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Microbiology > Microbiology Lect1 > Flashcards

Microbiology Lect1 Flashcards

1
Q

who discovered penicillin

A

alexander helming in 1929

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2
Q

ruminants

A

bacteria in rumen; breakdown cellulose

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3
Q

most diverse of all living microorganisms

A

parasites

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4
Q

exist as yeast or molds. most are free living

A

fungi

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5
Q

smallest independently living cells with no organelles

A

bacteria

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6
Q

how do bacteria replicate

A

binary fission

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7
Q

viruses

A

obligate intracellular parasite. protein coat surrounding nucleic acid (DNA or RNA)

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8
Q

tissue tropism

A

viruses only infect certain cells in the body

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9
Q

symbiotic

A

benefit host (gut bacteria)

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10
Q

commensals

A

neutral relationship to the host (oral streptococci). important in the mouth and teeth

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11
Q

parasitic relationship

A

harm to host (tape worm)

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12
Q

residents

A

established niche at a particular body site. important in the mouth and teeth

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13
Q

transients

A

acquired from the environment and establish themselves briefly (inhabited by resident bacteria or immune system)

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14
Q

carrier state

A

potentially pathogenic organisms becomes a resident (streptococcus mutans)

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15
Q

how do we acquire our immune system

A

as babies we are sterile. first microbes are from mothers vagina. bacteria colonize at the locations they are best suited for physiologically

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16
Q

what factors do bacteria consider when determining location to colonize

A

available nutrients, PH, oxidation-reduction potential, resistance to local antibacterial substances, adhesion mediated affinity to receptor on host cells, microbial interactions (what is already there, competition and inhibition)

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17
Q

most common potential pathogen on skin

A

staphylococcus aureus

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18
Q

most common potential pathogens on mouth

A

candida albicans

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19
Q

bacteria flora is highest on ___ skin areas

A

moist (armpits, perineum, between toes)

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20
Q

bacteria type in mouth and pharynx

A

many bacteria types. differ at different sites. Lots of streptococci. also neisseria and morazella

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21
Q

bacteria type in oropharynx

A

neisseria and streptococci

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22
Q

bacteria type stomach and small bowel

A

few organisms due to low ph. helicobacter pylori

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23
Q

bacteria type in colon

A

most abundant and diverse. 90% bacteria are anaerobes. bacteroids, fusobacterium, eubacterium, and clostridium. remainder are facultative organisms like e coli , yeast etc

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24
Q

the larynx and lower respirator tract protect health via

A

epithelial cilia and movement of mucocilary blanket

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25
Q

which parts of the body are normally sterile

A

accessory sinuses and urinary tract

26
Q

what affects the vaginal tract flora

A

hormonal fluctuations and different ages. pre-puberty and menopause are similar. they are scant and non specific mostly from skin flora and colon.

27
Q

vaginal tract flora during childbearing years

A

mostly lactobacillus and some anaerobic gran negative rods and gram positive yeast. slightly lower ph

28
Q

what hormone affects the vaginal epithelium and what does it cause?

A

estrogen; causes glycogen to be deposited which the lactobacilli feed on

29
Q

opportunistic infections

A

occur when microbes invade normally sterile locations (urinary tract, abdominal cavity). or reduce immunological response result in invasion by flora

30
Q

exclusionary effect

A

competition between normal flora and potential invaders; like when antibiotics wipe out normal flora and give pathogens an advantage

31
Q

priming the immune system

A

presence of microbiota is important for the development of our immune system (hygiene hypothesis)

32
Q

what separates a pathogen from a commensal?

A

organism must cause damage to host

33
Q

diphtheria makes a toxin that inhibits what?

A

protein synthesis

34
Q

ways pathogens can damage the host

A

the host immune reponspe to the organic can cause damage, bacteria can produce toxins that act on host cells, bacteria can secrete enzymes that degrade host tissue and facilitate spread

35
Q

ways that pathogens can evade the immune response

A
  1. attack immune effector cells
  2. secrete enzymes that degrade host effector molecules(antibodies)
  3. change surface structure to evade the immune response, so antibodies don’t work
  4. hide inside host cells (macrophage)
36
Q

three ways to collect a specimen

A
  1. direct specimen (highest quality)
  2. indirect specimen
  3. sample from site with normal flora
37
Q

direct specimen

A

localized in an otherwise sterile location (deep abscess or cerebrospinal fluid)

38
Q

indirect sample

A

must pass through a site containing normal flora do be collected (expectorated sputum and voided urine)

39
Q

sample from site with normal flora`

A

pathogen and nonpathogenic flora are mixed (throat and sty-ool)

40
Q

issues with sample collection

A
  1. time- time between sample collection and isolation is critical (3-4 hours)
  2. viability- some organisms don’t survive long outside body
  3. bacteria growth - particularly problematic if pathogen if pathogens found in low numbers
  4. transporting media- must prevent sample from drying out and minimal nutrients
41
Q

direct examination

A

light microscopy, detects bacteria fungi and parasites

42
Q

two types of bacterial stains

A

1.primary (crystal violet, carbon-fuchsin red)
2. counter stains (safranin(gram stain), methyelene blue)
(methylene blue stains everything)

43
Q

gram staining colors

A

positive= purple

negative=pink

44
Q

acid fast stain colors

A

acid-fast bacteria= red

non acid fast bacteria/cell=blue

45
Q

immunofluorescence

A

stain used for viral infections; will make the antibody fluorescent

46
Q

selective media

A

used to select and isolate a specific group of bacteria.
- can contain chemical substances that inhibit growth of one type of bacteria and permit growth of another. example: potassium tellurite inhibits growth of gram-negative bacteria

47
Q

differential media

A

distinguishes between closely related species of bacteria based on characteristics on media (color change or colony morphology; like blood agar)

48
Q

temperature for atmospheric conditions for culturing

A

35-37 degrees c

49
Q

do microaerophilic require more oxygen or co2

A

co2

50
Q

ways to identify cultures of isolated colonies

A
  1. culture characteristics
  2. biochemical tests
  3. toxin production and pathogenicity
  4. antigenic structure
  5. genomic structure
51
Q

culture chacateristics

A

nutritional requirements, pigment production etc

52
Q

biochemical tests

A

ability to attack various substrates or produce metabolic by products

53
Q

antigenic structure (serology)

A

ability to interact with antibodies

54
Q

genomic structure

A

dna sequence relatedness as determined by holy or direct sequence comparison

55
Q

how do you diagnose viral infections

A

Evidence of cytopathic effects (CPE).

  • look for morphological changes to cells
  • immunological tests- antibodies against the virus can be detected in blood
56
Q

precipitation reactions

A

type of immunological test when antibody and antigen interact they form a precipitate

57
Q

hemagglutination

A

type of immunological tests some viruses bind to red blood cells causing cross linking

58
Q

mononucleosis test

A

uses horse or sheep red blood cells, which cross react to antibodies against EBV (virus that causes mono) resulting in agglutination of red blood cells (Cross linking)

59
Q

DNA hybridization

A

target DNA is bound to a membrane and complementary DNA probe attached to a color producing enzyme is reacted with membrane. signal produced only if DNA finds its target (positive test)

60
Q

polymerase chain reaction (PCR)

A

DNA specific “primers” are used to amplify a target DNA molecule. a product signified target is present in sample (positive result)

Microbiology (7 decks)

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