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MICROM 442 > Exam 2 Lecture 16 > Flashcards

Exam 2 Lecture 16 Flashcards

1
Q

Pseudomonas gram stain/morphology

A

Gram negative, rods, frequently flagellated w/ 1 or more polar flagella

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2
Q

Where can you find Pseudomonas?

A

huge range of environments and climates:

  • water, soil, air
  • most common organism in clouds/sky
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3
Q

True or false: Pseudomonas includes plant pathogens and commensals as well as soil bugs

A

True

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4
Q

Pseudomonas are largely _____ ____ and usually do not cause disease in healthy individuals.

A

opportunistic pathogens

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5
Q

Pseudomonas are frequently encountered as ______ in a clinical laboratory

A

contaminants

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6
Q

Normally, Pseudomonas are _____ or ______.

A

commensal or not found in microbiota

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7
Q

In what types of people can Pseudomonas cause infections?

A

people with weakened immune system (sick, cancer, etc.) or altered microbiota

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8
Q

P. aeruginosa general appearance

A

long, narrow, Gram negative rods

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9
Q

P. aeruginosa are _____- positive and grow well at __ºC

A

oxidase; 42

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10
Q

Why is it important to know that P. aeruginosa are oxidase positive?

A

Allows us to differentiate from Enterobacteriaceae

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11
Q 
Which of these factors are uniquely identifying in P. aeruginosa?
A. smell 
B. non-spore forming
C. metallic sheen on blood agar
D. oxidase-positive
E. catalase-positive
F. none of these
A

A, B, C, D

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12
Q

P. aeruginosa smell can be characterized as:

A

musty grape; corn chips

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13
Q

The metallic sheen produced by P. aeruginosa colonies on blood agar is a result of _____ _____, namely _____.

A

pigment production; pyocyanin

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14
Q

Why does Pseudomonas produce pyocyanin?

A

It is a virulence factor - serves as siderophore for iron binding/transport

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15
Q

True or false: pyocyanin fluoresces under UV light

A

True

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16
Q

P. aeruginosa is known as a “___ ___” because it is found in various locations, such as:

A

ubiquitous organism; water, soil, plants, animals, sewage, human skin

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17
Q

What are 2 classic diseases in healthy individuals caused by P. aeruginosa?

A
  1. Hot tub folliculitis

2. Swimmer’s ear

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18
Q

Hot tub folliculitis characterizations (2)

A
  1. superficial infection of hair follicle root

2. inoculation from contaminated water (namely, hot tubs or swimming pools)

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19
Q

True or false: hot tub folliculitis rarely clears on its own and must be treated with IV antibiotics

A

False (!!)

  • usually clears on its own
  • can treat with topical antibiotics
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20
Q

Swimmer’s ear characterizations

A
  1. aka otitis externa
  2. superficial infection of external ear canal skin
  3. inoculation from contaminated water
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21
Q

P. aeruginosa can cause more serious diseases in these types of people: (6)

A
  1. sick
  2. elderly
  3. immunocompromised
  4. burn patients
  5. uncontrolled diabetes
  6. those with cystic fibrosis
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22
Q

Cystic Fibrosis (CF) is a ____ disease caused by a ____ in ____.

A

genetic; mutation; CFTR

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23
Q

What is the role of the CFTR protein?

A

modulates flow of water and chloride ions out of cells into secretions

24
Q

A mutation in CFTR results in:

A

inefficient pumping, causing thick, mucinous secretions

25
Q

Major symptoms of cystic fibrosis

A

chronic pulmonary infections

26
Q

CF occurs in about ____ of live births in the ____ population

A

1/25,000; caucasian

27
Q

Pathophysiology of CF

A

thick mucus builds up in airway, colonized by bacteria, chronic infections result, causes progressive lung function decline

28
Q

CF treatments

A
  1. chronic antibiotic therapy to keep bacterial burdens in check
  2. pulmonary hygiene (exercises + inhalations to loosen mucus so it can be coughed up)
29
Q

The predominant lung pathogen in CF is _____.

A

P. aeruginosa

30
Q

True or false: typically the same infecting P. aeruginosa strain persists in the lung for years or decades and changes over time to become better suited to CF lung environment

A

True

31
Q

When organisms are spatially isolated, they can undergo ____ ____ and _____

A

genetic diversification; specialization

32
Q

The human lung consists of physically discrete ____

A

lobes

33
Q

What did researchers find during their study of P. aeruginosa population structure in CF lungs?

A

cultured out ~200 P. aeruginosa isolates per geographical region of the lung (~1200 per patient)

34
Q

True or false: lineages of P. aeruginosa from different regions of the lung generally have the same metabolic profiles and similar antibiotic resistance

A

False (!!!)

35
Q

Up to ___ the amount of yearly genetic divergence seen at baseline for P. aerugonisa

A

600 times

36
Q

P. aeruginosa virulence factors (5)

A
  1. iron sequestration
  2. exotoxins
  3. proteases
  4. biofilm formation *
  5. mucoid phenotype *
37
Q

What is a biofilm?

A

multicellular collection of bacteria which form 3D structure on a surface

38
Q

What are biofilms held together by, and what is it composed of?

A

Extracellular matrix; made from secreted polysaccharides > proteins > bacteria debris

39
Q

What is the predominant form of bacteria in the environment?

A

biofilm: either mono- or multi-species

40
Q

True or false: once a biofilm has formed, it’s generally easy to get rid of them

A

false

41
Q

Competitive advantages of biofilm (4)

A
  1. increased antibiotic resistance
  2. increased resistance to host mediated killing
  3. enhanced adherence
  4. favorable for bacterial persistence
42
Q

Biofilms are inherently ___ ____

A

antibiotic resistance

43
Q

Mechanisms of antibiotic resistance in biofilms

A
  1. profound changes in gene expression, can influence metabolism/antibiotic resistance directly
  2. center core of biofilms are nutrient limited, thus metabolically inactive
44
Q

Center core of biofilms provides these two things:

A
  1. reservoir of dormant cells

2. can re-seed and repopulate the biofilm

45
Q

Mucoid phenotype virulence factor is caused by:

A

overproduction of alginate (polysaccharide), makes capsule around bacteria

46
Q

True or false: persistent P. aeruginosa infections in CF do not usually progress to a mucoid phenotype

A

false (nearly always)

47
Q

Why is the alginate capsule a virulence factor? (4)

A
  1. structural support for mature biofilms
  2. enables “micro-metastasis” for biofilms, gives them a head start
  3. binds some antibiotics
  4. protects against host response by inhibiting complement/opsonization; decreases phagocytosis and killing
48
Q

The P.aeruginosa contains ___ of genes, contributing to its ____ and ____ ____ ____.

A

lots (5500); flexibility; antibiotic resistance potential

49
Q

genetic differences known as ___ among bacterial strains are ___ than differences among humans

A

SNPs; greater

50
Q

True or false: entire genes can be variably present or absent in different bacterial strains from the same species

A

true

51
Q

pan-genome definition

A

comprises both the core and entire accessory genome for the entire species

52
Q

genes that are always found in that organism are known as:

A

core genome

53
Q

genes that are variably found in that organism are known as:

A

accessory genome

54
Q

true or false: the pan-genome is not much larger than the genomic content of any single strain

A

false: much larger

55
Q

What makes up a big fraction of the P. aeruginosa accessory genome?

A

antibiotic resistance gemes, metabolic genes, virulence islands

56
Q

P. aeruginosa is known as an ___ pan-genome

A

open

MICROM 442 (26 decks)

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