Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbiology > Enterobacteriae > Flashcards

Enterobacteriae Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

What is the significance of agglutinin titres in the context of typhoid?

A

Agglutinins appear by the end of the first week, with titres increasing until the third or fourth week, after which they decline gradually.

Significant titres: 1/100 or more for ‘O’ agglutinins and 1/200 or more for H agglutinins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What antibodies are present in individuals immunized with the TAB vaccine?

A

Antibodies to S. typhi, S. paratyphi ‘A’, and ‘B’.

In case of infection, antibodies will be seen only against the infecting species.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the Vi polysaccharide vaccine and its administration details?

A

It contains purified Vi capsular polysaccharide from Ty2 strain, given as a single dose by subcutaneous or intramuscular route, with re-vaccination every 3 years for individuals ≥ 2 years of age.

It can be co-administered with other vaccines, e.g., yellow fever and hepatitis A.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the characteristics of the Ty 21a Oral vaccine?

A

It is an orally administered live attenuated vaccine containing > 10º viable organisms of live attenuated Ty 21a strain, administered on days 1, 3, and 5, with a recommendation to repeat every 3 years for endemic areas and yearly for travelers from non-endemic to endemic countries.

The Ty 21a strain lacks the enzyme UDP-galactose-4-epimerase (Gal E mutant).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the drug of choice (DOC) for treating typhoid cases?

A

Ceftriaxone.

Ciprofloxacin should be used if the strain is sensitive to ciprofloxacin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the treatment for typhoid carriers?

A

Ampicillin or amoxicillin for 6 weeks.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the characteristics of Proteus bacteria.

A

Gram negative, motile, non-capsulated, pleomorphic bacilli that appear in various forms (coccobacilli, bacillary, filamentous) and are non-lactose fermenters.

Includes Proteus vulgaris, Proteus mirabilis, Morganella, and Providencia.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which bacteria are urease positive?

A

Proteus vulgaris, Proteus mirabilis, and Morganella.

Providencia is the exception, as it is urease negative.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does a positive result in the PPA test indicate?

A

It indicates urease positivity and H2S production, used for P. mirabilis and P. vulgaris.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the indole test results for P. vulgaris and P. mirabilis?

A

Positive for P. vulgaris, negative for P. mirabilis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What characteristic odor do Proteus cultures produce?

A

Characteristic putrid ‘fishy’ or ‘seminal’ odor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the mechanism of action of the active fragment A in the plasmid-coded toxin?

A

Causes ADP ribosylation of G protein, upregulates adenylate cyclase, leading to cyclic AMP production and resulting in water and electrolytes secretion, causing diarrhea.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does Fragment B of the plasmid-coded toxin bind to?

A

Binds to GM1 ganglioside receptors on intestinal epithelium.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the mechanism of action of the heat-stable toxin (ST) produced by Enterotoxigenic E. coli?

A

Binds to guanylate cyclase, leading to cyclic GMP production and diarrhea.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is Verocytotoxin also known as?

A

Shiga-like toxin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the mechanism of action of Shiga-like toxin?

A

Fragment B binds to globotriosyl ceramide (Gb3) receptor on intestinal cells; Fragment A inhibits protein synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How is Shiga-like toxin coded?

A

Bacteriophage coded.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the two types of surface antigens in E. coli?

A
  • O antigen (somatic lipopolysaccharide)
  • K antigen (capsular antigen/envelope antigen)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the role of the O antigen in E. coli?

A

Has endotoxic activity, protects bacteria from phagocytosis and bactericidal effects of complement.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the function of the K antigen in E. coli?

A

Affords protection against phagocytosis and antibacterial factors in normal serum.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the significance of fimbriae in uropathogenic E. coli?

A

Plasmid coded, important in urinary tract infections (UTI); no role in gastroenteritis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What disease is caused by Enterotoxigenic E. coli (ETEC)?

A

Traveler’s diarrhea and infant diarrhea in developing countries.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the site of action for Enteropathogenic E. coli?

A

Small intestine.

24
Q

What type of diarrhea is caused by Enteropathogenic E. coli?

A

Watery diarrhea in infants and children, with non-bloody stools.

25
Q

What is the pathogenesis of Enteropathogenic E. coli?

A

Non-invasive, causes disruption of intestinal cells without toxin production.

26
Q

Fill in the blank: The active fragment A of the toxin causes _______.

A

ADP ribosylation of G protein.

27
Q

True or False: Fragment A of Shiga-like toxin is responsible for protein synthesis inhibition.

A

True.

28
Q

What is the primary pathogenic feature of Entero-pathogenic E. coli (EPEC)?

