Microbial Diversity, Evolution, & Exit

·      What drives genetic diversity in bacteria?

  • Mutations and Horizonal Gene transfer 

·      Describe the mechanisms of horizontal gene transfer (HGT):

Mechanism

 

Description

 

Transformation

 

Bacterium acquires DNA from other dead cells that released DNA

 

Conjugation

 

Species exchange/donate a plasmid by a conjugation pilus physically connecting cells and transfers DNA

 

Transduction

 

Bacterium acquires DNA from other via a bacteriophage (virus)

 

·      Horizontal Gene Transfer (HGT) is ___more______ common between closely related bacteria.

 

 

Microbial Evolution

·      What are the three steps of natural selection?

  • There is a variation in a population (driven by mutations)

  • There is selection the variation (pressure on the population)

  • Trait (alleles) change in the population

 

 

·      How does antibiotic resistance arise in a microbial population?

  • Have antibiotic resistance genes in a population due to mutations through spontaneous production

  • Selective pressure (antibiotics) kills most of the bacteria (except antibiotic ones)

  • Only the resistance ones can do binary fission or conjugation to pass down resistance trait

 

·      How does horizontal gene transfer contribute to the development of antibiotic resistance in a population?

  • Horizontal gene transfer (conjugation) spreads the resistance traits to other bacteria

 

·      Who is Alexander Flemming?

  • Scottish researcher who discovered penicillin by accident

·      Why is antibiotic resistance a large concern in the healthcare field? 

  • Because they apply a selective pressure for bacterial populations to become resistant.

  • Harder and more expensive to treat.

 

·      What are the ESKAPE pathogens?

  • Leading causes of hospital-acquired infections. Multidrug-resistant and presents a great challenge to clinical practice.

  • Top priority

 

Microbial Exit

Describe the difference between a communicable and noncommunicable infection.

  • Communicable infections are transmissible (passed to others).

  • Noncommunicable infections are not transmitted or dead-end host

 

·      How do intracellular pathogen exit host cells?

  • cytolysis: cell lysis and pore formation

  • Budding

  • Extension from membrane

·      How do pathogens exit the host?

  • Through exit sites like respiratory, GI, UT, Reproductive tract, and disrupted/broken barriers

 ·      What is GBS?

  • Group B strep: The opportunistic pathogen in the gut, recognized as a pathogen of pregnancy and neonates