Gram Negative Pathogens (Neiserria and Enterics) Flashcards

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1
Q

T/F. Neisseria is G+.

A

False. G-

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2
Q

T/F. Neisseria exists as staphylococci.

A

False. Diplococci

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3
Q

T/F. Neisseria is aerobe.

A

False. Facultative anaerobe

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4
Q

T/F. Neisseria optimally grows in high O2 conditions.

A

False. Facultative anaerobe; optimal growth at high Co2 conditions

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5
Q

How do you differentiate N. meningitidis and N. gonorrheae?

A

N. meningitidis is a maltose and glucose fermenter

N. gonorrheae is a glucose fermenter only

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6
Q

T/F. N. meningitidis is part of the normal flora.

A

True. Accounting to 5% of the normal flora

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7
Q

T/F. N. meningitidis causes what characteristics diseases?

A

Meningitis and septicemia

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8
Q

N. meningitidis is spread via what infectious medium?

A

Respiratory secretions

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9
Q

The endotoxin associated with N. meningitidis is in the form of?

A

Lipopolysaccharide (LPS)

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10
Q

What are the virulence factors associated with N. meningitidis?

A

Pilus for adherence
Capsule
Endotoxin (LPS)
IgA Protease

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11
Q

Among the virulence factors of N. meningitidis, which provides capacity for adherence?

A

Pilus

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12
Q

Symptoms of N. meningitidis-induced meningitis:

A

fever
petechial rash
stick neck
lethargy
vomiting

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13
Q

Symptoms of N. meningitidis-induced septicemia:

A

fever
petechial rash
hypotension

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14
Q

Petechial rash appears to be associated with Neisseria infection. This condition is due to?

A

Destruction of the blood vessels caused by the LPS endotoxin in N. meningitidis

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15
Q

Treatment for N. meningitidis infection?

A

Penicilin G
rifampin
ceftriaxone
ciprofloxacin
Vaccine

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16
Q

T/F. Neisseria species are rods species.

A

False. Cocci

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17
Q

Culture medium for Neisseria isolation

A

Chocolate agar - supports fastidious nature of N species

Thayer- Martin VCN media - selective media against G+, other G- (esp rods), and fungi

V - vancomycin - against G+
C - Colistin - against other G-, esp G- rods
N - Nystatin - against fungi

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18
Q

What populations are particularly susceptible to N. meningitidis infection?

A

Neonates susceptible
Army recruits - coming from different places
Freshmen in dorms - coming from different place

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19
Q

What is the 2nd most common STD?

A

Gonorrhea

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20
Q

What are the virulence factors associated with N. gonorrheae?

A

Pilus
PorA and PorB (outer membrane porins)
Opa proteins

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21
Q

Of the virulence factors of N. gonorrheae, which allows invasion into epithelial cells?

A

PorA and PorB

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22
Q

Of the virulence factors of N. gonorrheae, which provides both adherence and invasion functions?

A

opa proteins

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23
Q

What is the primary presentation of N. gonorrheae infection in males?

A

urethritis

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24
Q

What is the primary presentation of N. gonorrheae infection in females?

A

cervical gonorrhea which may lead to pelvic inflammatory disease

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25
Q

What presentation of N. gonorrheae infection is common among males and females?

A

gonoccocal bacteremia and septic arthritis

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26
Q

What is the primary presentation of N. gonorrheae infection in neonates?

A

opthalmia neonatorum (neonatal conjunctivitis)

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27
Q

Treatment for N. gonorrheae (general population):

A

Ceftriaxone, cefixime, gentamicin

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28
Q

Treatment for N. gonorrheae (neonates):

A

erythromycin eyedrops and syrup for prophylaxis against N. gonorrheae and concurrent chlamydial infection

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29
Q

When diagnosing N. meningitidis, inoculum may be derived from?

A

CSF or petechial scrapings

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30
Q

T/F. Complete immunity can be developed after initial infection by N. gonorrheae making subsequent reinfection impossible.

A

False. No immunity; reinfection is possible

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31
Q

T/F. Enterobacteriaceae species are very common and are part of the normal gut microflora or may cause GI infections.

A

True.

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32
Q

How many genera are classified under Enterobacteriaceae?

A

63 genera

33
Q

How many species of Enterobacteriaceae is considered clinically significant?

A

20-25 species

34
Q

T/F. Enterobacteriaceae are G- coccus.

A

False. G- rods

35
Q

T/F. All Enterobacteriaceae are motile.

A

False. Some are nonmotile

36
Q

Motile Enterobacteriaceae are associated with having what structures?

A

A peritrichous flagella

37
Q

T/F. Enterobacteriaceae are facultative anaerobes.

A

True.

38
Q

T/F. Enterobacteriaceae can undergo glucose fermentation with gas production.

A

True

39
Q

T/F. Enterobacteriaceae catalase positive.

A

True

40
Q

T/F. Enterobacteriaceae are oxidase positive.

A

False. Oxidase negative

41
Q

T/F. Enterobacteriaceae cannot reduce nitrate.

A

False. Can reduce nitrate to nitrite

42
Q

Colony characteristics of E. coli include:

A

circular, convex, and smooth colonies

43
Q

T/F. Some strains of E. coli may be hemolytic

A

True.

