ENTEROBACTERIACEAE
ENTERIC GRAM NEGATIVE
RODS
Dr.Indumathi
Gokula Metropolis Clinical
laboratory
FEATURES
• LARGE HETEROGENOUS GROUP :
• NATURAL HABITAT : HUMAN/ANIMAL
INTESTINE
• MORE THAN 25 GENERA AND 110 SPECIES;
• 20-25 CLINICALLY SIGNIFICANT SPECIES
• FACULTATIVE ANAEROBES, FERMENT
CARBOHYDRATES, COMPLEX ANTIGENIC
STRUCTURE
• PRODUCE TOXINS AND VIRULENCE
FACTORS
CHARACTERISTICS
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GRAM NEGATIVE BACILLI
NON SPORING
MOTILE(PERITRICHOUS FLAGELLA)/NON MOTILE
CAPSULATED/NON CAPSULATED
NON FASTIDIOUS
FERMENT GLUCOSE WITH ACID/GAS
REDUCE NITRATES TO NITRITES
OXIDASE NEGATIVE/CATALASE POSITIVE
BIOCHEMICAL TESTS DONE TO DIFFERENTIATE
THE VARIOUS SPECIES
CLASSIFICATION
• COMPLEX
• CHANGING
TAXONOMY
LACTOSE
FERMENTERS
(LF)
LATE
LACTOSE
FERMENTER
(LLF)
LACTOSE NON
FERMENTERS
NLF
E.COLI
KLEBSIELLA
ENTEROBACT
ER
SERRATIA
SHIGELLA
CITROBACTER SALMONELLA
ARIZONA
PROTEUS
PROVIDENCIA
ANTIGENIC STRUCTURE
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COMPLEX
3 ANTIGENS
O (SOMATIC)
H(FLAGELLAR)
K(CAPSULAR)
O ANTIGEN (SOMATIC)
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MOST EXTERNAL PART OF CELL WALL LPS
REPEAT POLYSACCHARIDE UNITS
HEAT AND ALCOHOL RESISTANT
DETECTED BY AGGLUTINATION
ANTIBODIES TO ‘O’ ARE IgM
GENUS SPECIFIC
CROSS SHARING
ASSOCIATED WITH DISEASE (UTI OR
DIARRHOEA CAUSING E.COLI)
• MORE THAN 150 TYPES
H ANTIGENS(FLAGELLAR)
• LOCATED ON FLAGELLA
• HEAT AND ALCOHOL LABILE
• ANTIBODIES FLUFFY CLUMPS MAINLY
IgG TYPE
• MORE THAN 50 TYPES
K ANTIGENS (CAPSULAR)
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EXTERNAL TO O ANTIGEN
MORE THAN 100 TYPES
PRESENT IN SOME GENERA
POLYSACCHARIDE/PROTEINS
ASSOCIATED WITH VIRULENCE
E.G.K1 OF E.COLI MENINGITIS, UTI
KLEBSIELLA : UTI 8,9,10,24
Vi ANTIGENS IN SALMONELLA
INHIBITS PHAGOCYTOSIS
ANTIGENIC FORMULA : E.COLI 055:K5:H21
ESCHERICHIA COLI
• NORMAL INTESTINAL FLORA
• DETECTION IN WATER INDICATES
RECENT FECAL CONTAMINATION
• ONLY ONE SPECIES
• SEVERAL SEROTYPES AND BIOTYPES
• MA : LF
• IMVIC ++--
PATHOGENICITY
• URINARY TRACT INFECTION
• DIARRHOEA
• PYOGENIC INFECTION
• SEPTICAEMIA
UTI
• COMMON CAUSE OF ASCENDING
INFECTION
• PREGNANCY, SEXUALLY ACTIVE FEMALES,
OTHER PREDISPOSING FACTORS LIKE
OBSTRUCTION
• PYELONEPHRITIS
• UROPATHOGENIC STRAIN
• VIRULENCE FACTOR : HAEMOLYSIN
• P PILUS
• K ANTIGEN
• O1,2,4,6,7,75; K SEROTYPES K1,2,3,5,12,13
E.COLI DIARRHOEA