A

Causes persistent diarrhea; exhibits ‘stacked bricks’ adherence pattern on Hep-2 cells

EPEC is a significant cause of traveler’s diarrhea and affects the small intestine.

29
Q

What does Entero-hemorrhagic E. coli (EHEC) primarily cause?

A

Bloody diarrhea (hemorrhagic colitis)

EHEC produces Verocytotoxin or Shiga toxin, leading to microvilli destruction and platelet aggregation.

30
Q

What is the most prominent serotype of EHEC?

A

0157:H7

EHEC is the most common cause of hemolytic uremic syndrome.

31
Q

What is the primary cause of urinary tract infections (UTIs)?

A

E. coli

This is true for both catheterized and non-catheterized patients.

32
Q

What virulence factor is important in the pathogenesis of E. coli-related UTIs?

A

P-fimbriae (P-1 pili)

Early serotypes (0-1, 2, 4, 6) are most commonly responsible for UTIs.

33
Q

What are the characteristics of Shigella?

A

Gram negative, facultatively anaerobic rods, oxidase negative, non motile, non capsulated

There are four recognized species: S. dysenteriae, S. flexneri, S. boydii, S. sonnei.

34
Q

Which species of Shigella is the most virulent?

A

Shigella dysenteriae type I

It causes the most severe form of dysentery with maximum complications.

35
Q

Which Shigella species is considered the least virulent?

A

Shigella sonnei

It causes the mildest disease among the Shigella species.

36
Q

What is a key virulence factor of Shigella?

A

Invasiveness

Shigella actively penetrates and multiplies in the colonic mucosa.

37
Q

Fill in the blank: All Shigella species are lactose ______.

A

non-fermenters

Except for S. sonnei, which is a late lactose fermenter.

38
Q

What test is used to demonstrate the invasiveness of Shigella?

A

Sereny test

This test identifies virulence marker antigens.

39
Q

What is the most common species of Shigella in the world?

A

Shigella sonnei

In India, Shigella flexneri is more common.

40
Q

Which Shigella species ferments mannitol?

A

All Shigella species

Except for S. dysenteriae, which does not ferment mannitol.

41
Q

What is the IMViC profile of Shigella?

A

MR +ve; Indole, citrate, VP negative

This profile helps differentiate Shigella from other Enterobacteriaceae.

42
Q

What is the primary pathogenic feature of Entero-pathogenic E. coli (EPEC)?

A

Causes persistent diarrhea; exhibits ‘stacked bricks’ adherence pattern on Hep-2 cells

EPEC is a significant cause of traveler’s diarrhea and affects the small intestine.

43
Q

What does Entero-hemorrhagic E. coli (EHEC) primarily cause?

A

Bloody diarrhea (hemorrhagic colitis)

EHEC produces Verocytotoxin or Shiga toxin, leading to microvilli destruction and platelet aggregation.

44
Q

What is the most prominent serotype of EHEC?

A

0157:H7

EHEC is the most common cause of hemolytic uremic syndrome.

45
Q

What is the primary cause of urinary tract infections (UTIs)?

A

E. coli

This is true for both catheterized and non-catheterized patients.

46
Q

What virulence factor is important in the pathogenesis of E. coli-related UTIs?

A

P-fimbriae (P-1 pili)

Early serotypes (0-1, 2, 4, 6) are most commonly responsible for UTIs.

47
Q

What are the characteristics of Shigella?

A

Gram negative, facultatively anaerobic rods, oxidase negative, non motile, non capsulated

There are four recognized species: S. dysenteriae, S. flexneri, S. boydii, S. sonnei.

48
Q

Which species of Shigella is the most virulent?

A

Shigella dysenteriae type I

It causes the most severe form of dysentery with maximum complications.

49
Q

Which Shigella species is considered the least virulent?

A

Shigella sonnei

It causes the mildest disease among the Shigella species.

50
Q

What is a key virulence factor of Shigella?

A

Invasiveness

Shigella actively penetrates and multiplies in the colonic mucosa.

51
Q

Fill in the blank: All Shigella species are lactose ______.

A

non-fermenters

Except for S. sonnei, which is a late lactose fermenter.

52
Q

What test is used to demonstrate the invasiveness of Shigella?

A

Sereny test

This test identifies virulence marker antigens.

53
Q

What is the most common species of Shigella in the world?

A

Shigella sonnei

In India, Shigella flexneri is more common.

54
Q

Which Shigella species ferments mannitol?

A

All Shigella species

Except for S. dysenteriae, which does not ferment mannitol.

55
Q

What is the IMViC profile of Shigella?

A

MR +ve; Indole, citrate, VP negative

This profile helps differentiate Shigella from other Enterobacteriaceae.

Microbiology (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions