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ENTEROBACTERIACEAE ENTERIC GRAM NEGATIVE RODS

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

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ENTEROBACTERIACEAE ENTERIC GRAM NEGATIVE RODS

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  1. ENTEROBACTERIACEAEENTERIC GRAM NEGATIVE RODS Dr.Indumathi Gokula Metropolis Clinical laboratory

  2. 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

  3. CHARACTERISTICS • 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

  4. CLASSIFICATION • COMPLEX • CHANGING TAXONOMY

  5. ANTIGENIC STRUCTURE • COMPLEX • 3 ANTIGENS • O (SOMATIC) • H(FLAGELLAR) • K(CAPSULAR)

  6. O ANTIGEN (SOMATIC) • 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

  7. H ANTIGENS(FLAGELLAR) • LOCATED ON FLAGELLA • HEAT AND ALCOHOL LABILE • ANTIBODIES FLUFFY CLUMPS MAINLY IgG TYPE • MORE THAN 50 TYPES

  8. K ANTIGENS (CAPSULAR) • 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

  9. ESCHERICHIA COLI • NORMAL INTESTINAL FLORA • DETECTION IN WATER INDICATES RECENT FECAL CONTAMINATION • ONLY ONE SPECIES • SEVERAL SEROTYPES AND BIOTYPES • MA : LF • IMVIC ++--

  10. PATHOGENICITY • URINARY TRACT INFECTION • DIARRHOEA • PYOGENIC INFECTION • SEPTICAEMIA

  11. 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

  12. E.COLI DIARRHOEA • 5 STRAINS • ENTEROPATHOGENIC(EPEC) • ENTEROTOXIGENIC(ETEC) • ENTEROINVASIVE(EIEC) • ENTEROHAEMORRHAGIC(EHEC) • ENTEROAGGREGATIVE(EAEC)/ • DIFFUSE AGGREGATIVE

  13. DIARRHOEA • WATERY STOOLS • ABDOMENAL CRAMPS • VOMITING • WITH OR WITHOUT FEVER • WITH OR WITHOUT BLOOD AND MUCUS • SELF LIMITING 5-10 DAYS

  14. 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

  15. ENTEROPATHOGENIC E.COLI

  16. EPEC DIAGNOSIS • ISOLATION • SEROTYPING WITH POLYVALENT SERA • TISSUE CULTURE ADHESION : FLUORESCENT ACTIN STAIN • DNA BASED DETECTION FOR VIRULENCE GENES

  17. 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

  18. 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

  19. ETEC • 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)

  20. EIEC • 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

  21. EHEC • 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

  22. 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

  23. EAEC

  24. SEPSIS/MENINGITIS • INADEQUATE NORMAL DEFENSES • SUSCEPTIBLE : NEW BORN • UROSEPSIS • MENINGITIS : K1 ANTIGEN IN NEONATES

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