Microbiology, Haematology and LMQA

Hi all, I have been posted to microbiology and now, on to haematology after serology on my first 3 weeks.
In my lab at microbiology, I was assigned for 3 quarters of my time there, to open bags at the specimen reception. So, ppl, pls spare me from questions that are too in depth. =)

It is essential to ensure that all request forms comes with the appropriate and correctly labelled specimens. There were cases when the specimen and request form does not tally. For example, the name of the patient labelled on the specimen is different from the name printed on the request form, we will write the comment that the samples were labelled as "xxxx (the name found on the sample)" and the barcoders would call the clinic and query on that. On cases where the specimen comes without a request form, we would write down the patient's details on a request form and call up the clinic to ask for the type of test. If the specimen is not properly labelled or is unlabelled, we would pass the specimen to the HOD(head of department) to deal with it.

Since Sasi has explained Urinalysis in detail, I would like to share some interesting things I had seen during my time there.


Trichomonas vaginalis

Trichomonas vaginalis is the most common parasite in urine. This organimsm is the same size and also looks like a white blood cell (wbc) especially if it is next to a wbc, it may be mistaken as an wbc. But if you look carefully, you will notice 4 flagella. Since it is mostly accompanied by wbcs and epithelial cells, its motility is the diagnostic feature. It affects females the most although males can have infection of T. vaginalis, which is rare.

For more infomation and a video of how it looks like, please follow this link: http://www.microbiologybytes.com>video>Trichomonas.html

Tyrosine crystals

Tyrosine crystals occurs in severe liver disease, tyrosinosis and Oasthhouse urine disease. They look like refractile needle-like crystals under 1000x magnification and appears black especially around the centre. They may also look yellowish due to presence of bilirubin in urine. They are found in acidic urine only.











Obtained from : http://www.medicine.uiowa.edu>cme>clia>modules.asp?testID=20

Yeast cells

Refering to pictures that Sasi posted, she showed yeast cells budding. During my experience in the lab, I managed to spot yeast cells with hyphae!








Taken from
http://www.agora.crosemont.qc.ca>
urinesediments>Imdoceng>
d05d002.htm

This picture shows the hyphae of yeast cells =)




Mucous threads

Mucous threads are present in urine in small amounts. In presence of urinary tract infection or irritation of the urinary tract, large amounts of mucous may be discharged in urine. Wide mucous threads may be confused with hyaline casts or cylindroids. So look carefully under the microscope! Cylindrical composition of casts and their rounded ends distinguishes hyline casts from mucous threads.








Mucous threads with uric acid crystals

Taken from : http://www.agora.crosemont.qc.ca
>urinesediments>Imdoceng>d05d004.htm


Stool culture
I was briefed on how to do stool culture in the microbiology lab but did not have a chance to perform. Basically, because the lab unlike hospitals, we receive samples that are relatively less pathogenic and we only indentify for samonella and shigella spps only. The media we used are specific for isolation of such organisms. They are XLD, maconkey, TCBS and selenite F broth.


LMQA of Microbiology lab

Urisys 2400: The machine will prompt around once a month for a new calibration. 2 controls will be run per day. The low/normal value and the high/abnormal value. The values are recorded into a logbook and runs are rejected if they are out of range.

Agar for cultures: Agar plates are bought commercially. When they arrive, we check macroscopically for contamination before a sample is incubated at 37 degree celcius overnight. After incubation, if there are still no growth, we conclude that it is sterile. To check for the plate's viability, we streak commercially prepared ATCC strains and incubate overnight at 37 deg celcius. The growth of the strains indicates that the plates are viable. So after the plates passed the quality check, we can then use them for testing.

This is just the general briefing I was given. Thus, for the in depth information for quality control, I am not very sure of them.


Haematology

I had so far learnt ESR and malarial parasite testing. For ESR, the principle and method is the same from what we learnt in school.
For malarial parasite, the principle is the same as what Lizzie (from 77 med tech street) described 6 weeks ago. Any slide with platelet less than 150 or more than 500 is selected for a blood smear to check for malaria parasite. An autostainer is used to stain the blood slides before microscopy.
The prevalence of the disease is rather low-according to my mentor. But I am so lucky/unlucky to spot 1 patient's slide positive for Malaria parasite (plasmodium vivax) on my 3rd day of practice while earlier that day, there was a case of plasmodium falciparium ^^



Hope that you have learnt something from my post.

Yeng Ting
TG02