infection Flashcards
1
Q
what is helminths
A
tape worm ( have some complex lifecycles with more than one host - can accidents cause human disease
2
Q
what are some types of organisms that cause disease
A
insects (fleas) helminths protozoa (malaria) fungi (candidia) bacteria (staphylococcus) viruses (influenza) prions (kuru)
3
Q
what is a parasite
A
parasites depend on another for its survival to detriment the host -
4
Q
what is the difference between endoparasites and ectoparasites
A
end - live inside the body such as helminths or protozoa
ecto - live outside the body - minor symptoms but can cause other diseases - fleas, lice, bed bugs
5
Q
what is malaria, how is it transmitted and what are the symptoms
A
malaria (plasmodium falciparum), has a lifecycle in both mosquitos and humans - infects RBCs and liver - causes fever, headache, joint pains, kidney failure, coma and death - the risk of transmission is geographical
6
Q
what is cestodes
A
tape worm
7
Q
what is taenia saginata
A
beef tapeworm
8
Q
what does a tapeworm do and what are the symptoms
A
can invade animals and get into the muscle which is an intermediate host - they then get into humans stomachs when we eat the meat - causes abdominal pain, malnutrition
9
Q
how is a tapeworm diagnosed
A
used stool microscopy
10
Q
what is trematoda
A
flukes which is a type of flatworm parasite
11
Q
what do flukes do
A
cause infection of the veins around the bladder- causes bladder inflammation - bleeding in the urine
12
Q
what is the intermediate host of flukes and how do you diagnose it
A
freshwater snails - urine microscopy for eggs
13
Q
what are the two main forms of fungal infection
A
yeasts (single cells which bud)
moulds (filamentous strands)
14
Q
what is a dimorphic fungi
A
a fungus which cam swap from mould to yeast
15
Q
what are some examples of superficial fungal infections and what are the caused by
A
tinea pedis - athletes foot
tinea corporis - ringworm
both caused by common mould
16
Q
what is cryptoccocus neoformans
A
yeast infection - but a severe - infects patients with reduced immune system causes meningitis, headache, neck stiffness, confusion, coma and death
17
Q
in the classification of bacteria what do these mean: round = rod = clusters = pairs = chains = spirals
A
coccus bacillus staphy diplo strepto vibrio, spirilla, spirochetes
18
Q
what is streptococcus pneumonia
A
gram positive cocci in pairs - colonise in the throat and nose can invade other sites such as the lungs
19
Q
what is diplococci
A
cocci in pairs
20
Q
what are the symptoms of streptococcus pneumonia
A
cough, dirty sputum, chest pain, breathlessness, fever - can cause meningitis and blood stream infection
21
Q
how does a virus work
A
a virus needs a host and is dependent on that host for metabolism and replication
22
Q
what is a virus specifically
A
contain a protein core surrounding genetic material - very small
23
Q
how does HIV work and what type of organism is it
A
HIV replicates own DNA into our genome and uses our cells to reproduce - its a virus
24
Q
what causes these diseases: common cold = winter vomitting disease = chicken pox = shingles = glandular fever =
A
rhinovirus norovirus varicella zoster herpes zoster epstein barr
25
give an example of an acute, chronic and latent infection
norovirus - infects host for days - causes diarrhoea for days
hep C - causes liver inflammation for years
herpes virus dormant for decades before reactivating to cause disease
26
how does EBV - epstein barr virus affect humans
usually causes mild illness as it infects B cells in the immune system and epithelial of nose and mouth
it is very common and causes latent life long infection
27
what cancers do EBV cause
can cause nasopharyngeal cancer in southern china
| can cause lymphoma in HIV infection
28
how does HBV, Hep B lead to cancer
causes development of chronic infection that leads to cirrhosis which leads to increased risk of liver cancer
29
how does HPV lead to cancer
human papilloma virus which can survive for many years - eventually leads to conversion of normal cells on surface of cervix into cancerous cells
30
what are prions
smallest infective agents known - they lack nucleic acid and are not living organism
they are abnormal proteins that accumulate in neural tissue which are very difficult to destroy
31
what do prions cause and what does it do
