Enterobacteriaceae I Gram negative rods enteric tract Lecture

Enterobacteriaceae I (Gram negative rods enteric tract) Lecture 34 Faculty: Dr. Alvin Fox 1

Key Words Opportunistic diseases Diarrhea Dysentery Urinary tract infections Pili Lactose positive/negative Enterohemorrhagic E. coli - Vero toxin (Shiga-like) - Hemolysin Enterotoxigenic E. coli - Heat stable toxin - Heat labile toxin Enteropathogenic E. coli Enteroaggregative E. coli Enteroinvasive E. coli Shigella - Bacillary dysentery - Shiga toxin Salmonella enteritidis Salmonellosis Salmonella cholerae-suis Salmonella typhi - Typhoid - Vi Yersinia entercolitica Vibrio cholerae Choleragen (cholera toxin) Campylobacter jejuni Helicobacter pylori 2

Opportunistic diseases -Enterobacteriaceae – – septicemia, pneumonia, meningitis urinary tract infections Citrobacter Enterobacter Escherichia Hafnia Morganella Providencia Serratia 3

Enterobacteriaceae • gastrointestinal diseases – Escherichia coli – Salmonella – Shigella – Yersinia entercolitica 4

Reiter's syndrome • Histocompatibility antigen (HLA) B 27 – Enterobacteriaceae *Salmonella *Shigella *Yersinia – Non-Enterobacteriaceae *Campylobacter *Chlamydia 5

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 6

E. coli fimbriae Type 1 mannose P galactose – glycolipids – glycoproteins 7

Enterobacteriaceae • gram negative facultative anaerobic rods – oxidase negative (no cytochrome oxidase) 8

Feces • E. coli – lactose positive – not usually identified – lactose positive sp. common, healthy intestine • Shigella, Salmonella, Yersinia – lactose negative – identified 9

Enterobacteriaceae • other sites – identified biochemically 10

Serotypes • reference laboratory – antigens • O (lipopolysaccharide) • H (flagellar) • K (capsular) 11

Diarrhea (watery feces) and Dysentery (blood in stools) 12

Caption: E. coli 13

Escherichia coli • E. coli and Shigella – genetically very similar – separated for historical reasons – overlap in pathogenesis 14

Enterohemorrhagic E. coli • Usually O 157: H 7 Flagella Transmission electron micrograph 15

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 16

Enterohemorrhagic E. coli • Vero toxin – “shiga-like toxin” • Hemolysins 17

Enterotoxigenic E. coli • diarrhea like cholera • milder • travellers diarrhea 18

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 19

Enteropathogenic E. coli destruction of surface microvilli • fever Gut lumen • diarrhea • vomiting • nausea • non-bloody stools (not generally seen as dysentery) 20

Enteroaggregative • Brick-like bacterial aggregates - cell surfaces • Mucus biofilm inhibits fluid absorption • Diarrhea 21

Enteroinvasive E. coli (EIEC ) • Dysentery - resembles shigellosis Gut lumen 22

Treatment -gastrointestinal disease • fluid replacement • antibiotics – not used usually unless systemic – e. g. hemolytic-uremia syndrome 23

Shigella Modified from Fig, Dennis Kunkel 24

Shigella • S. flexneri, S. boydii, S. sonnei, S. dysenteriae – bacillary dysentery – shigellosis • bloody feces • intestinal pain • pus 25

Shigellosis • within 2 -3 days – epithelial cell damage Gut lumen 26

Shiga toxin • enterotoxic • cytotoxic • inhibits protein synthesis – lysing 28 S r. RNA 27

Shigellosis • man only "reservoir" • mostly young children – fecal to oral contact – children to adults • transmitted by adult food handlers – unwashed hands 28

Treating shigellosis • manage dehydration • patients respond to antibiotics – disease duration diminished 29

Salmonella [417 ] Caption: Salmonella typhi - Gram-negative, enteric, rod prokaryote (dividing); causes typhoid fever. Magnification*: x 5, 530 Type: SEM Keywords: 96430 B. TIF bacilli bacillus bacterial pathogen bacterium division Gram-negative human disease infection prokaryote rod Salmonella typhi typhoid fever enteric bacterial pathogen intestinal tract infection SEM | 30

Salmonella • 2000 antigenic "types” • genetically single species – S. enterica • disease category – S. enteritidis – many serotypes – S. cholerae-suis – S. typhi 31

Salmonellosis • S. enteritidis – the common salmonella infection – poultry, eggs – no human reservoir – Gastroenteritis • • nausea vomiting non-bloody stool self-limiting (2 - 5 days) 32

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 33

Salmonellosis Gut lumen uncomplicated cases (the vast majority) antibiotic therapy not useful 34

S. cholerae-suis • much less common • septicemia • antibiotic therapy essential 35