Term
| What are some ways the fecal-oral cycle can be broken? |
|
Definition
- proper sewage disposal
- disinfection of drinking water
- proper food preparation and storage
- rapid and reliable diagnosis
- Effective vaccines |
|
|
Term
| What are some defending mechanisms offered by the GI tract? |
|
Definition
-Lysozyme in saliva
-High acid content in the stomach
-Antimicrobial defenses of the small intestine such as the production of defensins and lysozyme by Paneth cells |
|
|
Term
| How is tooth decay initiated? Which bacteria is responsible? |
|
Definition
| It is initiated by the attachment of Streptococcus mutans, which further produces acids that degrade the enamel. |
|
|
Term
| How is decay advanced after it has initiated? Which bacteria is responsible? |
|
Definition
| It is advanced by Lactobacillus spp. It enters the enamel and dentin. |
|
|
Term
| How do you prevent tooth decay? |
|
Definition
- eat foods low in sucrose
- remove plaque by brushing/flossing |
|
|
Term
| What are some of the primary periodontal diseases? Periodontics are the structures which supports the teeth. |
|
Definition
Gingivitis --> bleeding of the gums while they are being brushed
Periodontitus --> the bone and tissue supporting the teeth are destroyed, eventually leading to loss of teeth. The bacterium responsible for this is Porphyromonas spp. |
|
|
Term
| How can periodontitus be treated? |
|
Definition
| Periodontitis can be treated surgically by eliminating the periodontal pockets or injecting a gel to slowly release doxycycline |
|
|
Term
| What are the three main symptoms of diseases in the lower digestive system? |
|
Definition
- diarrhea
- gastroenteritis
- dysentery
- nausea
- abdominal cramps |
|
|
Term
| What is intoxication caused by? |
|
Definition
| Caused by the ingestion of a toxin. Symptoms are quick to occur and there is usually no fever. |
|
|
Term
| What is intestinal infection caused by? |
|
Definition
| Caused by the growth of a pathogen in the GI tract. Has a longer incubation time(12hrs to 2 weeks). There is usually fever. The pathogens usually penetrate the mucosa and pass through barriers to other organs. |
|
|
Term
| What is Staphylococcal food poisoning? |
|
Definition
It is a sickness caused by the ingestion of S. aureus. The intoxication dose is 1 million microbes/gram. The enterotoxin which causes this illness triggers the brain's vomiting reflex. S. aureus do well in foods with high osmotic pressure and low moisture. Recovery is usually within 24hrs.
The diagnosis of this illness is based upon its short incubation time. |
|
|
Term
| What do you know about Gastroenteritis caused by Bacillus cereus? What do you know about Bacillus cereus in the first place? |
|
Definition
Bacillus cereus is a rod shaped, gram(+) bacterium that forms endospores. It is common in soil and vegetation. The spores of this illness are heat resistant, and it is most common in grains and cereals. Symptoms are diarrhea, vomiting and nausea.
This illness can be diagnosed by analyzing suspicious food. 10 billion cereus/gram will cause this illness. |
|
|
Term
|
Definition
Caused by the "shiga" toxin produced by Shigella spp. Causes inflammation and bleeding. It is invasive to M cells in the stomach. It causes ruffling in the membrane and the uptake of bacteria into the cells. It is resistent to phagocyte-mediated killing.
