ca 1 = micro Flashcards
(73 cards)
1
Q
how to differentiate between S. aureus & S. epidermis
A
S- aureus ferment mannitol
coagulase and DNase positive
2
Q
Enterotoxigenic E. coli produces? and causes?
A
enterotoxin - travellers’ diarrhoea
3
Q
Enteroinvasive E. coli causes? associated with?
A
diarrhoea - poor hygiene - children
4
Q
Enteropathogenic E-Coli causes?
A
outbreaks of infantile gastroenteritis
5
Q
Enterohaemorrhagic E. coli
A
produces verocytotoxin - E. coli 0157 - damages cells of lower intestine- inability to absorb fluids - undercooked foods
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
7
Q
which gram positive cocci in chains causes sepsis/ found in blood culture
A
Strep. pyogenes
8
Q
SOP
A
Standard operative procedure
9
Q
wound infection signs
A
Redness - Pus - Fever
10
Q
sites of infection 6 e.g.
A
skin+ soft tissue
post op infection/sites
Abscesses
burns
ulcers
infected biopsy material / joints
11
Q
2 types of swabs other contained how
A
serum / charcoal swabs - in transport medium
tissue and aspirate (pus) in sterile container
12
Q
specimen = labelled with? x6
A
name, address, hospital id (in-patients), DOB, investigation required, specimen type and site
13
Q
blood agar in anaerobic conditions is used to isolate.? x2
A
Bacteroide’s and clostrium
14
Q
sites where staph aureus may be found
A
post op- surfaces, superficial surfaces
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
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
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
18
Q
pathogenicity x4 of E. coli
A
- Produces adherence factors
- Produces verocytotoxin
- has genes that responsible for toxin production in shigella VT1 and VT2
- Small infecting dose
19
Q
Antigenic structure of bacteria
A
O - cell wall
K - capsular
H - flagellar
20
Q
Susceptibility to infection examples
A
- Age - fewer antibodies old or v. young
- smoker - weaker immune system
- immune diseases/ cancer / recovery from disease- fewer/weaker antibodies
- Un vaccination status - S. pneumonia has vaccine but still causes lots of child deaths
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
22
Q
confirmatory test on Strept. pneumonia
A
optochin susceptibility test- disc changes cell surface tension - zone inhibition greater than 5mm radius
23
Q
preventive measures of Streptococcus pneumonia x2
A
Pneumococcal conjugate vaccine - children immunisation
Pneumococcal polysaccharide vaccine - 65+
24
Q
reference lab
A
Irish Meningitis and sepsis lab Ireland
25
Virulence factors associated with strep. Pneumonia
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]
26
name non-sporing GNB anaerobic
Bacteroide fragilis
27
toxic oxygen products + enzymes + why can't anaerobic bacteria
superoxide anion, hydrogen peroxide + catalase [O2- -> H202] and peroxidase enzymes + superoxide dismutase [2H202 ->H20 + 02]
toxic oxygen kills and damages their cells
28
isolation of Bacteroid fragilis name 3 agars
1. neomycin
2. neomycin + vancomycin
3. Nalidixic acid tween agar
29
Biochemical test carried out to confirm Bacteroid fragilis x5
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
30
an-identification disc is used to detect.
what does it contain
pattern of susceptibility
erythromycin
vancomycin
kanamycin
colistin
penicillin
rifampicin
31
principle CLED without agar
differential agents
colour change
what can grow
-promotes growth of urinary pathogens - electrolyte deficient - prevents swarming of proteus
- cysteine + lactose
- blue - yellow
- Pseudomonas + Enterobacteriaceae
32
difference between CLED without and with indicator
with indicator changes blue to pink instead of yellow
33
Brilliant green agar principle
selective agent
differential agent
- 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
PCR stands for?
