coresistance

Coresistance refers to the phenomenon where an organism, particularly a microorganism, exhibits resistance to multiple antibiotics or antimicrobial agents simultaneously. This concept is closely related to multidrug resistance (MDR), though it often implies a more intrinsic or genetically encoded mechanism rather than acquired resistance through mutations or horizontal gene transfer. Coresistance typically arises when resistance genes are located on the same genetic element, such as a plasmid or chromosomal region, allowing the organism to resist several drugs at once.

The emergence of coresistance is a significant concern in clinical settings, as it complicates the treatment of infections caused by pathogens like *Staphylococcus aureus*, *Pseudomonas aeruginosa*, and *Enterobacteriaceae*. For example, some strains of *Escherichia coli* may carry resistance genes for beta-lactams, fluoroquinolones, and aminoglycosides on a single plasmid, making them highly resilient to standard antibiotic regimens. This co-occurrence of resistance traits often stems from evolutionary pressures, where selective pressure from one antibiotic can inadvertently promote resistance to others.

Coresistance is not always fixed; some cases involve overlapping resistance mechanisms, such as efflux pumps that expel multiple drugs or enzymatic degradation of unrelated antimicrobials. Additionally, coresistance can be influenced by environmental factors, including antibiotic use in agriculture or healthcare, which accelerates the spread of resistant strains. Efforts to mitigate coresistance include the development of novel antibiotics, improved infection control practices, and the strategic use of existing drugs to reduce selective pressure.

Understanding coresistance is crucial for public health, as it underscores the need for comprehensive strategies to combat antimicrobial resistance. Research in this area often involves genomic analysis to map resistance genes and their co-localization, as well as epidemiological studies to track the spread of coresistant pathogens.