S. sonnei - causes mild dysentery(most common in North America)
S. dysentery - causes severe dysentery(bloody diarrhea) and prostration.
Is spread from person to person
Treated via antibiotic therapy(fluoroquinolones) |
|
|
Term
|
Definition
- caused by salmonella
- begins with the invasion of intestinal mucosa(via invasins)
- occassionally pass M cells and enter the cardiovascular and lymphatic systems, affecting organs
- incubation time is 12 to 36 hours
- carried in meat products
- Salmonella enterica is common in poultry production
-
- is detected through PCR tests
- treated with oral rehydration therapy
- |
|
|
Term
|
Definition
- caused by Salmonella typhi
- only found in the feces of humans
- long incubation period(2-3 week)
- Symptoms are: high fever, continual headache, diarrhea, ulcers
-treated with quinolone antibiotics |
|
|
Term
|
Definition
- caused by Vibrio cholerae bacterium
- gram(-) rod, single polar flagellum
- sickness is caused by the cholera exotoxin
- high loss of fluids(12-20L/day)
- usually no fever
- treated with doxycycline
- |
|
|
Term
| What is Escherichia coli Gastroenteritis? |
|
Definition
- traveler's diarrhea
Enteroaggregative E. coli – not invasive but produces enterotoxin, produces a watery diarrhea, cause a “stacked-brick” configuration
Enteropathogenic – major cause of diarrhea in developed countries, attach to intestinal wall, eliminate microvilli and stimulate pedestals formation
Enteroinvasive – invades the intestinal wall, produces inflammation, fever & Shigella-like dysentery
- the best treatment is oral rehydration or antimicrobial drugs
- diarrhea is self-limiting(runs its course no matter what)
Preventive measures: proper foodhandling, safe water supply, proper sewage disposal, may use prescribed antibiotics or bismuth-containing preparations such as Pepto-Bismol |
|
|
Term
| What is Enterohemorrhagic E. coli (EHEC)? |
|
Definition
- illness caused by shiga toxin which adheres to intestinal mucosa
- destroys microvilli, forming projections
- cattle are the primary reservoir
- very small infective dose 100> |
|
|
Term
| What is hemolytic uremic syndrome(HUS)? |
|
Definition
- is a dangerous complication – blood in the urine, kidney failure
- 5% mortality for small children
- Treatments: rehydration and careful monitoring of serum electrolyte
- May require kidney dialysis or even transplants |
|
|
Term
| What is Helicobacter Peptic Ulcer Disease? |
|
Definition
- caused by a spiral shaped bacterium(H. pylori)
- causes stomach cancer
- causes stomach ulcers
- H. pylori grows in acidic environments of the stomach
- produces urease to convert urea to ammonia(resulting in high pH)
- Detection: urea breath test |
|
|
Term
| What are Clostridium infections? |
|
Definition
- Clostridium perfringens gastroenteritis
Gram positive, endospore-forming, obligatory anaerobic
Grow in intestinal tract, producing exotoxin (abdominal pain & diarrhea)
Usually associated with improper cooling of foods
Inoculate m/os by contaminating with intestinal contents of the animal during slaughter
- C. difficile–associated diarrhea
Grow following prolonged antibiotic therapy
Require discontinuation of the antibiotic and oral rehydration therapy
Associated with hospitalized patients and nursing home residents (often due to poor hand hygiene of health care workers) |
|
|
Term
| What is Campylobacter Gastroenteritis? |
|
Definition
- caused by Campylobacter jejuni
- gram(-), microaerophilic, spirally curved
- transmitted in cow's milk
- don't replicate in food
- Symptoms: fever, cramping abdominal pain & diarrhea or dysentery
- infective dose <1,000
- rare cases cause temporary paralysis |
|
|
Term
| What is Yersinia Gastroenteritis? |
|
Definition
- caused by Y. enterocolitica and Y. pseudotuberculosis
- Can reproduce at 4°C
- Are intestinal inhabitants of many domestic animals e.g. pig, and are usually transmitted in meat and milk
- Can contaminate blood supply and result in shock to the blood recipient
Treatments: antibiotics and oral rehydration |
|
|
Term
|
Definition
- causes inflammation of the liver
- caused by 5 different viruses
- Hepatitis may also result from drug or chemical toxicity, Epstein-Barr (EB) virus, cytomegalovirus (CMV) |
|
|
Term
| What is hepatitis A virus(HAV)? |
|
Definition
- contains single stranded RNA and lacks an envelope
- fecal-oral transmission
- 4 week incubation
- virus is shed during the acute phase
Detection: anti-HAV IgM
Prevention: hepatitis A vaccine for exposed people, high risk group & travelers |
|
|
Term
| What is Hepatitis B Virus(HBV)? |
|
Definition
- double-stranded DNA
- Risks: 90% for infants, 25-50% for 1-5 year olds
- 6-10% for adults and adolescents
- major cause through vertical transmission
- HBV is present in saliva, breast milk, and semen
- unassembled particles can be detected with antibodies
- 90% recovery rate, 1% mortality rate
- cause a million deaths each year
- chronic carriers are 200X more likely to develop liver cancer
- can be treated with vaccination. |
|
|
