Mrs. Stewart Medical Interventions Central Magnet School

GRAM (-)  Thin layer of peptidoglycan  Lipopolysaccharides (endotoxins)  Stain red GRAM (+)  Thick layer of peptidoglycan  Stain blueish - purple

Gram +  Blueish-purple  Peptidoglycan layer absorbs the crystal violet stain Gram –  Red  LPS cell wall prohibits peptidoglycan layer from absorbing crystal violet stain (absorbs counter stain) Bacteria are stained with two stains: 1.Crystal Violet stain (blue/purple) 2.Fuchsin counterstain (red)

 What cellular components do some bacterial cells have that make them powerful pathogens? Explain.

GRAM -

 Antibiotics are drugs used to treat infections caused by bacteria.  Antibiotic - A substance produced by or derived from a microorganism and able in dilute solution to inhibit or kill another microorganism

History of Antibiotics Alexander Fleming Accidentally discovered penicillin Left lab untidy for a month and went on vacation Came back and found a fungus growing in one of his bacterial cultures. Fungus was inhibiting the bacteria. Fungus = penicillium notatum Later named: penicillin

 Gangrene – wound infections that lead to many amputations or sepsis  Sepsis – bacterial infection in blood stream – leads to organ system failures

 The early antibiotics = natural products of other microorganisms (fungi or other bacteria)  Now = created synthetically (chemically altering existing natural products)

 Depends on the bacteria  Gram + OR  Gram -

 Bactericidal – Kills the bacteria  Bacteriostatic – inhibits growth & reproduction * The body’s natural defenses can usually take it from there

 Beta – Lactam  Fluoroquinolones  Tetracyclines  Sulfanomides

 Disrupt the synthesis of peptidoglycan thereby inhibiting cell wall synthesis & damaging cell wall integrity  Broad spectrum (can work against + or -)  Bactericidal  Example: Penicillins

 Why are penicillins often more effective against gram positive than gram negative bacteria?

 Inhibit topoisomerase enzymes which prohibit DNA replication and protein synthesis  Broad spectrum – effective against + and -

 Bind the 30s ribosomal subunit, blocking the attachment of tRNA, thereby inhibiting protein synthesis  Broad spectrum – effective against + and -

 1 st class of antibiotics ever used  Structurally similar to PABA – a substance that the bacteria use to synthesize folate (folic acid)  Inhibits the synthesis of folic acid (Folate)  folate is necessary for DNA synthesis  No DNA synthesis (replication) = No cell division

 Answer the following question in your journal. What class of antibiotics would you prescribe for Sue? Explain.

 What class of antibiotics would you prescribe for Sue? Explain.  With your lab groups, design an experiment to test your hypothesis.  15 minutes 15 minutes

 Bacterial infections only  Antibiotics target bacteria and a few parasites.  Most colds, and sore throats are viral

 They do not share the same structures  Viruses consist of a hereditary material (DNA or RNA) surrounded by a protein coat or fatty envelope.  They do not have any organelles – they hijack host cells to produce more DNA/RNA or proteins

1. How do antibiotics function without harming the surrounding human cells? 2. What cellular components do some bacterial cells have that make them powerful pathogens? 3. Why are penicillins more effective against Gram + bacteria? 4. Why is it important to understand the structure of a bacterial cell when developing an antibiotic? 5. Why are antibiotics NOT effective against viruses?

 Streptococcus pneumoniae, commonly referred to as pneumococcus, is a bacterium commonly found in the back of the nose in healthy people. Occasionally, pneumococcal bacteria spread to other parts of the body and cause diseases such as ear infections, sinus infections, pneumonia, and meningitis. Before the introduction of penicillin in the early 1940s, a person might die from a pneumococcal infection. After the introduction of penicillin, pneumococcal infections were effectively treated. However, strains of pneumococcal bacteria resistant to penicillin were discovered in the 1960s. Since then, new strains of pneumococcal bacteria resistant to multiple antibiotics have been emerging.

 Ear Infections  MRSA  TB – Tuberculosis  Strep throat

 Antibiotic resistance has been called one of the world’s most pressing public health problems and is one of the Centers for Disease Control’s top concerns.

Both the GOOD AND BAD bacteria in the body are attacked.

 How does the Theory of Natural Selection apply to the problem of antibiotic resistance in bacterium?  Survival of the Fittest  Those that survive the treatment (change in the environment) must carry beneficial DNA that provides resistance  Eventually, entire population is resistant

 How would a genetic mutation (variation) in the bacteria’s DNA cause the cell to gain resistance to an antibiotic?

 DNA code is where biodiversity occurs  Changes in DNA code gives variety  That variance could be harmful or beneficial in different environments  Natural Selection = Survival of the Fittest  Bacteria can share their DNA with other bacteria What makes bacteria unique?

 NO  That leads to antibiotic resistance due to overuse

 There are more bacterial cells in/on your body than there are human cells  Antibiotics will target all susceptible bacteria – not just the spot of infection  All bacteria living within your body will either die (susceptible) or will live (resistant)  Survival of the fittest

 Antibiotic resistance does not stop with one colony of bacteria  Bacterial cells can share the DNA that gives them resistance.  Animation of bacterial resistance Animation of bacterial resistance  Take notes on the sheet provided

 You and your lab group will create a 3D model of one of the mechanisms bacterial cells use to either gain antibiotic resistance OR to share antibiotic resistance.  You will present these to the class next block day

 How does a bacterium’s ability to share genes intensify the problem of antibiotic resistance?

 TED talk TED talk  Hunting the Nightmare Bacteria Hunting the Nightmare Bacteria