prions cause CJD which is a rare fatal degenerative neurological disease transmitted va human growth hormone, surgical instruments and corneal grafts
32
what is variant CJD
typically occurs in young adults thought to be derived from bovine spongiform encephalopathy (BSE) - mad cow disease
33
what is kuru
it is similar to vCJD - spread by cannibalism especially brains of relatives
34
where are normal microbial flora found
most mucocutaneous surfaces eg upper airways and GI tract
| also on skin and genital tract
35
how do normal microbial flora cause infection
when they get into the wrong places of the body by chance
36
what is an endogenous infection
a disease caused by something that is already in our body such as from microbial flora migrating to different portions of the body
37
what is perforation and what can it lead to
endogenous route of infection - leads to contamination of abdominal cavity with faecal flora - leads to faecal peritonitis which is life threatening
38
what diseases are caused by perforation
cancer and diverticulitis
39
give an example of a blood spread infection and what it does
endocarditis - caused by dental work which may allow mouth flora to enter blood stream (streptococci)
40
what is an exogenous disease
it is a communicable infection from person to person from non-human sources such as the environment
41
what is impetigo
a common direct contact skin infection which spreads rapidly from person to person due to staphylococci and/or streptococci
42
how do exogenous infection spread via indirect contact
through microorganisms transmitted indricly through hand touch or equipment or furniture - it is a major route of health care associated infection
43
what are some examples of indirect exogenous infections
MRSA
clostridium difficile
norovirus gastroenteritis
44
give an example of a infection through a dirty wound
tetanus
45
what does tetanus do and what is it
clostridium tetani
bacterium present in soil - contaminates wound and releases toxin which causes muscle spasm and !lockjaw!
it can be prevented via vaccine
46
give an example of a bite infection
malaria - causes severe febrile illness affecting all body systems
47
how are airborne viruses spread and what is an example
influenza virus
spread by coughing and sneezing
droplets form containing the virus and is inhaled by others
48
describe some routes of transmission
```
airborne
food and water
blood
sexual
vertical
```
49
how does transmission through food and water occur
food prepared with poor hygiene - harmful bacteria contaminate result in food poisoning, vomiting and diahorrea
50
give an example of a blood borne infection
hep b
51
how does transmission via the blood occur
sharing of needles
transfusion
tattoos and body piercing
52
what is vertical transmission and give examples
mother to baby
during pregnancy = rubella
at time of birth = herpes
breast milk = HIV
53
give an example of an infection that is spread in more than one way
HIV - blood bourne
vertical
sexual
54
what are some pathogen factors in infection
the infection dose - minimum number of organism required to cause disease
infection site and whether it is direct in cells and tissues
55
what are some virulence factors give an example
invasion and disease - allows invasion of the host tissues
| eg streptolysin O - causes lysis of cells (produced by streptococci A)
56
what is ebola
direct infection causing damage/destruction of cells and can often bypass steps of immune system
57
what are the symptoms of cholera
severe watery diarrhoea - kidney failure - dehydration and death
58
how does cholera infect the body
toxin enters lumen of the gut and activates adenyl cyclase increasing cAMP which reduces Na+ absorption
this increases Cl- secretion
end result is water and other electrolytes drawn into the bowel lumen causing diarrhoea
59
how does antibiotic resistance occur
microorganisms such as staphylococci readily divide and mutate which means they have adaptation to readily used antibiotics
also more antibiotic use means more chance of bacterial mutation and therefore resistance leading to failure of treatment
60
give an example of common antibiotic resistance
MRSA - gram positive bacteria which causes severe infection
61
what are some host factors for infection
the environment -
barriers to infection - damaged skin
genetics - how good you are at fighting the infection
62
what are some environmental factors to infection
