Enterobacteriaceae (E.coli & Klebsiella Pneumoniae)

7/27/2019 Enterobacteriaceae (E.coli & Klebsiella Pneumoniae)

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Enterobacteriaceae

Dr.Aravind


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Gram Negative Enteric Rods

Routinely Found In The Gastrointestinal Tract

Facultative Anaerobes Lipopolysaccharide (LPS): Antigenic & Endotoxin

Belong To Diverse Taxonomic Groups

Cause Diseases In The GI Tract, Outside The GI Tract, Or In

Locations.

Oxidase Negative

Non Spore-forming

Dr.Aravind


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Enterobacteriaceae

Classification

Lactose fermenters

Escherichia Coli

(Motile)

Klebsella Pneumonia

(Non motile)

NonLactose F

Salmonella

Proteus

Motile and H2S producing No

No

pro

Dr.Aravind


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Escherichia Coli(E.coli)

Dr.Aravind

Kingdom: Bacteria

Phylum: Proteobacteria

Class: Gamma Proteobacteria

Order: Enterobacteriales

Family: Enterobacteriaceae

Genus: Escherichia

Species: E. coli


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Gram Negative rod

Facultative anaerobic

Bacteroides species : E. coli = 20:1

O, H, and K antigens = 700 serotypes

Oxidase (-), Catalase (+)

Ferment glucose, Lactose, and can generate energy by reduc

nitrates to nitrites

MacConkey Agar- pink colonies

EMB - metallic shine appearance on colonies

Dr.Aravind


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Virulent Factors P Pili (Pyelonephritis-associated Pili):

Binds To Galactose Dissaccharide Of UT Epithelium Most Imp In UTI

Type I Pili: Bind To The D-mannose Receptors On Epithelial Cell Surfa

CFA Or BFA: Bind To Enterocytes

Non Fimbrial Adhesin (Intimin)

Siderophores E.Co

Dr.Aravind


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Capsule (K Antigens) :

K1 Capsule In Neonatal Meningitis

Antibodies And Complement Bacterial Surface, Phagocytosis

O Antigen : Outermembrane

Endotoxin

H Antigen: Flagella

Motility And Invasive Disease

Alpha-hemolysins Pore formation on membrane, toxic to many mammalian cells.

Lyse Lymphocytes, Beta-hemolysins, Inhibit Phagocytosis And ChOf Neutrophils

Dr.Aravind


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Exotoxins:

Heat-labile Enterotoxin (LT)

Similar Function To The Cholera Toxin

Binds Identical Ganglioside Receptors On Enterocytes Heat Stable Toxin (ST)

Binding To Guanylate Cyclase Receptors On The Apical MemHost Cells, Thereby Activating The Enzyme Diarrhea.

Resistant to boiling 300C

Shiga toxins (verotoxin) protein synthesis by destructing 28S ribosome

HUS syndrome

O157:H7 serotype

Dr.Aravind


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Epidemiology

Human Bowel Is Usually Colonized Within 40 Hours Of Birth.

700 Serotypes Of E. Coli Based On O, H, And K Antigens

Bacteroides Species : E. Coli = 20:1

Most Common Cause Of UTI

2rd Most Common Cause Neonatal Meningitis

A Leading Cause Of Infantile Diarrhea In Developing Countries

Transmission: UTI - intestinal E. coli perineal Urethra

Neonatal MeningitisBirth Canal

Intestinal diseasecontaminated Food or water

Dr.Aravind


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Pathogenic e.coli

Extra intestinal diseases

UTI

Neonatal meningitis

Pneumonia

Septicemia

Intestinal diseases

E.coli Strains

ETEC

EPEC

EIEC

EAEC

EHEC

Dr.Aravind


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E.Coli UTI Pathogenesis

Dr.Aravind


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Courtesy from Sherries

MicrobiologyDr.Aravind


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Intestinal E.coli Pathogenesis

Virulent factors

CFA

LT

ST

Virulent factors

Outer

Membrane

Proteins

Virulent factors

BFA,

Intimin

ESPS

Virulent factors

Intimin

Shiga like toxin

Vi

ST

he

Dr.Aravind

Cli i l diti


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Clinical conditions

Extra intestinal infections

Urinary Tract Infection: Uropathogenic E. Coli (UPEC) Cause 90% Of The UTI

pregnancy

Dysuria, Lower Abdominal Pain, Increase Discharges

Cystitis, Increased Frequency Of Urination, Dyspareunia

Pyelonephritis:

Fever, Dysuria, Radiating Back Pain, Tenderness At The Vertebral Angle, Shock.

