Kuliah Blok 10 Th 2013

8/13/2019 Kuliah Blok 10 Th 2013

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8/13/2019 Kuliah Blok 10 Th 2013


Gastroenteritis

• Inflammation of stomach or intestines

– Inhibits nutrient absorption and excessive H2O and

electrolyte loss

•

Bacterial• Viral

• Parasites

•

Poisoning by microbial toxins – food borne intoxication

2/3/2014 Gastroenteritis 2

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• Signs and Symptoms:

– General features: diarrhea, loss of appetite, abdominal

cramps, nausea, vomiting and possibly fever

– Dysentery

– Typically self Limiting

• Enteric fevers

– Systemic with severe headache, high fever, abscesses,

intestinal rupture, shock and death


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• Epidemiology

– Occurs worldwide

– Oral to fecal route of transmission

• Water common reservoir

• Overcrowding & poor sanitation are risk factors

• Animals may be source of infection


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• Prevention

– Hand washing

– Proper food handling and complete cooking

– Pasteurization of milk and juices

– Adequate sanitation

–

Safe water supplies

• Treatment

– Rapid replacement of fluids and electrolytes

– Anti-nausea medication

– Antimicrobials may be used in severe cases


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Bacterial Gastroenteritis

• 3 groups of gram negative bacteria account for most

bacterial intestinal infections:

– Vibrio cholerae ( Cholera)

– Enterics (Salmonella, Shigella, E. coli)

– Campylobacter jejuni


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Cholera

• Causative agent: Vibrio cholerae

• High infectious dose

– Bacteria sensitive to stomach acid

– Adheres to small intestine and multiply

– Bacteria don’t enter cells


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• Cholera toxin

– Potent exotoxin

– Causes intestinal cells to

rapidly pump out

electrolytes

– Passive osmotic H2O loss

follows

– Metabolic acidosis

– Shock


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• Heavy loss of fluid

–

“rice-water stool”• Up to 20L of fluids lost per day

• May discharge 1 million bacteria per ml of feces

• Untreated cases potentially fatal

– Fluid/electrolyte replacement

– Tetracycline reduces toxin production


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Shigellosis• Causative Agent: Shigella sp.

– S. dysenteriae, S. flexneri, S. boydii, S. sonnei

• Low infecting dose

– Bacteria not sensitive to stomach acid

– Characterized by fever and dysentery


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•Infects cells of large intestine and

initiates intense inflammatoryresponse

•Dead cells slough off

•Produces areas covered with

pus and blood

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• All species produce enterotoxin and type III secretion

systems

• S. dysenteriae produces powerful endotoxin

–shiga-toxin

• Ciprofloxacin, rifampin or azithromycin may reduce

duration and infectivity


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Traveler’s Diarrhea

•

Causative Agent: Escherichia coli – Multiple antigenic strains (O, H, K)

– Virulent strains have fimbriae, adhesions and

multiple toxins

• Enterotoxigenic E. coli

– Enterotoxins

– Type III secretion system

– Typically self limiting


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• Enterohemorrhagic E. coli

– O157:H7

– Produce potent Shiga-like toxins and type III secretion

systems

• Antimicrobials cause increase in toxin production


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Salmonellosis and Typhoid Fever

•

Causative agent: Salmonella enterica – 2000 strains (serotypes)

– Typhimurium and Enteritidis commonly cause Salmonellosis

– Typhi and Paratyphi cause Typhoid Fever


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•

Common intestinal floraof many animals

• Contaminated animal

products are reservoir

• Reptiles, eggs and

undercooked poultry


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•Virulent strains tolerate stomach

acid and pass to intestines

•Toxin induces phagocytosis in

intestinal cells

•Pathogen reproduces inside

phagosome killing host cell

•Bacteria (Typhi) may pass

through intestinal cells intobloodstream


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• Typhoid fever is an enteric

fever – Macrophages carry bacteria

to liver, spleen, bone marrow

and gallbladder

– Treated with ciprofloxacin or

ampicillin

– Surgical removal of

gallbladder


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Campylobacteriosis

•

Causative agent: Campylobacter jejuni – Leading cause of bacterial diarrhea in United States

– Estimated 1million cases annually with ~100 deaths

• Associated with poultry

– Low infecting dose


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• Virulent strains possess adhesions, cytotoxins and

endotoxin

– Induce endocytosis in cells of intestine and initiate

inflammation and bleeding lesions• Non-motile mutants are avirulent

• Severe cases treated with ciprofloxacin or

azithromycin


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• Guillain-Barré Syndrome

– Tingling of the feet leads to progressive paralysis of the legs,

arms and rest of the body

–

40% of cases preceded by campylobacteriosis – May be associated with autoimmune response

– 80% recover completely; 5% mortality with treatment


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Viral Gastroenteritis

•

Common causative agents: – Rotaviruses and Noroviruses

– Both naked RNA viruses


Star-like NorovirusesWheel -like Rotaviruses

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• Epidemology

– Infect intestinal cells causing cell death

– Typically self-limiting

– Norovirus epidemics cause 90% of cases

– Rotaviruses responsible for 50% infant cases of

serious diarrhea

• 600,000 worldwide annual fatalities• Oral vaccine available


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Bacterial Food Intoxication

• Staphylococcus aureus – Halotolerent; grows well in foods at room temp

– Associated with cafeterias and social functions


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• 5 heat stable enterotoxins:

– 1000 for up to 30 min

– Stimulate muscle contractions, nausea and intense

vomiting, diarrhea and cramping

–Acute and self limiting• symptoms begin 4-6 hrs after consumption and end

within 24 hrs


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Botulism•

Causative agent: – Clostridium botulinum

• Obligate anaerobic, Gram +, spore forming bacillus

– Produce 7 different neurotoxins

•

One of most deadly toxins known


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• Signs & Symptoms

– Dizziness, dry mouth, blurred vision

– Abdominal symptoms include pain, nausea,

vomiting and diarrhea or constipation

– Progressive paralysis• Paralysis of respiratory muscles most common cause of

death


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•

3 forms of botulism: – Food-borne botulism – progressive paralysis of all

voluntary muscles due to toxin production

– Wound botulism – similar symptoms

– Infant botulism – bacteria grow in the intestines,

producing non-specific symptoms• “floppy baby syndrome”


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Kuliah Blok 10 Th 2013

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