Multiresistenta

Multiresistenta is a term used in medicine to describe microorganisms that have acquired resistance to multiple antimicrobial drugs, reducing the effectiveness of standard treatments. While the concept applies to bacteria, fungi and parasites can also be multiresistant, but bacteria are most commonly discussed in this context. Infections caused by multiresistant organisms are harder to treat and may require alternative or combination therapies, longer hospital stays, and greater risk of complications.

Definitions and scope vary by context. In clinical microbiology, multidrug-resistant (MDR) organisms are often described as non-susceptible to at least one agent in three or more antimicrobial categories. Extensively drug-resistant (XDR) organisms are non-susceptible to all but one or two categories, and pandrug-resistant (PDR) organisms show resistance to all antimicrobial agents. These categories help guide treatment decisions and infection control but definitions may differ among countries and organizations.

Causes and mechanisms of multiresistance include genetic mutations and the acquisition of resistance genes through horizontal gene transfer, often via plasmids. Common mechanisms are enzymatic drug inactivation (such as beta-lactamases), alteration of drug targets, reduced drug permeability, and active efflux. Contributing factors include overuse and misuse of antibiotics, insufficient infection control, and increased opportunities for transmission in healthcare settings and, increasingly, in the community.

Detection and surveillance rely on antimicrobial susceptibility testing to determine which drugs a microorganism is susceptible to. Breakpoints established by organizations like CLSI and EUCAST guide interpretation. Surveillance networks monitor prevalence and trends to inform treatment guidelines and policy.

Prevention focuses on antimicrobial stewardship, strict infection control, hand hygiene, environmental cleaning, vaccination where applicable, and prudent antibiotic use to limit the spread and emergence of multiresistant organisms. Treatment decisions depend on susceptibility data and may involve alternative agents or combination therapies.