Specimen collection - media Flashcards

1
Q

Urine cultures media used and info

A
  • CLED (cysteine lactose electrolyte deficient agar) cysteine allows for growht of coliforms, electrolyte deficiency prevents swarming of proteus and lactose fermentation helps in identification. Incubated at 35-37 for 24 hours.

Other plates used include MacConkey without salt, chromogenic agar

Other more precious samples are also cultured on 1 MacConkey plate incubated in air, on 1 blood agar also in air and another blood agar anaerobically.

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2
Q

Stool sample media

A
  • Deoxycholate Lactose Sucrose agar for salmonella and shigella
  • Salmonella chromogenic agar
  • Selenite broth for salmonella
  • Preston broth for Campylobacter
  • Campylobacter slective agar (microaerophilic incubation at 43 degrees)
  • Sorbitol MacConkey agar for E.coli 0157.

To check for cholera : Alakline peptone water APW and TCBS (thiosulfate citrate bile salts sucrose agar). Yellow colonies on TCBS

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3
Q

what transport medium can stool samples be given in

A

Cary Blair’s transport medium

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4
Q

When shoudl stool samples NOT be given in transport medium

A

When testing for GIT parasites

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5
Q

CSF storage if it cannot be processed immediately

A

incubated at 37 degrees

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6
Q

Culture media for CSF

A

blood agar, chocolate agar (for neisseria and H. influenzae), MacConkey and CTA agar base

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7
Q

CSF in bacterial meningitis

A
  • turbid
  • not sterile, bacteria idetnfied from gram stain and culture
  • 50-20,000 polymoprhs
  • markedly raised protein
  • reduced or absent glucose
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8
Q

CSF in viral meningitis

A
  • clear or slightly turbid
  • 10-500 lymphocytes
  • viruses rarely isolated, normally isolated from stools if enterovirsues or by serology for mumps
  • protein is normal or slighlty riased
  • glucose is normal
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9
Q

CSF in tuberculous meningitis

A
  • clear or slightly turbid
  • 10-500 lymphocytes
  • Mycobacterium tuberculosis with ZN stain and growth on Lowenstein Jensen medium
  • protein is moderately raised
  • gluocse is normally reduced
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10
Q

Processing of CSF

A
  • centrifuge
  • remove supernatant (can be used to carry out rapid antigen screen)
  • deposit is inoculated on BA, CBA, MacConkey. Incubated for 24 hours in 507% CO2
  • slides are prepared for GS, ZN and MB
  • subculturing carried out on CTA ( cysteine tryptic agar) which acts as an enrichment medium.
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11
Q

What bacteria are tested for in rapid antigen screen for CSF

A
  • streptococcus pneumonia
  • strep agalactiae
  • haemophilus influenzae type b
  • neisseria meningitidis A,B,C,Y, W135
  • E coli K1
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12
Q

what crytococcus species are tested for in crytpococcus anitgen rapid test for CSF

A

cryptococcus neoformans and c. gattii

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13
Q

Culture media for sputum samples

A
  • blood agar (anaerobic) for Staph aureus and streps
  • Bacitracin choco agar (5-7% CO2) Haemophilus influenzae and Moraxella catarrhalis
  • MacConkey (in air ) for enterobacterales, pseudomonas etc

For cystic fibrosis: Burkholderia cepacia selective agar

For MRSA: oxacillin resistance screening agar

Sabouraud for mycology, candida

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14
Q

Culture media for wound cultures

A

blood agar (1 anaerobic and 1 5-7% CO2), media for anaerobes, MacConkey

Cooked meat medium for anaerobes (Clostridium)

Oxacillin resistance screening agar for MRSA

Sabouraud for yeatss

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15
Q

Commonly isolated pathogens of sputum

A

Staph aureus
Strep pneumonia
Strp pyogenes
enterobacterles
acinetobacter
pseudomonas
H influenzae
Burkholderia cepacia in cystic fibrosis

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16
Q

Commonly isoltaed pathogens of wound cultures

A

anaerobes (actinomyces, becteroides, clostridium)
staph aureus
strep pyogenes
enterobacterales(klebsiella,serratia, E,coli)
pseudomonas
acinetobacter

17
Q

Culture media for aspirates

A
  • blood agar 5-7% CO2
  • blood agar anaerobic
  • MacConkey agar for Enterobacterales
  • cooked meat medium
  • Castaneda broth; tryptone soya broth and colombia agar base

ORSA and sabouraud for MRSA and yeasts

18
Q

Throat swab cultures

A

blood agar (anaerobic) for lancefield groups A,C and G
- Bacitracin chocolate agar for h. influenzae type b

  • ORSA for MRSA
  • Sabouraud for yeasts in diabetic and immunocompromised people
  • TMSA (Thayer martin modified medium) for gonorrrhoeae
19
Q

commonly isolated pathogens in throat swabs

A
  • group a streps (pyogenes)
    group C group G streps
  • H influenzae
  • Neisseria gonorrhae (STI)
20
Q

Culture media for genital tract samples

A

high vaginal swabs - blood agar at 5-7% CO2, sabouraud agar.

