Presentation is loading. Please wait.

Presentation is loading. Please wait.

 Esophagus and stomach are relatively bacteria free  Mouth > Different Streptococci in different micro environments > Teeth colonized by bacteria.

Similar presentations


Presentation on theme: " Esophagus and stomach are relatively bacteria free  Mouth > Different Streptococci in different micro environments > Teeth colonized by bacteria."— Presentation transcript:

1

2

3  Esophagus and stomach are relatively bacteria free  Mouth > Different Streptococci in different micro environments > Teeth colonized by bacteria forming biofilm—plaque bacteria per gram!  Small Intestine—few microbes > Aerobic and facultative anaerobes > Gram-negative rods, streptococci, lactobacillus, yeast  Large Intestine (1/3 fecal mass): › Bacteroides--anaerobic › Enterobacteria—facultative anaerobes

4  Actions › Synthesis of Vitamins:  Niacin, thiamine, riboflavin, pyridoxine, folic acid, pantothenic acid, biotin, and vitamin K › Digestion of fiber—gas production! › Opportunistic pathogens of urogenital tract › Prevent colonization by pathogens  Antibiotic treatament that disrupts normal flora can result in diarrhea  Antibiotic-associated colitis due to colonization by clostridium difficile

5  Tooth decay › Dental caries › Streptococcus mutans  Produce lactic acid and thrive in acid environment  Produce extracellular glucans, base for biofilm › Prevention: decrease refined sugar, mechanical removal of plaque, fluoride  Periodontal disease › Caused by plaque formation and tartar in gingival crevice › Gingivitis › “Trench mouth” Acute necrotizing ulcerative gingivitis: poor dental hygiene and stress › Treponema sp., anaerobic spirochete

6

7  Helicobacter pylori › Generally asymptomatic unless accompanied by ulcers or cancer  Survive in stomach acid due to urease which converts urea to ammonia › Flagella allow penetrataion of mucosal layer and attachment to mucosal epithelium

8

9  Cold Sores and Fever Blisters › HSV-1  Ds-DNA  Enveloped virus › Latent infection of sensory nerve endings  Life-long infection,  treatment of symptoms does not remove latent virus › Transmitted in saliva either directly or by fomits (2-3 hours) › Large portions of the population are infected with the virus

10  Acute viral infection of parotid gland › Paramyxovirus  Ss-RNA virus › Infects parotid, pancreas, ovary, testicles › Immune response produces symtomatic swelling and accompanying pain › Complications can include: meningitis, orchitis, miscarriage, encehpalitis. › Vaccination aims at eradication of mumps

11  Causitive agents > Microbial toxins (food intoxication) > Bacterial infection > Viral infection > Protozoa infection  Symptoms › Diarrhea  Dysentery: blood and pus in feces › Loss of appetite › Nausea and vomiting › fever

12  Fecal-oral transmission (contaminated water supply)  Dehydration as result of diarrhea  Generalities in pathogenic mechanisms: > Attachment: pili or adhesin (proteins) > Toxin production Increase secretions cytotoxin > Alteration of host cells Type III secretion > Cell invasion

13  Vibrio cholerae › Curved, gram-negative rod › Salt tolerant › Acid sensitive  Produce exotoxin: cholera toxin › A-B toxin stimulates adenyl cyclase and locking cAMP cycle in “on” position › Stimulates Cl- secretion resulting in loss of water and electrolytes from the cells  Treatment focuses on oral rehydration therapy  Prevention: avoidance and vaccination

14  Causitive agent : › S. flexneri, S. boydii, S. sonneri, and S. dysenteriae › Gram-negative enterobacteria with plasmid › Acid tolerent › Increasingly antibiotic resistent  Invasion of intestinal epithelial cells  Dysentery  Shiga toxin › A-B cytoxin: inhibits ribosome › Hemolytic uremic syndrome (HUS)  RBC lysis, anemia, kidney failure

15

16  Normal flora › Pathogenic forms identified as cause of  Epidemic gastroenteritis, 1945  traveler’s diarrhea, 1970s  Dysentery and HUC  Pathogenicity: › Enterotoxigenic (plasmid mediated) › Enteroinvasive › Enteroaggregative (plasmid mediated) › Enterohemorrhagic (Shiga toxin production)

17  Salmonella enterica and S. bongori › Gram-negative, lactose-negative, Acid sensitive › Over 2400 serotypes indicated with non-italicized name › Zoonotic  Source of increased antibiotic resistance › Human reservoir—typhoid fever  Enteric fever: S. typhii  Gastroenterisis › Adhesion and Type III secretion

18  C. jejuni isolated in 1972: leading cause of diarrhea in US › Mobile, gram-negative rod › Microaerophile  Pathogenisis › Invasion of intestinal epithelium causing inflammatory response › Guillain-Barre syndrome complication in 0.1% of cases  Progressive paralysis  5% fatality, 95% recovery with treatment

19  Viroid › Double walled capsid › Ds, segmented RNA  Gastroenteritis › Abrupt onset vomiting and diarrhea › Fluid replacement therapy

20  Viroid › Small non-enveloped, ss- RNA › Survive well in enviroment › Incubation hurs  Considered a type B bioterrorism agent › Not cultivated in laboratory

21  Infectious Hepatitis › HAV  Small ss-RNA picornavirus › Liver is only infected organ › Spread through fecal contamintion of food and water  Symptoms › Fatigue, fever, abdominal pain, jaundice  Vaccine available since 1995

22  Serum hepatitis › Infects 5% of world population and 9 th leading cause of death › HBV virus—hepadanvirus  Ds-DNA, Lipid envelope, reverse transcriptase  HBsAg: surface antigen responsible for adhesion and infection › Long term infections result in cirrhosis of the liver and liver cancer › Spread in blood, blood products, semen, and vertically to newborns  Prevention by vaccination and avoidance

23  Most common blood-borne infection in the US  Symptoms similar to Hepatitis A or B or asymptomatic.  Viroid › Enveloped ss-RNA flavivirus  No vaccine  Pathogenesis › Inflammation of liver › Chronic infection leading to 10-20% cirrhosis or liver cancer.

24  Giardia lamblia › 6-20 day incubation › 1-4 week symptoms › Traveller’s diarrhea and local outbreaks › Present in water systems and spring water  Cysts are resistant to water purification chemicals, removed by filtration

25  Cryptodporidium parvum › Gastroenteritis symptoms › Parasite of the intestinal epithelium › More resistant to chemical treatment and filtration than Giardia › Infects both human and animal populations › Person to person spread is possible

26  Cyclospora cyetanensis › Spore forming protozoan › Gastroenteritis symptoms begin at about 1 week and last 3-4 days, relapse common up to 4 weeks. › No person to person spread, no animal sources identified

27  Entamoeba histolytica › Sarcodina species with cyst form that survives stomach acid › Some strains produce cytotoxin that allows entry into deeper tissue or blood  Symptoms are generally mild but can be chronic › Amebic dysentery


Download ppt " Esophagus and stomach are relatively bacteria free  Mouth > Different Streptococci in different micro environments > Teeth colonized by bacteria."

Similar presentations


Ads by Google