Lectures 23 & 24: Enterobacteriaceae- Enteric pathogens OBJECTIVES: The objectives of this lecture are to describe the General properties and categorization of bacteria in the family Enterobacteriaceae. describe the General properties and categorization of bacteria in the family Enterobacteriaceae. discuss the pathogenicity, virulence, and laboratory diagnosis of diseases caused by Escherichia, Salmonella, Shigella. discuss the pathogenicity, virulence, and laboratory diagnosis of diseases caused by Escherichia, Salmonella, Shigella. Assign Klebsiella, Citrobacter, Enterobacter as SDL exercise Assign Klebsiella, Citrobacter, Enterobacter as SDL exercise

Learning Outcomes At the end of the lecture, students should be able to: Describe the general morphological features and classification of the bacteria in the family Enterobacteriaceae. Describe the general morphological features and classification of the bacteria in the family Enterobacteriaceae. Describe the pathogenicity, virulence and laboratory diagnosis of diseases caused by Escherichia, Salmonella, Shigella. Describe the pathogenicity, virulence and laboratory diagnosis of diseases caused by Escherichia, Salmonella, Shigella. Complete the assignment suggested by the facilitator. Complete the assignment suggested by the facilitator.

Enterobactericeae General properties Gram negative bacilli Facultative anaerobes Catalase positive Oxidase negative Nitrate positive

Important Entero-disease caused E.coli-UTI/septicaemia, meningitis (in neonates) Salmonella typhi-Typhoid fever/toxaemia Shigella-Dysentry/Salmonella typhimurium (look up virulence factors of all the above) Klebsiella-UTI/RTI

Gram negative bacilliBacilli with peritrichous flagella Types of flagella

ANTIGENIC STRUCTURE

O antigens Specific polysacchride chains in the lipopolysaccharide complex of outer membrane. H antigens Flagellar antigen consisting of protein. K antigens Linear polymers of outer membrane built up of a repeated series of carbohydrate units. Fimbrial antigens helps in attachment of bacteria.

PATHOGENICITY DETERMINANTS

Repeat slide-disease caused E.coli-UTI/septicaemia, meningitis (in neonates) Salmonella-Typhoid fever/toxaemia Shigella-Dysentry (look up virulence factors of all the above) Klebsiella-UTI/RTI

Mac conkey Lactose fermenting Escherichia coli Klebsiella pneumoniae Non lactose fermenting Salmonella spp Shigella Proteus Many others (note this)

OrganismMac conkey E.coliLactose fermenting KlebsiellaLactose fermenting SalmonellaNon Lactose fermenting ShigellaNon Lactose fermenting

OrganismMac conkeyMotility E.coliLactose fermenting Motile KlebsiellaLactose fermenting Non motile SalmonellaNon Lactose fermenting Motile ShigellaNon Lactose fermenting Non motile

OrganismMac conkeyCitrateMotility E.coliLactose fermenting NegativeMotile KlebsiellaLactose fermenting PositiveNon motile SalmonellaNon Lactose fermenting Negative + only for paratyphi B Motile ShigellaNon Lactose fermenting Non motile

Lab in general for entero Specimen-Urine/Sputum/Stool Microscopy-Gram stain-Gram negative Motile or non motile Culture-mac conkey-Lactose ferm or non ferm Catalase +, Oxidase -, Nitrate + Citrate positive or negative (or no use of this test) Antigen detection Antibody detection PCR

Biochemical tests She is there! But who is she? What's the biochemistry?

Concept/exercise Proteus is also GNB, Non lactose fermenter Is Catalase +, Oxidase – Nitrate + Is citrate and urease positive and is motile. Ok….but how to differentiate between species that is Proteus vulgaris and mirabilis? vulgaris is a VIP I mean vulgaris indole + Mirabilis is Indole negative, now do u understand y indole?

Why so many TSI etc Just like how we had to do indole to differentiate between species of proteus we may have to resort to many otjer bio tests to diff biovars.(biovarieties) However serology took over and we have serovars. Now we r in the molecular era. Remember Chlamydia group specific/species specific/MOMP etc?

Various types of E. coli

Diarrhoeal agents OrganismVirulenceTests (Principle) E.coli 0 157: H 7Toxin mediated Secretory (DIARRHOEA) Stool culture (selective media) Detecting presence of toxin in isolate/stool EIEC Shigella spp Salmonella spp Invasiveness Toxin + Inflammatory (DYSENTERY) Stool culture (selective media) Detecting presence of toxin in isolate/stool

Salmonella typhi, paratyphi OrganismVirulenceEffectLab tests Salmonella typhi, S.paratyphi Adhesin Intracellular growth Toxemia Enteric fever (typhoid) Blood culture Antibody (Widal) Stool culture Urine culture

Dr.P.K.Rajesh.M.D. Salmonella Enterobactericaea Gram negative bacilli Motile, serpentine Feaco-oral transmission Non-lactose fermentor Enteric fever or Typhoid S.typhi,paratyphi A and paratyphi B Food poisoning S.typhimurium

Dr.P.K.Rajesh.M.D. Typhoid-no need to mug up Fever-Step ladder Relative bradycardia Constitutional symptoms Coated tongue Hepatomegaly Rash (rare) Complications Typhoid ulcers Abscess (LIVER etc) Typhoid spine (google)

Dr.P.K.Rajesh.M.D. Laboratory Diagnosis 1 st Week-Blood culture 2 nd Week-Agglutination test (WIDAL) 3 rd Week-Stool culture (Selenite-F-broth) 4 th Week-Urine culture

KLEBSIELLA-assignment Gram negative bacilli with capsule Mucoid lactose fermenting colonies on MacConkey’s agar