Multiresistans

Multiresistans refers to the ability of microorganisms, most commonly bacteria, to withstand treatment with several antimicrobial agents. Infections caused by multiresistant organisms are harder to treat, often requiring second-line or combination therapies and resulting in longer illness and higher risk of complications. The term is used across medicine, veterinary settings and the environment.

Notable examples of multiresistant bacteria include methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum beta-lactamase–producing Enterobacterales (ESBL), carbapenem-resistant Enterobacteriaceae (CRE), and multidrug-resistant Pseudomonas aeruginosa and Acinetobacter species. Multiresistance is also seen in Mycobacterium tuberculosis (MDR-TB) and the fungal pathogen Candida auris.

Resistance develops through genetic changes that can spread between organisms via plasmids, transposons and other mobile elements. Common mechanisms include enzymatic drug inactivation, alteration of drug targets, increased efflux, and reduced permeability. Biofilms and slow-growing subpopulations can also shield microbes from antimicrobial effects.

Drivers include overuse and misuse of antibiotics in human and veterinary medicine, incomplete treatment, inadequate infection control, and global travel enabling spread. Weak surveillance and a dearth of new antimicrobial classes further enable persistence of multiresistant strains.

Impacts include higher morbidity and mortality, longer hospital stays and higher costs. Management emphasizes infection prevention and antimicrobial stewardship, rapid diagnostics to guide therapy, and access to effective drugs. Ongoing research seeks new antimicrobials, alternative therapies, and strategies to reduce resistance through a One Health approach.