A 10- year-old, previously healthy child came to the emergency room for the evaluation of bloody diarrhea and diffuse 弥漫性 abdominal pain for 24 hours’. His mother said him eaten an hamburger at a fast food restaurant beside the school yesterday. Your diagnosis are …you must find the child’s….
Enteric Bacilli associated with diseass
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Chapters 10 of zhengren zhou
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Chapters 10 of enjie luo
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Textbook Chapters 15-17
1. Similar shape
form circular, convex凸的, and smooth colonies with distinct edges.
contain lactose and two dyes (eosin and methylene blue亚甲蓝)
+: purple colonies with green metallic sheen金属光泽 E. coli
-: colorless pathogenic bacteria
differentiating pathogenic enteric bacilli from non-pathogenic strains.
Important serotypes can be differentiated by their:
However, serotyping is generally not performed in the
At some level, E. coli and Shigella are
Escherichia coli O157:H7
CDC/Peggy S. Hayes
Enterohemorrhagic E. coli (EHEC).
the number of coliform bacteria detected out per 1000 ml sample; the standard of drinking water is less than 3
All cause bacillary dysentery or shigellosis.
Shigellosis is bloody feces associated with
“pus” feces ： mucus and blood ,leukocytes into the bowel.
Neurotoxic, Enterotoxic and Cytotoxic
Enterotoxicity can make the disease clinically
appear as a diarrhea. The toxin inhibits protein synthesis (acting on the 60S ribosome and lysing 28S rRNA).
It can be transmittedby fecal-oral contact.
Food hands contaminating food.
Adults can catch this disease from children.
The source in each case is unwashed hands.
Man is the only "reservoir".
Only a few types that are commonly associated
with characteristic human diseases -
1. S. enteritidis
2. S. cholerae-suis
3. S. typhi
1. a human reservoir
2. in the water supply (if sanitary conditions
3. in contaminated food
-Vi antigens, anti-phagocytosis
c. Exotoxin: (some)
-enterotoxin, like ETEC’s.
The antigenic structures of salmonellae used in serologic typing
a. Enteric fever
b. Enteritis (or food poisoning)
penetrate across the mucosa
multiplication in phagocytes
the first bacteremia
multiplication in phagocytes of some organs
the second bacteremia
(carrier state) gall bladder high fever, leukopenia, low pulse
reinvasion of the gut mucosa
intestinal hemorrhage or perforation穿孔
S. paratyphi - paratyphoid fever
S. typhimurium, S. enteritidis and S. choleraesuis.
low fever, nausea, vomiting, diarrhea.
fever, chill, and some local infection.
a) Enteric fever: blood, bone marrow, stool, urine.
b) Food poisoning: stool, vomitus, suspected food.
c) Septicemia: blood.
A quantitative agglutination test forenteric fever, which detects a patient’s antibodies to the specific O antigen of S. typhi and H antigens of S. typhi, S. paratyphi A, S. schottmuelleri, and S. hirschfeldii.
Vi (capsular) antigen :protective
1. What are the common properties of the Enterobacteriaceae?
2. What are the medically important genera of the Enterobacteriaceae? What diseases are caused by them?
3. What is the importance of lactose fermentation in distinguishing between certain genera of the Enterobacteriaceae?
4. What are the 5 serotypes of E. coli causing diarrhea? What is the pathogenesis of them?
5. What are the medically important species of Salmonella? What diseases are caused by them?
6. What is the pathogenesis of typhoid?
7. what is the medical significance of Widal test? How to interpret the results of the test?
by Region, United States, 1974-1994 CDC