ODESSA NATIONAL MEDICAL UNIVERSITY
Microbiology, virology and immunology department
MEDICAL FACULTY
MODULE 2. SPECIAL MICROBIOLOGY
LECTURE №18
PATHOGENIC ENTEROBACTERIA.
ESCHERICHIA. SHIGELLA.
Odessa-2013
MECHANISM OF INTERACTION BETWEEN CAUSATIVE AGENTS
OF ACUTE ENTERIC INFECTIONS WITH INTESTINAL EPITHELIUM
Тype of
interaction
Causative
agent
1 type
EТEC
2 type
3 type
4 type
Mechanism of pathogenic action
Multiplication on the surface of intestine
without damage of intestinal epithelium
Multiplication on the epithelium of intestine
EPEC EHEC and colon with destruction of microvilli, damage
of apical surface of epithelium
EIEC
Shigella
Penetration and multiplication in epithelial cells
of colon mucous membrane, cytotoxic injury
and d estruction of epitheliocytes
Transcytosis of intestinal epithelium through
Salmonella the М-cells with infection of Payer’s patches
Yersinia
with subsequent multiplication in the
macrophages
CLINICAL AND EPIDEMIOLOGICAL
CLASSIFICATION OF E.COLI
E. coli.
Gram stain
Colonies of lactose positive and
lactose negative bacteria
Antigenic structure of Еscherichia coli
Nutrient media
1.Endo medium: MPA,
lactose, fuchsine,
decolorized by sodium
sulfite
2. Ploskirev medium
MPA, bile salts, brilliant
green, iodine, sodium
thiosulfate, lactose, neutral
red
3. McConkey agar
4. Bismuth-sulfite agar
5. Bile broth
6. Selenite broth
BASIC GROUPS OF DIARRHEAL E.COLI
PATHOGENIC GROUPS
SEROGROUPS
Entheropathogenic E.coli
(EPEC)
O26, O55, O86, O111, O114, O119,
O125, O126, O127, O128, O142
Entherotoxigenic E.coli
(EТEC)
O6, O8, O15, O25, O27, O63, O78,
O115, O148, O153, O159, O167
Entheroinvasive E.coli (EIEC)
O28, O112, O124, O136, O143, O144,
O152, O164
Entherohemorrhagic E.coli
(EHEC)
О26, О55, О111, О113, О117, О145,
O157
Entheroadhesive E.coli
(EAEC)
О3, О15, О44, О77, О86, О111, О127
DISEASES, CAUSED BY DIARRHEAL E. coli
Agent
ETEC with cholera like
toxin. Small intestine is
affected
Virulence factor
Disease
Pili, thermolabile (analog of cholera
toxin) and thermostable toxins; factors Cholera like diarrhea
of adhesion and colonization (CF) of E. in adults and children
coli
ACTION OF THERMOLABILE TOXIN (LT)
OF E. coli
THERMOSTABLE TOXIN(ST)
Activates guanylate cyclase,
Accumalation of cGMP
(guanylatemono
phosphate), loss of ions and
water
DISEASES, CAUSED BY DIARRHEAL E. coli
Agent
EIEC with predominance of
invasion factors and
subsequent destruction of
intestinal epithelium
Virulence factor
Surface proteins, coded by
plasmid, and determine
penetration and destruction of
intestinal epithelium
Protein adhesine of external
EPEC with destruction of
membrane, coded by plasmid,
microvilli, damage of apical
protein of external
surface of intestinal epithelium and
membrane - intimine, coded by
chromosomal gene
Pilli, Shiga like toxin (SLT, Vero
EHEC,for example, Е. coli
destroying endothelium
0157:Н7, with predominance of toxin)
of small vessels, protein of
hemorrhagic factor,causing
membrane - intimine,
hemolytic-uraemic syndrome. external
coded by chromosomal gene
Colon and capillaries are
and hemolysine, coded by
damaged.
plasmid 0157
EAEC with persistance, causing
dehydratation od children.
Plasmid coded aggregation,
Adhesion on Hep-2 cell line.
prevent adsorption of water
Damage of intestine.
Disease
Dysentery-like
disease (stool with
blood)
Diarrhea in children
of 1-st year
Hemorrhagic colitis
(diarrhea with
blood); hemolyticuraemic syndrome
Diarrhea in children
PENETRATION OF SHIGELLA (and EIEC) INTO INTESTINE
Pay attention on «roughing» of М-cell membrane and surround
bacterial cell. Penetration of salmonella passes by the same way.
SHIGELLA
M-CELL
PATHOGENESIS of infection by E.coli O157: H7
Enterohemorrhagic E.coli 0157: H7(violet) attach to the intestinal
epithelium, destroy microvilli and form pedestal (yellow), which can
favorite spreading of shigella on adjacent cells.
Pure culture of
Shigella flexneri
CLASSIFICATION OF SHIGELLA ON
ANTIGENIC STRUCTURE
Sero
types
Lactose
Mannitol
1 -15
–
–
B – Shigella
flexneri
1-9
–
+
C – Shigella
boydii
1-19
–
+
D – Shigella
sonnei
1
(+)
late
+
GROUP
А – Shigella
dysenteriae
Gram stain
Immunofluorescence
M cells.
Present in Payer’s patches of intestine,
provide transport of antigens from
intestinal tract for contact with the
cells of immune system
M-cells of payer plaque. Pay attention on microvilli of
surrounding epithelial cells
Pathogenesis of Shigellosis. This sequence shows the sequence
of infection of the intestinal wall. The bacterium attaches to an
M cell of the epithelial wall located over a Peyer’s patch. This is a
region
adapted to facilitate transfer of antigens across the intestinal
mucosa
M-cells assures contact between antigens from intestine
and cells of immune system
VIRULENCE FACTORS OF Shigella
Factors
Biological effect
IраBDEinvasines
Ipa (invasion plasmide апtigen) –
invasines — proteins of external
membrane of bacteria, which attach
to apical membrane of M-cells; cause
apoptosis of epitheliocytes, lysis of
cellular membranes, favorite to intra
and intercellular spreading of Shigella
Proteinic
exotoxin
(Shiga toxin)
Cause damage of epithelium, injury of
kidney with development of
hemolytic-uraemic syndrome, injury
of CNS and methabolic processes
Endotoxin
General intoxication, increasing of
intestinal peristalsis
SCHEME OF BACTERIOLOGICAL EXAMINATION IN ESCHEROCHIOSIS
AND SHIGELLOSIS
1 stage
Sampling and inoculation of
material on selective and
differential media
Endo medium
Coloured colonies
FECES
Ploskirev media
Colourless colonies
2 stage
Choose of suspicious colony and Agglutination with material
Agglutination with
subinoculation on Ressel’s from 10 colonies and mixture
material from colonies
medium
of ОК-serums
and mixture of
CONCLUSION antiShigella serums
3 stage
Examination of isolated
culture for identification
1.
2.
3.
4.
5.
Smear, Gram staining
Subinoculation on Hiss media
AT on the glass with mixture of antiserums
AT with type specific antiserums
Sensitivity to antibiotics
4 stage
Registration of properties. Identification
of isolated culture
FINAL CONCLUSION