Enterobacteriaceae Quiz

WIKIQUIZ

Questions reviewed by:

Michael A. Jones, BSc (Hons) MSc PhD, Lecturer in Microbiology and Molecular Biology

1

What laboratory test allows differentiation between Proteus and Salmonella? Urease test Motility Growth on MacConkey agar Lactose fermenting abilities Oxidase test Please select an option Correct!Proteus is urease positive and Salmonella is urease negative. The urease test is used to determine the ability of an organism to split urea, through the production of the enzyme urease. Two units of ammonia are formed with resulting alkalinity in the presence of the enzyme and the increased pH is detected by a pH indicator. If you follow the second link you can see what a Proteus positive urease test looks like. WikiVet Article: Proteus. Link to external website: Urease test Incorrect. Although Proteus spp are considerably more motile than Salmonella spp, (Proteus is renowned for its swarming of bacterial plates), motility should not be used as a definitive test. Also some Salmonella are non motile. The correct answer is that differentiation can be acheived by the urease test - Proteus is urease positive and Salmonella is urease negative. The urease test is used to determine the ability of an organism to split urea, through the production of the enzyme urease. Two units of ammonia are formed with resulting alkalinity in the presence of the enzyme and the increased pH is detected by a pH indicator. If you follow the second link you can see what a Proteus positive urease test looks like. WikiVet Article: Proteus. Link to external website: Urease test Incorrect. Both Proteus and Salmonella can be grown on MacConkey agar and show a negative result for lactose fermentation, so this method can not be used to differentiate between the two. The correct answer is the urease test - Proteus is urease positive and Salmonella are urease negative. The urease test is used to determine the ability of an organism to split urea, through the production of the enzyme urease. Two units of ammonia are formed with resulting alkalinity in the presence of the enzyme and the increased pH is detected by a pH indicator. If you follow the second link you can see what a Proteus positive urease test looks like. WikiVet Article: Proteus. Link to external website: Urease test Incorrect. Both Salmonella and Proteus are non-lactose fermenters when cultured on MacConkey agar, so this method can not be used to differentiate between the two. The correct answer is the urease test - Proteus is urease positive and Salmonella is urease negative. The urease test is used to determine the ability of an organism to split urea, through the production of the enzyme urease. Two units of ammonia are formed with resulting alkalinity in the presence of the enzyme and the increased pH is detected by a pH indicator. If you follow the second link you can see what a Proteus positive urease test looks like. WikiVet Article: Proteus. Link to external website: Urease test Incorrect. Both Proteus and Salmonella are oxidase negative. So this method can not be used to differentiate between the two. The correct answer is the urease test - Proteus is urease positive and Salmonella is urease negative. The urease test is used to determine the ability of an organism to split urea, through the production of the enzyme urease. Two units of ammonia are formed with resulting alkalinity in the presence of the enzyme and the increased pH is detected by a pH indicator. If you follow the second link you can see what a Proteus positive urease test looks like. WikiVet Article: Proteus. Link to external website: Urease test

8

Which of the following is true about the heat-labile toxin of enterotoxigenic E. coli? The toxin is composed of 1 active A subunit and 1 B subunit Decreases cAMP levels The toxin causes reversible activation of adenylate cyclase It causes ADP-ribosylation of the stimulatory subunit of the adenylate cyclase complex in eukaryotic cell membranes Causes hyposecretion of water and chloride ions Please select an option Incorrect. The toxin is composed of one enzymatically-active A subunit and 5 identical B subunits forming the binding portion.The true answer is that the toxin causes ADP-ribosylation of the stimulatory subunit of the adenylate cyclase complex in eukaryotic cell membranes. This initiates a pathway that results in diarrhoea. WikiVet Article: E. coli. Incorrect. The heat labile toxin increases cAMP levels. The true answer is that the toxin causes ADP-ribosylation of the stimulatory subunit of the adenylate cyclase complex in eukaryotic cell membranes. This initiates a pathway that results in diarrhoea. WikiVet Article: E. coli. Incorrect. Heat labile toxin causes irreversible activation of adenylate cyclase. The true answer is that the toxin causes ADP-ribosylation of the stimulatory subunit of the adenylate cyclase complex in eukaryotic cell membranes. This initiates a pathway that results in diarrhoea. WikiVet Article: E. coli. Correct! Heat-labile toxin does cause ADP-ribosylation of the stimulatory subunit of guanine nucleotide binding proteins of the adenylate cyclase complex in eukaryotic cell membranes. This triggers a pathway that results in hypersecretion of water and chloride ions into the lumen of the small intestine and subsequent diarrhoea. WikiVet Article: E. coli Incorrect. The toxin causes hypersecretion of water and chloride ions into the lumen of the intestine. The true answer is that the toxin causes ADP-ribosylation of the stimulatory subunit of the adenylate cyclase complex in eukaryotic cell membranes. This initiates a pathway that results in diarrhoea. WikiVet Article: E. coli.

