Bacterial Resistance

Bacterial Resistance

Multi-Drug Resistance

• Multi-drug resistance has led to the increasing incidence of diseases with renewed virulence (re-emerging diseases).

• Antibiotics are losing their power and encouraging the emergence of infections that are difficult to treat.

Emerging Diseases

• Examples of emerging diseases include:

  • Hantavirus

  • E. coli 0157:H7

  • BSE and vCJD

  • West Nile virus

  • Multi-drug resistant Tuberculosis

  • SARS

  • Bubonic plague

  • H5N1 Bird flu

  • HIV and AIDS

  • Nipah virus

  • Hemorrhagic fevers: Ebola and Marburg

  • Hendra virus

Mechanisms of Resistance

• Germs develop new cell processes that avoid using the antibiotic's target.

• Germs change or destroy the antibiotics with enzymes, proteins that break down the drug.

• Germs restrict access by changing the entryways or limiting the number of entryways.

• Germs change the antibiotic's target so the drug can no longer fit and do its job.

• Germs get rid of antibiotics using pumps.

Development of Resistance

1. High number of bacteria, a few of them are resistant to antibiotic.

2. Antibiotic kills pathogenic bacteria as well as the good bacteria within the body (probiotics).

3. The antibiotic resistant bacteria now proliferates without competition.

4. The bacteria can transfer the antibiotic-resistance gene to other bacteria via plasmids (conjugation).

Horizontal Evolution

• CONJUGATION

  • Resistance genes can be transferred between bacteria of the same or different species via plasmids.

• TRANSDUCTION

  • Resistance genes are transferred from one bacteria to another via viral phages.

• TRANSFORMATION

  • Resistance genes released from live or dead bacteria are picked up by another.

Vertical Evolution

• Resistance traits are inherited from one generation to another through binary fission (the way in which bacteria reproduce).

• Over many generations/cloning of the bacteria, mutations occur.

• Some of these mutations are advantageous for the bacteria.

Examples of Antibiotic Resistance