Conjugation
One-Sentence Definition
Conjugation is direct, contact-dependent DNA transfer between bacteria, usually of a Plasmid (or integrative conjugative element), via a conjugative pilus/type IV secretion machinery.
Simple Explanation
Two bacteria connect and one sends a copy of a plasmid to the other — like sharing a resistance USB stick.
Detailed Scientific Explanation
- F plasmid in E. coli is the textbook model (tra genes, pilus).
- Many clinical resistance plasmids are conjugative or mobilizable.
- Transfer is typically ssDNA with rolling-circle replication; recipient becomes a new donor if tra genes are complete.
- Can occur across species/genera, especially among Enterobacterales and other Gram-negatives.
Mechanism
Donor–recipient contact → mating channel → plasmid transfer → complementary strand synthesis → heritable plasmid in recipient.
Clinical Importance
- Primary route for epidemic ESBL/carbapenemase plasmid spread in hospitals and One Health reservoirs.
- Explains identical resistance genes in unrelated species.
Research Importance
- Plasmid typing (Inc groups), conjugation frequency assays, plasmid epidemiology.
Diagnostic Relevance
- AST shows phenotype; WGS/PCR show mobile gene context (plasmid vs chromosome).
AMR Relevance
Highest-yield HGT route for clinical MDR. Infection control and stewardship respond to clonal and plasmid outbreaks.
Related Methods
Related Papers
Related MOCs
- MOC - Fundamentals of Microbiology · MOC - Antimicrobial Resistance (AMR) · Horizontal Gene Transfer
Learning Aids
Diagrams
Clinical Example
Example
Case: After a transfer from ICU, a patient’s E. coli urine isolate newly carries KPC; rectal screen of roommate grows Klebsiella with the same blaKPC.
Question: What spread — clone or gene?
Answer: Often both possible, but same carbapenemase across species screams Plasmid Conjugation. Use WGS/plasmid typing; escalate infection control for CRE.
Videos
| Video | Why watch |
|---|---|
| Genetic exchange overview | Conjugation section |
| HGT lecture | Pilus / mating pair detail |
Active Recall Questions
- What structure initiates contact in classic Gram-neg conjugation?
- Why can the same carbapenemase appear in E. coli and Klebsiella?
- Mobilizable vs conjugative plasmid?
Connections
- Element: Plasmid
- Parent: Horizontal Gene Transfer