Shaun LivseyBMS2

Leicester

Changes in working practice brought about

by the introduction of an automated EIA platform

in an enteric section

Before the Introduction of an Automated EIA System...Gave all stool samples to Virology to do tissue culture

CPE and neutralisation for C.difficile toxin detection. SOP required all stools for full culture to be tested for

Cryptosporidium using fluorescent microscopy. (Stuck in the dark for hours with a hundred negative slides)

Full, labour intensive, formal ether faecal concentration and manual microscopy was performed on:Any foreign travel – Paris !Prolonged gastric upset‘Box tickers’ (>30 OCP’s to read)

Large QuantiFERON runs done manually twice a week. (Occasional expensive plate failure, unknown number of pipetting errors)

Opportunity- Every cloud....About 4 years ago, major problem with C.difficile

levels in the Trust - needed action - funding available.

Diagnostic speed needed to be increased to help reduce the problem – tissue CPE too slow – EIA.

Funding for an auto-analyser agreed if 24hr turn-around 365 days a year.

‘T4’ or ‘Triturus’ (Inverness Medical) trialled then bought.

ToxA/B II EIA test (Techlab) chosen for CDT diagnosis.

Changes...

Enteric lab took back CD Toxin testing.Changed to faster, reliable EIA format.Also moved to EIA for combined

Cryptosporidium/Giardia diagnosis.POC device used to differentiate

positives (RIDA Quick Crypto & Giardia from r-biopharm).

Moved QuantiFERON EIA from manual format to automated.

More changes...Review of manual OCP data – showed that the number

of significant findings, excluding Giardia and E.coli = 0.24% of OCP’s

Therefore decision to drop OCP on request or vague indicators

Now only OCP if: OCP is only request Travel outside N. Europe or N. America Specific indicators e.g. Eosinophilia.

Drop from >30 to 5-10 a day = big time saving.Giardia diagnosis has more than doubled (Now

detected for in all cultured samples)

Doubled Cryptosporidium diagnosisFar less tray failure in QuantiFERON runs.

Confident that right sample in right well

T4:

Problems...Particulates blocking pipettes:

System designed to pipette blood/serum- not lumpy faeces. Lumen of conductive tips is very small.

Initial work caused high levels of blocking.Resolution:

Needed to increase volume of stool and diluent.Needed to reduce lumen of sample tube.Needed to centrifuge mixture just before T4

sampling.Mucoid samples are still problematicBlock rate around 2-3 per full tray

More problems...Bubbles –

Level detection looks for two identical levels before ‘going under’

If large bubble does not burst – air pocket sampled

Resolution -Gentle handling after centrifugeCaution with controls which are not

centrifuged

More problems....Limit to T4 Software:

Software not up to QuantiFERON calculationsThree tube system is too odd to handle

Resolution:Cellestis produced a sub-programmeNot slick, but works

Current situation:Full automation – others manual pipetteChanges accepted and ‘routine’Younger staff happy with this technologyOlder staff – some issues!SOP written with Band 4 in mind – One

BMA2 coped very wellInstrument is robust but repairs via

Grifols are very prompt

Future:

Dropping CD Toxin A/B testing?Using GDH as a primary screen for

C.difficileIntroduction of other enteric toxin

detectionClostridium perfringens toxin?Shigga toxin detection replacing O157 culture?

Some space for other non-enteric EIA’s on machine – more if extended working hours

Thanks for listening