Micro - Bacterial Pathogens Flashcards Preview

Block 5 Material > Micro - Bacterial Pathogens > Flashcards

Flashcards in Micro - Bacterial Pathogens Deck (25):
1

Symptoms of bacterial vs viral infections (mouth)

Only Bacterial:
White spots
Gray furry tongue
Swollen uvula

Bacterial and Viral:
Red throat
Red swollen tonsils

2

Basic characteristics of bacteria

Prokaryotes

circular chromosomes

Can also be extra-chromosomal - plasmids

3

Gram positive characteristics

+
Thick
TA & LTA
Promote attachment to mammalian cells
Low endotoxin activity
external to cell membrane

4

Gram staining

Crystal violet
Grams iodine
Decolonize
Counterstain with Safranin red

Purple is Positive

5

Classification of bacteria based on shape

Coccus
-spherical

Bacillus
-rod shaped

Coccobacillus
-between spherical and rod shaped (ovalish?)

Vibrio
-banana

Spirillum
-~~~~

Spirochete
- more spiral and thinner than spirillum

6

Classification of bacteria based on growth requirement

Aerobic
Anaerobic

Facultative-can grow in the presence OR absence of oxygen

Fastidious-special growth requirement

Non-fastidious-simple growth requirement

Capnophilic-requires CO2

Halophilic-salt loving

7

Teichoic and Lipoteichoic acid are important for ___

Viability
Virulence
Serotyping

The only difference between the two is that LTA starts from the plasma membrane

8

Encapsulated bacteria benefits:
What is the capsule made of?

Promotes adherence
Anti-phagocytic
Poor antigen

*capsules are unnecessary for growth but important for virulence

Loose Polysaccharide layer of protein layer

9

Endospores

Produced by some gram + bacteria

Non-replicating
Thick coat
Contain DNA

Toughest life form
Can germinate back into vegetative cells

10

Bacterial flagella

H-antigens

Propellers that confer motility towards food and away from poisons

Assist in bacterial attachment to human cells -virulence factor

11

Flagella classification

Monotrichous
-one flagella

Lophotrichous
-multiple flagella originating from one side

Amphitrichous
-two flagella originating from opposite sides

Peritrichous
-flagella all over

12

Bacterial Fimbriae

Pili

F-antigens

Hair-like projections
Thinner and shorter than flagella
Originate in plasma membrane
Protrude through cell wall
Can act as adhesins
Major virulence factors

13

Gram negative bacteria characteristics

Thin

Between inner and outer membrane

Permeability barrier for large molecules

Protects from adverse conditions


Asymmetric bilayer (normal inner leaflet, outer leaflet is primary LPS)

14

Bacterial Lipopolysaccharides (LPS)

Characteristic of gram - bacteria

Integral part of outer membrane

Released after cell death

When host senses LPS it turns on every defense at its disposal

15

Acid-fast bacteria

PG layer is surrounded by wax-like lipid coat
-contains mycolic acid, cord factor, wax D, sulfolipids

Lipid coat is responsible for virulence
Lipid coat is antiphagocytic

16

What determines acid fastness?

C-chain length

17

Sites with low numbers of bacteria

Bladder
Uterus
Parts of digestive tract (Stomach-acid)
Parts of respiratory tract

18

Normally sterile sites (no bacteria)

Blood
Lymph
CSF
Synovial fluid
Sub-epidermal tissue

19

How can we use the fact that bacterial ribosomes are different from human cells?

Makes it easy to target and kill them

Protein synthesis inhibitors serve better in toxigenic diseases than cell wall inhibitors

20

Are most normal flora in the GI tract gram + or - ? Why?

-
They have an outer membrane that protects them

21

How long does the lag phase typically last?

60-90 minutes

22

During the exponential phase, the bacterial population ____ every ___ minutes

Doubles
20

23

During which phase of bacterial growth are antimicrobials most effective?

Exponential phase

24

Phases of bacterial growth

Lag
Exponential
Stationary
Death

25

Obligatory steps for infections

1. Acquisition/colonization
2. Immune evasion/infection
3. Replication/proliferation
4. Dissemination/disease
5. Treatment


1 is epidemiology
2-4 is virulence
5 is identification