Urines

Question 1

What tests are done on urine samples

Answer 1

Sedimax analysis for wcc, rcc, epi count
HCG/Pregnancy Test
Listeria rapid antigen test

Question 2

How does the SediMax work

Answer 2

On board the analyser, urine is mixed until homogenised

0.2ml of the sample is taken up and transferred ino a special disposable cuvette by a pipette

The pipette is then rinsed with instrument feed water (IFW) to avoid cross-contamination

Cuvettes containing sample are then centrifuged at 2000 RPM for 10 seconds which forces all the particles in the urine to sediment onto a single plane on the bottom of the cuvette, this is where the camera focuses on

The built-in camera then takes both bright-field and phase-contrast pictures through a microscope at 10 different points across the specimen

A high-performance image evaluation software then processes all of the images to detect and classify and particles

All the images are then stored on the analysers memory which can hod 10000 records

Question 3

What is the principle behind the SediMax

Answer 3

A fully automated urine analyser

Uses bright-field and phase-contrast microscopy to visualise and recognise formed elements of urine

Question 4

What cells can the SediMax identify?

Answer 4

Red Blood Cells (RBC);
White Blood Cells (WBC);
White Blood Cell clumps (WBCc);
Hyaline Casts (HYA);
Pathological Casts (PAT);
Squamous Epithelial Cells (EPI);
Non-Squamous Epithelial Cells (NEC);
Bacteria (BAC); Bacteria Rods(BACr);
Bacteria Cocci(BACc)
Yeast (YEA);
Crystals (CRY):
Calcium-oxalate monohydrate (CaOxm),
Calcium-oxalate dihydrate (CaOxd),
Uric acid (URI),
Triple phosphate (TRI);
Mucus (MUC),
Sperm (SPRM),
Amor­phous material (AMO)

Question 5

How is the SediMax maintained?

Answer 5

Run Milton disinfectant once every day first thing in the morning
QC ran twice a day, once in morning, once in afternoon -> Two controls, a high and a low control

Question 6

What urines are cultured

Answer 6

Any urines with a white cell count greater than 20
Urines are also cultured upon request or if the patient is immunocompromised i.e. from St. Vincent’s ward etc

Question 7

What will you have to do if the white cell count is very high on a urine sample?

Answer 7

If WCC is very high you will have to dilute the sample 1 in 10 in saline

You then run the sample as normal but change the dilution factor so that the correct result goes across

If wcc still too high then repeat the dilution to create a 1 in 100 dilution

Question 8

What is the name of the tubes used on the SediMax?

Answer 8

Sedivette tubes

Question 9

How much urine is needed for analysis of urine?

Answer 9

At least 2 mls -> if less urine then this than a manual will have to be done using a cell counter

Question 10

How many pictures does the SediMax take of a sample?

Answer 10

SediMax will take 10 pictures of different areas on the sample

If wccs too high in a certain picture the SediMax will not count this: 9/10 pictures taken

7/10 pictures or less will have to be diluted

Question 11

Do you culture a urine if the bacterial count or rcc is high?

Answer 11

No -> only if wccs also high

Question 12

What would a high urine bacteria count without a raised white cell count mean?

Answer 12

Poorly taken sample
Urine is meant to be a midstream urine
Bacteria without wcc = commensal bacteria
Patient could also be immunocompromised

Question 13

What would a raised red cell count without wcc mean?

Answer 13

Patient could be menstruating
It would be up to the consultant to determine the cause of the raised rbcs, the urine can be cultured if requested

Question 14

When would you carry out a manual urine

Answer 14

Only done when there is very little sample i.e. less than 2mls

Question 15

How would you carry out a manual urine?

Answer 15

Carried out using a cell counter
Cell counter composed of six squares broken down into 16 squares
Manually count the ebcs, rbcs and epis in one of the sets of 16 squares
If too many cells in sample you can carry out a dilution just make sure to multiply results up to account for the dilution factor

Question 16

How did you deal with casts and crystals in urine

Answer 16

There is no quantitative measurement of either
They are detected through microscopy
Detection is qualitative
Detection is not diagnostic, only really informs the consultant on the patient’s diet

Question 17

Talk about the HCG pregnancy test

Answer 17

One of our urgent tests as the patient is usually due to go for surgery
A negative pregnancy test is required prior to surgery for females
It’s a simple antigen test which only takes 3 minutes
If there is any feint line showing any positivity then a second test should be carried out
If still unsure then ask another scientist

Question 18

Talk about the legionella or pneumococcal antigen tests

Answer 18

Specific antigen tests done upon request
Pneumococcal antigen test usually done if query pneumoniae -> detects S. pneumo in urine
Legionella antigen test only done for patients in A&E or HDU/CHDU but can be added on by the consultants if required

Question 19

What agar are positive urines put up on?

