Week 3 explanations...

hey everybody.. i suppose it would e easier if i answer everybody's queries in a post rather than in the comments page. anyways, here goes...

to Athirah:
contamination do happen and that's why good pipetting skills is very important. i always try not to let the tip of the pipette touch the wells as it will introduce other contaminants into the wells. however, according to a colleague of mine, the test is specific for mycoplasma pneumonia antibodies and other bacteria are not easily detectable.

to Xin Yi:
interdeterminate means you can't really tell if it is positive or negative. that's why it is indicated as a plus-minus sign. however we do not report as plus-minus. we try to compare the results of one well with the result of the well next or after it. using a ruler to measure the compactness is rather ridiculous actually. so what i was taught was, to observe the tightness of the ring. in other words, which ring appears darker or bolder. the lest tighter ring will be the positive end-point titre. i hope that answers your question S:.
presence of a least compact ring should still be reported and not ignored as it could indicate presence of weaker mycoplasma antibodies. it is simply to be on the safer side lah actually.

to Liyanah:
i dont really miss you but i know you're probably getting skinnier now cos you miss me too much. right? hah!
anyways, the samples are diluted to achieve a titre. a titre is like, series of dilution. we carry out a titre to find out how weak or how strong the antibodies are. if all the dilution is the same, or if everything is done as a neat (1:1), then it would defeat the purpose. we wouldnt be able to tell how "dangerous" the antibodies are. or how wide the disease has spread.
we don't use the awesome multi channel pipettes in serology but we do use them in hematology labs to prepare the reagents in the morning but i shall not go into that for now. haha. reason being, we have to pipette different amounts of reagents or samples each time and multi channel pipette usually gives the same amount of solution each time we pipette.

to Lee Jin:
sensitised particles basically means that the particles are pre-coated with antigens. we learnt this in hematology i think. usually, they come in lyophilised form in the test kits. lyophilised means powdered form. we learnt that in LMQA if i'm not mistaken. lyophilised substances are usually not ready-to-use. therefore, we have to prepare them ourselves by adding the required amount of diluent.

to Han Yang:
- regarding your first question, i'm not very sure why. it's just the way the lab works. we receive samples from hospitals, clinics, etc. and they usually collect samples in the morning, thus we receive them in the afternoon.
- some examples of automated tests are Candida virus tests, Epstein-Barr virus tests which tests for nasopharyngeal carcinoma, Varicella-Zoster tests which is the main cause of chicken pox, and many more. there're really A LOT. we usually carry out these tests using a machine called the EVOLIS and it works using the ELISA method.
- for the third question, i can't really answer that because it is what given in the test kit. probably, rabbit's serum has the same reaction as human serum towards the specific viral antibodies.
- a positive result will show agglutination THROUGHOUT. presence of a button or a ring shows that the sensitised particles are not able to agglutinate due to absence of the specific antibodies and therefore they SETTLE at the bottom of the well. when they settle at the bottom, they form either a compact button or a ring, depending on the presence of the antibodies or the strength of the antibodies if they are present.
- yes, you may assume that the most compact ring is negative as the wells before that shows a less compact ring. however, that doesnt mean the patient is free from infection. due to the less compact ring observed in the wells before, it does indicate presence of the specific antibodies.
- do you mean aseptic environment, for example, close to a bunsen burner or something? sadly, we don't practise that in our lab. but the pipette tips and microwells used are sterile before we use them. and of course, we put on gloves too to protect ourselves and prevent introduction of our bacteria into the wells.
- the reason why some tests remain manual is, there are probably no machines invented yet to carry out such tests. however, special tests such as this MPA tests are usually carried out on certain samples as requested by the hospitals/ clinics. they're usually less than 50 per day. human error is inevitable, thus, secondary checks are very important and are usually done by someone more experienced. we usually do 4-5 samples at one time and it usually take less than half an hour. during the incubation time, of course we carry out other tests on other samples as not to waste time.
- i'm not sure if there are any confirmatory tests. what i know and was taught, the MPA test is specific to test for presence of mycoplasma pneumoniae antibodies. after carrying out the test, we record the results and the results are sent out to respective hospitals/clinics.

wow, that was long.. i hope i've answered all 8 or probably more of your questions. heh..

to Quan Jun:
haha. you're weird. nobody would mistake 1 - 9 as 1 -6 ... cos then, it would only be 5 hours of work.
i think your question is kind of similar to someone's question. well, as i said, a button means that the particles settled at the bottom of the well and not agglutinate. my supervisor told me that we should look out for agglutination THROUGHOUT the well and not settling of the particles in a button or a ring. i know it's a bit confusing. i was confused the first time too but i was explained as such so yea.. if wou try to disrupt the button, the particles would dissolve and still NOT form any agglutination.

to Farhanah:
for serology lab, the screening test that we usually do is the Venereal Disease test, followed by the VD titre. i don't think we have any other screening tests. the confirmatory test would be the TPHA (treponema pallidum haemagglutination) test. other screening or confirmatory manual tests include ATG-AMC (anti-thyroglobulin and anti-microsomal antibodies) test, ASO (anti-streptolysin O) test, IM (infectious mononucleosis) test, WWF (Widal and Weil Felix) & Brucella test.

thank you all for the great response. i'm very sorry if my explanations arent that clear or it still leaves you clueless but i've really tried my best to explain to you guys as what was taught to me during my stay in the serology lab for the first 2 weeks. if you still wanna ask me anything, go ahead. keep asking. it's good.

see you all C: