Micro Chap 22
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Micro Chap 22
Micro Chap 22
Micro Chap 22
Define Dental Plaque
a continuously formed coating of micro-organisms and organic matter on tooth surfaces.
first step in tooth decay & gum disease.
Define Dental caries.
The chemical dissolution of enamel and deeper parts of teeth.
Define Periodontal Disease.
A combination of gum inflammation and erosion of periodontal ligaments and the alveolar bone that supports teeth.
Mildest form of Periodontal Disease that only affects the gums.
Define Acute Necrotizing Ulcerative Gingivitis.
Modst severe form of ginigvitis aka Trench Mounth.
Unchecked Periodontal disease leads to chronic periodontitis which affects the bone and tissue that support the teeth as well as the gums.
What is the major causative agent of Dental caries?
The combination of sucrose and the action of S. mutans
How are cavities formed, specifically how is the enamel breached?
Sugars easily diffuse through plaque to bacteria embeded in it, but acids produced by bacterial fermentation fail to diffuse out.
The acids gradually dissolve enamel, after which protein-digesting enzymes break down any remaining material.
How is plaque formed?
Plaque begins as positively charged proteins in saliva adhere to negatively charged enamel surfaces and form a pellicle(film) over the tooth surface.
Streptococcus mutans and some filamentous bacteria among the normal oral flora microbiota attach to the newly formed pellicle.
These organisms may hydrolyse sucrose to fructose and gluecose both of which can be metabolized for energy production and growth.
What is the causative agent for Bacterial Food Poisoning?
What is the causative agent for Bacterial Enteritis Salmonellosis?
Salmonella (serveral serovars).
What is the causative agent for Bacterial Enteritis Typhoid Fever?
What is the causative agent for Bacterial Enteritis Shigellosis?
Shigella dysenteriae (serovar A)
Shigella flexneri (serovar B)
Shigella boydii (serovar C)
Shigella sonnei (serovar D)
What is the causative agent for Bacterial Enteritis Cholera?
Vibrio cholerae. O1 and O139
Whate is the causative gent for Bacterial Enteritis Traveler's Diarrhea?
Pathagenic strains of E. coli.
What is the causative agent for Bacterial Enteritis Enterohemorrhogic Strains?
E. coli O157:H7
What is the causative agent for Bacterial Infection Peptic Ulcer?
What is the toxin released by Bacterial Food Poisoning Staphylococcus aureus?
Enterotoxin A or D (heat stable)
What is the function of the Bacterial Food Poisonings Toxin?
Enterotoxin=exotoxins that inflame intestines and block water absorption.
Intoxications rather than infections.
What is the toxin for Bacterial Food Poisoning Clostridium perfringens?
enterotoxin A released only during sporulation
What is the toxin for Bacterial Food Poisoning Bacillus cereus?
heat labile enterotoxin - function to Diarrheal disease.
What is the function of Bacterial Enteritis Typhoid Fever Toxin?
Death may result from endotoxin shock
What is the function of the Bacterial Enteritis Cholera toxin?
Enterotoxin (cholera toxin) binds to epithelial cells of the small intestine and makes plasma membranes highly permeable to water.
What is the function of Bacterial Enteritis Traveler's Diarrhea?
enterotoxigenic strains - have plasmid which encodes for enterotoxin.
What is the toxin of Bacterial Enteritis Enterohemorrhagic Strains?
Shiga Toxin 1 & 2
What is endotoxin?
aka LPS (lipopolysaccharide)
A toxin incorporated in Gram-neg bacterial cell walls and released when the bacterium dies.
What is an Enterotoxin?
An exotoxin that acts on tissues of the gut.
What is exotoxin?
A soluble toxin secreted by microbes into their surroundings, including host tissues.
What is toxin?
Any substance that is poisonous to other organisms.
What is the major symptoms of Bacterial Food Poisoning Staphylococcus aureus?
Extremely fat onset 1-6hrs after injestion.
self-limiting intoxication 1-3 days.
What are the symptoms of Bacterial Food Poisoning Clostridium perfringens.
