1. ENTEROBACTERIACEAE
Prof. Khalifa Sifaw Ghenghesh

2. •
•
•
•
Gram-negative rods
Facultative anaerobes
Oxidase-negative
Most members are motile

3. • Gastrointestinal diseases
(Diarrhoea and Dysentery)
–
–
–
–
Escherichia coli (Lac+)
Salmonella (Lac-)
Shigella (Lac-)
Yersinia entercolitica (Lac-)

4. Salmonella
E. coli

5. • Opportunistic diseases
–
–
–
–
•
•
•
•
•
•
•
•
•
septicemia,
pneumonia,
meningitis
urinary tract infections
Citrobacter
Enterobacter
Escherichia
Hafnia
Klebsiella
Morganella
Proteus
Providencia
Serratia

7. IDENTIFICATION
• In Stool:
– E. coli
• lactose positive
• not usually identified
• Common in healthy intestine
– Shigella, Salmonella,Yersinia
• lactose negative
• identified
• Other sites:
– identified biochemically

8. SEROTYPING
• Reference laboratory:
– antigens
• O (lipopolysaccharide)
• H (flagellar)
• K (capsular)

9. Escherichia coli

10. • Enteropathogenic E. coli (EPEC):
– Adhere to surface of mucosal cells inducing dramatic alteration on
microvilli and the rearrangement of the host cell actin cytoskeleton.
– Adhesion is medicated by two genes:
• A Plasmid-encoded gene (bfpA), responsible for the formation
of the bundle forming pilus.
• A chromosomal-mediated gene (eae) coding for the adhesion
intimin.
•
•
•
•
•
fever
diarrhea
vomiting
nausea
non-bloody stools

11. • Enterotoxigenic E. coli (ETEC):
– Cholera-like diarrhoea
– milder
– Travellers diarrhoea
• Heat labile toxin (LT)
–
–
–
–
like choleragen (Cholera toxin)
activate enterocyte adenyl cyclase
cyclic AMP
chloride and water secretion >>Diarrhea
• Heat stable toxin (ST)
– activate enterocyte guanylate cyclase
– cyclic GMP
– Chloride and water secretion >> Diarrhea

12. • Enteroinvasive E. coli (EIEC):
– Dysentery
– resembles shigellosis

13. • Enterohemorrhagic E. coli (EHEC):
– Usually O157:H7
– Meat
• Hemorrhagic
– bloody, copious diarrhea
– few leukocytes
– afebrile
• Hemolytic-uremic syndrome
– hemolytic anemia
– thrombocytopenia (low platelets)
– kidney failure
• Vero toxin (Shiga-like):
– 2 toxins: SLTI and SLTII (coded by sxt1 and sxt2)

14. TREATMENT
• Gastrointestinal disease:
– Fluid replacement
– Antibiotics
• not used usually unless systemic
–e.g. hemolytic-uremia syndrome
• UTIs:
– Antibiotic Sensitivity Is Necessary.

15. Resistance of Escherichia coli isolated from
urinary tract infections in Benghazi to antibiotics.
------------------------------------------------------------------------------------Hospital
Community
Antibiotic
acquired
acquired
(n=62)
(n=148)
------------------------------------------------------------------------------------Ampicillin
52(84)*
111(75)
Carbenicillin
53(85)
117(79)
Cephaloridine
22(35)
53(36)
Chloramphenicol
37(60)
67(45)
Gentamicin
19(31)
27(18)
Nalidixic acid
3(5)
15(10)
Nitrofurantoin
4(6)
10(7)
Tetracycline
45(73)
121(82)
Trimethoprim
52(84)
120(81)
sulphamethoxazole
*(%)
-------------------------------------------------------------------------------------

16. Shigella

17. • Bacillary Dysentery
• Shigellosis
– bloody faeces
– intestinal pain
– pus
•
•
•
•
•
4 Major O Antigenic Groups:
Serogroup A = Sh. dysenteriae
Serogroup B = Sh. flexneri
Serogroup C = Sh. boydii
Serogroup D = Sh. sonnei
• No H-Antigens.

