1. Chapter 25 Digestive system infections
Medgar Evers College, CUNY
Bio 261
Dr. Santos

2. Basic anatomy of the human digestive system
IIeum of small intestine
Duodenum of small intestine
Appendix
Cecum
Ascending portion of large intestine
Anus
Small intestine
Large intestine
Rectum
Liver
Gall- bladder
Tongue
Oral cavity
Pharynx
Esophagus
Stomach
Pyloric sphincter
Cardiac orifice
Mouth
Salivary glands
Pancreas
Large intestines
Small intestines
Parotid gland
Sublingual gland
Submandibular gland
A schematic diagram of the human digestive system

3. Normal microbiota of the digestive system
Different species colonize the mouth depending on their ability to attach to specific receptors.
Dental plaque consists of many bacteria of different species attached to the teeth or each other.
Anaerobic bacteria are also present.

4. Bacterial infections of upper digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Dental caries or tooth decay
*incubation period is 1 to 24 months
Streptococcus mutans
Severe pain, discoloration of tooth or breakage
Glucan is produced from sucrose. This is needed for dental caries production
Restrict sugar, fluoride in toothpastesee dentist regularly

5. Bacterial infections of upper digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Periodontal disease
Dental plaque
Bleeding, sensitive gums, bad breath, loosening of the tooth,
Bacteria produces inflammatory response, plaque forms, widens and anaerobic bacteria grow, toxins and enzymes degrade tissue
Avoid buildup of plaque and surgery if needed

6. Bacterial infections of upper digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Trench mouth
(acute necrotizing ulcerative gingervitis)
A spirochete of genus Treponema
Fever, painful bleeding gums, foul mouth odor
Tissue destruction, ulceration and tissue invasion by spirochete.
Antibiotic treatment

7. Bacterial infections of upper digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Helicobacter pylori
gastritis
H. pylori
Vomiting, belching, abdominal pain and tenderness and bleeding if ulcer or cancer associated
Pathogen survives acidity of stomach, penetrates mucus, inflammatory response, thinning of mucus can occur if ulcer forms
Antibiotics and medication to suppress acid formation

8. H. pylori Gram – Microaerophile Multiple polar flagella for motility
Produces urease to neutralize acidity of stomach
Buries itself on the mucus layer to survive

9. Viral infections of upper digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Herpes
HSV Type 1
Fever, sore throat, pain in lip followed by blisters
Virus replicates in the epithelium, an immune response follows, but virus hides in sensory nerves
Anti viral medication such as acyclovir, penciclovir

10. Viral infections of upper digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Mumps
*incubation period is 15 to 21 days
Mump virus
**Only one serotype of the mumps virus is known.
Fever, headache, loss of appetite, painful swollen parotid glands, painful enlarged testicles, pelvic pain in women
Virus replicates in the upper respiratory tract and then travels to parotid glands, inflammatory response occurs
An effective attenuated vaccine since 1967 has been in place since then.

11. Bacterial infections of lower digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Cholera
Vibrio cholerea
Massive diarrhea, vomiting, muscle cramps
Exotoxins that cause excessive excretion of electrolytes by the intestinal epithelium; leads to dehydration and shock
Purification of water supply, rehydration with electrolyte and glucose

13. Bacterial infections of lower digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Shigellosis
Species of shigella
Fever, dysentery, vomiting headache, stiff neck, painful joints
Pathogen invades and multiplies within the intestinal epithelium
Antibiotics such as ampicillin, sanitary measures,

14. Bacterial infections of upper digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Gastroenteritis caused by E.coli
E. coli
Vomiting and diarrhea, sometimes dysentery (crampy abdominal pain and bloody diarrhea)
Attachment, toxins, invasion of intestinal epithelium, loss of microvilli
Bismuth compound treatment, sanitary conditions, replacement of fluids loss

15. Bacterial infections of lower digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Salmonellosis
Salmonella enterica
Diarrhea, vomiting,
Invasion and penetration of tissue, inflammatory response
No treatment unless tissue invasion then antimicrobial agent

16. Bacterial infections of lower digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Campylobacteriosis
Campylobacter jejuni
Diarrhea, fever, abdominal cramps, nausea, vomiting, bloody stool
Low infecting dose, pathogen multiplies within and beneath the epithelial cells, inflammatory response
Sanitary measures, and no antimicrobial treatment

17. Viral infections of lower digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Hepatitis A
(acute and rarely leads to long term liver or permanent damage)
Nonenveloped ss RNA picorna virus
Fatigue, fever, loss of appetite, nausea, right sided abdominal pain, dark colored urine
Viral replication and damage restricted to liver. How it gets there is still being investigated
Inactivated vaccine

19. Viral infections of lower digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Hepatitis B
(infected blood or body fluid/oral)
Enveloped ds DNA hepadnavirus
More severe than A, progressive liver damage, can lead to cirrhosis and cancer
HBV is carried to liver by bloodstream, attaches and invades liver cells
Combined Hepatitis A and B vaccine

20. Viral infections of lower digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Hepatitis C
(most commonly transmitted by sharing needles)
*baby boomers!
Enveloped ss RNA flavivirus
Few or no symptoms, progressive liver damage or cancer in 10 to 20% of cases
Liver cells are infected and replication occurs, inflammatory response occurs
No vaccine but one should avoid alcohol use and anti viral medication if needed

21. 2 other viral infections of the lower
1- rotaviral gastroenteritis, most common cause of viral gastroenteritis in children and infants
2- noroviral gastroenteritis, most common cause of viral gastroenteritis in the USA

22. Protozoan infections of lower digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Giardiasis
Giardia lamblia, a pear shaped protozoan
Flatulence, nausea, vomiting, diarrhea, abdominal cramps, weight loss
Host immune response to attachment of pathogen to epithelial lining
Antimicrobial medications such as atabrine or flagyl

23. Protozoan infections of lower digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Cryptosporidiosis
Cryptosporidium parvum
Fever, loss of appetite, nausea, crampy abdominal pain, watery diarrhea lasting 10 to 14 days
Invasion of epithelial cells, inflammatory response
No effective treatment exists but sanitary conditions should be kept, pasteurization of beverages

24. Protozoan infections of lower digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Cyclosporiasis
Cyclospora cayetanensis
Fatigue, loss of appetite, vomiting, watery diarrhea, weight loss
Very little is known
Bactrim, Septra antimicrobial agents, boil water before drinking

25. Protozoan infections of lower digestive system
Disease
Cause
symptoms
pathogenesis
treatment
Amebiasis
Entamoeba histolytica
Diarrhea, abdominal pain, blood in feces
Ingested cysts liberate the pathogen, reach large intestine, feed on mucus and cells lining the intestine, and sometimes they penetrate the lining by using enzymes
Metronidazole or paromomycin