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; CLINICALLY SIGNIFICANT SPECIES FACULTATIVE ANAEROBES, FERMENT CARBOHYDRATES, COMPLEX ANTIGENIC STRUCTURE PRODUCE TOXINS AND VIRULENCE FACTORS

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

CLASSIFICATION COMPLEX CHANGING TAXONOMY LACTOSE FERMENTERS (LF) LATE LACTOSE FERMENTER (LLF) LACTOSE NON FERMENTERS NLF E.COLI KLEBSIELLA ENTEROBACT ER SERRATIA CITROBACTER ARIZONA PROVIDENCIA SHIGELLA SALMONELLA PROTEUS

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

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

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

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

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 5 STRAINS ENTEROPATHOGENIC(EPEC) ENTEROTOXIGENIC(ETEC) ENTEROINVASIVE(EIEC) ENTEROHAEMORRHAGIC(EHEC) ENTEROAGGREGATIVE(EAEC)/ DIFFUSE AGGREGATIVE

DIARRHOEA 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 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 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 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 INADEQUATE NORMAL DEFENSES SUSCEPTIBLE : NEW BORN UROSEPSIS MENINGITIS : K1 ANTIGEN IN NEONATES