Bacterial Gastrointestinal Infection
2-Year Medical Students
Prof .Dr. Asem Shehabi
Faculty of Medicine
University of Jordan
Diarrheagenic E. coli-1
 There are 6 groups of E. coli strains which have
virulence factors causing human diarrhea..Widely
distributed in water, animals & Birds..4 most important
1-Enterotoxigenic E. coli (ETEC). Common in domestic
animals, Poultry, Humans ..Produces Heat stable
/Heat –labile enterotoxins (plasmid borne) or both
(LT+ ST).. fimbrial adhesins attached to enterocytes of
the proximal small intestine epithelium..
 LT Subunit B.. attached to GM1 Ganglioside.. release
Subunit A.. Activate adenylyl cyclase .. increase
cellular cAMP release .. Heat-stable toxin (ST)
activates cGMP.. Both cause prolonged hyper
secretion of water .. Sodium + chloride.. Inhibit
reabsorption of sodium.. Mild/severe watery diarrhea,
vomiting, abdominal pain.. No fever.
E. coli
Mucosal Attachment ..
Adhesions Fimbriae-Pili.. CFA I & CFA II
Diarrheagenic E. coli-2
 ETEC strains are an important cause of diarrhea in
infants – very young children in developing countries
 Common cause of Traveler’s diarrhea in developed
countries.. Contaminated water .. Dairy products..
fresh vegetable food.
 Self- limited with Rehydration.. Antibiotics are rarely
needed.
 2- Entero-haemorrhagic E. coli (EHEC) or Verotoxigenic E. coli (VTEC).. mostly serotype O157: H7..
Produces Shiga-like toxin.. common in intestines of
animals.. cows.. contamination milk & ground beef
meat.. causes outbreaks of gastroenteritis ..4000
cases, 600 HUS, 55 deaths.. 2012,Germany
Diarrheagenic E. coli-3
 Complications.. severe inflammation & ulceration
colon.. bleeding.. Haemorrhagic colitis.. If toxin
reached blood.. Haemolytic Uraemic Syndrome
(HUS).. More severe in children.. Blood+ Protein in
urine.. Kidney failure ..fatal
 Prevention is better than treatment with antimicrobials.
 3-Entero-pathogenic E.coli (EPEC).. adherence to GI
epithelium.. distortion.. Numerous serotypes.. K, LPS
Antigens .. Common infection in neonates.. Outbreaks
in babies nurseries aged less 6 months.. watery
diarrhea & vomiting.. Chronic diarrhea.
 4-Entero-invasive E.coli (EIEC).. like Shigella.. cause
bloody diarrhoea.. Vomiting.. Abdominal pain.. Fever..
by invasion of damaging intestinal epithelial cells..
necrosis.. Affect all ages..more pathogenic in children.
Lab Diagnosis
 Detection of Diarrheagenic E. coli strains in the
laboratory is difficult.. complicated by the fact that nonvirulent E. coli strains are normally present in the
feces.. Lactose+ve
 Stool culture.. MacConkey agar.. Identification by PCR
more accurate than biochemical and serotyping..
 Antibiotic treatment is recommended in severe &
chronic cases.. Ciprofloxacin, Co-trimoxazole is
recommended for drug-sensitive strains.... parenteral
second-generation or third-generation cephalosporin
for systemic complications.
 No vaccines are available
Campylobacter
 Campylobacter spp. are Microaerophlic.. Gram-negative ..Spiral
shape.. Bipolar flagella.. Motile.. Isolation on selective special
medium at 42 C.
 Commonly present in the GIT of domestic animals.. poultry &
pets .. Contaminate easily Meat.. Dairy products.. Food
contamination & direct contact with animals.. Common cause of
diarrhea in Western countries..Less in Arab countries.
 Campylobacter jejuni.. common cause acute enteritis.. Bloody
diarrhea.. Infants, children > adults, Elderly, Immunecompromised.. Rare septicemia.. Reactive arthritis.. Infection
mostly self-limited without treatment.. few days.. Pathogenesis..
Endotoxin & various enterotoxin, cytotoxins..Prolong carriage
associated with imunodeficincey.
 C. fetus.. Less common in human.. Causes sepsis & abortion
in animals.
 Serological test is not significant in diagnosis clinical cases.
 Treatment: Macrolides/Azithromycin, Ciprofloxacin, Ampicillin
Campylobacter- Vibrio cholera
Helicobacter pylori
 H. pylori infection is expected to be present in
stomach of 30%-90% of world’s population ..causes
no signs or symptoms and doesn't lead to any
complications in the majority of persons.. H. pylori
infection discovered 1983 as cause of chronic
gastritis.. Serious complications.. Peptic /dudenal
ulcers.. Lymphoma, stomach cancer in 2% of
colonized persons worldwide over a long period
 H. pylori ..Microaerophlic to Anaerobes.. Gram-ve
bacteria, spiral shape, motile, polar 4-6 flagella ..
produces potent urease, support its survive in gastric
mucous layer near the epithelial surface.. neutralize
stomach acidity. Protease & outermembrane
antigens (Cytotoxins) Causing chronic inflammation
of the inner lining of the stomach mucosa
Helicobacter infection
Diagnosis & Treatment
 Infection is most likely acquired by ingesting
contaminated food, water , personal contact Causes
Re-infection is common..No vaccine
 Optimal growth..Special culture medium, 90%, Co2
37C.
 Urease breath test by drink a harmless liquid and in
less than 1 hour, a sample of breath is tested.. Rapid
urease test for identification H. pylori in gastric biopsy
taken by endoscope or culture
 Giemsa /silver stain.. histological biopsy specimens.
