Sunday, July 22, 2007
Wow time sure flies, 4 weeks have gone by... and i've just ended my month long stint at the microbiology lab. I'm looking forward to cytogenetics! For a couple of reasons im sure you people can think of! =)
Alright basically i've learnt tons of new stuff at microbiology but i'm going to relate to you about my experiences of working the "Affirm VPIII Microbial Identification test" by Becton Dickinson. Basically the whole process of the experiment/test, involves both manual and automated parts.d Sample preparation is done manually, while the processing is done by the machine BD MicroProbe. I will elaborate more below.
Introduction
The Affirm VPIII Microbial Identification Test is a DNA probe test, used by the laboratory for the detection and identification of Candida species, Gardnerella vaginalis and Trichomonas vaginalis nucleic acid in vaginal fluid specimens from patients with symptoms of vaginitis.
Vaginitis is one of the most common problems observed in clinical medicine. There are 3 main categories of vaginitis, they are bacterial vaginosis (BV), yeast vaginitis (Candidiasis) and trichomoniasis vaginitis. BV is the most commmon form of vaginal infection, followed by vaginal candidiasis and trichomoniasis. This vaginal infections are clinically significant especially in pregnant woman, as they can lead to pre-term labor and birth and various adverse pregnancy outcomes.
Principles of the procedure
The Affirm VPIII Microbial Identification Test is based on the principles of nucleic acid hybridization. In nucleic acid hybridization tests, complementary nucleic acid strands join to form specific, double-stranded complexes called hybrids.
The test uses 2 specific single-stranded nucleic acid probes for each organism, a capture probe and a colour development probe. These 2 probes are complementary to the distinct genetic sequences of the target organism. The capture probes are immobilized on a bead embeded in a Probe Analysis Card (PAC). Each of the three organisms being tested has a separate bead on the PAC. The colour development probes are contained in a mutli-well reagent cassette.
The various components are put into the BD microprobe machine and run. At the end of the run, if there is even a slight colour change on any of the organism beads, it would indicate that that the specific organism is present in the patient's sample. Note that there are 2 beads that act as a positive and negative control. After the run, if the positive control bead does not show a change of colour or if the negative control shows a change of colour, it means that the results of the run are obsolete and that the sample must be rerun.
Procedure's after receiving patient sample
Alright basically i've learnt tons of new stuff at microbiology but i'm going to relate to you about my experiences of working the "Affirm VPIII Microbial Identification test" by Becton Dickinson. Basically the whole process of the experiment/test, involves both manual and automated parts.d Sample preparation is done manually, while the processing is done by the machine BD MicroProbe. I will elaborate more below.
Introduction
The Affirm VPIII Microbial Identification Test is a DNA probe test, used by the laboratory for the detection and identification of Candida species, Gardnerella vaginalis and Trichomonas vaginalis nucleic acid in vaginal fluid specimens from patients with symptoms of vaginitis.
Vaginitis is one of the most common problems observed in clinical medicine. There are 3 main categories of vaginitis, they are bacterial vaginosis (BV), yeast vaginitis (Candidiasis) and trichomoniasis vaginitis. BV is the most commmon form of vaginal infection, followed by vaginal candidiasis and trichomoniasis. This vaginal infections are clinically significant especially in pregnant woman, as they can lead to pre-term labor and birth and various adverse pregnancy outcomes.
Principles of the procedure
The Affirm VPIII Microbial Identification Test is based on the principles of nucleic acid hybridization. In nucleic acid hybridization tests, complementary nucleic acid strands join to form specific, double-stranded complexes called hybrids.
The test uses 2 specific single-stranded nucleic acid probes for each organism, a capture probe and a colour development probe. These 2 probes are complementary to the distinct genetic sequences of the target organism. The capture probes are immobilized on a bead embeded in a Probe Analysis Card (PAC). Each of the three organisms being tested has a separate bead on the PAC. The colour development probes are contained in a mutli-well reagent cassette.
The various components are put into the BD microprobe machine and run. At the end of the run, if there is even a slight colour change on any of the organism beads, it would indicate that that the specific organism is present in the patient's sample. Note that there are 2 beads that act as a positive and negative control. After the run, if the positive control bead does not show a change of colour or if the negative control shows a change of colour, it means that the results of the run are obsolete and that the sample must be rerun.
Procedure's after receiving patient sample
- Label a sample collection tube (SCT) with the patients identification no.
- Take the swab obtained from the patient and and cut it such that the SCT can be closed.
- Drop 12 drops of lysis solution to the tube.
- Mix the swab in the tube with the lysis solution.
- Cover the tube with a cap and place in a lysis block of 85 degrees for 10 mins.
- Remove the tube from the block and add 12 drops of buffer solution to the tube.
- This time add a filter cap to the tube
- Prepare the PAC and write down patients id no. in the space.
Prepare the reagent casette
- Add 4 drops of substrate solution to well no.7 of the reagent cassette.
- Drop the patients sample into well no.1 of the reagent cassette.
- Place the PAC into well no.1 of the reagent cassette.
- Press the run key to start the process and wait for about 32-35 minutes for the process to be done.
Reporting of results
Since we students do not have access to the hospitals system, we can only write down the test results on the test request form and wait for a medical technologist to come by verify the result and key the results in.
If the tests results show that the patient is negative for all 3 organisms, we write on the test request form "All -ve/ All Neg".
If the test results show that the patient tests results show 1 or more postive for the disease we write it on the test request form as eg. Gard +ve (Gardnerella positive)/ Cand +ve (candidiasis).
Thats all for my report! i'll get back to you all if you have any comments or queries.
