Download Microbial Gastrointestinal Diseases: Pathogens and Associated Syndromes and more Quizzes Microbiology in PDF only on Docsity!
Microbial Gastrointestinal Diseases
Enteric pathogen Dysentery Diarrhea TERM 2
Enteric pathogen
DEFINITION 2 an organism that causes disease in the GI tract Gastritis - inflammation of the stomach Enteritis - inflammation of the small intestines Colitis - inflammation of the large intestines TERM 3
Dysentery
DEFINITION 3 disorder marked by inflammation of the intestines, especially the colon, accompanied by abdominal pain w/ difficult & frequent stools containing blood and mucus TERM 4
Acute infectious diarrhea -Inflammatory
DEFINITION 4 Location - Large intestineWBC's in Feces - YesBlood in Feces
- YesVolume of Feces - smallConsistency - MucoidPathogens - Shigella Salmonella Campylobacter jejuni E. Coli (EHEC / STEC) TERM 5
Acute infectious diarrhea -non-Inflammatory
DEFINITION 5 Location - Small IntestineWBC's in Feces - noBlood in Feces - noVolume of Feces - largeConsistency - wateryPathogens - Virio cholerae E. Coli (ETEC) Viruses (Rotavirus , Norovirus)
Shigella - Identification
facultative Gram-negative rods non-lactose fermenters H2S & urea negative non-motile shigellosis - bacillary dysentery TERM 7
Shigella -Epidemiology
DEFINITION 7 exclusively human pathogen no animal reservoirtransmitted by fecal-oral routelow infectious dose (as few as 10- bacteria) direct contact contaminated foods & water~ 50% of infections in children < 10 years-old day care centers mental institutions TERM 8
Shigellosis bacillary dysentery
DEFINITION 8 onset ~12 - 50 hours abdominal pain, diarrhea, fever, vomiting blood, pus, or mucus in stoolsexclusively enteric pathogen invade & multiply in intestinal mucosal epithelial cells does not cause septicemiausually self-resolving but fatality as high as 15% with some strains no chronic or carrier state prevention - public health & personal hygiene TERM 9
Salmonella -Identification
DEFINITION 9 Salmonella enterica (1 species - > 2,500 serotypes) facultative Gram-negative rods non-lactose fermenters H2S positive urea negative motileenterocolitis (dysentery)septicemia w/ metastatic abscessestyphoid (enteric) fever TERM 10
Salmonella -3 major serotypes based on O
and H antigens
DEFINITION 10 Salmonella Enteritidis (most frequent cause of infections) primarily causes enterocolitis Salmonella Choleraesuis (swine ) enterocolitis w/ more frequent septicemia osteomyelitis Salmonella Typhi typhoid (enteric fever)
Campylobacter jejuni -Epidemiology -
R/T/D
reservoir poultry, wild birds, other animals transmission (not usually human to human) ingestion of contaminated foods & beverages present on 47% of raw chicken breasts tested in 2005 cross-contamination during food preparation unpasteurized milk & contaminated water diagnosis stool culture TERM 17
Campylobacter jejuni -
Complications
DEFINITION 17 Guillain-Barr syndrome autoimmune disease attacks peripheral nerves paralysis that lasts several weeks & usually requires intensive care~ 40% of Guillain-Barr syndrome cases in USA may be triggered by campylobacteriosis Treatment & Prevention (gastrointestinal infections) most infected individuals recover w/o specific treatment antimicrobials can shorten duration if given early TERM 18
Shiga toxin-producing E.coli (STEC)
DEFINITION 18 formerly enterohemorraghic E. coli: EHEC strains of E. coli that produce specific exotoxins shiga toxin & verotoxin (E. coli O157:H7 & others) TERM 19
STEC - Escherichia coli O157:H7 -
Epidemiology -R/T
DEFINITION 19 reservoir animals (healthy cattle, pigs,) & infected humans transmission ingestion contaminated foods & water direct fecal-oral low infectious dose (similar to Shigella)Consumers should only eat ground beef patties that have been cooked to a safe temperature of 160 F. TERM 20
Complications of STEC Infection
DEFINITION 20 hemmorrhagic colitis severe abdominal cramping/pain watery bloody diarrhea usually self-limited infectionhemolytic uremic syndrome (HUS) serious complication / post-diarrheal ~ 5-10 % of persons infected with E. coli O157:H7 majority of cases occur in children aged <5 years hemolytic anemia, thrombocytopenia, renal failuredamaged RBCs clog filtering system of kidneys
Non-inflammatory syndrome pathogens
Viruses very common cause Rotavirus & Norovirus Bacteria Vibrio cholerae Escherichia coli (enterotoxigenic E. coli: ETEC) gastroenteritis (travelers diarrhea) Bacillus cereus , Clostridium perfringens , Staph. aureus TERM 22
Vibrio cholerae -identification and
epidemiology -R/T
DEFINITION 22 Gram-negative curved rod motile Reservoir humans (asymptomatic & symptomatic) infection is often mild or without symptoms ~ 5% of infected persons severe disease Transmission contaminated water (developing world) contaminated shellfish/seafood (developed world) no invasion of bloodstream TERM 23
Cholera / epidemic & pandemic
disease
DEFINITION 23 vomitingsevere watery diarrhea (rice water stools)leg crampsdehydrationcardiac & renal failuredeath can occur within hours40% mortality w/o treatment TERM 24
Exotoxin-mediated disease Cholera toxin
DEFINITION 24 cholera toxin - ADP-ribosylation of adenylate cyclase increased intracellular adenylate cyclase causes efflux of Cl- and secretion of H2O & electrolytes into the intestinal lumen rapid fluid loss from the intestine, up to 2 liters per hour TERM 25
Binding and Entry of an A-B Toxins (cholera
toxin & several others)
DEFINITION 25 A (active) component & B (binding) component.B component binds to a receptor on host cell surfaceexotoxin enters the host cell by endocytosis, and causes harm by inactivating a host cell target protein through ADP-ribosylation