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5 STRAINS
ENTEROPATHOGENIC(EPEC)
ENTEROTOXIGENIC(ETEC)
ENTEROINVASIVE(EIEC)
ENTEROHAEMORRHAGIC(EHEC)
ENTEROAGGREGATIVE(EAEC)/
DIFFUSE AGGREGATIVE
DIARRHOEA
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WATERY STOOLS
ABDOMENAL CRAMPS
VOMITING
WITH OR WITHOUT FEVER
WITH OR WITHOUT BLOOD AND
MUCUS
• SELF LIMITING 5-10 DAYS
EPEC
• INFANTILE DIARRHOEA : SPORADIC
CASES/INSTITUTIONAL OUTBREAK
• INCUBATION 1-2 DAYS
• O26B6,055B5 STRAINS
• VIRULENCE FACTOR: PILI (Bfp) ;
intimin(adhesin); Tir ( translocated intimin
receptor)
• BACTERIAL ATTACHMENT TO MICROVILLI;
AND EFFACING (DISTRUPTION) MECHANISM
ENTEROPATHOGENIC E.COLI
EPEC DIAGNOSIS
• ISOLATION
• SEROTYPING WITH POLYVALENT
SERA
• TISSUE CULTURE ADHESION :
FLUORESCENT ACTIN STAIN
• DNA BASED DETECTION FOR
VIRULENCE GENES
ETEC
• TRAVELLERS’ DIARRHOEA
• BOTH ADULTS AND CHILDREN
• CONSUMPTION OF WATER
CONTAMINATED WITH SEWAGE
• IP 1-7 DAYS NO FEVER
• SELF LIMITING 2-6 DAYS
• O6, 08, 025, 027
ETEC
• VIRULENCE FACTOR
• ENTEROTOXIN : LT AND ST: GENETIC
CONTROL
• PILI OR K PROTEINS
• LT : CHOLERA LIKE TOXIN, ACTIVATES
CYCLIC AMP PATHWAY : FLUID
HYPERSECRETION INTENSE & PROLONGED
ST : ACTIVATES CYCLIC GMP PATHWAY:
SHORT ONSET OF ACTION
ETEC
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DIAGNOSIS
CULTURE FAECES
DETECT LT/ST TOXIN
LT TOXIN BY : IN VIVO
IN VITRO
IN VIVO : LIGATED RABBIT ILEAL LOOP (6-18HRS)
ADULT RABBIT SKIN TEST
IN VITRO : ELISA
RIA
TISSUE CULTURE (CHO CELL LINES)
EIEC
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DYSENTRY/FEVER
OLDER CHILDREN AND ADULTS
O124, 136, 144
IP 3 DAYS ; DURATION 7-10DAYS
VIRULENCE FACTOR: PLASMID CODED OMP
INVASIVE:
ENDOCYTOSIS→INFLAMMATION→
NECROSIS→ULCERATION
DETECTION : SERENY TEST
HeLA CELL INVASION
EHEC
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DEVELOPED COUNTRIES
CONTAMINATED BEEF AND UNPASTEURIZED MILK
HAEMORRHAGIC COLITIS/HUS
IP 3-4 DAYS
DURATION : 5-10 DAYS
O157H7
VEROTOXIN :CYTOTOXIN:SHIGA LIKE TOXIN
DETECTION OF VERO TOXIN BY GENETIC PROBES
GROWTH ON MA SORBITOL AGAR
EAEC
ACUTE OR CHRONIC DIARRHOEA
>14DAYS DURATION
DEVELOPING COUNTRIES
FOOD BORNE
CHARACTERISTIC ATTACHMENT TO
CELLS : STACKED BRICK FORMATION
VIRULENCE : FIMBRIA, HEAT LABILE
ENTEROTOXIN AND CYTOTOXIN
EAEC
SEPSIS/MENINGITIS
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INADEQUATE NORMAL DEFENSES
SUSCEPTIBLE : NEW BORN
UROSEPSIS
MENINGITIS : K1 ANTIGEN IN
NEONATES