Pathogens and Hosts

Question 1

commensal

Answer 1

organism which is part of normal flora

Question 2

kochs postulates

Answer 2

organism must be found in all cases of the disease, able to be cultured outside the body for several generations, should reproduce the disease on inoculation

Question 3

infectivity

Answer 3

ability to become established on or within a host

Question 4

virulence

Answer 4

capacity to cause harmful effects once established

Question 5

exotoxins

Answer 5

released extracellularly by the micro organism

Question 6

enterotoxins

Answer 6

exotoxins that act on the GI tract

Question 7

endotoxin

Answer 7

structurally part of the gram negative cell wall

Question 8

superantigens

Answer 8

able to stimulate division of T cells in the absence of specific antigen. extremely toxic

Question 9

group A streptococci

Answer 9

bacteria commonly found in the throat and on the skin

Question 10

group B streptococci

Answer 10

neonatal sepsis, genital tract carriage is common

Question 11

group D streptococci

Answer 11

often non haemolytic, found in gut, cause of UTI

Question 12

test for pathogenicity of staphylococci

Answer 12

coagulase test. if positive then staphylococcus aureus is present

Question 13

which is penicillin and methicillin resistant

Answer 13

staphylococcus aureus

Question 14

MRSA

Answer 14

methicillin resistant staphylococcus aureus

Question 15

coagulase negative staphylococci

Answer 15

many different species, skin commensals, can be pathogenic in presence of foreign bodies eg prosthetic heart valves, hip joints, immunocompromised etc

Question 16

clostrida dificile

Answer 16

difficult to culture, can be carried asymptomatically in gut of healthy people, cause of diarrhoea, increased risk with antibiotic use as it disrupts the normal gut flora

Question 17

clostridium perfringes

Answer 17

found in soil and normal commensal in human and animal gut and faeces. can cause food poisoning if in contaminated food. in serious wounds can cause gas ganrege.

Question 18

clostridium tetani

Answer 18

cause tetanus, food poisoning, uncontrolled muscle spasming due to loss of inhibition at neuromuscular junction

Question 19

clostridium botulinum

Answer 19

source of botox

Question 20

bacillus anthraces

Answer 20

cause of anthrax. associated with exposure to infected animals or produce eg wool hair bone meat horns

Question 21

influenza A virus infection

Answer 21

infects cells of respiratory tract, destruction of respiratory epithelium, altered cytokine expression leads to fever

Question 22

types of enterovirus infections

Answer 22

polio, aseptic meningitis, respiratory infections, myocarditis

Question 23

how does enterovirus infection occur

Answer 23

enter via gut then spread to tissues. excretion in faece. if spread to neuronal tissue- paralysis

Question 24

virus induced tumors

Answer 24

papillomaviruses, retroviruses