1. Antibiotic Resistance: How it happens and why all the fuss?
(in your packet)

2. Bacteria are Everywhere!
Bacteria have been around for ___?___ billion years
Bacteria are Everywhere!

3. Bacteria are Everywhere!
Skin: about a trillion bacteria
Alimentary canal (mouth, throat, stomach, intestines): tens of trillions of bacteria!
Nose, eyes, toes . . .
Bacteria comprise about 1/20th of your total body weight!

4. What is a bacterium? Bacterial chromosome (DNA) Cell membrane
Cell wall or envelope
Plasmid DNA - small circles of DNA that contain a few genes

5. . Human cell nucleus chromosomes E.coli bacterium Flu virus
10 micrometers
= 1/100th of a millimeter

6. Bacterial Replication

11. Bacteria can double in less than twenty minutes under optimal conditions!

12. Bacteria can double in less than twenty minutes under optimal conditions!

13. Bacteria can double in less than twenty minutes under optimal conditions!

14. Bacteria can double in less than twenty minutes under optimal conditions!

15. Bacteria can double in less than twenty mintues under optimal conditions!

16. “Good” bacteria Form defensive barrier Skin, intestines Aid digestion
Produce vitamin K
Clear away debris
- E. Coli
- Lactobacillus

17. Pathogenic (disease-causing) bacteria
Streptococcus pneumoniae - pneumonia
Haemophilus influenzae - meningitis
Streptococcus pyogenes -
strep throat
Staphylococcus aureus -
wound infections
Helicobacter pylori -
Stomach ulcers

18. How antibiotics work
Antibiotics are chemicals that disrupt bacterial processes
Stop protein building: cell dies
Stop cell wall construction: cell bursts
Stop copying DNA: cells can’t divide

19. What is Antibiotic Resistance?
Resistant bacteria no longer killed in presence of specific antibiotic.
Antibiotic X
All killed
Antibiotic X
Antibiotic Y
All killed

20. How do bacteria become resistant?
Spontaneous mutation of DNA
Many different random mutations are present in a population of bacteria.
Some “lucky” mutations may provide an advantage, especially if the environment changes.

21. How Else?
Acquire resistance genes from other bacteria

22. How can the bacteria become resistant?
Spontaneous mutations
They transfer DNA in a plasmid

23. Mechanisms of Resistance
Resistant Bacteria Can:
Modify or destroy the antibiotic.
Force out antibiotic.
Alter the target.
Essential
Bacterial
Protein
Essential
Bacterial
Protein

24. “Superbugs” Bacteria that are resistant to many antibiotics
Uptake of plasmid: over 12,000 in Guatemala died in 1968 of acute diarrhea
Bacteria that are resistant to many antibiotics
Need for stronger, newer drugs

25. Antibiotic Resistance
Not immunity!!

26. In the absence of antibiotics, resistant bacteria are less likely to survive.
Resistant strain cannot compete with all other bugs
With antibiotic, resistant bacteria rapidly take over.

27. So does this mean antibiotics are evil?

28. Antibiotics are wonderful drugs when administered and used properly!
Penicillin on market in saved numerous lives in WWII!
Ear infections in children treatable.
Lower incidence of infection in surgical patients.

29. But there are problems!
4 years after introduction of penicillin, resistance began to develop.
Needless exposure to antibiotics selects for resistant strains.

30. Who can change? Doctors and Patients Livestock/Poultry Industry
Antibacterial Home Products

31. Patients and Doctors Take for prescribed period of time.
Don’t go to doctor with expectation of receiving prescription.
Only prescribe when necessary.
Narrow spectrum drugs.

32. Subtherapeutic Dosage Problem
1/2
Dose
Full
Dose
Stop Taking
Antibiotic
Resistant bacteria
Highly susceptible
bacteria
Less susceptible
bacteria

33. Summary
Bacteria become resistant through mutations or by getting genes from other bacteria.
We should only use antibiotics when we really need to.
Overuse in agriculture and at home encourages appearance of resistant bugs.

34. OCVSRS Overpopulation – lots of bacteria, not all can survive
Competition – for survival in the presence of antibiotic
Variety – Some bacteria are naturally resistant, some are not
Selection – The resistant ones are “selected for” and survive the presence of the antibiotic
Reproduction – The resistant ones are able to reproduce more and pass the resistance gene to their offspring, making it more common in the population

35. CDC Message about antibiotic resistance

37. Livestock/Poultry Industry
Antibiotics given to livestock, poultry, and even to plants as a preventative measure to promote growth.
Link between this use and people infected with resistant strains.

38. Good News 1997 - Vancomycin banned from chicken feed in Europe.
July McDonald’s vendors will no longer treat animals with preventative antibiotics.
In Europe, animal health maintained through improvements in living conditions.

39. Antibacterials at Home
Triclosan resistance emerging.
Triclosan contributes to resistance of other drugs.

40. From Dishwater to Groundwater
Triclosan very abundant in residential streams.

42. How do bacteria become resistant?
Resistance arises from changes in the bacterial genome.
DNA -> RNA -> Protein
These changes happen randomly
These new proteins can help protect the bacteria from the antibiotic.