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microbiology > ca 1 = micro > Flashcards

ca 1 = micro Flashcards

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Biology 101 flashcards
1
Q

how to differentiate between S. aureus & S. epidermis

A

S- aureus ferment mannitol
coagulase and DNase positive

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2
Q

Enterotoxigenic E. coli produces? and causes?

A

enterotoxin - travellers’ diarrhoea

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3
Q

Enteroinvasive E. coli causes? associated with?

A

diarrhoea - poor hygiene - children

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4
Q

Enteropathogenic E-Coli causes?

A

outbreaks of infantile gastroenteritis

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5
Q

Enterohaemorrhagic E. coli

A

produces verocytotoxin - E. coli 0157 - damages cells of lower intestine- inability to absorb fluids - undercooked foods

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6
Q

coagulase test

A

latex reagent is added, and 2 colonies are mixed in and the card is rocked side to side - agglutination is observed - negative control

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7
Q

which gram positive cocci in chains causes sepsis/ found in blood culture

A

Strep. pyogenes

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8
Q

SOP

A

Standard operative procedure

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9
Q

wound infection signs

A

Redness - Pus - Fever

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10
Q

sites of infection 6 e.g.

A

skin+ soft tissue
post op infection/sites
Abscesses
burns
ulcers
infected biopsy material / joints

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11
Q

2 types of swabs other contained how

A

serum / charcoal swabs - in transport medium
tissue and aspirate (pus) in sterile container

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12
Q

specimen = labelled with? x6

A

name, address, hospital id (in-patients), DOB, investigation required, specimen type and site

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13
Q

blood agar in anaerobic conditions is used to isolate.? x2

A

Bacteroide’s and clostrium

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14
Q

sites where staph aureus may be found

A

post op- surfaces, superficial surfaces

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15
Q

agars used to isolate E. Coli 0157 x5
selective for x and E. Coli can be observed because of?

A

chromogenic agars
SMAC
SMAC - with cefixime and rhamnose
SMAC with cefixime and potassium tellurite
BPW-VCC enrichment broth - contains antibodies
selective for e. coli species
E. coli 0157 no colour change (remains pink) only E. coli that cannot ferment mannitol

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16
Q

E. coli Gram, aerobic or an? ferment glucose? oxidase result
opportunistic pathogens e.g.
strict pathogens

A

GNB facultative anaerobic, all ferment glucose, oxidase - negative
opportunistic - Proteus, Escherichia, Klebsiella
strict p - salmonella shigella, yersinia

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17
Q

arrangement of Streptococcus
gram result
catalase result
haemolysis and example

A

diplococci/pairs
GPC
negative
alpha haemolytic - Group A, B, C -Pneumonia
beta haemolytic - Strep pyogenes

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18
Q

pathogenicity x4 of E. coli

A
  1. Produces adherence factors
  2. Produces verocytotoxin
  3. has genes that responsible for toxin production in shigella VT1 and VT2
  4. Small infecting dose
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19
Q

Antigenic structure of bacteria

A

O - cell wall
K - capsular
H - flagellar

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20
Q

Susceptibility to infection examples

A
  1. Age - fewer antibodies old or v. young
  2. smoker - weaker immune system
  3. immune diseases/ cancer / recovery from disease- fewer/weaker antibodies
  4. Un vaccination status - S. pneumonia has vaccine but still causes lots of child deaths
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21
Q

Name distinct colonies S. pneumonia has
Why?

A

Draughtsman colonies
Fragility of the colonies. Autolysin is produced causes self-autolysis at stationary phase entire culture= killed

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22
Q

confirmatory test on Strept. pneumonia

A

optochin susceptibility test- disc changes cell surface tension - zone inhibition greater than 5mm radius

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23
Q

preventive measures of Streptococcus pneumonia x2

A

Pneumococcal conjugate vaccine - children immunisation
Pneumococcal polysaccharide vaccine - 65+

