General Bacteriology quiz

1

Which of these characteristics of Campylobacter is true? All species are thermophilic Insensitive to drying Polar flagellum Oxidase negative Gram positive rods Please select an option Incorrect. C. jejuni and C. coli are thermophilic but C. fetus and other species are not. A thermophile is an organism that thrives at temperatures between 45 and 70 degrees centrigrade. The correct answer is that Campylobacter have a polar flagellum which aids motility. The flagellae of C. jejuni are required for colonisation. Incorrect. Campylobacter are sensitive to drying. The correct answer is that Campylobacter have a polar flagellum which aids motility. The flagellae of C. jejuni are required for colonisation. Correct! Campylobacter have a polar flagellum which aids motility. The flagellae of C. jejuni are required for colonisation. Incorrect. Campylobacter is oxidase positive. The oxidase test is used to determine if a bacterium produces certain cytochrome c oxidases. If a bacterium is positive this indicates it can utilise oxygen for energy production. The correct answer is that Campylobacter have a polar flagellum which aids motility. The flagellae of C. jejuni are required for colonisation. Incorrect. Campylobacter are all curved Gram negative rods. The correct answer is that Campylobacter have a polar flagellum which aids motility. The flagellae of C. jejuni are required for colonisation.

2

Which of the following is true of Actinobacillus lignieresii? Bacteria usually invade the mandible to cause osteomyelitis A. lignieresii penetrates damaged oral mucosa to initiate an infection The bacteria are only able to invade porcine mucosa Infection is localised and rarely spreads Infection occurs from a reservoir of bacteria in the environment Please select an option Incorrect. Actinomyces bovis, a different commensal oral bacteria has this pathogenesis. It causes granulomatous inflammation of the soft tissue like A. lignieresii but also affects the bone hence the disease is called lumpy jaw. The correct answer is A. lignieresii penetrates damaged oral mucosa to initiate an infection. Correct! A. lignieresii is a commensal of the mouth and intestinal tract of cattle and sheep. When the oral mucosa is damaged the bacteria invade to cause a chronic granulomatous inflammation. Incorrect.A. lignieresii commonly infects cattle and sheep but not pigs. Actinobacillus pleuropneumoniae does however infect pigs to cause pleuropneumonia. The correct answer is A. lignieresii penetrates damaged oral mucosa to initiate an infection. Incorrect. A. lignieresii often spreads to lymphatics to cause pyogranulomatous lymphadenitis. Spread to the retropharyngeal lymph node can impair swallowing and breathing. The correct answer is A. lignieresii penetrates damaged oral mucosa to initiate an infection. Incorrect. A. lignieresii is a commensal of the mouth and intestinal tract. It is unable to survive in the environment for extended periods and so relies on carrier animals to propagate infection. The correct answer is A. lignieresii penetrates damaged oral mucosa to initiate an infection.

3

Above what pH does Listeria moncytogenes replicate in silage? pH 5 pH 4 pH 5.5 pH 4.5 pH 3.5 Please select an option Incorrect. Above pH 5.5 Listeria can replicate in silage. Avoid poor quality silage and discontinue silage-feeding in an outbreak. WikiVet Article: Listeria Incorrect. Above pH 5.5Listeria can replicate in silage. Avoid poor quality silage and discontinue silage-feeding in an outbreak. WikiVet Article: Listeria Correct! Above pH 5.5 Listeria can replicate in silage. Avoid poor quality silage and discontinue silage-feeding in an outbreak. WikiVet Article: Listeria Incorrect. Above pH 5.5 Listeria can replicate in silage. Avoid poor quality silage and discontinue silage-feeding in an outbreak. WikiVet Article: Listeria Incorrect. Above pH 5.5 Listeria can replicate in silage. Avoid poor quality silage and discontinue silage-feeding in an outbreak. WikiVet Article: Listeria

4

Which of the following is true regarding zoospores of Dermatophilus congolensis? Dormant zoospores become activated in conditions of high rainfall and temperature Zoospores do not stain with Giemsa Zoospores are unable to survive in scabs Activated zoopspores produce filaments which can not invade the epidermis Zoospores can not be cultured Please select an option Correct! After heavy rainfall previously dormant zoospores can be released from scabs and initiate an infection. Dermatophilus infection is especially prevalent in tropical countries due to the favourable climate. Incorrect. Giemsa-stained smears from scabs reveal branching filaments containing zoospores. The correct answer is that dormant zoospores become activated in conditions of high rainfall and temperature. Dermatophilus infection is especially prevalent in tropical countries due to the favourable climate. Incorrect. Zoospores are able to survive in scabs for up to 3 years. The correct answer is dormant zoospores become activated in conditions of high rainfall and temperature. Dermatophilus infection is especially prevalent in tropical countries due to the favourable climate. Incorrect. Activated zoospores produce germ tubes which develop into filaments which invade the epidermis. The correct answer is dormant zoospores become activated in conditions of high rainfall and temperature. Dermatophilus infection is especially prevalent in tropical countries due to the favourable climate. Incorrect. Zoospores can be cultured on blood agar. Colonies are yellow and haemolytic (after 48 hours); they later become rough and yellow, and gain a mucoid appearance. The correct answer is that dormant zoospores become activated in conditions of high rainfall and temperature. Dermatophilus infection is especially prevalent in tropical countries due to the favourable climate.

