Week 1: Microbiology Dept

Name: Siti Hawa Bte Azali
Admin No.: 0704087F

During the 1st week of my attachment , i was assigned to work in the Microbiology Department where specimens are tested for presence of any pathogenic organisms and where identification of causative agents were carried out. This section is important as it aids in the final confirmation of clinical diagnosis.

Several tests were introduced to me by the section supervisor,some of which were familiar whereas others were not. Among the microbiological tests that i was assigned to practice on and eventually carry out are Gram and AFB Staining, Syphillis Test- VDRL and TPHA, PYR Enterococci test,Mycoplasma Test, etc.

Nature of specimens that this section usually test on are those such as serum (most common), sputum, stool, blood culture,bile, GI fluid and different types of aspirate taken during operation.

One of the test which i frequently did was the Widal Weil Felix Test - a test used to detect and measure levels of warm and cold agglutinins in blood.

Agglutinins are basically antibodies that causes haemagglutination to occur in the body. Cold agglutinins are active at low temperature (IgM) whereas warm agglutinins are active at warm temperatures (IgG).

This test is done on a patient's serum( in a plain tube) by testing it against 11 different reagents consisting of different commercial antigens (mainly different types of Salmonella).

Normal Values:
Warm agglutinins: no agglutination in titres at or below 1:80
Cold agglutinins: no agglutination in titres at or below 1:160

Procedure:
1) 20ul of serum is decanted onto each of 11 individual areas of test card
2) 1 drop of each reagent added to serum on respective test areas (reagent 1 into test circle 1, reagent 2 into test circle 2, etc)
3) Mix the serum and reagent on each circle
3) Rotate the test card for 1 min
4) Check for agglutination
Reagent-serum mixture with agglutination will then be tested again, this time with lower concentrations of serum (10ul and 5ul).
5) Check for agglutination for the 10ul and 5ul serum concentrations
6) Using a standard Widal Test reference table, we can calculate the titre of the agglutinins in the serum (eg. 1:40,1:80,1:160,1:320)

Abnormal values of cold and warm agglutinins may cause hemolytic anemia and therapeutic actions are then taken by the doctor.

High levels of Warm Agglutinins (~1:160,1:320) can be due to:
-Salmonella infections
-Lymphoma
-Systemic Lupus Erythomatosus

High levels of cold agglutinins (~ 1:320) can be due to:
-Mycoplasma and viral infections
-Multiple myeloma.

This test is not normally a routine test but is usually needed for urgent specimens.