Digestive System Infections Chapter 23. –Gastrointestinal tract (GI tract) Digests food, absorbs...
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Transcript of Digestive System Infections Chapter 23. –Gastrointestinal tract (GI tract) Digests food, absorbs...
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Digestive System Infections
Chapter 23
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– 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
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– Accessory digestive organs• Organs involved in grinding food or providing
digestive secretions• Tongue, teeth, salivary glands, liver, gallbladder,
pancreas
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•Most organs of GI tract protected by peritoneum
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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
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• Lower small intestine and colon– Enterobacteria (enterics) dominant
– Anaerobic Bacteriodes and Lactobacillus
– Mutualism
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• Defenses – Normal flora
• Microbial antagonism
– Saliva– Acid and digestive enzymes – Continuously shed cells of mucus membrane
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Dental Caries• Most common bacterial disease of humans
– Main reason for tooth loss
• Causative agent– Streptococcus mutans
– Dextran and pili allow biofilm formation– Lactic acid fermenter
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• 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
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• 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
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• Prevention– 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
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Peptic Ulcers
• Erosions of stomach or duodenum lining• Causative agent
– Helicobacter pylori• Gram-negative; vibrio • Multiple polar knobbed flagella
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• 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
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• Virulence factors• Adhesions • Urease • Protein to inhibit acid production• Enzyme to inhibit digestion by WBCs
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– Inflammatory response and bacterial toxins causes decrease in mucus production
– Stomach lining not protected from acidic environment
– Chronic infection
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• 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
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• Prevention – 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
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Mumps• Acute viral illness
– Attacks large parotid salivary glands
• Causative agent– Mumps virus
• Enveloped, -ssRNA Rubulavirus
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• 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
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– Virus reproduces in the upper respiratory tract• Spreads to salivary glands
– In salivary glands• Destroys epithelium and releases virus into saliva
causing inflammation
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• Epidemiology– Humans only natural host– Contact transmission
• Droplets or fomites• Peak infection time from 1-2 days before swelling
until swelling subsides
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• Prevention – Prevention directed at immunization
• MMR• Lifelong immunity
• Treatment– Treatment directed at alleviating symptoms – No effective antiviral treatment