(Gram negative rods enteric tract) Enterobacteriaceae I (Gram negative rods enteric tract) Lecture 34 Faculty: Dr. Alvin Fox
Key Words Opportunistic diseases Shigella Diarrhea - Bacillary dysentery Dysentery - Shiga toxin Urinary tract infections Salmonella enteritidis Pili Salmonellosis Lactose positive/negative Salmonella cholerae-suis Enterohemorrhagic E. coli Salmonella typhi - Vero toxin (Shiga-like) - Typhoid - Hemolysin - Vi Enterotoxigenic E. coli Yersinia entercolitica - Heat stable toxin Vibrio cholerae - Heat labile toxin Choleragen (cholera toxin) Enteropathogenic E. coli Campylobacter jejuni Enteroaggregative E. coli Helicobacter pylori Enteroinvasive E. coli
Opportunistic diseases -Enterobacteriaceae septicemia, pneumonia, meningitis urinary tract infections Citrobacter Enterobacter Escherichia Hafnia Morganella Providencia Serratia
Enterobacteriaceae gastrointestinal diseases Escherichia coli Salmonella Shigella Yersinia entercolitica
Reiter's syndrome Histocompatibility antigen (HLA) B27 Enterobacteriaceae Salmonella Shigella Yersinia Non-Enterobacteriaceae Campylobacter Chlamydia
Enterobacteriaceae community acquired otherwise healthy people Klebsiella pneumoniae respiratory diseases prominent capsule urinary tract infection fecal contamination E. coli Proteus urease (degrades urea) alkaline urine
E. coli fimbriae Type 1 mannose P galactose glycolipids glycoproteins
Enterobacteriaceae gram negative facultative anaerobic rods – oxidase negative (no cytochrome oxidase)
Feces E. coli lactose positive not usually identified lactose positive sp. common, healthy intestine Shigella, Salmonella,Yersinia lactose negative identified
Enterobacteriaceae other sites identified biochemically
Serotypes reference laboratory antigens O (lipopolysaccharide) H (flagellar) K (capsular)
Diarrhea (watery feces) and Dysentery (blood in stools)
Caption: E. coli Escherichia coli
Escherichia coli E. coli and Shigella genetically very similar separated for historical reasons overlap in pathogenesis
Enterohemorrhagic E. coli Usually O157:H7 Transmission electron micrograph Flagella
Transmission – meat products or sewage-contaminated vegetables Hemorrhagic Bloody dysentery copious diarrhea few leukocytes afebrile hemolytic-uremic syndrome hemolytic anemia thrombocytopenia (low platelets) kidney failure
Enterohemorrhagic E. coli Vero toxin “shiga-like toxin” Hemolysins
Enterotoxigenic E. coli diarrhea like cholera milder travellers diarrhea
Enterotoxigenic E. coli Heat labile toxin like choleragen Adenyl cyclase activated cyclic AMP secretion water/ions Heat stable toxin Guanylate cyclase activated cyclic GMP uptake water/ions
Enteropathogenic E. coli destruction of surface microvilli fever diarrhea vomiting nausea non-bloody stools (not generally seen as dysentery) Gut lumen
Enteroaggregative Mucus biofilm inhibits fluid absorption Diarrhea Brick-like bacterial aggregates - cell surfaces Mucus biofilm inhibits fluid absorption Diarrhea
Enteroinvasive E. coli (EIEC ) Dysentery - resembles shigellosis Gut lumen
Treatment -gastrointestinal disease fluid replacement antibiotics not used usually unless systemic e.g. hemolytic-uremia syndrome
Shigella Modified from Fig, Dennis Kunkel
Shigella S. flexneri, S. boydii, S. sonnei, S. dysenteriae bacillary dysentery shigellosis bloody feces intestinal pain pus
Shigellosis within 2-3 days epithelial cell damage Gut lumen
Shiga toxin enterotoxic cytotoxic inhibits protein synthesis lysing 28S rRNA
Shigellosis man only "reservoir" mostly young children fecal to oral contact children to adults transmitted by adult food handlers unwashed hands
Treating shigellosis manage dehydration patients respond to antibiotics disease duration diminished
Salmonella [417] Caption: Salmonella typhi - Gram-negative, enteric, rod prokaryote (dividing); causes typhoid fever. Magnification*: x5,530 Type: SEM Keywords: 96430B.TIF bacilli bacillus bacteria bacterial pathogen bacterium division Gram-negative human disease infection prokaryote rod Salmonella typhi typhoid fever enteric bacterial pathogen intestinal tract infection SEM |
Salmonella 2000 antigenic "types” genetically single species S. enterica disease category S. enteritidis many serotypes S. cholerae-suis S. typhi
Salmonellosis S. enteritidis the common salmonella infection poultry, eggs no human reservoir Gastroenteritis nausea vomiting non-bloody stool self-limiting (2 - 5 days)
Control of salmonellosis Monitoring of food in the US is limited microbiology is difficult Regulation is not optimal Chickens are not vaccinated in US UK, salmonellosis largely erradicated
Salmonellosis uncomplicated cases (the vast majority) Gut lumen uncomplicated cases (the vast majority) antibiotic therapy not useful
S. cholerae-suis much less common septicemia antibiotic therapy essential