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

•ExotoxinsToxins made from bacterial proteins

Gram positive bacteria- secrete into surrounding environment (protection mechanism)

e.g. Clostridium tetani

EndotoxinsToxins made from lipids +

carbohydrates (outer membrane of Gram negative bacteria)

Not released until bacterial deathComplications with Antibioticse.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 ClassesPenicillin 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