Mechanisms of resistance

Intrinsic resistance describes a trait of resistance which has not been developed due to mutations (mutational resistance), in response to any selection pressures like antibiotic exposure (acquired resistance), or developed via horizontal gene transfer. The resistance which P. aeruginosa shows to tigecycline is an example of intrinsic resistance in NFGNB.

Regardless of the method of resistant gene acquisition, however, bacterial antimicrobial resistance genes fall into the 4 main categories summarised in the diagram below:

The four main categories of antimicrobial resistance in bacteria. Click here for a closer look.

For more on these categories, a comprehensive paper on the antimicrobial resistance mechanisms of bacteria can be found in the see also section below.

For NFGNB, some resistance mechanisms are more concerning than others. For example, resistance to the carbapenem antibiotic class is increasing globally for NFGNB. Within this area of resistance, genes encoding carbapenemases (antibiotic-degrading enzymes) are particularly concerning for NFGNB as these genes are easily transmitted, and are associated with MDR genes.

Later on, we will further explore specific issues of antimicrobial resistance in NFGNB.