Microbiology Notes

Microbiology Notes

Learning Objectives
List examples of normal microbiota for each part of the gastrointestinal tract
Describe the events that lead to dental caries and periodontal disease
List the causative agents, suspect foods, signs and symptoms, and treatments for staphylococcal food poisoning, shigellosis, salmonellosis, typhoid fever, cholera, gastroenteritis, and peptic ulcer disease
Differentiate between hepatitis A, hepatitis B, hepatitis C
List the causative agents, mode of transmission, and symptoms of viral gastroenteritis
List the causative agent, modes of transmission, symptoms, and treatment for giardiasis
List the causative agents, modes of transmission, symptoms, and treatments for tapeworms, pinworm, and ascariasis

§ Diseases of the digestive system are the 2nd most common illnesses in the US.
§ Diseases of the digestive system usually result from the ingestion of microorganisms or their toxins in food and water
§ Fecal–oral transmission can be interrupted by
§ proper disposal of sewage
§ disinfection of drinking water
§ proper food preparation and storage
§ >700 bacterial species in mouth
§ Stomach and small intestine have few resident microbes
§ Up to 40% of fecal mass is microbial cells
§ Bacteria in large intestine assist in degrading food and synthesizing vitamins. They also competitively inhibit pathogens, chemically alter medications, and produce carcinogens

Dental Caries (Tooth Decay)
§ S. mutans is 1 causative agent
§ Cariogenic plaque binds to
receptors on tooth pellicle
§ Sucrose glucose + fructose
§ Glucose polymerization dextran
§ Fructose fermentation lactic acid cavity formation
§ Starch, mannitol, xylitol, etc. are not used by cariogenic bacteria
§ Dental Calculus or Tartar old calcified plaque
§ Control: fluoride and restricting dietary sucrose

Periodontal Disease
§ Ginigivitis: Inflammation of gums. Due to inflammatory response to a variety of bacteria growing on gums
§ Gingivitis can...

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