geography
climate
poverty - availability of health care such as vaccine
public health infrastructure - sanitation
distribution of other infection hosts - insects or other vectors
63
what is dengue fever (environmental disease)
viral infection
transmitted by aedes mosquito
causes fever, rash, muscle pain
severe form causes bleeding, shock and organ failure
64
what are some barrier to infection
```
skin
mucous membran e
stomach acid
native bacteria
immune system
genetics
behaviour
```
65
skin and mucous barrier breakdown can lead to what
cuts and wound infection
| abrasions such as conjunctivitis
66
the stomach is usually a good barrier at pH 2 - when does the barrier stop
when the patient is given an anti-acid drug such as to treat stomach ulcers - patients taking may be more susceptible to food poisoning
67
how does native gut bacteria work as a barrier
faeces prevent colonisation of pathogenic bacteria
68
what causes native gut bacteria to stop working as a barrier
when taking antibiotics - destroy normal gut flora so pathogen can colonise eg diarrhoea from clostridium difficile
69
when does the immune system break down as a barrier
when given chemotherapy
and during autoimmune diseases due to overactive immune system such as arthritis or asthma
as well as in HIV - infects white blood cells - makes more infections more common
70
what is it called when we are genetically weaken to infection
inherited immunodeficiency
71
when do genetics benefit to infection
heterozygotes of sickle cell anaemia are protected against malaria
72
what behaviours affect infection risk
```
occupation
travel
sex
drugs
friends or pets
```
73
what are some basic tests to identify infectious biomarkers
count of white blood cells
C reactive protein marker of inflammation
U & E markers if kidney
LFT for liver function test
74
which sample would you take for
pneumonia
gastroenteritis
tonsilitis
sputum
faeces
throat swab
75
how do you take and send a sample
samples should be sent before antibiotic treatment starts and provide background clinical information to help the lab
76
if it is a blood culture why must you be cautious
use aspetic technique as the skin is covered in bacteria and don't want to contaminate the sample
77
what is visual testing
staining a colony of bacteria and looking under a microscope
78
what is antibiotic sensitivity testing
take colony and rub over plate - place on discs with different antibiotics - whichever has the largest clear patch is most effective
79
what is antibiotic dose testing
strip with one antibiotic on it - different concentrations along the strip and find where bacteria grows in what concentration
80
how do we identify organisms we can't grow in a lab
identify which we need - dan or rna / a protein
can get via the PCR
can use antibodies to find immune response to infection
81
give examples of protein testing
rapid hep B test via blood test
| legionnaires disease - urine test
82
what can PCR be used to identify for?
meningitis, hep B/c, HIV, respiratory viruses
83
what is the difference between IgM and IgG
igm is initial body response - appears within a week and usually disappears after a month
IgG - appears after 14 days - persists throughput life - test for whether you are immune to something
84
where are these antibiotics derived from
penecillin
mupirocin
derived from mould
| produced from pseudomonas fluroscens (bacterium)
85
what characteristics would the ideal anti-microbial agent have
selective toxicity
effective against microbe without harming host
it actually kills the organism rather than just inhibiting its growth
no resistance
good pharmacokinetics
not side effects
not activated by enzymes
86
what parts of the cells can antimicrobial drugs affect
```
cell wall synthesis
dna replication
dna dependant rna polymerase
protein synthesis
folic acid synthesis
```
87
what are the problems with antimicrobial agents
they can be broad or narrow - broad kill natural flora as well
narrow may not kill multiple infection
can have many side effects
narrow - antimicrobial resistance
88
what are the three stages of stopping transmission
at the source
tranmission method
host susceptibility
89
what are some common methods to reduce transmission
improve sanitisation, clean water supplies, good food prep, avoid mosquito bites
90
how would you protect a host from infection
antimalaries
| immunisation