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24
Q

reference lab

A

Irish Meningitis and sepsis lab Ireland

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25
Q

Virulence factors associated with strep. Pneumonia

A
  1. Polysaccharide capsule - protects from phagocytosis - can enter alveolar tissue and cause inflammatory response - encapsulated strains - virulent non-cap=non-variant
  2. Adhesion factors prevents immune response from washing it away allows 1. colonisation & 2 infection to occur
  3. toxin produced - pneumolysin inserts into lipid bilayer causes cytolysis [autolysin-breaks up cell wall]
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26
Q

name non-sporing GNB anaerobic

A

Bacteroide fragilis

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27
Q

toxic oxygen products + enzymes + why can’t anaerobic bacteria

A

superoxide anion, hydrogen peroxide + catalase [O2- -> H202] and peroxidase enzymes + superoxide dismutase [2H202 ->H20 + 02]
toxic oxygen kills and damages their cells

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28
Q

isolation of Bacteroid fragilis name 3 agars

A
  1. neomycin
  2. neomycin + vancomycin
  3. Nalidixic acid tween agar
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29
Q

Biochemical test carried out to confirm Bacteroid fragilis x5

A

anaerobic GNB 1. NAAT - Nucleic Acid amplification test
2.API A- anaerobic
3. VITEK -A
4. MALDI-TOK
5. Rapid Ana- molecular method
all anaerobic bacteria = susceptible to MTZ5

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30
Q

an-identification disc is used to detect.
what does it contain

A

pattern of susceptibility
erythromycin
vancomycin
kanamycin
colistin
penicillin
rifampicin

31
Q

principle CLED without agar
differential agents
colour change
what can grow

A

-promotes growth of urinary pathogens - electrolyte deficient - prevents swarming of proteus
- cysteine + lactose
- blue - yellow
- Pseudomonas + Enterobacteriaceae

32
Q

difference between CLED without and with indicator

A

with indicator changes blue to pink instead of yellow

33
Q

Brilliant green agar principle
selective agent
differential agent

A
  • prevents growth gram positive + gram negative (majority) isolates salmonella
  • brilliant green
  • lactose + sucrose - phenyl red indicator
  • Salmonella can grow red-pink non-lactose or sucrose ferementer
    e-coli turns yellow
34
Q

PCR stands for?
DEFINE IT

A

polymerase chain reaction
technique amplifies sequence of DNA

35
Q

Name + Explain 4 steps of PCR

A
  1. Denaturation - at 94 degrees Celsius double strand - single strand
  2. Annealing - primers complementary to DNA sequence anneal to ssDNA at 54 degrees Celsius dsDNA made
  3. Extension - occurs at 72 degrees 4 dNTPs are added by Taq polymerase to copy DNA sequence and make desired DNA sequence
  4. Exponential amplification occurs in repeated cycles
36
Q

clostridium perfringens causes what disease

A

gas gangrenes

37
Q

describe lab isolation of clostridium perfringens
Observation on gram stain

A

usually from wound infection site
neomycin and nalidixic acid tween agar
anaerobic + aerobic blood agar
Roberton’s cooked meat then grown on blood agar
GPB - subterminal spores

38
Q

LAB identification clostridium perfringens x6

A

gram - sub-terminal club shaped spores
double zone of beta haemolysis 1. Egg yolk agar (black centres white around)
2. sheep blood trypticase agar
Nagler reaction
proteolytic metabolism
API A
Sensitivity to MTZ5

39
Q

what GPC in clusters causes impetigo

A

Staphylococcus aureus

40
Q

confirmatory test - S. aureus

A
  • DNase agar - has enzyme - breaks DNA on agar to nucleotides + phosphate clear area around inoculum
  • coagulase -latex reagents + 2 colonies rocked - agglutination
    MSA - ferments mannitol (only staph that can)
41
Q

Confirmatory tests carried out for STREP pyogenes

A

GPC - catalase negative = strep - chains
Lancefield grouping
Group A - bacitracin susceptibility test

42
Q

Lab confirmation of salmonella enterica
serotyping

A
  1. catalase + oxidase negative GNB
  2. API strip
  3. selective agars [s.s - black, bismuth sulphite- metallic black, DCA -orange, Hektoen - blue]
    XLD - deoxycholate & low nutrients - selectivity - neutral ph. hydrogen sulphide is produced due to reduction thiosulphate shown by - black centred colonies
    Biochemical screen is carried out
    water - 2 colonies - specific antiserum
    Polyvalent O - detects if salmonella
    Monovalent O- detects O antigen
    Polyvalent H - H antigens
    Monovalent H - detects H antigen
43
Q

WIDAL test is x kind of test used to identify? species
dilution of ?

