Gastroenteritis Inflammation of stomach or intestines Inhibits nutrient absorption and excessive H2O and electrolyte loss Bacterial Viral Parasites Poisoning by microbial toxins food borne intoxication Signs and Symptoms General features diarrhea loss of appetite abdominal cramps nausea vomiting and possibly fever Dysentery Typically self Limiting Enteric fevers Systemic with severe headache high fever abscesses intestinal rupture shock and death Epidemiology Occurs worldwide Oral to fecal route of transmission Water common reservoir Overcrowding poor sanitation are risk factors Animals may be source of infection Prevention Hand washing Proper food handling and complete cooking Pasteurization of milk and juices Adequate sanitation Safe water supplies Treatment Rapid replacement of fluids and electrolytes Anti nausea medication Antimicrobials may be used in severe cases Bacterial Gastroenteritis 3 groups of gram negative bacteria account for most bacterial intestinal infections Vibrio cholerae Cholera Enterics Salmonella Shigella E coli Campylobacter jejuni Cholera Causative agent Vibrio cholerae High infectious dose Bacteria sensitive to stomach acid Adheres to small intestine and multiply Bacteria don t enter cells Cholera toxin Potent exotoxin Causes intestinal cells to rapidly pump out electrolytes Passive osmotic H2O loss follows Metabolic acidosis Shock Heavy loss of fluid rice water stool Up to 20L of fluids lost per day May discharge 1 million bacteria per ml of feces Untreated cases potentially fatal Fluid electrolyte replacement Tetracycline reduces toxin production Shigellosis Causative Agent Shigella sp S dysenteriae S flexneri S boydii S sonnei Low infecting dose Bacteria not sensitive to stomach acid Characterized by fever and dysentery Infects cells of large intestine and initiates intense inflammatory response Dead cells slough off Produces areas covered with pus and blood All species produce enterotoxin and type III secretion systems S dysenteriae produces powerful endotoxin shiga toxin Ciprofloxacin rifampin or azithromycin may reduce duration and infectivity Traveler s Diarrhea Causative Agent Escherichia coli Multiple antigenic strains O H K Virulent strains have fimbriae adhesions and multiple toxins Enterotoxigenic E coli Enterotoxins Type III secretion system Typically self limiting Enterohemorrhagic E coli O157 H7 Produce potent Shiga like toxins and type III secretion systems Antimicrobials cause increase in toxin production Salmonellosis and Typhoid Fever Causative agent Salmonella enterica 2000 strains serotypes Typhimurium and Enteritidis commonly cause Salmonellosis Typhi and Paratyphi cause Typhoid Fever Common intestinal flora of many animals Contaminated animal products are reservoir Reptiles eggs and undercooked poultry Virulent strains tolerate stomach acid and pass to intestines Toxin induces phagocytosis in intestinal cells Pathogen reproduces inside phagosome killing host cell Bacteria Typhi may pass through intestinal cells into bloodstream Typhoid fever is an enteric fever Macrophages carry bacteria to liver spleen bone marrow and gallbladder Treated with ciprofloxacin or ampicillin Surgical removal of gallbladder Campylobacteriosis Causative agent Campylobacter jejuni Leading cause of bacterial diarrhea in United States Estimated 1million cases annually with 100 deaths Associated with poultry Low infecting dose Virulent strains possess adhesions cytotoxins and endotoxin Induce endocytosis in cells of intestine and initiate inflammation and bleeding lesions Non motile mutants are avirulent Severe cases treated with ciprofloxacin or azithromycin Guillain Barr Syndrome Tingling of the feet leads to progressive paralysis of the legs arms and rest of the body 40 of cases preceded by campylobacteriosis May be associated with autoimmune response 80 recover completely 5 mortality with treatment Viral Gastroenteritis Common causative agents Rotaviruses and Noroviruses Both naked RNA viruses Star like Noroviruses Wheel like Rotaviruses Epidemology Infect intestinal cells causing cell death Typically self limiting Norovirus epidemics cause 90 of cases Rotaviruses responsible for 50 infant cases of serious diarrhea 600 000 worldwide annual fatalities Oral vaccine available Bacterial Food Intoxication Staphylococcus aureus Halotolerent grows well in foods at room temp Associated with cafeterias and social functions 5 heat stable enterotoxins 1000 for up to 30 min Stimulate muscle contractions nausea and intense vomiting diarrhea and cramping Acute and self limiting symptoms begin 4 6 hrs after consumption and end within 24 hrs Botulism Causative agent Clostridium botulinum Obligate anaerobic Gram spore forming bacillus Produce 7 different neurotoxins One of most deadly toxins known Signs Symptoms Dizziness dry mouth blurred vision Abdominal symptoms include pain nausea vomiting and diarrhea or constipation Progressive paralysis Paralysis of respiratory muscles most common cause of death 3 forms of botulism Food borne botulism progressive paralysis of all voluntary muscles due to toxin production Wound botulism similar symptoms Infant botulism bacteria grow in the intestines producing non specific symptoms floppy baby syndrome Epidemiology Food borne botulism Commercial sterilization Toxin destroyed by heating foods Wound botulism deep crushing wounds Infant botulism Inhalation or ingestion of spores Commonly associated with honey or juices Prevention Proper sterilization and sealing of canned food No honey or unpasteurized juices for infants Treatment Antitoxin Gastric washing and surgical removal of tissues Artificial respiration may be required Anti microbials given to kill bacteria in infant and wound botulism