Antibiotic resistance

Antibiotic resistance is the ability of bacteria and other microorganisms to survive drugs that previously inhibited or killed them. It can arise through genetic change and spread between microbes.

Antibiotic resistance mechanisms: Biological strategies microorganisms use to withstand antimicrobial drugs. This umbrella concept groups the molecular strategies that produce resistance.
Antimicrobial stewardship: Coordinated efforts to use antimicrobial drugs appropriately and preserve their effectiveness. Stewardship reduces avoidable selection pressure from antibiotic use.
Alexander Fleming: Scottish physician and microbiologist who discovered penicillin in 1928. Fleming warned in 1945 that misuse of penicillin could select resistant bacteria.
Antibiotic tolerance: A temporary ability of a bacterial population to survive antibiotic exposure without a higher minimum inhibitory concentration. Tolerance can mimic resistance clinically but does not necessarily involve increased drug concentration thresholds.
Antibiogram: A summary of antimicrobial susceptibility results for bacterial isolates in a defined population or setting. Antibiograms guide empiric treatment using local resistance patterns.
Beta-lactamase: An enzyme that hydrolyzes the beta-lactam ring in certain antibiotics. Enzymatic drug destruction is a widespread route to resistance.
Multidrug-resistant tuberculosis: Tuberculosis caused by bacteria resistant to at least isoniazid and rifampicin. This disease shows how resistance can make standard treatment regimens fail.
Penicillin: A group of beta-lactam antibiotics first derived from Penicillium fungi. Its clinical use helped make antibiotic resistance a visible medical problem.
Antibiotic persistence: A phenomenon in which a small subpopulation survives antibiotic exposure and later regrows without inherited resistance. Persisters survive treatment transiently, unlike genetically resistant descendants.
Antibiotic susceptibility testing: Laboratory testing that determines how susceptible a microorganism is to antimicrobial drugs. Clinicians use results to choose treatments likely to work against resistant infections.

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