Dr.Aravind


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Neonatal meningitis:

2 nd most common

Transmission - Birth canal

Virulent factorK1 capsular antigen

Fever, irritability, constipation, poor feeding, bulging fronseizures

Neonatal Pneumonia:

Birth canal Respiratory symptoms

Septicemia

Dr.Aravind


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Intestinal DiseasesEnterotoxigenic E. Coli (ETEC):

Infants And Travelers To Underdeveloped Countries Or RPoor Sanitation

In U.S Outbreaks By Water, Soft Cheeses, Mexican-styleAnd Raw Vegetables

Infective Dose 108

Onset In 12 Days

Virulent Factors:

CFA, LT And ST Watery Diarrhea Similar To Cholera Syndrome

Non Inflammatory, Non Invasive

Adults in endemic areas evidently develop immunity Self limiting

Dr.Aravind


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Enteroinvasive E. Coli (EIEC): Similar To Shigella Dysentery

Under 5 Years Of Age

Oro fecal route

Lack Fimbriae Adhesins And LT And ST (has Outer Membrane Pr Inflammatory And Invasive

dysentery-like diarrhea (mucous, blood), severe inflammation, feve

Enteroaggregative E. coli (EAEC):

persistent diarrhea in young children Non inflammatory, non invasive

ST toxin and hemolysin

Biofilm

Dr.Aravind


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Enteropathogenic E. Coli (EPEC)

20% Of Diarrhea In Bottle-fed Infants < 1 Year

Transmission: Fomites, Drinking Water ,Meat Products

Day cares and hospitals

Infecting Dose For Infants Is Low

Virulent Factors: Intimin,

E. Coli Secretion Proteins (Esps),

Tir (Translocated Intimin Receptor)

A/E Lesions

Symptoms: Watery Diarrhea

Enteropatho

(EPEC) attac

cells. The EP

and effacing

epithelial ce

filamentous

the attachm

Dr.Aravind

C h i


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EPEC Pathogenesis

Courtesy by CrDr.Aravind


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Enterohemorrhagic E. Coli (EHEC): Hemorrhagic Colitis (HC) Or Bloody Diarrhea

Serotype O157:H7

Reservoir are Infected Cattle, Beef Products, Lettuce, Sprouts, Fruit, Fruit JuUnpasteurized Milk.

Low Infectious Dose 10 - 100 Organisms.

Virulent factors: Intimin Shiga like toxin or Vero toxin

Symptoms: Watery Diarrhea ,Severe Cramps And Progresses To Bloody Diarrhea. Fever Is Low Grade Or Absent

Complication: Hemolytic-uremic Syndrome (HUS) Thrombotic Thrombocytopenic Purpura, Renal Failure And Microangiopathic Hemo HUS Ensues In Approximately 5% To 10% Antibiotics may induce Shiga toxin.

Dr.Aravind

EHEC P th i


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Courtesy

EHEC Pathogenesis

Dr.Aravind

Diagnosis


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Diagnosis

Extra intestinal Infections: Specimens - bladder or CSF

Culture on MacConkey agar (pink colonies)

Serological tests

Intestinal infections: Culture on MacConkey agar ( Pink colonies)

EMB agar

EHECMacConkey sorbitol agar - No growth

Oxidase Negative

Leukocyte esterase positive

Nitrates to nitrites

Dr.Aravind


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Treatment

Extra Intestinal Infections:

UTI: Ciprofloxacin, Trimethoprim, Sulfamethoxazole.

Meningitis: Cefalosporins

Intestinal Infections:

Rehydration And Supportive Measures

Trimethoprim/SulfamethoxazoleETEC, EPEC And EIEC.EHEC:

Hemodialysis Or Hemapheresis

No Anti Motility Drugs

Dr.Aravind

Ki d B i


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Klebsiella Pneumoniae

Dr.Aravind

Kingdom:Bacteria

Phylum: Proteobacteria

Class: Gamma Proteobacteria

Order: Enterobacteriales

Family: Enterobacteriaceae

Genus: Klebsiella

Species: K. pneumoniae


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Gram-negative Rod Shaped Bacterium

Non-motile, Oxidase (-)

Lactose Fermenting, Facultative Anaerobic

Found In The Normal Flora Of The Mouth, Skin, And Intestines

Thick Capsule-made Of Polysaccharides Virulent Factors: Capsule & Endotoxin

Susceptible Pts: VAP Hospitals Alcoholics & Diabetics Immuno-compromised Patients & Catheter

Causes Pneumonia, Meningitis And UTI Thickness And Bloody Sputum- B/C Of Thick Capsule

Diagnosis: Culture, Serology

Treatment: Cephalosporin's - Cefotaxime & Fluor quinolones

Dr.Aravind

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Enterobacteriaceae (E.coli & Klebsiella Pneumoniae)