Procedure Of Some Laboratory Tests

TEST PRINCIPLE FOR TYPHOID FEVER

KIT USED=MICROPATH ANTIGENS/FEBRILE ANTIGEN KITS

The test depend on the ability of antibody in the patient serum to agglutinate the stained bacterial antigens. When this occur the aggregate become visible to the naked eye

SAMPLE COLLECTION

Blood was collected with a lancet. The area to be pricked was cleaned with an alcohol swab. The end of the finger tip was squeezed and pierced with a sterile lancet. The blood was collected into an herparinized capillary tube,sealed on a sealant and labeled according to collection which were brought to the laboratory for further analysis.

PROCEDURE

The blood collected were allowed to clot to form a retract. The blood was centrifuge at 1500rpm for 5minutes to get a clearer serum for the test. The herparinized tube containing the blood samples were broken to collect the serum. Drop of serum was placed on the consecutive circle on the tile provided along with the kit. A drop of the antigen was added to the appropriate circle on the tile and was mixed and spread  to cover the entire test circle with a disposable micro pipette and was gently and evenly rocked and rotated for 1minute while examining for agglutination.

RESULT

Agglutination of the antigen indicates the presence of antibody(Cowan 1965).

TEST PRINCIPLE FOR HEPATITIS B VIRUS(HBV)KIT USED=HBsAg Gold Rapid Screen Test

The HBsAg RST is a chromatographic immunoassay (CIA) for the detection of surface antigen of Hepatitis B in human serum/plasma and whole blood. Specific antibody against HBsAg is precoated onto a membrane as a capture reagent on the test region. During the test, specimen is allowed to react with the colloidal gold particle, which have been labeled with other specific antibodies. If HBsAg is  present, a pink colored band will develop on the membrane in proportion to the amount of HBsAg presented in the specimen.Absence of this pink colored band in the test region suggest a negative result. To serve as a procedural control, a pink colored band in the control region will always appear regardless the presence of HBsAg.

SAMPLE COLLECTION

The area to be lanced was cleaned with an alcohol swab. The end of the fingertip was squeezed and pierced with a lancet. The first drop of blood was wiped away with a sterile cotton wool and a micro pipette was used to obtain a little amount of fresh blood.

PROCEDURE

One drop of the blood sample was dropped on the sample pad after all blood have been completely absorbed a drop of the blood diluents was dropped on the blood and was allowed to run for 5 to 20 minutes before reading the result.

INTERPRETATION OF RESULT

-         Negative result= No band appears in the test region(T), only one pink band appears in the control region(C). This indicate that no HBsAGg has been detected.

-         Positive result=In addition to the band in the control region(C) another pink band will appear in the test region(T). This indicate that the specimen contain HBsAg

-         Invalid result= If no band appears in the control region (C), regardless of the presence or absence of line in the test region (T). It indicate a possible error in performing the test. The test should be repeayed using anew device.