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Gastrointestinal infections
In a relatively short time following birth a "normal" flora is
established in each part of this tube. Each end of the tube, the
oral cavity and the colon, is heavily colonized while the
central part of the tube, the stomach, duodenum, jejunum and
the proximal half of the ileum, are lightly colonized.
Microbial flora:
Barriers
A. Mucosal epithelium
C. Mucous.
D. Acidity of the stomach.
E. Bile
F. IgA.
G. Gut motility
H. Peyer's patches.
I. Normal flora
Bacteroides, Prevotella, Clostridium, and Peptostreptococcus Escherichia,
Proteus and Pseudomonas
Some of the more common factors that compromise
barriers
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A. Ingestion of antacids
B. Antibiotic therapy
C. Glucosteroid therapy
D. Cancer chemotherapy
E. Radiation therapy
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F. Ingestion of pre-formed toxins with food and/or water (Staphylococcus=
enterotoxin).
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G. Ingestion of microorganisms that produce toxins/enzymes/ immune
suppression factors in situ (E. coli, Shigella, Salmonella).
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H. Anatomic alterations.
Epidemiology
• Nearly all persons have had dental caries
sometime in their life. Most people have at least
one case of diarrhea each year. Children average
2-3 episodes of diarrhea in a year. Diarrhea is the
most common cause of death in the developing
world. There are over 76 million cases of food
poisoning each year in the U.S. Most of the time
these diseases are self-limiting and people do not
go to their physician unless their symptoms
become severe or chronic.
Pathogenesis
• Intoxication
• Attachment
• Invasion
Intoxication
Staphylococcus aureus
produces an enterotoxin in improperly stored food that
upon ingestion causes primarily nausea and vomiting.
Botulism
Attachment
1) surface of the epithelial cells
- ETEC E. coli, Giardia lamblia
- watery diarrhea without inflammatory
cells or blood in the stools
Invasion
• Campylobacter, Shigella, Salmonella, Rotavirus,
Norwalk agent
• watery diarrhea (viral gastroenteritis) to bloody
mucus covered stool (dysentery; Shigellosis), to
invasion of the bloodstream (enteric fever;
Salmonella typhi).
Manifestations
• Mouth; various lesions, dental cavities, tooth pain/sensitivity to hot
and/or cold, bleeding gums, petechia, facial pain and/or swelling,
abscesses, cellulitis.
• Salivary glands: jaw pain when swallowing, swelling under jaws.
• Esophagus: dysphagia (difficulty in swallowing), odynophagia (painful
swallowing; unique to infectious causes of esophagitis), heartburn,
atypical chest pain, regurgitation.
• Stomach: vomiting, epigastric pain that occurs 90 min to 3 hours after
eating; eating relieves the pain; belching, indigestion, heartburn.
Manifestations
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Small intestines: large volume watery diarrhea, sometimes fatty stools,
increased bowel sounds, cramps, diffuse abdominal pain, no guarding or
rebound tenderness, rarely has white blood cells in stool.
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Large intestines: small volume bloody diarrhea with mucus in it (dysentery),
cramps, diffuse abdominal pain, rarely any guarding or rebound tenderness,
frequently has white blood cells in stool, fever.
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Liver: upper right quadrant pain of the abdomen, fever, icterus, clay-colored
stools, dark urine.
Gallbladder (cholecystitis and cholangitis): Jaundice, right upper quadrant
pain, high fever, chills.
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Peritoneum: sharp localized abdominal pain aggravated by motion, fever,
chills, constipation, abdominal distension, decreased bowel sounds, guarding,
rebound tenderness.
Laboratory examination
Stools: watery, mucoid or bloody + cultivation
Blood culture for septicemia
Serological tests (e.g., typhoid fever, amebiasis)
Toxin assays
- Fibroblast cell assay for toxin A and B produced by C. difficile.
- ELISA tests (LT of E. coli and cholera toxin of Vibrio cholerae)
Infections of the Teeth, Jaw and Mouth
• Dental caries- Streptococcus mutans (most common cause; initiates
dental cavity), Lactobacillus sp. (appear to be important in progression
of lesion deep into enamel and the dentine).
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• Plaque-associated periodontal disease- gingivitis/periodontal
disease- is a polymicrobial process.
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The following are commonly seen in these infections: Eubacterium sp.,
Peptostreptococcus micros, Actinobacillus actinomycetemcomitans,
Porphyromonas gingivalis, Bacteroides forsythus, Fusobacterium nucleatum,
Prevotella intermedia, Capnocytophaga sp., Selenomonas sp., Spirochaetes.
Diseases of the Periapical Tissue and
Jaw
• Dentoalveolar abscess- an abscess that forms at the end of the tooth
root. (obligate anaerobes, Streptococcus milleri).
• Periodontal abscess- an abscess that forms deep in the gums along the
tooth root following advanced periodontal disease. Gram-negative rods,
streptococcus viridans, anaerobic streptococci, and spirochaetes.