Vomiting w/n 12 hours after injestion.
Self-limiting, 1-2 days.
What are the symptoms of Bacterial Food Poisoning Bacillus cereus?
Induces vomiting w/n 12hrs after ingestion.
What are the symptoms of Bacterial Enteritis Salmonellosis?
Muscular weekness, faintness.
Mod. Fever/ festlessness and drowsiness.
What are the symptoms of Bacterial Enteritis Typhoid Fever?
Fever 104' due to pyrogens.
Constipation (normally no diarrhea).
: abdominal rose spots.
septicemia, bacteria localized in the gall bladder.
Death may result form endotoxin shock.
What is septicemia?
An infection caused by rapid multiplcation of pathogens in the blood.
What are the symptoms of Bacterial Enteritis Shigellosis?
bacillary dysentery (a severe diarrhea that often contains mucus and sometimes blood or pus).
What are the symptoms of Bacterial Enteritis Cholera?
significant secretion of fluids and chloride ions and inhibition of Na absorption.
watery diarrhea speckeld with flakes (rice water stool)
loss of potassium ions results cardiac complicaitons and circulatory failure.
untreated results in high mortality rates.
What is the symptoms of Bacterial Enteritis Enterohemorrhagic Strains?
Causes hemorrhagic uremic syndrome.
Kidney damage and bleeding in the urinary tract.
Hemolytic uremic syndrome (HUS).
baby born w/ enlarged liver and spleen Rh- mom.
What are the symptoms of Peptic ulcer?
lesions of the mucous memberanes lining the esophagus, stomach or duodenum.
chronic gastritis (stomach inflammation) can produce pain and indigestion.
What are the Three types of Bacterial Food Poisoning?
How can Bacterial Food Poisoning Staphylococcus aureus be prevented?
Avoid preparing food with open wounds or skin infections on hands, wrists.
How can Bacterial Food Poisoning Clostridium perfringens be prevented?
leftover cooked meat should be refrigerated promptly and reheatd thoroughly before serving (75'C).
Why is it better to let the Bacterial Food Poisoning run its course rather than rely on anti-diarrhea medicines?
Most are self limiting and will resolve on their own.
To avoid creating resistant strains.
Explain why antibiotics are not useful against the toxins.
Antibiotics kill bacteria but the bacteria releases toxins either into host tissue or releases toxins as it dies.
Which organisms produce Heat stable toxins.
Staphyloccoccus aureus - BFP
Clostridium perfringens - BFP
Which organisms produce heat liable toxins?
Who was Typhoid Mary?
Mary Mallon: an immigrant, Irish woman who made her way a a cook.
How did she transmit Typhoid Fever to so many over so long a period?
She was well liked.
the bacteria was localized in her gall bladder which she refused to have removed.
She was a cook.
What isTravelor's Diarrhea E. Coli enteroinvasive gain their Pathogenic?
Enteroinvasive strains of E. Coli have plasmid encoded K antigen that allows bacterial cell to invade intestinal mucosal cell.
What is Traveler's Diarrhea of E. Coli Enterotoxigenic gain their Pathogenic strains?
Enterotoxigenic strains of E.coli have plasmids whcih encode for enterotoxin.
E.coli O157:H7 What does the O and the H refer to?
O refers to the O-antigen (lipopolysaccharide).
H refers to the H-antigen (flagella)
Produces Shiga toxins 1 and 2 (may have received these genes from a plasmid from Shigella)
How does the causative agent Helicobacter pylori (peptic ulcer) survive the acidic conditions of the stomach?
survives acidic conditions of the stomach by generating ammonia from urea.
Urea + H20 --> 2NH3 + C02.
The amonia neutralizes gastric acidity around the cells, allowing the organism to survive and reproduce.
colonize and multiply in the gastric mucosa directly above the epithelial cell layer of the stomach.
Explain how an ulcer is formed.
Hylicobacter Pylori colonize the gastric mucosa.
Causes sloughing away of dead inflammatory tissue and exposure to acid in the epithelium.
Lesions eventually result in excavation into the surface of the organ.