DEFINE IT
polymerase chain reaction
technique amplifies sequence of DNA
35
Name + Explain 4 steps of PCR
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
clostridium perfringens causes what disease
gas gangrenes
37
describe lab isolation of clostridium perfringens
Observation on gram stain
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
LAB identification clostridium perfringens x6
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
what GPC in clusters causes impetigo
Staphylococcus aureus
40
confirmatory test - S. aureus
- 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
Confirmatory tests carried out for STREP pyogenes
GPC - catalase negative = strep - chains
Lancefield grouping
Group A - bacitracin susceptibility test
42
Lab confirmation of salmonella enterica
serotyping
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
WIDAL test is x kind of test used to identify? species
dilution of ?
serological test
salmonella enterica
dilution of patient's serum reacts with stained suspension of O + H antigens - antibody titre = established
44
ELISA stands for ?
enzyme linked immunosorbent assay
45
procedure for ELISA direct
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
Indirect ELISA test procedure
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
Application of ELISA
1. antibody detection - HIV
2. antigen detection
48
What are the virulence factors of Streptococcus pyogenes - where found
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
clostridium perfringens contaminates which area with?
toxin produced causes.?
deep wounds with spores
necrosis + systemic toxaemia
50
initial infection of clostridium perfringens causes? x3
damage tissue, muscle + impairs blood supply
51
name 2 toxins produced by C. perfringens
- exotoxin - increases spread of disease
-alpha toxin - increase vascular permeability damage muscle, necrosis, bleeding - disrupts RBC, WBC membrane
52
symptoms associated with gas gangrene
foul smell, discolouration, gas bubbles (anaerobic respiration)
breakdown of phospholipid - host defences are ineffective
53
Clostridium tetani contaminates?
name toxin it produces and effect what condition is it produced
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
why are they uncommon in developed countries
There are vaccines against them DTP vaccine against c-tetani - routine child testing
Clostridium domain vaccines against C. perfringens
55
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
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
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?
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
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
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
name GNCB that can cause eye infection oxidase result lactose fermentative? infections it can cause
pseudomonas aeruginosa oxidase +, non-lactose fermenter - wound - eye - UTI
59
Virulence factors x4 pseudomonas aeruginosa
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
Lab Isolation observation / growth requirements pseudomonas aeruginosa
non-fastidious, strict aerobe, produces 2 pigments pyocyanin- blue fluorescein-yellow 42 degrees - fried egg due to alginate spider web
61
Identification test x3 s. pseudomonas
API 20 NE, CSF- green colonies, Bacterocine typing (effects it has on other bacteria)
62
S. aureus and s. epidermis - differentiating
coagulase and DNase + =aureus and mannitol fermenter s. epidermis complete opposite
63
AnaeroGen gas sachet
change colour when anaerobic condition = reached 30 secs to get plates in
methylene blue indicator strip
control plate
64
GNCB name (respiratory pathogens) + appearance on agar (shape)
LAB isolation
Haemophilus influenzae - pleomorphic
isolated on chocolate agar - NADase - destroyed and RBC contents-lysed bacitracin disc inhibits growth normal flora
65
lab identification of Haemophilus influenzae
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
name 3 Haemophilus species
H. influenza
H. ducrei
H. parainfluenza
67
Haemophilus is a commensal of?
upper respiratory tract
68
H. Influenza virulence factors
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
Infections it can cause / sites h. influenza
1. middle ear
2. lunges
3. eyes
- 1. meningitis
2. septicaemia
3. conjunctivitis
4. septic arthritis
70
Moraxella catarrhalis basic characteristic test + sample used to test for it
catalase - oxidase +
GNC diplococcus
non-fermentive - non-motile
push able colonies
sputum
71
Lab Identification of Moraxella catarrhalis x2
1. API 20 NE
2. Triglyceride/tributyrin test [ catarrhalis disc on lid petri disc - colonies rubbed across disc - blue-green colour]
72
S. pyogenes & S. aureus both cause x infection what haemolysis do they demonstrate
throat infection
p- alpha haemolysis
a- beta haemolysis
73
3 important respiratory pathogens
Moraxella catarrhalis
Haemophilus influenza
S. pneumonia