18. Shiga Toxin
• enterotoxic
• cytotoxic
• inhibits protein synthesis
– lysing 28S rRNA

19. • The Organism Survive
the Passage Through the GIT.
>> Due to O Antigen
• Attach to Colonic Cells.
• Penetrate the Epithelial
Cells.
• Multiply Inside
• Pass to Another Cell.
>>
>>
"Invasiveness"
"Inflamation, Cell Death,
Ulceration, Impaired
Colonic Fluid Absorbtion
and a Discharge of
Blood, Mucus and Pus"

20. • Man only "reservoir"
• Mostly young children
– fecal to oral contact
– children to adults
• Transmitted by adult food handlers
– unwashed hands

21. Treating Shigellosis
• Manage dehydration
• Patients respond to antibiotics
– disease duration diminished

22. CONTROL
– Adequate Sanitization.
– Detection and Treatment of Carriers.
– Carriers Should Not Be Allowed to Handle
Food.
– Proper Sewage Disposal and Chlorination
of Water.
– FLIES >>>>>>>>>>>>>>>>

23. Information about Libyan children with diarrhea
and their Shigella isolates
Patient Sex
Age
(Mo)
Month of Length of Episode Species and
occurrence diarrhea
per day
serotype of
(days)
Shigella
-------------------------------------------------------------------------------------------------------1.
F
11
Sep
1
5
S. sonnei
2.
F
30
Sep
2
3
S. flexneri type2
3.
M
27
Oct
1
6
S. sonnei
4.
F
18
Oct
1
8
S. flexneri type2
5.
F
36
Oct
2
5-7
S. flexneri type2
6.
M
7
Dec
7
7-8
S. flexneri type1
7.
M
7
Apr
1
10
S. flexneri type2
8.
M
13
Jun
10
6-7 S. flexneri type3
9.
M
32
Jul
1
4
S. sonnei

24. Information about Libyan children with diarrhea
and their Shigella isolates
Patient
Faeces with
Mucus
Blood
Presence of
Fever
Vomiting
Species and
serotype of
Shigella
--------------------------------------------------------------------------------------------------------------------1.
+
+
--S. sonnei
2.
----S. flexneri type2
3.
--+
-S. sonnei
4.
----S. flexneri type2
5.
+
+
+
-S. flexneri type2
6.
--+
-S. flexneri type1
7.
+
+
+
+
S. flexneri type2
8.
+
+
+
+
S. flexneri type3
9.
+
+
+
+
S. sonnei

25. Salmonella

26. • More than 2000 antigenic types
(Serotypes).
– Salmonella Typhi
– Salm. Enteritidis
– Salm. Cholera-suis
– Salm. Typhimurium
• Genetically single species
– Salmonella enterica
• Salm. enterica serotype Typhi
ANTIGENIC STRUCTURE:
– O & H Antigens >>> Serotyping.
– Vi-Antigen (protective) >>> Salm. Typhi.

27. CLINICAL INFECTION AND PATHOGENSIS
1. S. Typhi, S. Paratyphi A and B:
– Gastroenteritis, bacteremia and typhoid fever.
– Typhoid Fever (Enteric fever):
•
Fever, headache, diarrhoea, and abdominal pain.
– Human Carriers Are the Only Source of
Infection.
– Transmission:
• contaminated food
• water supply
• poor sanitary conditions
– Mortality Rate:
– Relapse:

28. 2. S. Enteritidis, S. Typhimurium, etc..
– Salmonellosis:
• Self-limiting gastroenteritis with fever for <2 days
and diarrhoea < 7 days.
– Source:
• poultry, eggs
• no human reservoir
– Transmission:
– Pets:

29. • TREARMENT:
– Supportive Therapy and Maintaining Fluid and
Electrolyte Balance.
– Enteric Fever or Septicaemia:
• Antibiotics
– essential
– Carriers of Salm. typhi:
• CONTROL:
– Carriers:
– Food Cooked Properly
– Water Standards Be Observed.

30. Salmonella Serotypes Isolated from Diarrhoeic
Faeces in Tripoli (1975-1980)
– S. Wien
– S. Muenchen
– S. Typhimurium
Salmonella Serotypes Isolated from Children with
Diarrhoea in Tripoli (1992-1993)
– S. Saintpaul
– S. Muenchen
Salmonella Serotypes Isolated from Children with
Diarrhoea in Zliten (2000-2001)
– S. Heidelberg
– S. Enteritidis

31. Reistance of Salmonella species isolated from children
with diarrhoea in Zliten (2000-2001) to antibiotics
________________________________________________
Antibiotic
No. (%) resistant:
(n=23)
--------------------------------------------------------------------------------Ampicillin
23 (100)
Amoxicillin+calvulanic acid
22 (95.7)
Cefoxitin
20 (87)
Gentamicin
18 (78.3)
Doxycycline
21 (91.3)
Chloramphenicol
22 (95.7)
Nalidixic acid
1 (4.3)
Norfloxacin
0 (0.0)
Trimethoprim-sulphamehtoxazole
1 (4.3)
________________________________________________

32. • Department e-mail = dmi.ly
• Khalifa Sifaw Ghenghesh e-mail =
ghenghesh_micro@yahoo.com