Microbiology 1 and 2 - Nature of infection, systemic bacteriology 1 Flashcards Preview

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Flashcards in Microbiology 1 and 2 - Nature of infection, systemic bacteriology 1 Deck (81)
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1

List of microorganisms in increasing size

Prion proteins
Viruses
bacteria
fungi
parasites

2

What type of names do all organisms have?

A genus name and a species name

3

What type of diseases does prion proteins cause?
Give an example.

Transmissible Spongiform Encephalopathies (brain infection)
Mad cow disease (Crutzefelt Jacob Disease)

4

Problem with prion proteins?

Cannot be reliably removed by sterilisation

5

What type of organism is a virus?
What is it surrounded by?

"obligate intracellular parasite"
A capsomere (protein coat)

6

Diagnosis of viral infections?(3)

PCR
Cell culture
Serology

7

Difference between the genetic material contained within viruses and bacteria?

Viruses = DNA or RNA
Bacteria = DNA and RNA (one double stranded chromosome with some genetic material sometimes stored within plasmids)

8

What surrounds a bacteria in terms of walls, etc.?

Plasma membrane
Cell wall
Capsule (+/-)

9

What does a bacteria use for adhesion and movement?

Adhesion: Pilli and fimbriae
Movement: Flagellae

10

Bacterial shapes? (3)

Coccus
Bacillus
Spirochaetes

11

Can spirochaetes be stained using the gram method?

No but they have a gram negative structure

12

Gram stain reactions?

Gram positive = purple
Gram negative = pink

13

Difference between gram positive and gram negative?

Gram positive cell wall contains a thick layer of peptidoglycan compared to a thin layer between the cytoplasmic membrane and outer membrane in gram negative bacteria

14

What 2 organisms do not stain well?

Mycobacterium tuberculosis (causes TB, has a waxy coat)
Treponema pallidum (spirochaete that causes syphilis)

15

Where in the body is there a natural bacterial flora? (5)

URT
Lower small intestine
Large intestine
Vagina
Skin (resident and transient flora)

16

What is commensalism?

Where one organism benefits from the relationship without affecting the other (commensal is part of the normal flora)

17

Opportunistic pathogen?

An organisms that will cause infection in an immunocompromised individual

18

Virulence?

Degree of pathogenicity of an organism (i.e. how easily can an organism cause disease)

19

How does bacteria replicate?
What do they require to replicate? (4
)How quickly can bacteria replicate in ideal growth conditions?

Binary fission
Food
Moisture
Correct temp. (usually 37 for human pathogens)
correct pH (about 7.4)
Every 20 minutes

20

3 main types of atmosphere?

Aerobic (growth in presence of oxygen, many aerobic organisms will also grow in anaerobic conditions but less well)
Microaerophillic (reduced O2 and enriched with CO2)
Anaerobic (no O2, "anaerobes" are strict anaerobes)

21

Why does bacteria make us ill?2 types of these?

Many produce toxins (enzymes)
Exotoxin (mainly gram positive, produced side cell and exported out)
Endotoxin (mainly gram negative, part of GN cell wall)

22

What do toxins produced from bacteria do?

Interact with cells of the immune system causing release of cytokines
Damage RBCs and WBCs, make small blood cells 'leaky", decrease BP, affect blood clotting and eventually lead to sepsis and septic shock

23

What type of organisms tend to form spores?2 examples

Gram positive bacilli (put DNA in thick coat = can't replicate but can survive for long time)
Clostridium sp. (e.g. C. difficile)
Bacillus sp. (e.g. Bacillus anthracis)

24

How does a spore develop? (3 stages)

Chromosome condenses
Septum forms
Calcium dipliconate accumulates

25

Diagnostic methods for bacteria?

Microscopy (same day)
Culture (48 hours)
Detection of antigens (e.g. in urine)
Detection of antibodies (e.g. serology) - same day
PCR (same day) for NAATs (detection of DNA/ RNA through nucleic acid amplification tests

26

Streptococcus pneumoniae causes?

Pneumonia and meningitis

27

Streptococcus viridans?

Endocarditis

28

Streptococcus pyogenes (group A strep.)

Skin (e.g. necrotising fascitis), throat infecitons (e.g. tonsillitis - if rash present = scarlet fever), peurperal sepsis = severe life threatening infection in pregnant and post natal women)

29

Group B strep.?

Neonatal meningitis

30

Enterococcus sp.

Gut infections, UTI