Urethral swabs and cervical swabs - blood agar, sabouraud and thayer martin modified medium for gonorrhoea

  • Trichomonas vaginalis selective medium
  • blood agar (anaerobic) for anaerobes
  • MacConkey for enterobacterales and pseudomonads
  • Haemophilus ducreyi selective agar for chancroids
  • ## listeria selective agar for listeriosis
21
Q

bacterial vaginosis signs symptoms and more

A
  • heavy discharge, thin, white to grey in colour
  • foul odour after intercourse
  • amine odour present
  • increase in pH
  • presence of clue cells, few lactobacilli and wbc
22
Q

lactobacillosis

A
  • pruritis (itching)
  • vulvar dysuria
  • variable discharge which is thick white and curdy
  • possible slightly higher pH
  • many lactobacilli in chains
23
Q

cytolytic vaginosis

A
  • pruritis (itching)
  • dyspareunia (painful intercourse)
  • vulvar dysuria
  • increase in luteal phase of menstrual cycle
  • discharge; thick or thin, white, creamy or curdy
  • few wbc
  • large number of lactobacilli
  • desquamated epithelial cells
24
Q

selective culture media for Gardnerella vaginalis

A

Human Blood polysorbate 80 - polysorbate 80 enhances the diffusion of beta haemolysis
- Colistin - Oxalinic Acid Blood agar (COBA

25
Q

criteria used for bacterial vaginosis

A

Hay’s criteria
Class I - normal, predom lactobacilli
Class II - intermediate; lactobacilli and other morphotypes
Class III - few or absent lactobacilli, presence of gardnerella vaginalis or other morphotypes, possible BV

Other is Nugent’s criteria

26
Q

media for balanitis and balanoposthitis

A

Blood agar anaerboic, sabouraud and mannitol salt agar for staph aureus vs coagulase -ve staphs

27
Q

Culture medias used for anaerobic bacteria

A
  • Wilkins Chalgren medium (anaerobes)
  • Wilkins Chalgren + Nalixidic Acid Tween 80 (non sporing anaerobes eg. Actinomyces, Prevotella, Peptostreptococci)
  • Wilkins Chalgren +Nalidixic Acid Vanvomycin agar (gram - anaerobes eg Bacteroides, Fusobacterium)
  • horse blood agar
  • Brucella agar (with haemin and vit K)
  • Neomycin BA (Clostridia and fastiduous anaerobes)
  • Thioglycollate broth (enrichment for anaerobics)
  • Cooked meat medium (differentiate anaerobes by saccharylotic and proteolytic)
28
Q

anaerobic incubation

A

anaerobic jar with gas generating sachet of CO2 nad H2

or
anaerobic chamber with 5% COw2, 10% H, 85% N

29
Q

which bacteria are mentioned in Nugen’t criteria for bacterial vaginosis

A

Lactobacillus
Prevotella
Gardnerella vaginalis
Mobiluncus

30
Q

incubation info for candida chromogenic agar

A

48 hours in 30 degrees

31
Q

incubation info for sabouraud dextrose agar

A

incubate at 28 degrees for 21 days or until growth is observed.

32
Q

media to use for bacilllus anthracis

A

blood agar
chocolate agr
nutrient broths (CMM; NB 2)
bicarbonate media
do not grwo on MacConkey
Specifc culture mdia PLET

incubation 24 hrs 35 degrees in air or 5% CO2

33
Q

specific culture media for selective bacillus anthracis

A

PLET (polymyxin lysozyme EDTA thallous acetate
This inhibits bacillus cereus

34
Q

culture media for corynebacteria

A
  • blood tellurite agar
  • loeffler agar
    -cystine tellurite agar

37 degrees 5%CO2
black/brown colonies with brwon halo on tellurite mediua

35
Q

Media used for diagnosis of salmonella

A
  • blood agar
    mac conkey agar 3 - salmonella non lactose fermenters
  • DCLS for gram negative enteric bacilli, seen as colourless to pink colonies
    urease agar slants with triple sugar iron agar
  • selenite broth highly selective
  • salmonella chromogenic agar
36
Q
A