ENTEROBACTERIACEAE

Prof. Khalifa Sifaw Ghenghesh

• Gram-negative rods

• Facultative anaerobes

• Oxidase-negative

• Most members are motile

• Gastrointestinal diseases(Diarrhoea and Dysentery)

– Escherichia coli (Lac+)– Salmonella (Lac-)– Shigella (Lac-)– Yersinia entercolitica (Lac-)

Salmonella E. coli

• Opportunistic diseases– septicemia, – pneumonia, – meningitis– urinary tract infections

• Citrobacter• Enterobacter• Escherichia• Hafnia• Klebsiella• Morganella• Proteus• Providencia• Serratia

IDENTIFICATIONIDENTIFICATION

• In Stool:– E. coli

• lactose positive • not usually identified• Common in healthy intestine

– Shigella, Salmonella,Yersinia• lactose negative• identified

• Other sites:Other sites:– identified biochemicallyidentified biochemically

SEROTYPINGSEROTYPING

• Reference laboratory:– antigens

• O (lipopolysaccharide) • H (flagellar) • K (capsular)

Escherichia coliEscherichia coli

• 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

• 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

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

• 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)

TREATMENTTREATMENT

• Gastrointestinal disease:Gastrointestinal disease:– Fluid replacement– Antibiotics

• not used usually unless systemic

–e.g. hemolytic-uremia syndrome

• UTIs:– Antibiotic Sensitivity Is Necessary.

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 *(%)

-------------------------------------------------------------------------------------

ShigellaShigella

• 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.

Shiga Toxin

• enterotoxic

• cytotoxic

• inhibits protein synthesis– lysing 28S rRNA

• The Organism Survivethe Passage Through the GIT. >> Due to O Antigen

• Attach to Colonic Cells.

• Penetrate the Epithelial Cells. >> "Invasiveness"

"Inflamation, Cell Death, Ulceration, Impaired

• Multiply Inside >> Colonic Fluid Absorbtion and a Discharge of

Blood, Mucus and Pus"

• Pass to Another Cell.

• 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

CONTROL

– Adequate Sanitization.– Detection and Treatment of Carriers.– Carriers Should Not Be Allowed to Handle

Food.– Proper Sewage Disposal and Chlorination

of Water.– FLIES >>>>>>>>>>>>>>>>

Information about Libyan children with diarrhea and their Shigella isolates

Patient Sex Age Month of Length of Episode Species and (Mo) occurrence diarrhea per day serotype of

(days) Shigella--------------------------------------------------------------------------------------------------------1. F 11 Sep 1 5 S. sonnei2. F 30 Sep 2 3 S. flexneri type2

3. M 27 Oct 1 6 S. sonnei4. 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

Information about Libyan children with diarrhea and their Shigella isolates

Faeces with Presence ofPatient Mucus Blood Fever Vomiting Species and

serotype ofShigella

---------------------------------------------------------------------------------------------------------------------1. + + -- -- S. sonnei2. -- -- -- -- S. flexneri type23. -- -- + -- S. sonnei4. -- -- -- -- S. flexneri type25. + + + -- S. flexneri type26. -- -- + -- S. flexneri type17. + + + + S. flexneri type28. + + + + S. flexneri type39. + + + + S. sonnei

SalmonellaSalmonella

• More than 2000 antigenic types More than 2000 antigenic types (Serotypes).(Serotypes).– Salmonella Typhi– Salm. Enteritidis– Salm. Cholera-suis– Salm. Typhimurium

• Genetically single speciesGenetically single species– Salmonella enterica

• Salm. enterica serotype TyphiANTIGENIC STRUCTURE:

– O & H Antigens >>> Serotyping.– Vi-Antigen (protective) >>> Salm. Typhi.

CLINICAL INFECTION AND PATHOGENSISCLINICAL 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:

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:

• 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.

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

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-sulphamehtoxazole1 (4.3) ________________________________________________

• Department e-mail = dmi.ly

• Khalifa Sifaw Ghenghesh e-mail =ghenghesh_micro@yahoo.com