44
Q

Colony characteristic of Enterobacter

A

Mucoid colonies

45
Q

Colony characteristic of Klebsiella

A

large and mucoid colonies

46
Q

Colony characteristic of Salmonella and Shigella

A

Colonies like E. coli but do not ferment lactose

47
Q

What are the differential and biochemical tests for Enterobacteriaceae.

A

IMViC test
TSIA in slant/butt tubes
Use of differential media, e.g., EMB, MAC, and deoxycholate
MPN test

48
Q

Which member of Enterobacteriaceae can ferment lactose and which do not?

A

E. coli - ferments lactose
Salmonella, Shigella, and Pseudomonas do not

49
Q

In Eosin Methylene Blue (EMB) is a differential and selective medium. How does it differentiate/selects?

A

Eosin-Methylene Blue - selects G- bacteria and inhibits G+

Differentiates lactose fermentors (dark colonies) from non fermentors (pale/colorless)

E. coli, in particular, appear with characteristic green metallic sheen

50
Q

In TSIA slant/butt test, A/A indicates that

A

bacterium can ferment all three sugar

51
Q

The Triple Sugar Iron Agar (TSIA) contains what sugars allowing test for the capacity of bacteria to ferment these said sugars?

A

glucose
lactose
sucrose

52
Q

In TSIA slant/butt test, a crack in the agar indicates

A

gas production

53
Q

In TSIA slant/butt test, black precipitate indicates

A

hydrogen sulfide production through reduction of sulfur compounds

54
Q

IMViC is a series of biochemical tests for the characterization of Enterobacteriaceae species and includes

A

Indole test
Methyl red test
Voges-Proskauer test
Citrat test

55
Q

In TSIA slant/butt test, an A/K result indicates

A

glucose fermentation only

56
Q

In writing the serotype notation of bacteria, O refers to what antigen?

A

O antigen component of the LPS of the outer membrane

O antigen also provides resistance to alcohol and heat and induces IgM production by host

57
Q

In writing the serotype notation of bacteria, K refers to what antigen?

A

capsule

58
Q

In writing the serotype notation of bacteria, H refers to what antigen?

A

Flagella

59
Q

In this type of intestinal invasion by Enterobacteriaceae species, bacteria binds only to the cell and the release of exotoxins (de facto enterotoxins) cause watery diarrhea.

A

No cell invasion

60
Q

Which member of the Enterobacteriaceae usually performs no cell invasion and causes watery diarrhea?

A

Enterotoxigenic E. Coli and V. cholerae

61
Q

In this type of intestinal invasion by Enterobacteriaceae species, bacteria binds and invades the intestinal epithelium resulting in host cell death. This type is also associated with systemic immune response by the host.

A

Invasion of intestinal epithelial cells

62
Q

Which member of the Enterobacteriaceae usually performs invasion of intestinal epithelium.

A

Enteroinvasive E. coli, Shigella, Salmonella enteritidis

63
Q

In this type of intestinal invasion by Enterobacteriaceae species, bacteria enters and bloodstream and reaches the lymph nodes causing bacteremia, and sepsis.

A

invasion of lymph nodes and bloodstream

64
Q

Which member of the Enterobacteriaceae usually performs invasion of lymph nodes and bloodstream?

A

Salmonella typhi; Yersinia enterocolitica, Campylobacter jejuni

65
Q

What are the virulence factors associated with E. coli?

A

Pilus
Capsule
Exotoxin production (LT, ST, and Shiga-like toxin)
Endotoxin (Lipid A)
Iron-binding siderophores
Hemolysin

66
Q

Among the virulence factors of E. coli, which allows mucosal interaction?

A

Pilus

67
Q

E. coli exotoxin is in the forms of?

A

LT (cAMP) and ST (cGMP) toxins
Shiga-like toxins (acquired due to sharing of plasmid by Shigella)

68
Q

E. coli endotoxin is in the form of?

A

Lipid A

69
Q

What are the clinical findings associated with E. coli?

A

Neonatal meningitis
Diarrhea (Montezuma’s revenge aka traveller’s diarrhea)
UTI
Sepsis

70
Q

What is the most common cause of UTI?

A

E. coli

71
Q

What is the virulence factor allowing E. coli to produce urinary tract infection?

A

Pilus and fimbriae (allows E. coli to travel up the urethra)

Hemolysin

72
Q

Clinical findings associated with E. coli induced UTI:

A

Cystitis
Pyelonephritis

73
Q

Symptoms of E. coli induced UTI:

A

Dysuria - painful or difficult urination
Hematuria - blood in urine
Pyuria - pus in urine
Frequent urination

74
Q

What is the virulence factor allowing E. coli to induce sepsis?

A

(endo)Toxins

75
Q

T/F. E. coli induced sepsis is usually a primary infection.

A

False. E. coli induced sepsis is often secondary to UTI

76
Q

What is the most common cause of G- sepsis?

A

E. coli

77
Q

T/F E. coli induced sepsis generally affects the general population.

A

False. usually just the immunocompromised and neonates

78
Q

What is the virulence factor allowing E. coli to produce neonatal meningitis?

A

capsule