Bacteria and You! Helicobacter pylori Barry Marshal

Last Day - Taking the steps of a clinical Microbiology laboratory - Swabbing and plating bacterial cultures - Observing colonies and performing a Gram Stain - Which bacteria will show purple, and why? - Which bacteria will show pink, and why?

Today - Observing Gram stain under a microscope - Bacteria + Human disease - Antibiotics and Antibiotic resistance

Outcomes - You will be able to see the differences between Gram positive and negative bacteria under a microscope, and identify microbial shapes. - You will understand the interactions between bacteria and humans; giving examples of both the bad and the good. - You will understand how antibiotic resistance works, and think of ways it can be controlled or prevented.

Bacteria + Disease Study of Diseases- Pathology Bacteria and other disease causing agents are known as pathogens Table 24.4 in textbook A look at some common and serious microbial infections

So, How do they do it? Bacteria can cause disease in 2 ways 1. Directly- attacking and digesting living cells/tissue 2. Indirectly- production of poisons known as toxins A. Exotoxin B. Endotoxin

Exotoxins  Toxins made from bacterial proteins  Gram positive bacteria- secrete into surrounding environment (protection mechanism)  e.g. Clostridium tetani

 Endotoxins  Toxins made from lipids + carbohydrates (outer membrane of Gram negative bacteria)  Not released until bacterial death  Complications with Antibiotics  e.g. Escherichia coli

Antibiotics Drugs that combat bacteria by interfering with various cellular functions (Table 24.5) Can be broad spectrum (works against a variety of different bacteria) or narrow spectrum (selected group of bacterial types)

Antibiotic Classes  Penicillin and Cephalosporin class antibiotics interfere with cell wall synthesis  Tetracycline Class inhibits protein synthesis (used to treat acne)  Sulfonamide (Sulfa Drugs) inhibit cell metabolism

To Do Now  We will learn much more about antibiotics later on, but for now, let’s take a look at our Gram stains!  Using your lab manual, provide a scientific drawing of your bacteria  Note whether your bacteria is Gram positive or Gram negative

In Lab Manuals  Draw the entire F.O.V (Everything you see inside the microscope… works best if you draw a large circle in the middle of your page, and fill it in with what you see)  Keeping in mind rules for Scientific Drawings  Need to provide magnification power, actual size and magnification of drawing.

F.O.V