Answer 19

Chromagar Orientation Plates

Question 20

What is the Chromagar Orientation plate?

Answer 20

a non-selective chromogenic culture medium intended for use in the qualitative direct detection, differentiation and presumptive identification of uropathogens to aid in the diagnosis of urine tract infection

Question 21

What are the most common urinary pathogens?

Answer 21

E. Coli (majority)
Enterobacter (Ents)
Staphylococcus Saprophyticus in young women

Question 22

What colour will an E. Coli grow on urine chromagar?

Answer 22

E. Coli = pink

Question 23

What colour will GNBs grow on brilliance chromagar

Answer 23

GNBS = large and blue but some can also be colourless

Question 24

What colour will your Ents grow on Brilliance chromagar

Answer 24

Ents = bright blue (smaller than GNBS and not as dark)

Question 25

What colour will S. saprophyticus grow on brilliance?

Answer 25

Light pink -> not as bright as E. Coli

Question 26

How will Pseudomonas grow on Brilliance

Answer 26

Pseudomonas will have a greeny metallic sheen to the colonies

Question 27

For how long are the agars incubated?

Answer 27

At least 16 hours
Preferably 16 - 24 hours but GNBs usually grow in a few hours

Question 28

How do you carry out a colony count for urines

Answer 28

1-9 colonies = <10^4 cfu/ml
10-100 colonies = 10^4-10^5 cfu/ml
>100 colonies = >10^5 cfu/ml

Question 29

Why do we carry out a colony count for urines?

Answer 29

Less than 5 colonies/scanty growth is rarely every causative of infection

Unless the organism is a query GNB then we don’t pick a scanty growing organism i.e. less than 5 10 colonies

Question 30

How is growth reported for urines

Answer 30

Pure growth
Predominant growth
- 2 different organisms -> usually ID both
Mixed growth
- 3+ colonies -> don’t ID these

Question 31

What would you do with if a query E. coli and a uery Pseudo grew on the plate

Answer 31

Put up a purity plate for each
ID both organisms
Sens for both?

Question 32

What would cause a very mixed growth on a plate?

Answer 32

Mostly just an incorrectly taken sample i.e. not a mid stream urine -> contains commensals

Question 33

How could you tell if a sample was poorly taken?

Answer 33

Raised epithelial cells
Raised bacterial cells
Normal white blood cells
Mixed growth on plate if cultured

Question 34

What would you do if there was predominant growth of E. Coli but the other organisms was a coag neg staph?

Answer 34

You can ignore the coag neg staph as this is probably just a commensal and just ID the E. Coli

Question 35

What would you do if there was predominant growth of an E. Coli but the other organism was a query GNB

Answer 35

You must ID both organisms
Unlike with a coag neg staph you cannot assume the GNB is not the infectious agent - it probably isnt but just to be safe you must put up both

Question 36

Why might there be no growth on a plate but urine was positive

Answer 36

Patient is probably on antibiotics i.e. the wccs and bacteria are high because they have an infection but the bacteria cannot grow just to the presence of antibiotics in the sample

The bacteria causing the infection could also be fastifious e.g. TB (rare) or Chlamydia

Question 37

What would you do with a scanty growing organism where there is less than 10 colonies on the plate?

Answer 37

Less than 10 colonies is rarely ever infectious so unless it is a GNB we don’t pick it

Question 38

Talk about E. Colis in urine

Answer 38

E. Coli is the most frequently seen bacteria causing UTIs
Grow as pinky/purple colonies on Chromagar
Query E. Colis don’t need to be Maldi’d before going for sens
Some E. Coli’s may be pale if they havent been able to produce their pink colour yet

Question 39

What would you do with a white colony on a Brilliance chromagar

Answer 39

Query Staph/Query Yeast
S. aureus will be yellow coloured but a coag neg staph maybe white
Colonies will look spiky if query yeast

Staphyslide -> Staphaurex agglutination test -> S. aureus is coag pos, CNS or Yeast will be negative

Wet prep for yeast to look for budding

Question 40

What is a wet prep?

Answer 40

Looking for budding yeast cells
Add 1 drop of saline to a glass slide
Pick up the query colonies with a glass coverslip and smear onto the slide

Question 41

How will lactobacillus appear on Orientation agar

Answer 41

Lactobacillus can usually seen as a pink haze in the background agar

The lactobacillus is just a commensal

The background will be pink, colonies will not be pink (Not like E. Coli), pale colonies

Question 42

What organisms do you send for Maldi ID?

Answer 42

All organisms other than E. Coli

Question 43

What do you do after Maldi has ID’d your organism

Answer 43

See if the preliminary ID matches the Maldi ID -> if not then why
Write the ID of the organism on the plate
Will have to merge PID and Maldi ID for results e.g. ?GNB to Klebsiella etc