Medical Microbiology

Microbiota and Human Relationship

• The sites that do not have resident microbiota are the brain and the bloodstream.
• Microbes develop a mutualistic relationship with humans, where both the microbe and the human benefit.

Human Provision to Microbes

• Humans provide microbes with a warm, moist environment, nutrients, and a constant temperature.

Endotoxins and Exotoxins

• True statements about endotoxins/exotoxins:
  • Endotoxins are lipopolysaccharides found in Gram-negative bacteria.
  • Exotoxins are proteins produced by Gram-positive and Gram-negative bacteria.
  • Endotoxins are heat-stable, while exotoxins are heat-labile.

Microbe Survival in Human Body

• Microbes do not need a constant supply of oxygen to survive in the human body.

Direct Transmission Method

• A direct transmission method is through direct contact with infected people.

Exoenzymes and Toxins

• The difference between exoenzymes and toxins is that exoenzymes break down complex nutrients, while toxins harm the host.

AB Toxins

• AB toxins consist of an A subunit ( enzymatic component) and a B subunit (binding component).

Sites of Normal Flora

• Examples of sites that harbor normal flora include the skin, respiratory tract, gastrointestinal tract, and genitourinary tract.

Koch's Postulates

• The statement "The microorganism must be present in all people with the disease" is not one of Koch's Postulates.