Interpretation of complement fixation test results as displayed on Auto-Analyzer charts

Abstract

The Auto-Analyzer is used to perform complement fixation testing for the Brucellosis Eradication Scheme. In this system, the reactions of the complement fixation test are carried out using the continuous flow analysis principle. A colorimeter measures the transmittance of red cells left in suspension at the end of the reactions and this is traced on to the Auto-Analyzer recorder chart.

The normal trace consists of a “standard” control serum, which corresponds to 50% haemolysis of red cells, followed by 39 small crests indicating negative samples. Any sample giving a peak equal to or higher than the standard serum is positive. Aberrant traces may be caused by carry-over from positive samples, poor sample preparation, and machine or reagent faults.