A

serological test
salmonella enterica
dilution of patient’s serum reacts with stained suspension of O + H antigens - antibody titre = established

44
Q

ELISA stands for ?

A

enzyme linked immunosorbent assay

45
Q

procedure for ELISA direct

A
  1. antibody is adsorbed to well surface
  2. patient sample is added
  3. well = washed
  4. 2nd antibody specific to antigen = added [ enzyme linked to horseradish or peroxidase]
  5. well = washed
  6. enzyme substrate = added + colour change due to bound antibody [detects antigen]
46
Q

Indirect ELISA test procedure

A
  1. antigen is adsorbed unto well surface
  2. patient serum = added
  3. Well = washed
  4. 2nd anti-antibody is added linked - horser.
  5. well = washed
  6. enzyme substrate = added colour change =detected antibody
47
Q

Application of ELISA

A
  1. antibody detection - HIV
  2. antigen detection
48
Q

What are the virulence factors of Streptococcus pyogenes - where found

A
  1. Capsule - non-antigenic similar to host C.T. not recognised by host immune system
  2. Adhesion factor - M protein & fibronectin binding proteins
  3. exotoxins produced - Streptokinase
    protease - toxic shock syndrome
    - throat swab
  4. Hyaluronidase can digest host C.T.
49
Q

clostridium perfringens contaminates which area with?
toxin produced causes.?

A

deep wounds with spores
necrosis + systemic toxaemia

50
Q

initial infection of clostridium perfringens causes? x3

A

damage tissue, muscle + impairs blood supply

51
Q

name 2 toxins produced by C. perfringens

A
  • exotoxin - increases spread of disease
    -alpha toxin - increase vascular permeability damage muscle, necrosis, bleeding - disrupts RBC, WBC membrane
52
Q

symptoms associated with gas gangrene

A

foul smell, discolouration, gas bubbles (anaerobic respiration)
breakdown of phospholipid - host defences are ineffective

53
Q

Clostridium tetani contaminates?
name toxin it produces and effect what condition is it produced

A

wound infections with spore
potent neurotoxin - tetanospasmin effects CNS by preventing release of inhibitory transmitters - cramping and twitching around the wound - spasms + lock jaw can cause death due to death due to health failure and respiratory failure

54
Q

why are they uncommon in developed countries

A

There are vaccines against them DTP vaccine against c-tetani - routine child testing
Clostridium domain vaccines against C. perfringens

55
Q

The VITEK is biochemical x, observes x of the organism, automated system which uses x, each test read every x minutes
x amount of wells with x read at x
raw data is calculated by?
clear film at both sides allows?
measure? x3
Barcode contains?
List 4 types of cards available- ADVANTAGES

A

analyser, biochemical profile, growth-based technology, 15minutes, 64 wells, different reagents, different wavelengths of spectrum, comparing result to threshold, O2 transmission
turbidity, colour, metabolic activity,
patient + card/test details
BCL - GPB spore forming
GP - GPC non-spore forming
Yeast & yeast like
GNB- fermenting and non-fermenting

56
Q

Fluorescent Antibody Test identify? x2
what is combined? to make them?
advantages x3
name 2 types?
DFAT detects?
what is fixed to slide
what added -
after short incubation? is done
slide = examined under x and what colour looking for?

