Gastrointestinal Tract

Microorganisms causing Diseases of the Gastrointestinal Tract
Gram +:
Disease and Transmission
Clostridium difficle
Acute diarrhea (antibiotic assoc.);
Acute diarrhea and/or vomiting
(food poisoning); vehicle (food)
Acute diarrhea and/or vomiting
(food poisoning); vehicle (food)
Acute diarrhea and/or vomiting
(food poisoning);vehicle (food)
Dental caries; direct contact
Clostridium perfringens
Bacillus cereus
Staphylococcus aureus
Streptococcus mutans
Streptococcus sobrinus
Gram –:
Campylobacter jejuni
Helicobacter pylori
Escherichia coli O157:H7
Acute diarrhea; vehicle (food and
water), fecal-oral
Signs and Symptoms
Acute diarrhea: 3 or more loose
stools in 24 hour period
Pseudomembrane, large number of
spores released in stool.
Onset 8-16 hours, acute abdominal
pain, self limiting
Emetic and diarrheal exotoxins, 24
hour, self limiting
1-6 hour incubation, self limiting
Prevention and Treatment
Enamel destruction to destruction
of whole tooth
Good oral hygiene, fluoride;
removal of plaque, fillings, root
Most common bacterial cause of
diarrhea in USA. Frequent watery
stools, fever, vomiting, headache
and severe abdominal pain. May
last up to 2 weeks. 20-40% of
cases of Guillain-Barre syndrome
(autoimmune reaction that leads to
acute paralysis) follow a
Campylobacter infection.
Gastritis and gastric ulcers; ?
Sharp, burning pain in abdomen,
with severe ulcers, bloody stool
and/or vomiting. Link to stomach
Acute and chronic diarrhea; vehicle Mild gastroenteritis with fever to
(food or beverage), fecal-oral
bloody diarrhea. 10% of patients
develop HUS (hemolytic uremic
syndrome) a severe hemolytic
anemia with resulting kidney
damage and failure. Neurological
None; stop antibiotic regimen, fluid
and electrolyte replacement
Proper food handling; none
Proper food handling; none
Proper food handling; none
Food and personal hygiene;
rehydration; erythromycin
None; antibiotics with acid
Thorough cooking of meats, clean
vegis, personal hygiene;
Acute diarrhea; vehicle (food or
beverage, fecal-oral
Acute diarrhea; fecal-oral, direct
Vibrio cholerae
Acute diarrhea; vehicle (water and
some foods), fecal-oral
DNA viruses:
Hepatitis B virus
RNA viruses:
Hepatitis A virus
Hepatitis C virus
Hepatitis E virus
symptoms-blindness, seizure and
stroke are more likely in children
under the age of 5 and the elderly.
Enteric fever or gastroenteritis.
High fever and septicemia in
severe cases. Generally mild with
vomiting, non-bloody diarrhea,
cramping. Last 2-5 days.
Shiga toxin leads to dysentery
(frequent bloody stools, abdominal
pain and tenesmus-the constant
urge to defecate
Vomiting, copious watery feces.
“rice water stool”-filled with
mucus, nonodorous. Severe fluid
and electrolyte loss leads to
hypovolemic shock and mortality
is 55% without treatment. Takes a
very large inoculums to cause
disease however.
Food and personal hygiene;
Food and personal hygiene;
Water hygiene; rehydration,
Chronic liver infection, liver cancer Jaundice, hepatomegaly, ascites,
(with hep D), death; Parenteral
bleeding in skin and internal
(blood), direct (sexual), passage
organs, coma
through birth canal
HBV vaccine, safe sex practices;
Infectious hepatitis; fecal-oral
Vaccine; immunoglobulins
Liver infection; parenteral (blood),
direct (body fluids)
Enteric hepatitis; fecal-oral
Mumps; droplet contact
Fever, nausea, anorexia, jaundice,
99% recovery
Chronic infection and liver disease,
cancer and death
Mild except in 20% of pregnancies
where fatal
Incubation 2-3 weeks, fever,
rhinorrhea, myalgia, malaise,
parotitis. Viral invasion to testes,
ovaries, thyroid, pancreas,
meninges, heart and kidney.
Avoid exposure; interferon
Vaccine; immunoglobulins
MMR vaccine; supportive
Entamoeba histolytica
Giardia lamblia
Helminths: nematodes
Ascaris lumbricoides
Enterobius vermicularis
Necator americanus
Taenia solium
Shistosoma mansoni or japonicum
Acute diarrhea;fecal-oral, vehicle,
Usually complete recovery.
Infantile gastroenteritis, 50% of all
diarrhea in children. Usually self
Chronic diarrhea; vehicle, fecaloral
Greasy, malodorous stool.
Water and personal hygiene;
antiprotozoan drugs
Intestinal distress; vehicle (soil,
fecal-oral). Self-inoculation
Most common nematode infection
globally. Loeffler’s syndromefever, dry cough, SOB. With high
burden, nausea, vomiting, intestinal
Pinworm. Most common parasitic
worm in USA. Perianal itching.
Hookworm, second most common
nematode infection globally.
Chronic anemia, ground itch,
Loeffler’s syndrome.
1st symptoms mimic flu with
diarrhea, nausea, abdominal pain,
fever and sweating. 2nd phase,
puffy eyes, intense myalgia and
arthralgia, SOC and eosinophilia.
Hygiene; antihelminthics
Intestinal distress; vehicle (pork),
Not many symptoms. Vague pain
in abdomen and nausea in some.
Presence of eggs and proglottids in
Proper cooking of meat, avoid pig
feces; antihelminthics
Shistosomiasis; vehicle
(contaminated water)
“swimmer’s itch”, fever, chills,
diarrhea and cough. Severehepatoslenomegaly and bladder
Water sanitation; antihelminthics
Intestinal distress; vehicle (food
and water), self inoculation
Intestinal distress; vehicle (soil)
Muscle and neurological
symptoms; vehicle (food)
Oral vaccine; rehydration
Hygiene; antihelminthics
Sanitation; antihelminthics
Proper cooking of meats;
antihelminthics and steroids
Defenses & Normal Microbiota of CVS and Lymphatics
Oral cavity: IgA, lysozymes, lactoferrin, saliva, tonsils
Upper GI: IgA, HCl, GALT
Lower GI: IgA, GALT (Peyer’s patches), bile, enteric bacteria
Normal Microbiota
Streptococcus, Moraxella, Bacteroides,Actinomyces, Treponema,
Candida, Entamoeba, Haemophilus
Sparsely populated (Helicobacter pylori)
Bacteroides, Bifidobacterium, Streptococcus, Clostridium, Lactobacillus,
Escherichia, Enterobacter, Candida, Entamoeba, Trichomonas
Virulence factors: attachment structures, acid production, urease, effacement, endotoxins, intracellular growth, latency, syncytia, exotoxins,
invasiveness, induction of hypersensitivity reaction, antigenic “cloaking”