 Treatment: Metronidazole + Clarithromycin or Bismuth
sulfate + Metronidazole + Amoxicillin + H2 Blockers..
Vibrios-1
 Vibrios are Gram-negative straight or curved rods,
oxidase-positive, motile.. single polar flagellum
..widely distribute in sea water ..2-3% NaCl..
 Classical V. cholerae (serotypes 01, 0139).. Cause
Epidemic- Pandemic Cholera.. Noninvasive.. Affecting
small intestine through secretion of an EnterotoxinHeat-labile /Cholera Toxin.. Increasing cAMP..
 Incub. 8-24h..Severe watery diarrhea, dehydration,
shock, acidosis, death within 24 h.. Cause Only
Human Infection.
 Partial immunity developed following infection..
Specific developed antitoxin antibodies in intestine last
for 1-year ..Oral Vaccine used in endemic areas..
prevent re-infection up to 50%
Vibrios-2
 Non-01 V. cholerae.. Less virulent.. watery diarrhea
due to Cytotoxins..found in water with o-1 V.cholerae
 V. parahaemolyticus.. Halophilic Vibrio.. Cytotoxins
Raw fish.. Swimming.. Gastroenteritis.. Rare Sepsis,
Wound infection.. Contaminated fish
* Lab Diagnosis: Stool culture.. TCBS, Biochemical &
serotyping confirmation.
* Treatment: Oral re-hydration is the main treatment..
Replacement of fluid loss.. Water & Electrolytes..
doxycycline, cotrimoxazole (children), ciprofloxacin
Prevention: Safe water & Food.. Early detection of
positive infected cases prevent outbreak of cholera in
community..No Healthy carriers.
Foodborne Toxigenic Bacteria-1
 Staphylococcus aureus strains associated with
particular bacteriophage types can produce a Heatstable enterotoxin in food ( 20 minutes 100C),
Absorbed from small Intestine.. Blood, CNS
 Staphylococcal food poisoning is commonly
associated with salty foods, cream cakes, grounded
meat.. Fresh dairy products.. White chesses
 Main Symptoms.. Mostly Vomiting.. starts between 30
minutes and 6 hours following the consumption of the
contaminated food.. No Fever and rarely Diarrhea..
One day.. Self-Limited.
Foodborne Toxigenic Bacteria-2
 Bacillus cereus.. G+ve Aerobic Spore-Forming Bacilli
..Common in Nature.. Spores survive boiling and
cooling in Food.. Various Enterotoxins produced
during bacilli sporulation either in Food or Intestine..
Associated with two main gastrointestinal symptoms.
 1-Intoxication .. Heat-stable Emetic Enterotoxins
..Typically developed within 24 hours of eating
contaminated fried rice.. Meat.. last for few hours
without diarrhea and fever.
 2- Diarrheal Toxins ..watery mild diarrhea.. No Fever
or Vomiting.
 3- Both Types of toxins may produce by certain B.
cereus strains.. Mostly outbreaks in family, schools..
Commonly associated with Chinese food.. fried Rice
Foodborne Toxigenic Bacteria-3
 Clostridium perfringens.. G+ve Anaerobic SporeForming .. Widely distributed in the environment..
Common Intestines of humans and animals.. Produce
Various Enterotoxins, Cytotoxins, Enzymes
 C. perfringens toxin-type A .. Food-poisoning..
Incubation Period..8-24 Hrs.. Diarrhea.. Nausea..
Abdominal Pain.. Vomiting.. No Fever.. Mostly Selflimited.. 1-2 Days.. No Antibiotic treatment
 C. perfringens toxin-Type C.. Released following
multiplication in intestine.. Sever Diarrhea.. No
vomiting.. Necrotizing Enteritis.. Rare Sepsis.. Can be
fatal in certain Conditions.. Antibiotic treatment
 Detection toxin in blood.. Food specimens.
Clostridium difficile
 Anaerobic, spore-forming Gram+ve; Part of normal
intestinal flora (5-20%).. Rapidly increased and
become danger following antibiotic treatment for more
than 1 week.. with all wide-spectrum peniciilins..
clindamycin cephalosporins.. Often among
hospitalized patients.. Compromised ..Antibioticassociated enterocolitis ..nosocomial infection.
 Produce two exotoxins types A,B.. Bloody diarrhea..
Pseudomembranous colitis.. Discontinue potential
causative antibiotics.. use oral metronidazole or
vancomycin.. to stop disease complication.
Foodborne Toxigenic Bacteria-4
 Clostridium botulinum G+ve Anaerobic SporeForming ..Botulism.. Food-Intoxication.. Incubation124 h
 Consumption improperly or inadequately processed
canned food.. Spores.. Vegetative cells.. Release
highly potent heat-stable neurotoxin ( A-G types)..
inactivation 30min boiling.
 Botulinum toxin binds to presynaptic nerve ending of
peripheral nervous system & cranial nerves.. Inhibits
acetylcholine release .. Flaccid paralysis, Respiratory
or Cardiac failure.. Death.. Early Specific Antitoxin
Treatment may help.. No Antibiotics
Other Bacteria species
 Yersinia enterocolitica ..Gram-ve bacilli, common in
cold water, pigs.. Less in dogs, cats, other animals..
the bacteria are most likely to be found on the tonsils
and intestines..Contaminate often dairy products infect
mostly children younger< 1 year & compromised host .
 Common symptoms in children are fever, abdominal
pain, bloody diarrhea.. complications such as skin
rash, joint pains, or blood sepsis can occur in
compromised patients.
 Aeromonas species.. Gram-ve bacilli, common in
natural water sources.. a significant cause of bacterial
gastroenteritis ..cytotoxins .. young children.. Diarrhea,
dehydration.. Less Fever, vomiting.