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Bugs and Drugs > Gram Negative Bacteria > Flashcards

Gram Negative Bacteria Flashcards

1
Q

Describe the structure of a G- bacteria.

A

It has an inner membrane with proteins, a periplasm with lipoproteins and a peptidoglycan cell wall, and an outer membrane with proteins, LPS and porins

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2
Q

What are the four components of LPS from out to in?

A
  1. O-antigen made of repeating sugars
  2. Outer core with heptose, glucose, galactose
  3. Inner core with heptose and KDO
  4. Lipid A which confers virulence
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3
Q

Gram negative rods can be divided into two major groups. What are they?

A

Fermenters and non-fermenters

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4
Q

Are enterobacteriacae fermenters or non-fermenters? What strains of bacteria fall in this category?

A

They are gram negative rods that are fermenters.

Enterobacteriacae are vibrio and aeromonas

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5
Q

What bacteria are gram negative rod fermenters that are lactose fermenters? Which are fast and which are slow?

A
  1. E. coli- fast
  2. Klebsiella-fast
  3. Enterobacter-fast
  4. citrobacter-slow
  5. serratia-slow
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6
Q

What are gram negative fermenters that cannot ferment lactose? (only other sugars)

A

Salmonella
shigella
proteus
yersinia

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7
Q

Which gram negative rods are non-fermenters?

A
  1. pseudomonas aeruginosa
  2. acinetobacter
  3. Xanthomanas
  4. Strenotrophomonas
  5. Burkholderia
  6. Helicobacter
  7. Campylobacter
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8
Q

What are examples of gram negative cocci that ferment maltose and glucose?

A

Niesseria menigitidis

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9
Q

What are examples of gram negative cocci that do not ferment maltose, but can ferment glucose?

A

Niesseria gonorrheae

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10
Q

Gram negative cocci are all strongly ______ positive.

A

oxidase

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11
Q

Gram negative coccobacillary _____________ oxidase positive.

A

+/-

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12
Q

What are examples of coccobacillary gram negatives?

A
  1. Haemophilus influenza- cofactors
  2. Bordatella pertussis- special media
  3. moraxella catarrhalis
  4. brucella abortus
  5. pasteurella multocida
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13
Q

Lactose fermenting ____________ can be differentiated from non-lactose fermenting ________________.

A 
Lactose= E. coli
Non-lactose = Salmonella
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14
Q

What agar would be used to isolate gram negative bacteria?

A

MacConkey’s because crystal violet and bile restrict the growth of gram positives

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15
Q

What agar is used to isolate gram positives?

A

Colistin (nalidixic acid) because it binds LPS to inhibit growth of gram negatives

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16
Q

Describe the oxidase test.

A

It is used to see if a bacteria can produce cytochrome c oxidase (showing it uses an electron transport chain – aerobic)
If something is oxidase positive, it will convert colorless solution to purple

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17
Q

Describe Enterobacteriaceae:

  1. gram stain and shape
  2. oxygen usage
  3. spore capability
  4. catalase + or -
  5. Fermentation ability
  6. motility/type of flagella
A
  1. Gram negative rod
  2. facultative anaerobe
  3. can NOT form spores
  4. Catalase +
  5. ferments glucose and others
  6. motile with peritrichous flagella
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18
Q

What is the most common enterobacteriaceae?

A

E. coli

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19
Q

Where is the reservoir for E. coli?

A

GI tract and they are commensal

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20
Q

What are the three most common syndromes associated with E. coli?

A
  1. Diarrhea
  2. UTI
  3. neonatal sepsis and meningitis
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21
Q

What is the number one cause of UTI?

A

E. coli

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22
Q

What pili are associated with the attachment of E. coli?

A
  1. Type 1 pillin

2. P fimbrae

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23
Q

For E. coli, certain ____ and _____ antigens correlate to disease

A

O (LPS) and K (capsular)

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24
Q

What antigen of E. coli is responsible for the vast majority of neonatal sepsis?

A

K1 capsular antigen

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25
Q

The KI capsular antigen of E. coli resembles the structure of ___________________________ because of the sailic acid.

A

group B streptcoccus capsule

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26
Q

What are the three major toxins associated with diarrheal syndromes of E. coli?

