ENTEROBACTERIACEAE ENTERIC GRAM NEGATIVE RODS Dr Indumathi Gokula

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 • • • 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 • • • 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 Ig. M 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 Ig. G 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. K 1 OF E. COLI MENINGITIS, UTI KLEBSIELLA : UTI 8, 9, 10, 24 Vi ANTIGENS IN SALMONELLA INHIBITS PHAGOCYTOSIS ANTIGENIC FORMULA : E. COLI 055: K 5: H 21

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 • O 1, 2, 4, 6, 7, 75; K SEROTYPES K 1, 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 • O 26 B 6, 055 B 5 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 • O 6, 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 -18 HRS) ADULT RABBIT SKIN TEST IN VITRO : ELISA RIA TISSUE CULTURE (CHO CELL LINES)

EIEC • • • DYSENTRY/FEVER OLDER CHILDREN AND ADULTS O 124, 136, 144 IP 3 DAYS ; DURATION 7 -10 DAYS VIRULENCE FACTOR: PLASMID CODED OMP INVASIVE: ENDOCYTOSIS→INFLAMMATION→ NECROSIS→ULCERATION DETECTION : SERENY TEST He. LA CELL INVASION

EHEC • • • DEVELOPED COUNTRIES CONTAMINATED BEEF AND UNPASTEURIZED MILK HAEMORRHAGIC COLITIS/HUS IP 3 -4 DAYS DURATION : 5 -10 DAYS O 157 H 7 VEROTOXIN : CYTOTOXIN: SHIGA LIKE TOXIN DETECTION OF VERO TOXIN BY GENETIC PROBES GROWTH ON MA SORBITOL AGAR

EAEC ACUTE OR CHRONIC DIARRHOEA >14 DAYS 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 : K 1 ANTIGEN IN NEONATES