3 Digestive SystemGastrointestinal tract – mouth, pharynx, esophagus, stomach, small and large intestineAccessory structures – teeth, tongue, salivary glands, liver, gallbladder, pancreas
4 Bacterial Population of the GI Tract Mouth – large microbial populationStomach – relatively small due to high acid contentSmall intestine – small populationLarge intestine – VERY large. 100 billion bacteria per gram of feces
5 Bacterial Diseases of the Mouth Dental caries (tooth decay)So many bacteria in the mouth that it is difficult to say which bacteria is the most common cause of decayStreptococcus mutans is one of the more important cariogenic bacteria
6 Development of cariesBacteria accumulate on the teeth, this is called PLAQUEThe bacteria in the plaque break down sucrose in our diet to produce glucose and fructoseGlucose is converted to dextran, the fructose is metabolized and produces acids that attack the enamel of the toothOver time the enamel can be destroyed and the softer tissue inside the tooth is attacked by bacteria causing decay which can lead to tooth loss!
7 Decay PreventionRemoval of the plaque – visit the dentist and dental hygienistRegular brushing and flossing to remove and reduce the bacterial population of the teethConsume less sucroseIf you ignore decay it can lead to tooth loss, gum disease, periodontal disease, and visits to the dentist that you would rather avoid!
10 Bacterial Diseases of the Lower Digestive System InfectionsPathogen in the GI tract and multiplesDelayed symptoms while bacterial population growsFever usually presentDiarrheaAbdominal cramps, nausea, vomitingIntoxicationsIngestion of preformed toxinRapid onsetFever usually not presentDiarrheaAbdominal cramps, nausea, vomitingSelf limiting, feel better within 24 hours usually
11 Staphylococcal food poisoning Staphylococcus aureus is the causeLeading cause of gastroenteritisIngest the toxin that causes the symptoms of the conditionFood is contaminated during preparation, bacteria incubate in the food and produce the toxin that is heat stable, you ingest the toxin (yummy)Symptoms usually appear in one to six hours
12 Staphylococcal food poisoning (continued) Foods at risk are custards, cream pies, ham, and poultryFoods prepared and not chilled have the potential for this type of food poisoningToxin is heat stable so it is usually not destroyed when the food is reheatedIt is the toxin the causes the usual symptoms
13 Traveler’s Diarrhea Estimated 25-50% of travelers affected High risk areasLatin AmericaAfricaMiddle EastAsiaCausative agent 80% of the time is E. coliPreventionHand washingAvoid eating food from street vendorsCareful use of purified water
15 Shigellosis (Bacillary dysentery) Bacterial infection caused by members of genus ShigellaShigella sonnei most common cause in the USBacteria multiply in the small intestine releasing a toxin that causes severe diarrhea, fever, vomiting, cramps, mucous in stoolOnset in hoursAcquired through contaminated food or waterSalads, raw vegetables, milk, dairy, meatFecal-oral routeAdults can get it from children sick with the diseaseRecovery in a few days, antibiotics used in only the most serious casesFluid replacement
16 Shigellosis statistics 165,000,000 cases per year - mainly in developing countries1,000,000 deaths - mostly in childrenIn the US reported cases are about 18,000 per year
18 SalmonellosisMembers of genus Salmonella are found in the GI react of humans and other animalsAlmost all are pathogenicBacteria multiply in the intestine and can enter the blood and lymphatic system becoming systemicFever, nausea, abdominal pain, cramps, diarrheaRecovery in a few daysEggs and meats especially poultry are sources of the infectionPet turtles and iguanas are carriers of Salmonella“Four inch law” passed in 1975 banning the sale of turtles with a shell of smaller than 4”
19 Typhoid Fever Salmonella typhi Carried by humans, acquired by poor sanitationSymptoms are high fever, headache, diarrheaDeath is rare, usually associated with ulceration of the intestinal wall1-3% of recovered patients become carriersTyphoid MaryStill a problem during foreign travel
20 Cholera Vibrio cholerae Acquired from contaminated water (fresh of salt), and foods from contaminated waterSevere diarrhea from cholera toxinRice water stoolsTreated by electrolyte replacement
22 Helicobacter pylori Robin Warren and Barry Marshall 2005 Nobel prize Cause of stomach and duodenal ulcersStomach cancer?Fecal-oral transmission?Treatment with antibiotics usually cures the ulcerBacteria lives and survives in the mucous layer of the stomach
23 Mumps Viral infection of the parotid salivary gland Swelling of the parotid gland, fever, pain when swallowingTransmitted via saliva and respiratory secretionsMMR vaccineMumps in adult males causes swelling of the testes (ouch!)In RARE cases sterility can result
25 Hepatitis Inflammation of the liver Viral hepatitis is the second most reported infectious disease in the USAt least 5 different viruses have been discovered that cause hepatitisHepatitis A, B, C, D, and E
27 Hepatitis A Single-stranded RNA virus Oral-fecal transmission Infection form food common, blood infection is rareAnorexia, malaise, nausea, diarrhea, fever, chillsJaundiceSymptoms last 2-21 daysFull recovery is typicalNo carrier stateVaccine available
28 Hepatitis B Enveloped DNA virus Blood products Sexually transmitted 10% of patients become chronic carriersLiver cancer?Vaccine is available
29 Hepatitis C Single stranded RNA virus Silent epidemic Symptoms may take 20 years to appear100,000 new infections per year8000 deaths per yearNo vaccineInterferon treatment
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