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Copyright © 2009 Pearson Education, Inc. , publishing as Pearson Benjamin Cummings

Copyright © 2009 Pearson Education, Inc. , publishing as Pearson Benjamin Cummings

Acute Intestinal Infection

Acute Intestinal Infection

Gastroenteritis Infection of gut Signs & Symptoms • Nausea • Vomiting • Diarrhoea

Gastroenteritis Infection of gut Signs & Symptoms • Nausea • Vomiting • Diarrhoea

rectal swab Faeces

rectal swab Faeces

§ If there is delay it is advised to transport specimen in glycerol saline

§ If there is delay it is advised to transport specimen in glycerol saline because this prevent the overgrowth of commensal bacteria. § Rectal tube: tube used in cases of cholera for collection of stool from inside the colon.

§ Bile is collected in cases of cholycystitis by duodenal drainage. § Vomitus may

§ Bile is collected in cases of cholycystitis by duodenal drainage. § Vomitus may be taken in cases of poisoning.

ENTEROBACTERIA CEAE

ENTEROBACTERIA CEAE

ENTEROBACTERIACEAE Habitat: intestine Morphology & motility: - Gram negative bacilli - Non spore forming

ENTEROBACTERIACEAE Habitat: intestine Morphology & motility: - Gram negative bacilli - Non spore forming - Motile ‘peritrichate flagella / non - Capsulated / non Growth characters: Aerobe or F. anaerobe 37°C Atmospheric Co 2 Grow easily on ordinary media

FAMILY ENTEROBACTERIACEAE Enterobacteriaceae, are faculatively anaerobic Gram-negative rods.

FAMILY ENTEROBACTERIACEAE Enterobacteriaceae, are faculatively anaerobic Gram-negative rods.

LF Classification Coliform group: • Escherichia coli • Klebsiella • Citrobacter • Enterobacter NLF

LF Classification Coliform group: • Escherichia coli • Klebsiella • Citrobacter • Enterobacter NLF • Salmonella • Shigella • Serratia • Proteus • pseudomonas Providencia • Yersinia

Coliform bacilli(LF) 1 -E. coli 2 -Klebsiella 3 -CITRO BACTER

Coliform bacilli(LF) 1 -E. coli 2 -Klebsiella 3 -CITRO BACTER

Escherichia, Klebsiella, Citrobacter Gram negative bacilli, non spore forming § Escherichia, Citrobacter: motile §

Escherichia, Klebsiella, Citrobacter Gram negative bacilli, non spore forming § Escherichia, Citrobacter: motile § ‘peritrichate flagella, most are noncapsulated

Lab diagnosis of (E. coli) caused disease Commensal ‘intestine’. 1 - Sample: Urine, pus,

Lab diagnosis of (E. coli) caused disease Commensal ‘intestine’. 1 - Sample: Urine, pus, sputum, blood, CSF, stool, . . 2 - Direct Gram stained film:

Direct smear: stained by Gram: • �Gram negative bacilli, �non spore forming, �motile, �some

Direct smear: stained by Gram: • �Gram negative bacilli, �non spore forming, �motile, �some strains are capsulated.

3 - Culture: - Culture characters: O 2 – CO 2 – Temp. -

3 - Culture: - Culture characters: O 2 – CO 2 – Temp. - Media: - Ordinary media: grow easily - Differential media: Mac Conkey’s rose pink colonies(LF) - Colony identification - Characters: - Gram st. film: - B. Rs (I, M, V, C), sugar f. ‘A, G’ - Litmus milk: 4 - Serology: Slide agglutination ‘enteropathogenic antisera’ in case of acute gastroenteritis

Culture: Facultative anaerobes, grow on Mac. Conkey’s agar and produce rose pink colonies.

Culture: Facultative anaerobes, grow on Mac. Conkey’s agar and produce rose pink colonies.

Mucoid colonies = capsule

Mucoid colonies = capsule

�Biochemical reaction: �Ferment glucose, maltose, mannite, lactose and sucrose with acid and gas production.

�Biochemical reaction: �Ferment glucose, maltose, mannite, lactose and sucrose with acid and gas production. �IMVC (+, +, -, -).

Differentiation: - B. Rs: (IMVC) Indole MR VP Citrate Escherichia + + - -

Differentiation: - B. Rs: (IMVC) Indole MR VP Citrate Escherichia + + - - Klebsiella Citrobacter - + + Coliform group - Sugar fermentation: Glucose, lactose, maltose, mannite.

Indole: Demonstrates the ability of certain bacteria to decompose the amino acid ‘tryptophane’ present

Indole: Demonstrates the ability of certain bacteria to decompose the amino acid ‘tryptophane’ present in peptone to (indole). MR: Demonstrates the ability of some bacteria to produce large amounts of [acid] from fermentation of ‘glucose’, thus lowering the p. H of the medium below 4.

VP: Demonstrates the ability of some bacteria to ferment glucose with production of acetyl

VP: Demonstrates the ability of some bacteria to ferment glucose with production of acetyl methyl carbinol. Citrate: Demonstrates the ability of some bacteria to utilise Na citrate as the only carbon source.

Biochemical differentiation of coliform bacilli Coliform group Indole MR VP Citrate Escherichia + +

Biochemical differentiation of coliform bacilli Coliform group Indole MR VP Citrate Escherichia + + - - Klebsiella - - + + Citrobacter - +

5 - Typing: - Antibiotic sensitivity strain - Serotyping: O, H, K antigens -

5 - Typing: - Antibiotic sensitivity strain - Serotyping: O, H, K antigens - Ejkmann test: Use: To differentiate fecal from non-fecal E. coli Principle: Fecal strains of E. coli can grow on fluid Mac. Conkey’s medium at 44°C producing ‘acid & gas’ (Ejkmann positive).

Non Lactose fermenters (NLF)

Non Lactose fermenters (NLF)

Shigella § Gram negative bacilli, non spore forming § non motile, non-capsulated

Shigella § Gram negative bacilli, non spore forming § non motile, non-capsulated

Laboratory diagnosis of shigellosis Diagnosis depends upon the isolation and identification of Shigella from

Laboratory diagnosis of shigellosis Diagnosis depends upon the isolation and identification of Shigella from the feces. Specimens: stool which contains mucus and blood.

Culture : Mac. Conkey agar, DCA, salmonella shigella agar (SS agar). enrichment medium may

Culture : Mac. Conkey agar, DCA, salmonella shigella agar (SS agar). enrichment medium may be inoculated with the stool specimen and subcultured into the selective agar media after a short growth period. Shigella is facultative anaerobe, produce pale non lactose fermenting colonies on Mac. Conkey agar and DCA and salmonella shigella agar.

Identification of obtained colonies by: Film stained by Gram: Shigellae are Gramnegative, non motile,

Identification of obtained colonies by: Film stained by Gram: Shigellae are Gramnegative, non motile, non-sporulated, non capsulated rod-shaped bacteria. Biochemical reactions: All fement glucose, all ferment mannite except S dysenteriae all are non lactose fermenter except S sonnei which is late lactose fermenter.

Shigella Lactose Mannite Glucose Sh. dyenteriae - - A Sh. flexneri - A A

Shigella Lactose Mannite Glucose Sh. dyenteriae - - A Sh. flexneri - A A Sh. boydi - A A Late A A Sh. sonnei

Copyright © 2009 Pearson Education, Inc. , publishing as Pearson Benjamin Cummings

Copyright © 2009 Pearson Education, Inc. , publishing as Pearson Benjamin Cummings