Diseases of the Digestive System (Part 1) - Exam 5

Normal flora in the mouth is mostly...

gram postive species

_____________ is made by the normal flora in the mouth and coats the teeth

biofilm

Do the stomach and small intestine have few or lots of normal flora?

few normal flora

Does the large intestine/colon have few or lots of normal flora?

lots of normal flora

-gram - rods

-lactose fermenting

What is diarrhea?

frequent watery, loose stool

What is dysentery?

diarrhea plus mucus, blood, and/or inflammation

What is gastroenteritis?

inflammation of the stomach and intestinal mucosa

What is enterocolitis?

inflammation in the small and large intestines

The most common normal flora from stool are...

Facultative Gram-negative rods (coliforms- lactose fermentors)

Gram positive cocci

What is one example of a common gram negative rod normal flora in the stool?

E-coli

What is one example of a common gram positive cocci normal flora in the stool?

Enterococci

Gram positive cocci will not grow on __________________ agar

MacConkey

-selective AGAINST gram +

The 4 selective and differential media used in stool cultures are...

1) Hektoen-enteric agar

2) MacConkey agar

3) Campylobacter agar

4) MacConkey sorbitol

Is Hektoen-Enteric media selective or differential?

both

What is Hektoen-Enteric media selective for?

grows gram - rods

-selects against gram +

How is Hektoen-Enteric media differential?

Lactose pos = yellow/orange

Lactose neg = pale green

-Shig = pale green

-Salm = pale green w/ black centers

Organisms on Hektoen-Enteric media

Pathogens are non-lactose fermenting; lactose positive is normal flora (except EHEC)

-differentiates Salmonella from Shigella

Is MacConkey agar selective or differential?

both

What is MacConkey agar selective for?

grows gram - rods

-selects against gram +

How is MacConkey agar differential?

Lactose pos = magenta

Lactose neg = pale pink

Organisms on MacConkey agar

Pathogens are non-lactose fermenting; normal flora are lactose fermenting

Is Campylobacter agar selective or differential?

selective only

What is Campylobacter agar selective for?

antibiotics select against all others

Organisms on Campylobacter agar

grow at 45 degrees celsius only Campy grows

Is MacConkey Sorbitol media selective or differential?

both

What is MacConkey Sorbitol media selective for?

grows gram - rods

-selects against gram +

How is MacConkey Sorbitol media differential?

Sorb pos = magenta

Sorb neg = pale pink

Organisms on MacConkey Sorbitol media

Differentiates NF E.coli (sorb +) from EHEC (sorb -)

What are the 2 major types of foodborne pathogen diseases?

1. Food intoxication

2. Food infection

What is food intoxication?

symptoms caused by toxin

-quick onset (3-6 hrs)

What is food infection?

symptoms caused by organism

-24-48 hours until onset (delay while organism colonizes and multiples)

What are 4 bacterial diseases in the mouth?

1. Cavities (caries)

2. Gingivitis

3. Periodontitis

4. Acute necrotizing ulcerative gingivitis

What is the main cause of cavities?

Viridans/oral streptococci: normal flora in the mouth that overgrow

-streptococcus mutans

-streptococcus sobrinus

What is gingivitis?

infection or inflammation of the gums usually caused by anaerobes

What is periodontitis?

chronic issues with gingivitis

What is acute necrotizing ulcerative gingivitis or "trench mouth"?

disease caused by anaerobes

What are 6 causes of food intoxications?

1. Staphylococcus aureus

2. Clostridioides difficile

3. Bacillus cereus

4. Clostridium perfringens

5. Vibrio cholerae

6. Shigella dysenteriae

Staphylococcus aureus causing food intoxications

-some strains produce enterotoxins

-superantigen: elicits a strong immune response by over activation of T cells

-onset in 3-6 hours

What is typically the cause of staphylococcus aureus food poisoning?

bacteria on food handler hands, nasal, skin to food

Clostridioides difficile is common...

following broad spectrum antibiotic use (superinfection)

-Antibiotic-associated diarrhea (AAD)

Epidemiology of C.diff

often nosocomial (hospital associated)

Where is Bacillus cereus found?

on meats, vegetables, and rice

Clostridium perfringens

-spores contaminate meat, canned good

-toxin is made during the sporulation process

Vibrio cholerae (cholera)

produces cholera toxin that makes cells secrete water

-causes "rice water stools" and patient may die of dehydration

Shigella dysenteriae

-uncommon in the US

-shiga toxin (an AB toxin that damages cells & causes inflammation and bleeding)

Symptoms of Shigella dysenteriae

severe, bloody diarrhea