Thanks
Randall Chua (TG02) 0503272G
# posted by Star team @ 1:12 PM 
Comments:
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rand!
the lysis block u mentioned, is it like a heating block kinda thing? and why 85 degrees?
charmaine
TG01
the lysis block u mentioned, is it like a heating block kinda thing? and why 85 degrees?
charmaine
TG01
hello! lol, y leh micro lab no good ar... got many shit sample?
okay, can u explain more abt Probe Analysis Card (PAC)?
Chaur Lee
TG01
okay, can u explain more abt Probe Analysis Card (PAC)?
Chaur Lee
TG01
to charmaine:
The lysis block is a heating block itself, and the reason for the temperature being at 85 degrees, is that it is the optimum temperature that ensures that the cell walls of all 3 microorganisms can by ruptured to release the DNA fragments.
The lysis block is a heating block itself, and the reason for the temperature being at 85 degrees, is that it is the optimum temperature that ensures that the cell walls of all 3 microorganisms can by ruptured to release the DNA fragments.
to chaur lee:
The PAC card is just a card that will be moved from well to well at various stages of the automation. The end product or interpretation of the results can be seen from the colour changes on the organism specific beads.
I'll try to get a picture of the PAC up on the blog. Cause i know its hard to picture what i mean.
The PAC card is just a card that will be moved from well to well at various stages of the automation. The end product or interpretation of the results can be seen from the colour changes on the organism specific beads.
I'll try to get a picture of the PAC up on the blog. Cause i know its hard to picture what i mean.
To Martin:
The purpose of the filter cap is to ensure that only the DNA fragments of the microorganism are dispensed into well no.1 of the reagent pack. Without the filter cap there would be excess waste material being included into the experiment which could affect the efficiency of the test.
The purpose of the filter cap is to ensure that only the DNA fragments of the microorganism are dispensed into well no.1 of the reagent pack. Without the filter cap there would be excess waste material being included into the experiment which could affect the efficiency of the test.
hey... although i see u everyday... but i still got to ask questions... lol...
so what are the limitations of this method?
~Jeremy~
TG01
so what are the limitations of this method?
~Jeremy~
TG01
Hi Randall, I would like to quote you:
"These vaginal infections are clinically significant especially in pregnant woman, as they can lead to pre-term labor and birth and various adverse pregnancy outcomes."
In simple terms, why would these vaginal infections lead to pre-term birth and adverse pregnancy outcomes?
Desmond Heng
TG02
0503179D
"These vaginal infections are clinically significant especially in pregnant woman, as they can lead to pre-term labor and birth and various adverse pregnancy outcomes."
In simple terms, why would these vaginal infections lead to pre-term birth and adverse pregnancy outcomes?
Desmond Heng
TG02
0503179D
hello!
Er, why would vagina infection lead to pre-term labor ah? Do u mind elaborating a lil bit more? Thanks!!
Chen Kangting
0503331A
TG02
Er, why would vagina infection lead to pre-term labor ah? Do u mind elaborating a lil bit more? Thanks!!
Chen Kangting
0503331A
TG02
to jeremy:
Some limitations would be that,
optimal test results require appropriate specimen collection. Test results may be affected by imptoper specimen collection, handling or storage.
Another limitation, would be the fact that sometimes the colourization of the probes may be so slight that its hard to differentiate between a positive or negative result. Therefore errors may be made when reporting the results by different people.
Eg. Med Tech A interprets the test as +ve, while Med Tech B interprets the test as -ve.
Some limitations would be that,
optimal test results require appropriate specimen collection. Test results may be affected by imptoper specimen collection, handling or storage.
Another limitation, would be the fact that sometimes the colourization of the probes may be so slight that its hard to differentiate between a positive or negative result. Therefore errors may be made when reporting the results by different people.
Eg. Med Tech A interprets the test as +ve, while Med Tech B interprets the test as -ve.
To Ci Liang:
The confirmatory test for these vaginal infections, would be to grow the microorganisms on culture. Identification of these organisms by methods such as gram stain, wet smear and viewing under microscope etc.
The confirmatory test for these vaginal infections, would be to grow the microorganisms on culture. Identification of these organisms by methods such as gram stain, wet smear and viewing under microscope etc.
To Desmond and KangTing:
In the case of vaginal infections, the membrane surrounding the baby has a "lower resistance" and will rupture easily. In majority of the cases, these would lead to preterm labor. Although note that there have been cases whereby the membrane ruptured but labor was not induced.
In the case of vaginal infections, the membrane surrounding the baby has a "lower resistance" and will rupture easily. In majority of the cases, these would lead to preterm labor. Although note that there have been cases whereby the membrane ruptured but labor was not induced.
HEllo
Jus want to find out, is there anyy other disease that can use this test to confirm the diagnosis or smth?? other than vaginal infections
Vinodhini
TGO2
Jus want to find out, is there anyy other disease that can use this test to confirm the diagnosis or smth?? other than vaginal infections
Vinodhini
TGO2
To Vino:
Eh... For VpIII test, the probe analysis card is only specific for the 3 organisms messioned in my blog posting. So there's no alternate disease which it is used for.
Eh... For VpIII test, the probe analysis card is only specific for the 3 organisms messioned in my blog posting. So there's no alternate disease which it is used for.
It is great to have visited your website. Thanks for sharing useful information. And also visit my website about health. God willing it will be useful too
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Pengobatan Scabies secara Alami
Obat Penghilang Jerawat dan Bekasnya
Cara Menyembuhkan Batuk Berkepanjangan
Cara Mengobati Pengapuran Tulang
Obat Pengapuran Otak pada Anak
Cara Mengatasi Mata Bengkak
Obat Herpes Zoster
Obat Tradisional Cedera Lutut/Keseleo Lutut
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