5

Which of the following is a characteristic of Listeria spp? Aerobic Extracellular pathogens Catalase negative Soil inhabiting saprophyte Grow on enriched media only Please select an option Incorrect. Listeria spp are facultative anaerobes. The correct answer is that Listeria spp. are soil inhabiting saprophytes and obtain nutrients from decomposing organic matter.WikiVet Article: Listeria Incorrect. Listeria spp.are intracellular pathogens. The bacteria penetrate M cells in intestinal Peyer's patches. The correct answer is that Listeria spp. are soil inhabiting saprophytes and obtain nutrients from decomposing organic matter.WikiVet Article: Listeria Incorrect. Listeria spp. are catalase positive. The correct answer is that Listeria spp. are soil inhabiting saprophytes and obtain nutrients from decomposing organic matter.WikiVet Article: Listeria Correct!Listeria spp. are soil inhabiting saprophytes and obtain nutrients from decomposing organic matter. WikiVet Article: Listeria Incorrect. Listeria spp. will grow on non-enriched media. Small, smooth, transparent colonies form after 24 hours' incubation. The correct answer is that Listeria spp. are soil inhabiting saprophytes and obtain nutrients from decomposing organic matter.WikiVet Article: Listeria

6

What is the longest time Corynebacterium pseudotuberculosis has been known to survive in the environment? Several years Several months Several days Several weeks Several hours Please select an option Incorrect. C. pseudotuberculosis causes caseous lymphadenitis in sheep and goats in the UK and ulcerative lymphangitis in horses in the USA, but has only been known to persist in the environment for several months. WikiVet Article: Corynebacterium Correct! C. pseudotuberculosis causes caseous lymphadenitis in sheep and goats in the UK and ulcerative lymphangitis in horses in the USA, and has been known to persist in the environment for several months. WikiVet Article: Corynebacterium Incorrect. C. pseudotuberculosis causes caseous lymphadenitis in sheep and goats in the UK and ulcerative lymphangitis in horses in the USA, and has been known to persist in the environment for several months. WikiVet Article: Corynebacterium Incorrect. C. pseudotuberculosis causes caseous lymphadenitis in sheep and goats in the UK and ulcerative lymphangitis in horses in the USA, and has been known to persist in the environment for several months. WikiVet Article: Corynebacterium Incorrect. C. pseudotuberculosis causes caseous lymphadenitis in sheep and goats in the UK and ulcerative lymphangitis in horses in the USA, and has been known to persist in the environment for several months. WikiVet Article: Corynebacterium

7

What laboratory test allows differentiation between Proteus and Salmonella? Growth on MacConkey agar Motility Oxidase test Lactose fermenting abilities Urease test Please select an option 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. 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 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 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 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

8

Which of the following is a characteristic of Salmonella? Oxidase positive Catalase negative Unable to grow on MacConkey agar Produce urease from tryptophan Non lactose fermenter Please select an option 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 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 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. 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

9

Which growth medium is most suited to Nocardia growth? Xylose lysine deoxycholate (XLD)agar MacConkey agar Blood agar Eosin-methylene blue agar Mannitol salt agar Please select an option Incorrect. Xylose lysine deoxycholate agar (XLD)is a selective growth medium used in the isolation of Salmonella and Shigella species. The correct answer is blood agar. Incorrect. Norcardia is Gram-positive and so would not grow on MacConkey agar which is selective for Gram-negative bacteria. The correct answer is blood agar. Correct! Nocardia grows on blood agar after incubation in aerobic conditions for 10 days at 37 degrees centigrade. Nocardia can also be subcultured on Sabouraud dextrose agar. Incorrect. Eosin-methylene blue agar is toxic to Gram-positive bacteria and so would not allow Nocardia growth. The correct answer is blood agar. Incorrect. Mannitol salt agar is selective for Gram-positive bacteria but only of the staphylococci species and so is not a suitable growth medium to culture Nocardia. The correct answer is blood agar.

10

On what medium do NAD-dependent strains of Haemophilus grow on? Chocolate agar Blood agar Mannitol salt agar MacConkey agar Eaton's agar Please select an option Correct! NAD-dependent strains require chocolate agar to grow when cultured. Haemin-dependent strains will also grow on blood agar and neither strain grows on MacConkey agar. Incorrect. NAD-dependent strains require chocolate agar to grow when cultured. Haemin-dependent strains will also grow on blood agar and neither strain grows on MacConkey agar. Incorrect. Mannitol salt agar is selective for Gram positive bacteria. NAD-dependent strains require chocolate agar to grow when cultured. Haemin-dependent strains will also grow on blood agar and neither strain grows on MacConkey agar. Incorrect. NAD-dependent strains require chocolate agar to grow when cultured. Haemin-dependent strains will also grow on blood agar and neither strain grows on MacConkey agar. Incorrect. Eaton's agar is selective for Mycoplasma pneumoniae. NAD-dependent strains require chocolate agar to grow when cultured. Haemin-dependent strains will also grow on blood agar and neither strain grows on MacConkey agar.

11

Which of the following is a characteristic of Actinomyces bovis bacteria? They are short filamentous branching rods They form club shaped colonies They are gram negative Colonies are haemolytic They are strict aerobes Please select an option Incorrect. Actinomyces bovis is a long filamentous branching gram positive rod. The correct answer is actinomyces bovis forms club shaped colonies. Correct! Actinomyces bovis forms club shaped colonies. Incorrect. Actinomyces bovis are gram positive rods. The correct answer is that Actinomyces bovis forms club shaped colonies. Incorrect. Colonies of actinomyces bovis are actually non-haemolytic when grown on blood agar. The correct answer is that Actinomyces bovis forms club shaped colonies. Incorrect. Actinomyces bovis prefers anaerobic conditions but is not a strict anaerobe. The correct answer is that Actinomyces bovis forms club shaped colonies.