for antimicrobial resistance

Clinical microbiologists are fundamental in providing analytical information. Additionally, they provide direction on strategies for prevention. Correct sampling and interpretation of test results, difficult-to-treat pathogens, and complicated infections are all steps of accurate identification of a species known to be resistant and they are fundamental to respond accordingly.

Over the years, scientists’ capacity to cure regular infections is being challenged by new resistance mechanisms. To fight AMR, it’s important to develop harmonized partnerships starting from the labs, since trending investigations and root-cause analysis should set the basis to lead to continuous improvement and, hopefully, find a cure to this global burden.

There are some programs and guidelines that have been developed to face all these consequences. The Antimicrobial stewardship, for example, describe programs that encourages the proper use of antimicrobials (including antibiotics), improve therapeutic results, decrease microbial resistance, and reduce the spread of infections caused by multidrug-resistant organisms. Unfortunately, the correlation between antimicrobial usage and resistance is not always straightforward. The comprehension of which procedures are most efficient is limited because many studies are quasi-experimental. Recent evaluations of stewardship programs encourage reduction of antimicrobial pressure in some interventions and their positive impact in resistance ratios, while other organizations, such as the European Union, are issuing guidelines for the prudent use of antimicrobials in human health to prevent the spreading of AMR.

For further information on AMR and how to address it accordingly, be sure to check out our 3-part Radiation and Disinfectant Resistance in Microorganisms video series.