I remember writing these notes in Y12, I know first hand the amount of time that has to be invested into this subject and how difficult it can be to identify the key information. These notes are time savers, giving you more time to practice questions and past papers. The notes used for all my A-lev...
Creatingdrugresistantbacteria
Duringbacterialreproductionmutationsmayhelpthe microorganismresisttheeffects of the antibiotic
a
as a resulta naturalselectionthesemutationsbecomemore common and the bacterialpopula
becomesincreasinglyresistant
Thewidespreaduse o antibioticsacceleratesthe process
Thisevolutionary race is creatingsuper
bugs bacteriaresistantto manytypes of antibiotics
To reduce the development o antibioticresistance we need tovary theantibiotics we use and
introduce new ones
The number of antibioticsdevelopedare dropping East
teathcare associatedinfections
Superbugs arecommonlyfound in hospitaland carehomes werepeopleareill
or have had surgery and whereantibioticuse is at it s highest
superbugs or healthcareassociatedinfection tenis are referred to inthe
media as hospital acquiredinfections
MRSA
IE thebacterium S aureusgetis into the body it can cause boils or
eveninfections around the body as septicemia
It has beentreated veryeeeectively with methicillin butmutations
has enabled them to producepenicillinase an enzyme that breaks down methicillin
this strain is called MRSA
Clostridiumdifficile
Clostridiumdifícile is an anaerobicbacteriumfound in the largeintestine Itproducesextrem
toughpores that can survive for months outside the human body
Some antibioticsdestroygutElora what protects us eran Clostridium C difficile
populations
increaserapidly Theyproduce two toxins that damage thetimingof the intesti
causingseverediarrhoea which may lead to gutbleeding or evendeath
neectionpreventionand control
controllingantibioticuse usingthemwhen it is absolutelynecessary andensuringthecourseis
complete
Failuretodo so wouldpreventall bacteria ero m beingeliminatedleavingtoo many ear the
immunesystemto copewith
Hygienemeasures washinghandsusingalcohol basedgels Thoroughcleaningandguidelines
about stateclothing
Isolation o patientsspread can beminimised
Prevention o infectioncominginto the hospital Screeningpatientsallows possiblecarriersto be
identified and isolated
Restrictingvisits to preventinfectionsspreadingin
Monitoring levels oe Hcais is now mandatory and publishedThey measure cases of Mrsa
and Cdieticile
, Bacteria as pathogens
low do bacteriacausepathogens
some bacteria cause symptoms as a resultoe the the invade anddestroy the host tissues
way
Most bacteria make people illthroughthe toxins the produce as a by productotheirmetabolis
Toxins can either be exotoxins or endotoxins
Endotoxins
Endotoxins are lipopolysaccharidestheyare an integralpart of the cell wall a Gram negative
bacteria
Thelipid parto the lipopolysaccharide is the one that acts as a toxin whilst the polysaccharide
stimulates an immuneresponse
Symptomsinclude fever vomiting and diarrhoea Antibioticdestroythe cell by the lysis
of the cell wall which leads to further endotoxin release due to the lipopolysaccharide
component of the cell wall
Casestudy Salmonella spp
Salmonelosis is causedby one of the strains o Salmonella bacteria 100,000 people
die everyyeardue to this infection
Bacteriainvade thelining oe the intestine and the endotoxins cause inflammation
cells will no longerabsorb water so the faecesbecomeliquid The gutgoes into spans of
peristalsis that result in diarrhoea
Salmonella isspreadbyingestion of food and water
contaminad byinfected faeces
Bacteria willsurvive the stomach acid
Antibiotics just reduce symptoms but actas
carriers or longer
Exo toxins
Exotoxins are usuallysolubleproteins which areproduced
and released by bacteria They are producedby both
gram positive and gram negative bacteria Theireffect is more widespread as they
often act at sites at a distance eran the infecting bacteria
Some exotoxins damage cell membranes causing cell breakdown or internal bleeding
some act as competitiveinhibitors to neurotransmitters whilst other directlypoisoncells
Case study Staphylococcus spp
There are Yotypesoe staphylococcus bacteria theyonlycause disease ittheygetinsidethe
tissue of the body
Gram positivebacteriaproduceexotoxins that can causeanything
from mild skin to death
The most common are s aureus and S epidermis which are both
found on the skin
S aureus causes skininfections or infection at the joints in septic
arthritis All of which can be rapidly fatal
S epidermis can cause bacterialmeningitis iftheygetacess to
the brain as a result of surgery or through brain membranes in poorly controlled
diabetes It can be treated with antibiotics but the exotoxinsproduced act veryquick
, asi tissueinvasion
invadingthe hosttissues is way bacteria
the third actas pathogens it is the response of the
host organis to the celldamagethat causes the symptoms of disease
case study Mycobacteriumtuberculosis
Thebacteriummycobacteriumtuberculosis causes tuberculosis
TBis commonlyspreadbydropletinfection crowded livingconditionsincrease it s spread as
people breathe cough sneeze
Peoplewith Hiv aids are particulary vulnerable due to theirreducedimmune response
MycobacteriumBoris aceces cattle peoplegetinserted bydrinkinginfected milk or living
close to cattle
When TBinvadesthe cells oelungstheymultiplyslowlyThisprimaryinfectioncauses noobvious
symptomsTheinflammatoryresponse earns a mass attissue tubercule whichcontains dead
bacteriaand macrophages
TB has an adaptation that allows some bacteria to survive the primaryinfectionstage
The bacteria produce a thickwaxyouterlayer that protects them eran the enzymes
a macrophages
Bacteria will remain dormant growing for years until
the immune system of the personbecomes weak
unen immune systemis weak the bacteria cause
activetuberculosiswhere the most eeeective bacteria are
selectedand will bepassedon
once the become active again they can grow and
reproduceveryquicklycausingseriousdamage anddisea
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