Medicine
Molecular epidemiology of antimicrobial resistance in hospital-acquired infections
Quick fact
Whole-genome sequencing can trace the exact transmission route of a resistant bacteria between patients, even identifying the specific source patient.
Why this is interesting
Have you ever wondered how hospitals know whether two patients with the same superbug are linked?
Read the full explanation
Understanding Molecular epidemiology of antimicrobial resistance in hospital-acquired infections
Molecular epidemiology is like forensic fingerprinting for microbes. When a patient gets a hospital-acquired infection, the bacteria are cultured and their DNA is sequenced. If two patients carry bacteria with nearly identical genomes, it suggests they were infected from a common source, such as a contaminated medical device or staff hands. If the genomes differ significantly, the infections are probably unrelated, arising from separate events.
A deeper explanation
The core principle is that bacteria reproduce clonally, so their DNA is passed on almost unchanged. During a hospital outbreak, the pathogen spreads from one patient to another, and each transfer leaves an identical genetic copy behind. By comparing whole-genome sequences, epidemiologists can identify the transmission chain: isolates that are genetically identical or differ by only a few mutations are considered linked. This approach can distinguish a point-source outbreak (from a single contaminated item) from ongoing patient-to-patient transmission. Critically, it also reveals the movement of resistance genes, which often travel on plasmids or mobile genetic elements that can jump between bacterial species, explaining why resistance can appear in unrelated strains. This information informs infection control measures, such as isolating patients, enhancing hygiene, and reviewing invasive procedures.