2

Which of the following is a characteristic of Salmonella? Produce urease from tryptophan Catalase negative Unable to grow on MacConkey agar Oxidase positive Non lactose fermenter Please select an option Incorrect. Salmonella are unable to produce urease or indole from tryptophan. The correct answer is that Salmonella are non-lactose fermentors which is demonstrated by culturing on a MacConkey agar plate. Non-lactose fermenters appear pale on MacConky agar and lactose fermenters appear pink e.g. E. coli. WikiVet Article: Salmonella. Incorrect. Salmonella are typically catalase positive. This means that the bacteria posess the Catalase enzyme, and upon testing with Hydrogen Peroxide, bubbles of oxygen are seen. The correct answer is that Salmonella are non-lactose fermenters which is demonstrated by culturing on a MacConkey agar plate. Non-lactose fermenters appear pale on MacConky agar and lactose fermenters appear pink e.g. E. coli. WikiVet Article: Salmonella. Incorrect. Salmonella does grow on MacConkey agar. This differentiates Salmonella from E. coli according to their lactose fermenting abilities. The correct answer is that Salmonella are non-lactose fermenters which is demonstrated by culturing on a MacConkey agar plate. Non-lactose fermenters appear pale on MacConky agar and lactose fermenters appear pink e.g. E. coli. WikiVet Article: Salmonella. Incorrect. Salmonella are oxidase negative and so do not possess cytochrome C oxidase. The correct answer is that Salmonella are non-lactose fermentors which is demonstrated by culturing on a MacConkey agar plate. Non-lactose fermenters appear pale on MacConky agar and lactose fermenters appear pink e.g. E. coli. WikiVet Article: Salmonella Correct. Salmonella are unable to ferment lactose. This is demonstrated by culturing on a MacConkey agar plate. This method is used to distinguish between non lactose fermenting Salmonella, which appear paleon MacConkey agar and E. coli which appear pink in colour, as they are lactose fermenters. WikiVet Article: Salmonella

0

How does enteroinvasive E. coli invade epithelial cells? Facilitated diffusion Pinocytosis Primary active transport Receptor-mediated endocytosis Secondary active transport Please select an option Incorrect. Facilitated diffusion is a form of passive transport facilitated by transport proteins. Enteroinvasive E. coli induce receptor-mediated endocytosis in the epithelial cells of the intestine. WikiVet Article: E. coliLink to Wikipedia: Facilitated diffusion Incorrect. Pinocytosis is concerned with the uptake of solutes and single molecules such as proteins. Enteroinvasive E. coli induce receptor-mediated endocytosis in the epithelial cells of the intestine. WikiVet Article: E. coli. Link to Wikipedia: Pinocytosis. Incorrect. Primary active transport uses energy (ATP) to transport molecules across a membrane. Enteroinvasive E. coli induce receptor-mediated endocytosis in the epithelial cells of the intestine. WikiVet Article: E. coliLink to Wikipedia: Primary active transport Correct!Enteroinvasive E. coli induce receptor-mediated endocytosis in the epithelial cells of the intestine. WikiVet Article: E. coliLink to Wikipedia: Endocytosis Incorrect. In secondary active transport the electrochemical potential difference created by pumping ions out of the cell is used for movement. Enteroinvasive E. coli induce receptor-mediated endocytosis in the epithelial cells of the intestine. WikiVet Article: E. coliLink to Wikipedia: Secondary active transport

3

Which structure is used to classify Salmonella into 9 groups by the Kauffmann-White Scheme? Enterotoxin LPS endotoxin Somatic (O) antigen Fimbrae Flagella (H) antigen Please select an option Incorrect. Salmonella is not classified by enterotoxin into 9 groups but by somatic (O) antigen (lipopolysaccharide). The method of classification is the Kauffmann-White scheme - determined by slide agglutination of the bacteria with specific antisera. WikiVet Article: Salmonella Incorrect. Salmonella is not classified by LPS endotoxin into 9 groups but by somatic (O) antigen (lipopolysaccharide). The method of classification is the Kauffmann-White scheme - determined by slide agglutination of the bacteria with specific antisera. WikiVet Article: Salmonella Correct! There is a single species of Salmonella but over 2400 pathogenic serotypes. These are classified into 9 groups by somatic (O) antigen (lipopolysaccharide) by the Kauffmann-White scheme - determined by slide agglutination of the bacteria with specific antisera. WikiVet Article: Salmonella Incorrect. Salmonella is not classified by fimbrae into 9 groups but by somatic (O) antigen (lipopolysaccharide). The method of classification is the Kauffmann-White scheme - determined by slide agglutination of the bacteria with specific antisera. WikiVet Article: Salmonella Incorrect. The H antigen (flagella) is used to class Salmonella into serovars not groups. There are two phases of H antigen and this must also be determined. Salmonella is classified into 9 groups by somatic (O) antigen (lipopolysaccharide) by the Kauffmann-White scheme - determined by slide agglutination of the bacteria with specific antisera. WikiVet Article: Salmonella