A

microbes in clinical specimens and specific antibody in serum
fluorescence dyes i.e. fluorescein isothiocyanate and antibodies to make them fluoresce - when exposed to UV light
quick sensitive
specific
microbes
specimen = fixed
fluorescent dye labelled antibody
slide = washed UV microscope
yellow-green fluorescence

Direct Fluorescent antibody Test

57
Q

MALDI-TOK identifies? x2
observes?
what = mixed added inserted into?
1st thing that happens to sample
step 2 explains further steps
result compared to.? determines exact?
ADVS+DISA

A

pathogen to species level -antimonial resistant mechanisms
observes- biochemical profile
matrix + sample - machine
irradiated by lasers - absorbs lasers- ionized and vaporized by laser and gains electrical charge, electrical field = applied and separation occurs according to mass: charge ration- different ratio = different fragment lengths
database
molecular mass of peptide and small proteins
Quick + easy to set - results - quick p -can do antibiotic susceptibility testing

58
Q

name GNCB that can cause eye infection oxidase result lactose fermentative? infections it can cause

A

pseudomonas aeruginosa oxidase +, non-lactose fermenter - wound - eye - UTI

59
Q

Virulence factors x4 pseudomonas aeruginosa

A

Initial adhesion to damaged cells - fimbriae and pili
Alginate - slimy substance formed helps stick to respiratory cells and matrix- survival
Exotoxin A - very potent prevents mammalian protein synthesis LPS
Polysaccharide capsule protects from phagocytosis and opsonisation allows infection to progress
Extracellular enzymes break down cilia in respiratory tract

60
Q

Lab Isolation observation / growth requirements pseudomonas aeruginosa

A

non-fastidious, strict aerobe, produces 2 pigments pyocyanin- blue fluorescein-yellow 42 degrees - fried egg due to alginate spider web

61
Q

Identification test x3 s. pseudomonas

A

API 20 NE, CSF- green colonies, Bacterocine typing (effects it has on other bacteria)

62
Q

S. aureus and s. epidermis - differentiating

A

coagulase and DNase + =aureus and mannitol fermenter s. epidermis complete opposite

63
Q

AnaeroGen gas sachet

A

change colour when anaerobic condition = reached 30 secs to get plates in
methylene blue indicator strip
control plate

64
Q

GNCB name (respiratory pathogens) + appearance on agar (shape)
LAB isolation

A

Haemophilus influenzae - pleomorphic
isolated on chocolate agar - NADase - destroyed and RBC contents-lysed bacitracin disc inhibits growth normal flora

65
Q

lab identification of Haemophilus influenzae

A
  1. catalase + oxidase +
  2. MALDI-TOK- ribotyping
  3. X and V factor both needed growth around this disk X -haemin needed to produce cytochrome c+ other iron containing respiratory enzymes haemin V factor - by products are NAD (nicotinamide adenine dinucleotide) and NADP needed for redox reactions in cell metabolism
  4. 30% produce beta lactamase
  5. Satelism total plate inoculated with H-F and single streak od s. aureus - most growth around streak V= produced - NAD = by product
66
Q

name 3 Haemophilus species

A

H. influenza
H. ducrei
H. parainfluenza

67
Q

Haemophilus is a commensal of?

A

upper respiratory tract

68
Q

H. Influenza virulence factors

A
  1. capsular polysaccharide - 6 types b caused most infections - before HIP vaccine
  2. Adhesions - to mammalian cells allows for colonisation
  3. Endotoxin - LPS- toxic to ciliated respiratory cells
69
Q

Infections it can cause / sites h. influenza

A
  1. middle ear
  2. lunges
  3. eyes
    - 1. meningitis
  4. septicaemia
  5. conjunctivitis
  6. septic arthritis
70
Q

Moraxella catarrhalis basic characteristic test + sample used to test for it

A

catalase - oxidase +
GNC diplococcus
non-fermentive - non-motile
push able colonies
sputum

71
Q

Lab Identification of Moraxella catarrhalis x2

A
  1. API 20 NE
  2. Triglyceride/tributyrin test [ catarrhalis disc on lid petri disc - colonies rubbed across disc - blue-green colour]
72
Q

S. pyogenes & S. aureus both cause x infection what haemolysis do they demonstrate

A

throat infection
p- alpha haemolysis
a- beta haemolysis

73
Q

3 important respiratory pathogens

A

Moraxella catarrhalis
Haemophilus influenza
S. pneumonia

microbiology (2 decks)

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