A
  1. Heat-labile toxin (plasmid)
  2. Heat-stable toxin (plasmid)
  3. Shiga-like toxin (lysogenic prophage)
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27
Q

Describe the heat-labile toxin of E. coli. What does it cause?

A

It is an A-B toxin (like cholera) that activates adenylate cyclase.
It causes traveler’s diarrhea

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28
Q

Describe the heat-stable toxin of E. coli What does it cause?

A

It is an AB toxin that activates guanylate cyclase and causes diarrhea

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29
Q

Describe the shiga-like toxin of E. coli.

What is the major example?

A

It is a lysogenic prophage that acts as an enterotoxin causing fluid secretion

Prime example: O157:H7

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30
Q

Describe Vibrio spp:

  1. gram stain
  2. motility (what kind of flagella)
A
  1. They are curved gram negative rods

2. sIngle Polar flagella

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31
Q

What is the habitat of Vibrio spp?

A

Aqueous environments

oceans, brackish water, eating shellfish, fecal-oral spread

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32
Q

What are the three most notable kinds of vibrio spp?

A
  1. Vibrio cholera
  2. Vibrio parahaemolyticus
  3. Vibrio vulinficus
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33
Q

What type of toxin is associated with vibrio cholera?

A

AB toxin that is a lysogenic prophage. It increases cAMP in the host causing secretory diarrhea (20L/day–> dehydration/death)

34
Q

What serotypes of O antigen are associated with vibrio cholera?

A

O1 and O139

35
Q

What disease is caused by vibrio parahaemolyticus?

A

gastroenteritis- cramping, abdominal pain, nausea, vomiting, fever, bloody diarrhea

36
Q

What disease is associated with vibrio vulnificus? How do you acquire this infection?

A
  1. Soft tissue infection and sepsis
  2. liver disease

You get V. vulnificus from eating raw oysters

37
Q

Describe Helicobacter pylori:

  1. gram stain and shape
  2. oxygen consumption
A

They are gram negative rods with a curved shape.
They are motile
Microaerophiles

38
Q

What do helicobacter pylori utilize for energy?

A

Amino acids.

they utilize a urease to break urea into ammonium and carbon dioxide

39
Q

Where do helicobacter pylori reside?

A

In the stomach and duodenum

40
Q

What disease do helicobacter pylori cause?

A

Peptic ulcers that can lead to:
Malignant carcinoma
MALT lymphoma (cured by antibiotics)

41
Q

What is unique about the growth of C. jejuni and other campylobacter?

A

They grow best at 42 degrees celcius

42
Q

Describe the shape, gram stain and motility of Campylobacter.

A

They are GNR that are curved and motile

43
Q

What is the reservoir for campylobacter?

A

Birds

44
Q

What bacteria contaminates most chickens in the US?

A

Campylobacter

45
Q

What disease presentation is associated with campylobacter?

A

Febrile, bloody diarrhea

46
Q

Describe Pseudomonas aeruginosa:

  1. gram stain and shape
  2. Motility
  3. oxygen consumption
A
  1. GNR
  2. motile with polar flagella
  3. aerobic- (non-fermentor, oxidase +)
47
Q

Pseudomonas aeroginosa is an aerobic GNR. This means that is will test ________ positive and will be a ______________.

A

It will test oxidase positive and will be a non-fermentor

48
Q

What is unique about the growth of pseudomonas aeroginosa?

A

It has a fruity smell in culture and has pigments:

Pyocyanin and pyoverdin

49
Q

What is the reservoir for pseudomonas aeruginosa?

A

Soil and water organisms (ubiquitous)

50
Q

What virulence factor is associated with pseudomonas aeruginosa?

A

It can form biofilm

51
Q

What diseases are associated with pseudomonas aeruginosa?

A
  1. Nosocomial pneumonia associated with ventilators
  2. Burn patients
  3. cystic fibrosis
52
Q

What is the gram stain and shape of pasteurella mutlocida?

A

It is a gram negative coccobacillary that is small and non-motile

53
Q

What is the reservoir of pasteurella mutlocida?

A

It lives in the mouths of cats and dogs so it can cause infection after a bite

54
Q

Describe the gram staining and shape of francisella?

A

GNR that is small and non-motile

55
Q

What region of the country has francisella?