• Ludwig’s angina- a cellulitis of the sublingual and submandibular
spaces (floor of the mouth). Can rapidly become fatal without
treatment (mortality rate before the antibiotic era was 50%)
Streptococci, Bacteroides, Fusobacterium, Staphylococcus aureus
• Osteomyelitis of the jaw- an inflammation of the bone (medullary
space) and the muscles around it. More commonly affects the
mandible. (Gram-negative rods, anaerobic streptococci, Actinomyces israelii)
Infections of the Tongue and Mouth
Stomatitis is an inflammation of the mucosal surfaces in the mouth and
on the tongue.
HSV 1 and 2 viruses and Candida albicans are the most common causes of
this inflammation.
- gingivostomatitis
Angular Cheilitis (angular stomatitis, perlèche) is an inflammation of the
angles of the mouth. Candida albicans. Staphylococcus aureus
Infections of the Esophagus
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Candida albicans (most common cause)
Cytomegalovirus (CMV)
Herpes simplex virus (HSV)
Varicella-zoster virus (VZV)
Human Immunodeficiency Virus (HIV)
Other fungi (eg, Aspergillus, Histoplasma, Cryptococcus, Blastomyces)
Epstein-Barr virus (EBV)
In HIV-infected hosts - CMV, HSV, Mycobacterium avium-intracellulare,
idiopathic
Human papillomavirus (HPV)
Poliovirus
Bacterial species (eg, normal flora, Mycobacterium tuberculosis,
Mycobacterium avium-intracellulare, other)
Parasitic infections ( Trypanosoma cruzi, Cryptosporidium, Pneumocystis,
Leishmania donovani)
Infections of the Stomach and Upper
Duodenum
• Chronic Gastritis- is the inflammation or irritation of the stomach
lining. Chronic gastritis is usually caused by Helicobacter pylori.
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• Peptic ulcer disease (PUD)
• Duodenal ulcer disease
• Gastric ulcer disease
Helicobacter pylori is also the cause of most of these ulcers
(60-70%).
Infections and Intoxications of the
Intestines
Bacteria:
Staphylococcus aureus, Bacillus cereus, Clostridium
perfringens, Clostridium botulinum, Escherichia coli
(ETEC, EPEC, EHEC, EAEC, EIEC), Salmonella sp.,
Shigella sp., Campylobacter sp., Yersinia enterocolitica,
Clostridium
difficile,
Vibrio
cholerae,
Vibrio
parahemolyticus, Listeria monocytogenes, Aeromonas
hydrophila, Plesiomonas sp.
Infections and Intoxications of the
Intestines
• Viruses
Rotaviruses, Norwalk virus, Noroviruses (Norwalk-like
viruses), Adenoviruses, Astroviruses, other Caliciviruses,
Parvoviruses
Parasites- Giardia lamblia, Entamoeba histolytica,
Cryptosporidium parvum, Cyclospora cayetanensis,
Diphyllobothrium latum, Ascaris lumbricoides, Trichuris
trichiura, Taenia solium, Taenia saginata
Intoxications
• Bacteria-
Staphylococcus aureus, Bacillus cereus,
Clostridium perfringens, Clostridium
botulinum
Small intestine infections
• Bacteria- E. coli (ETEC, EPEC), Clostridium perfringens,
Cholera sp., Vibrio sp.
• Viruses- Rotavirus, Adenovirus, Calicivirus, Astrovirus,
Norwalk virus, Noroviruses (Norwalk-like viruses)
• Parasites- Giardia lamblia, Cryptosporidium parvum,
Ascaris lumbricoides, Taenia solium, Taenia saginata,
Cyclospora cayetanensis
Large intestine infections
• Bacteria- E. coli (EHEC, EIEC, EAEC), Shigella
sp., Salmonella sp., Campylobacter sp., Yersinia
sp., Aeromonas sp., Plesiomonas sp., Clostridium
difficile
• Parasites- Entamoeba histolytica, Trichuris
trichiura
FOOD TOXEMIA
• ETIOLOGICAL AGENTS:
• Staphylococcus aureus (gram+, aerobic,
coccus),
• Bacillus cereus (gram+, aerobic, rod),
• Clostridium perfringens Type A (gram+, anaerobic,
rod),
• Clostridium botulinum (gram+, anaerobic, rod)
VIRAL GASTROENTERITIS
• Rotavirus, Adenovirus, Astrovirus, Calicivirus
(Noroviruses and Norwalk virus).
Bacterial GastroenteritisNoninflammatory (no fecal WBC’s)
Escherichia coli INFECTION
• Enterotoxigenic E. coli (ETEC)- infantile
diarrhea and Traveler’s diarrhea
• Enteropathogenic E. coli (EPEC)- diarrhea
in infants less than 6 months of age
• Enteroaggregative E. coli (EAEC)- a major
cause of Traveler’s diarrhea, a more
persistent diarrhea
Vibrio
• Vibrio cholerae
Other causes of noninflammatory
gastroenteritis
GIARDIASIS
• Giardia lamblia (duodenalis) cysts
Other causes of noninflammatory gastroenteritis
primarily associated with immunocompromised
hosts.
CRYPTOSPORIDIUM PARVUM
• Cryptosporidium parvum is a coccidium
parasite.
• Cyclospora cayetanensis, Isospora belli,
and Microsporida (Enterocytozoon
bieneusi)