bacterial infections

Question 1

components of bacterial cell

Answer 1

ribosomes, DNA, cell wall, cytoplasm, cell membrane; capsule, flagellum, pili

Question 2

common virulence factors

Answer 2

diverse secretion systems, flagella (move, attach), pili (adhere), capsule (protect vs phagocytosis), endospores (dormant bacteria which are temperature, dessication and chemical resistant), biofilms (organised aggregates which cause antibiotic resistant), endotoxins, exotoxins

Question 3

bacteria with capsule

Answer 3

Step. pneumoniae

Question 4

2 bacteria with endospores

Answer 4

Bacillus sp., Clostridium sp.

Question 5

2 bacteria with biofilms

Answer 5

Pseudomonas aeruginosa, Staph. epidermidis

Question 6

5 types of exotoxins and what they act on/stimulate/allow

Answer 6

neurotoxins (act on nerves or motor endplate), enterotoxins (act on GI tract), pyrogenic exotoxins (stimulate release of cytokines), tissue invasive exotoxin (allow bacteria to destroy and tunnel through tissue), miscellaneous exotoxin (specific/not well understood)

Question 7

examples of bacteria producing neurotoxins

Answer 7

Tetanus, Botulinum

Question 8

examples of bacteria producing enterotoxins (infectious diarrhoea)

Answer 8

V. cholera, E. coli

Question 9

examples of bacteria producing enterotoxins (food poisoning)

Answer 9

B. cereus, Staphy. aureus

Question 10

examples of bacteria producing pyrogenic toxins

Answer 10

Staph. aureus, Strep. pyogenes

Question 11

what do bacteria which cause tissue invasive exotoxin contain

Answer 11

enzymes that destroy DNA, collagen, fibrin, RBC, WBC etc.

Question 12

examples of bacteria causing tissue invasive exotoxin

Answer 12

Staph. aureus, Strep. pyogenes

Question 13

example of bacteria causing miscellaneous exotoxin

Answer 13

B. anthracis

Question 14

what is an endotoxin

Answer 14

lipid A component of LPS (not protein) in gram -ve bacteria

Question 15

gram +ve vs gram -ve

Answer 15

gram +ve has thick peptidoglycan layer, gram -ve has thin peptidoglycan layer and another layer of LPS

Question 16

why can treating patient with gram -ve infection with antibiotics sometimes worsen condition

Answer 16

bacteria lyse, releasing large quantities of LPS and endotoxin, causing septic shock

Question 17

5 things which are determined following an outbreak

Answer 17

causative agent, illness, source, time frame, scale

Question 18

what can be used to detect outbreak strain

Answer 18

PCR (isolates can be screened by multiplex PCR for characteristic features of outbreak strain; can be done on stool samples); can then compare outbreak strain with known strains (determine what toxins have transferred to strain via bacteriophage)

Question 19

describe Shiga toxin structure

Answer 19

have an AB5 subunit composition, with toxin (StxA) which can block protein synthesis in eukaryotic cells

Question 20

what determines what a bacteria acts on in body

Answer 20

strains and virulence factor

Question 21

define outbreak

Answer 21

greater-than-normal or greater-than-expected number of individuals infected or diagnosed with a particular infection in a given period of time, or a particular place, or both

Question 22

how can an outbreak be identified

Answer 22

surveillance provides an opportunity to identify outbreaks; good and timely reporting systems are instrumental to identify outbreaks

Question 23

6 types of communicable diseases in Europe

Answer 23

respiratory tract infections, sexually transmitted infections, food and waterborne diseases and zoonoses, emerging and vector-borne diseases, vaccine-preventable diseases, antimicrobial resistance and healthcare-associated infections

Question 24

examples of respiratory tract infections

Answer 24

influenza (virus), TB (gram +ve), SARS (virus), avian influenza (virus), Legionnaire’s disease (gram -ve)

Question 25

infection route of Legionella pneumophilia (causes Legionnaire's disease)

Answer 25

inhalation of contaminated aerosols

Question 26

where does Legionella pneumophilia grow in humans (causes Legionnaire's disease)

Answer 26

alveolar macrophages

Question 27

describe Legionella pneumophilia (causes Legionnaire's disease) type IV secretion system

Answer 27

secretion of effector proteins by type IV secretion system allow bacteria to replicate in Legionella containing vacuole (LCV)

Question 28

why is treatment of TB (mycobacterium tuberculosis) more difficult

Answer 28

very different cell wall with extra lipid layer

Question 29

describe latent TB

Answer 29

can enter dormant state, as evidence of infection but no clinical signs and symptoms of active disease

Question 30

examples of sexually transmitted infections

Answer 30

HIV/AIDS (virus), syphilis (Treponema pallidum; gram -ve), Hep B and C (viral), gonorrhoea (Neisseria gonorrohoeae; gram -ve), Chlamydia trachomatis (gram -ve)

Question 31

describe Chlamydia trachomatis (gram -ve)

Answer 31

obligate IC pathogen, either causing STI or eye infection (causing blindness)

Question 32

describe Neisseria gonorrohoeae (gram -ve)

Answer 32

diplococcus; interacts with non-ciliated epithelial cells to establish infection in urogenital tract; has pili and antigenic variation to escape detection and clearance by immune system

Question 33

examples of food and waterborne diseases and zoonoses

Answer 33

anthrax, botulism, campylobacteriosis, cholera, infection with vero/shiga toxin producing E. coli, salmonellosis

Question 34

describe campylobacteriosis

Answer 34

small children are high risk group; due to undercooked poultry; adhesion and invasion factors, flagella motility, type IV secretion system, toxin

Question 35

describe Salmonella sp.

Answer 35

undercooked poultry, highest infection rate in small children; type III secretion system encoded on pathogenicity islands

Question 36

describe V. cholerae

Answer 36

acute, severe diarrheal disease needing prompt rehydration; type IV fimbria, cholera toxin carried on a phages

Question 37

describe how cholera toxin causes diarrhoea

Answer 37

AB5 toxin, with A subunit being enzymatic and makes cell produce signalling molecule which activates CFPR channel, pumping out Cl- and causing diarrhoea

Question 38

describe Listeria monocytogenes

Answer 38

risk group immunocompromised, elderly, pregnant and foetus; can enter non-phagocytic cells and cross tight barriers e.g. intestinal, foetal

Question 39

examples of emerging and vector-borne diseases

Answer 39

malaria, plague (Yersinia pestis - gram -ve), Q fever (Coxiella burnetti, gram -ve), SARS, smallpox, VHF, West Nile fever, yellow fever

Question 40

examples of bacterial vaccine preventable diseases

Answer 40

diptheria (gram +ve), invasive haemophilus influenzae disease (gram -ve), invasive meningococcal disease (gram -ve), invasive pneumococcal disease (gram +ve), pertussis (gram -ve), tetanus (gram +ve)