1. Digestive System Infections
Chapter 23

2. Gastrointestinal tract (GI tract)
Digests food, absorbs nutrients and water into blood, and eliminates waste
Mouth, esophagus, stomach, small intestine, large intestine (colon), rectum and anus

3. Accessory digestive organs
Organs involved in grinding food or providing digestive secretions
Tongue, teeth, salivary glands, liver, gallbladder, pancreas

4. Most organs of GI tract protected by peritoneum

5. Normal Flora Tongue and teeth Viridans streptococci most prevalent
Form biofilms
Esophagus, Stomach, Duodenum
almost free of microbes
Peristalsis, rapid transport of food and acids

6. Lower small intestine and colon
Enterobacteria (enterics) dominant
Anaerobic Bacteriodes and Lactobacillus
Mutualism

7. Defenses Normal flora Saliva Acid and digestive enzymes
Microbial antagonism
Saliva
Acid and digestive enzymes
Continuously shed cells of mucus membrane

8. Dental Caries Causative agent Most common bacterial disease of humans
Main reason for tooth loss
Causative agent
Streptococcus mutans
Dextran and pili allow biofilm formation
Lactic acid fermenter

9. Signs and symptoms Usually advanced before symptoms arise
Throbbing pain
Discoloration, roughness or holes in tooth (caries)
Tooth can break while chewing
Gingivitis – inflammation of gums
May lead to periodontal disease
Inflammation and infection of surrounding tissues

10. Epidemiology Worldwide distribution Incidence varies
Mainly on availability of dietary sucrose and dental care
In US, 78% of children have at least one cavity by 17
99.5% by age 65

11. Prevention Treatment Restriction of dietary sucrose
Mechanical removal of plaque
brushing and flossing
Application of sealant
Fluoride treatment
Treatment
Drilling out cavity and filling with amalgam
Crown or root canal
Antibacterial rinses and scaling for gingivitis

12. Peptic Ulcers Erosions of stomach or duodenum lining Causative agent
Helicobacter pylori
Gram-negative; vibrio
Multiple polar knobbed flagella

13. Signs & Symptoms Abdominal pain
Nausea, vomiting (with or without blood), weight loss and bloody stools
May lead to internal bleeding and shock
Due to perforations of stomach or intestine

14. Virulence factors Adhesions Urease Protein to inhibit acid production
Enzyme to inhibit digestion by WBCs

15. Inflammatory response and bacterial toxins causes decrease in mucus production
Stomach lining not protected from acidic environment
Chronic infection

16. Epidemiology
Transmission most likely fecal-oral route
Flies also capable of transmission
20% of US population infected
Many asymptomatic carriers
Diagnosed by assessing damage to stomach lining and isolation of urease+, Gram- vibrios

17. Prevention Treatment Change lifestyle to eliminate risk factors
Good hygiene to avoid fecal-oral transmission
Treatment
Combined antibiotic treatment
Medication to inhibit production of stomach acid
Surgery may be required if ulceration is extensive or perforation occurs

18. Mumps Acute viral illness Causative agent
Attacks large parotid salivary glands
Causative agent
Mumps virus
Enveloped, -ssRNA Rubulavirus

19. Signs & Symptoms Long incubation period
Fever, loss of appetite, headache, parotitis and sore throat
Symptoms disappear in about a week
Symptoms much more severe past puberty
May cause orchitis or meningitis
Pregnant women often miscarry

20. Virus reproduces in the upper respiratory tract In salivary glands
Spreads to salivary glands
In salivary glands
Destroys epithelium and releases virus into saliva causing inflammation

21. Humans only natural host Contact transmission
Epidemiology
Humans only natural host
Contact transmission
Droplets or fomites
Peak infection time from 1-2 days before swelling until swelling subsides

22. Prevention Treatment Prevention directed at immunization MMR
Lifelong immunity
Treatment
Treatment directed at alleviating symptoms
No effective antiviral treatment