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 • • • • • A. Ingestion of antacids B. Antibiotic therapy C. Glucosteroid therapy D. Cancer chemotherapy E. Radiation therapy • F. Ingestion of pre-formed toxins with food and/or water (

Staphylococcus

= enterotoxin). • G. Ingestion of microorganisms that produce toxins/enzymes/ immune suppression factors

in situ

(

E. coli, Shigella, Salmonella

).

• 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.

• Intoxication • Attachment • Invasion Pathogenesis

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

• 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.

• 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.

• • 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.

• 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).

Plaque-associated periodontal disease

disease- is a polymicrobial process.

- gingivitis/periodontal • 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

• • • • • • • • • • • •

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.

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 hydrophila, Plesiomonas

sp.

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

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

coccus), (gram + , aerobic,

Bacillus cereus

(gram + , aerobic, rod),

Clostridium perfringens

rod), Type A (gram + , anaerobic,

Clostridium botulinum

(gram + , anaerobic, rod)

VIRAL GASTROENTERITIS

• Rotavirus, Adenovirus, Astrovirus, Calicivirus (Noroviruses and Norwalk virus).

Bacterial Gastroenteritis Noninflammatory (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 cholerae

Vibrio

Other causes of noninflammatory gastroenteritis

GIARDIASIS

• Giardia lamblia ( duodenalis ) cysts

Other causes of noninflammatory gastroenteritis primarily associated with immunocompromised hosts.

CRYPTOSPORIDIUM PARVUM

• • Cryptosporidium parvum parasite. is a coccidium Cyclospora cayetanensis, Isospora belli, and Microsporida ( Enterocytozoon bieneusi

)