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Medical and general microbiology > biofilms > Flashcards

biofilms Flashcards

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USMLE® Step 1 flashcards Biology 101 flashcards
1
Q

biofilms

A

cause damage and disease

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2
Q

what sort of sieges to biofilmscause

A

chronic infections on heart valves, implants, dental decay, catheters

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3
Q

biofilms act as

A

reservoirs of contimination/ infection

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4
Q

biofilms are difficult to control since

A

they require a higher dose of antibiotics

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5
Q

biofilms are economically costly

A

e..g NHS costs/ steel pipers under the north sea which are corroded by sulphate reducing bacterial biofilsm

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6
Q

cistern 2001

A

best that 65% of infections may be biofilm related

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7
Q

approx 60% of….

A

HAIs are biofilm related

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8
Q

biofilm

A

“matrix associated microbial populations adherent to each other and or to surfaces ir interfaces” Casterton et al

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9
Q

medical infections

A

implants/ contact lenses

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10
Q

domestic

A

drains/ toilets

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11
Q

main infections causes by biofilms in tissues/ fluids are

A

Bacteremia (blood stream infection). UTIs, pneumonia

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12
Q

biofilm microorganisms are

A

more successful than planktonic

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13
Q

advantages of biofilms include

A
  • increased resistance to antimicrobial agents
  • increased resistance to host defences e.g TB, intracellular salmonella, reduced capacity for clearing by phagocytosis)
  • enhanced genetic interaction e.g. movement of resistance plasmids
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14
Q

when antimicrobials diffuse into the biofilm

A

reaction hiitions leads to tolerance: sub lethal cones lead to selection for resistance e.g. reaction eiwth EPS, chelation, enzymatic degradation, precipitation, volatilisation as alkylated metal compounds.

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15
Q

uninhibited diffusion of antimicrobials

A

tolerance by slow growth e.g. VBNC and persisters. transfer of resistance genes- due to all being in close proximity.

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16
Q

biofilms are destroyed using

A

biocides

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17
Q

which microflora was the first to be studied

A

the mouth

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18
Q

over…. species have been identified in the oral cavity

A

700

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19
Q

toothpaste and fluoride the fluoride in it

A

is used to control biofilm formation

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20
Q

why is oral health so important

A

infections in the mouth can pass through the blood system and cause infection in organs

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21
Q

how do plaques form

A

1) primar colonisers- on the surfaces of teeth and soft tissues
2) secondary colonisers- attach to primary colonisers
3) mutation of plaque- growth in situ and attachment and detachment to the existing biofilm
4) disease causation-pathogenic effect include release of toxins/acids

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22
Q

which biofilm causes disease

A

the mature bioilms

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23
Q

three main groups of plaque bacteria

A

aerobes, facultative anaerobes and obligate anaerobes

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24
Q

aerobes

A

high proportion of young plaque. usually does not cause harm e.g. Neisseria subflaa

25
Q

facultative naerobes

A

these are the majority of microbes in the mouth. able to survive and grow with high/ low oxygen concentration- usually gram positive e.g. Streptococcus mutants - usually gram neg

26
Q

obligate anaerobes

A

high number in mature plaque- O2 is toxic or inhibitory to grothw. some of these species are harmful and associated with gum disease e.g.fusobacterium nucleotum

27
Q

example of an aerobe

A

Neisseria subflave

28
Q

example of a facultative anaerobe

A

Streptococcus mutans

29
Q

example of an obligate anaerobe

A

Fusobacterium nucelotum.

30
Q

examples of surfaces in healthcaree where pathogens survive

A

instruments, bed line, the floor

31
Q

which pathogens survive well on healthcare surfaces

A

MRSA, salmonella, entrococci, Pseudomons aeruginosa, E.coli, Fusarium

32
Q

% of UTIs caused by biofilms

A

95

33
Q

% of bateremia cases

A

87%

34
Q

86$ of pneumonia cases are

A

ventilator associated

35
Q

prophylaxis

A

treatment to prevent disease

36
Q

example of public prophylaxis

A

fluoride use in water- no consent, but very effective in reducing dental decay. only medical treatment give passively without consent

37
Q

mode of action of fluoride

A

reduction in enzyme activity reduces acid production from carbohydrates. pathogens are outcompeted

38
Q

biofilms cells in comparison to planktonic cells are generally much more

A

resistant to antibiotics and biocides

39
Q

urinary catheters

A

quickly acquire organisms on the surge- 5-10% colonisation within 7 days (MRS may achieve a depth up to 5-6 ells in 2h) e.g. proteus spp

40
Q

orthopaedic devices

A

external fixation from open fractures are out likely to be colonised. Often penetration of antibiotics into biofilms on stainless steel may fail to eradicate the infection

41
Q

prosthetic joint infections

A

sometimes impossible to cure using antibiotics alone- this may lead to more surgery of even amputations.

42
Q

basic stages of biofilm formation

A

attachment, growth ,detachment

43
Q

attachment

A

free floating or planktonic bacteria encounter a submerged surface and within minutes become attached

44
Q

Growth

A

Extracellular polymeric structure (EPS) production allows the emerging biofilm community to develop a complex, three dimensional structure

45
Q

detachment

A

biofilms can propagate through detachment of small or large clumps of cells, or by a type of ‘seeding dispersal’ that releases individuals cells

46
Q

biofilms can move in numerous ways

A

collectively by rippling or rolling across the surface, or by detachingin clubs or individuals by swarming and seeding

47
Q

emergent properties fo biofilms and habitat formation

A

1) localised gradients- provide habitat diversity
2) sorption- resource capture
3) enzyme retention-external digestion system
4) cooperation- synergistic micro-consortia
5) competition- continous regeeration
6) tolerance and resistance- biofilm as a fortress

48
Q

localised gradients

A

provide habitat diversity i.e. different bacteria will survive better at diff oxygen cones/ nutrients conc

49
Q

a key resource of biofilms

A

calcium

50
Q

cooperation

A

due to there being a variety of different bacteria which have different biochemical abilities, bacteria are able to use each others products to benefit themselves

51
Q

competition

A

keeps all bacteria active

52
Q

copiotrophs

A

an organism found in environments rich in nutrients particularly carbon. tend to grow iim high organise substrate conditions

53
Q

oligotrophs

A

organisms that live in environments that offer very low levels of nutrients. characterised by slow growth, low rates of metabolism and generally low population density

54
Q

copiotrophic biofilm

A

creates an oxygen gradient, producing niches for aerobes, fermenters and anaerobes

55
Q

oligotrophic biofilm

A

nutrient gradients- some cell are more metabolically active, are starving, formation, VNBC, persister and dead cells.

56
Q

communication

A

chemic and electrical communication

57
Q

cooperation

A

nitrification- some cells are ammonia oxidisers and other nitrite oxidizers- syngerisist

58
Q

competition

A

antibiotic, bacteriocins, killer vesicles, biosurfactants, inhibition of quorum sensing, nutrient depletion, cheating

Medical and general microbiology (36 decks)

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