Download Digestive System Infections

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