A

Tulare county in CA is where it was found, but it is now seen most in the midwest (oklahoma especially)

56
Q

What disease is associated with francisella?

How is the infection acquired?

A

It is a zoonotic infection that causes “rabbit fever” and is acquired via puncture through skin or inhalation

57
Q

What is the gram staining and oxygen consumption of legionella pneumophila?

A

It is a GNR that is aerobic and requires fastidious nutrition on culture

58
Q

What is the reservoir for legionella?

A

It is ubiquitous in water and has adapted to parasitize free living amoeba

59
Q

What specific cell is legionella an intracellular pathogen to?

A

Macrophages where they inhibit phagolysosomal fusion, acidification and respiratory burst

60
Q

What disease is caused by legionella infection?

A

Community acquired pneumonia

61
Q

Describe Neisseria:

  1. gram staining
  2. shape
  3. oxygen consumption
  4. fastidious growth
A
  1. GN cocci
  2. diplococci
  3. aerobic- (oxidase +, non-fermentor)
  4. requires excess CO2 to grow in lab
62
Q

What agar would you use to grow Neisseria gonorrhea and Neisseria meningitidis?

A

Chocolate agar- blood agar that has been heated to release internal contents of RBC

Thayer-Martin from nonsterile sites

63
Q

What is the reservoir of N. meningitidis?

A

nasopharynx of humans

64
Q

What is the most common cause of sporadic bacterial meningitis in young adults (20-30)?

A

N. meningitidis

65
Q

Where are epidemics of N. meningitidis likely to occur?

A

Highly crowded areas like dorms, prisons, military barracks

66
Q

What is the main virulence factor of N. menigitidis?

A

It has a capsule to allow it to be antiphagocytic

67
Q

How many serotypes does the N. meningitidis capsule have? What serotypes cause disease?

Which serotypes are there vaccines for?

A

There are 13 serotypes and A B C Y and W135 cause disease

There are vaccines for A C Y and W135 (NOT B)

68
Q

What is the reservoir for N. gonorrhea?

A

humans- common STD

69
Q

What are the 2 virulence factors associated with N. gonorrhea?

A
  1. Pilin for attachment (with phase variation)

2. IgA protease to avoid immune detection

70
Q

How do neisseria (both gonorrhea and meningitidis) avoid immune detection?

A

They have IgA protease

71
Q

What is the most common presentation of N. gonorrhea?

A
  1. Urethritis- drip/clap where there is milky white discharge and burning dysuria
  2. prostatitis and orchitis in men
  3. cervicictis and salpingitis (PID) in women
72
Q

If gonorrhea disseminates beyond genitalia, what can it cause?

A

Dermatitis-arthritis syndrome

73
Q

There are many other Neisseria besides gonorrhea and meningitidis.
They are all __________ positive
They differ in what four ways?

A 
They are all oxidase positive
They differ in :
1. sugar use
2. growth in CO2
3. pigment production 
4. capsular formation
74
Q

What two enzymes do anaerobes lack that do not allow them to detoxify oxygen biproducts?

A
  1. superoxide dismutase

2. catalase

75
Q

Anaerobes are the predominant species in what four body regions?

A
  1. mouth
  2. GI tract
  3. GU tract
  4. Skin appendages (hair follicles and sweat glands)
76
Q

Mouth flora is a mixture of _______ and ________/

A

viridans streptococci and anaerobes

77
Q

Anaerobes comprise what percent of the colonic flora?

A

99.99%

78
Q

What diseases are caused by anaerobes in the mouth?

A
  1. Peridontal disease
  2. Oral and pharyngeal absess
  3. Lung absess
79
Q

What diseases are caused by anaerobes in the GI tract?

A

intraabdominal abscesses

80
Q

What diseases are caused by anaerobic bacteria in the GU tract?

A

Pelvic inflammatory disease and tubo-ovarian abscesses

81
Q

What are the 5 main anaerobes that infect the head and neck?

A
  1. bacteroides
  2. fusobacterium
  3. porphyromonas
  4. prevotella
  5. veillonella
82
Q

What are the 2 main anaerobes that cause intraabdominal abscesses and gynecologic problems?

A
  1. bacteroides

2. prevotella

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