Antibiotic Resistant Bacteria: Natural Selection at Work

Bacteria are everywhere Bacteria are single-celled organisms Many different kinds of bacteria can grow together in similar environments Millions of different bacteria live on and inside of you! Pictures taken with an electron microscope

Serratia marcescens Grow in damp places Bathrooms Soil Biofilm on teeth Digestive tract As a human pathogen, can be associated with urinary tract and wound infections What’s a pathogen?

What are antibiotics? Powerful medicines that treat bacterial infections - Do NOT work on viruses! WHY? Think “Anti-Bio”… Kills living things… Are viruses alive? Antibiotics kill bacteria

How do bacteria become resistant? A mutation in the DNA of the bacteria makes it resistant the harmful effects of the antibiotic So, it cannot be killed by the medicine If the bacteria is not destroyed… What will it do????? Genes for resistance can appear spontaneously (genetic mutation) This can happen with insects as well! Bacteria can prevent ab from entering cells by making strong cell wall or making a false receptor in the membrane or they can make an enzyme that breaks down the ab within the cell

Natural Antibiotic Resistance Mutations that allow bacteria to resist the effects of antibiotics already exist in the bacterial population Not all bacterial cells within a population are identical Like a population of humans, they all contain slight differences in their DNA (variation) Why do you think this may be a good idea for the bacteria? -Survival of the Fittest

Can the misuse of antibiotics result in resistant bacteria? Antibiotics are prescribed by doctors to fight bacterial infections Antibiotics do not treat viral infections! How do doctors know what to prescribe? throat, urine cultures Why is it important to finish your prescription?

Tuberculosis TB affects your lungs and coughing is often the only sign of infection until it’s too late Yes… you can die from TB In the US, TB declined in the 1950s mainly because of antibiotics TB is re-emerging World Health Organization indicates that rates of tuberculosis resistant to multiple drugs (MDR-TB) are now at their highest level ever Mycobacterium tuberculosis TB lung infection

What are some potential problems because of antibiotic resistant bacteria? MRSA What is MRSA The Truth about Methicillin-resistant Staphylococcus aureus

Good Bacteria? YES! Our bodies provide a home for many kinds of good (and necessary) bacteria! In our gut In our mouth On our skin Bacteria in the mouth Pimple caused by bacteria

How can we prevent bacterial growth? We try to prevent the growth of some bacteria on our bodies and in our homes What are some common products you use on a regular basis for cleaning? Soaps (hand soap, face wash) Toothpaste/mouthwash Dish soap Laundry detergent Mops and sponges Most if not all contain a chemical to prevent bacterial growth

99.9%.... Antibacterial soaps, hand sanitizers, household cleaners and Listerine state that they kill 99.9% of bacteria What about the remaining 0.1%? Remember… If you survive… you feed and breed? What does that mean?? The 0.1% of bacteria that are not affected by the cleaners will reproduce… Creating an entire generation of bacteria which are resistant to sanitizers!

Are we causing the evolution of resistant bacteria with the use of antibacterial products? Long term exposure to chemicals allows the bacteria that contain genes for resistance to survive and reproduce at a rapid rate! What do you think? Should antibacterial products be used in such a common way?

The Same Happens With Insects

Remember… VARIATION (diversity) ensures that a species will survive… Remember “Contagion”! The MORE VARIATIONS in a species (ANY species… from humans to daffodils to amoebas to mosquitoes to dalmations…) the greater the chance of survival! More genetic diversity ensures the species will continue to exist!