4

Which of the following is a characteristic of E. coli? Unable to grow on MacConkey agar Non haemolytic Oxidase negative Non lactose fermenter Non motile Please select an option Incorrect. E. coli does grow on MacConkey agar. This differentiates E. coli from Salmonella according to their lactose fermenting abilities. The correct answer is E. coli are oxidase negative and so do not possess cytochrome C oxidase. WikiVet Article: E. coli Incorrect. E. coli are haemolytic on blood agar. The characteristics of this haemolysis can be used to identify certain strains. The correct answer is E. coli are oxidase negative and so do not possess cytochrome C oxidase. WikiVet Article: E. coli Correct! E. coli are oxidase negative and so do not possess cytochrome C oxidase. WikiVet Article: E. coli Incorrect. E. coli are able to ferment lactose. This is demonstrated by culture on a MacConkey agar plate by the development of pink colonies. The correct answer is E. coli are oxidase negative and so do not possess cytochrome C oxidase. WikiVet Article: E. coli Incorrect. E. coli are motile and have flagellae and fimbriae to achieve this. The correct answer is E. coli are oxidase negative and so do not possess cytochrome C oxidase.WikiVet Article: E. coli

5

In older birds with avian enterotoxigenic E. coli to where does infection spread from the respiratory tract? Liver Blood Pancreas Kidneys Heart Please select an option Incorrect. Birds inhale the bacteria which sets up infection in the respiratory tract and then spreads to the blood not the liver. In the blood infection leads to acute colisepticaemia. WikiVet Article: E.coli Correct! Birds inhale the bacteria which sets up infection in the respiratory tract and then spreads to the blood. In the blood infection leads to acute colisepticaemia. WikiVet Article: E. coli Incorrect. Birds inhale the bacteria which sets up infection in the respiratory tract and then spreads to the blood not the pancreas. In the blood infection leads to acute colisepticaemia. WikiVet Article: E.coli Incorrect. Birds inhale the bacteria which sets up infection in the respiratory tract and then spreads to the blood not the kidneys. In the blood infection leads to acute colisepticaemia. WikiVet Article: E.coli Incorrect. Birds inhale the bacteria which sets up infection in the respiratory tract and then spreads to the blood not the heart. In the blood, infection leads to acute colisepticaemia. WikiVet Article: E. coli

6

What species of Salmonella causes bacillary white diarrhoea in poultry? Salmonella enteritidis Salmonella dublin Salmonella typhimurium Salmonella gallinarum Salmonella pullorum Please select an option Incorrect. S. enteritidis causes enteritis in birds and cattle which can be spread to humans leading to gastro-enteritis, septicaemia and death in the very young and old. Birds act as subclinical carriers and spread infection through their eggs. The correct answer is S. pullorum causes bacillary white diarrhoea or pullorum disease in chickens and turkeys in the first days of life. WikiVet Article: Salmonella Incorrect. S. dublin causes enterocolitis in adult cattle and diarrhoea, fatal septicaemia, arthritis, meningitis and pneumonia in calves. Most survivors become subclinical excretors. This species of Salmonella can also cause abortion in adult cattle and sheep. S. dublin can infect humans but it doesn't occur very often. The correct answeris S. pullorum causes bacillary white diarrhoea or pullorum disease in chickens and turkeys in the first days of life. WikiVet Article: Salmonella Incorrect. S. typhimurium can cause chronic infections in young birds due to a lack of commensals. Adult birds, cattle, sheep and pigs act as asymptomatic carriers and pass infection onto humans via meat and egg products.The correct answer is S. pullorum causes bacillary white diarrhoea or pullorum disease in chickens and turkeys in the first days of life. WikiVet Article: Salmonella Incorrect. S. gallinarum causes fowl typhoid in adult birds. This is a septicaemic conditionwith sudden death (enlarged, friable, bile-stained liver and enlarged spleen). On post mortem examination bronzing of the organs is notable. The correct answer is S. pullorum causes bacillary white diarrhoea or pullorum disease in chickens and turkeys in the first days of life. WikiVet Article: Salmonella Correct! S. pullorum causes bacillary white diarrhoea or pullorum disease in chickens and turkeys in the first days of life. The disease has high mortality rates and is characterised by anorexia, depression, white diarrhoea; white nodules throughout lungs and focal necrosis of liver and spleen. WikiVet Article: Salmonella