[GAST after 3 years' use].

Abstract

Increasing of systematic syphilis screening has led many scientists to think to automatisation of classical cardiolipid reactions. The Debains-Kolmer reactions have been adapted to continuous flow but they appear actually inefficient. The use of ART (automated reagin test) gives very satisfying results and this reagent has obtained its homologation in the United States. The apparition of Groupamatic has incitated M. GARRETTA to adapt on this material the K. Antigen reagent manufactured by the Blood Transfusion Center in Lille and has led to the definition of GAST reagent (Groupamatic automated syphilis test). The authors describe the method of preparation of this reagent and its utilization on Groupamatic. It appears that the bovin cardiolipidic extract, non specific by definition, lays down to antagonist problems: to be sensitive enough when specific enough. It's the final reagent settlement which is the more delicate and which needs the maximum in manipulation. Yet, the composition of GAST is now well established and this reagent, ready for use, may be kept during three months at 4 degrees C. Then the authors describe the results of their own use of GAST, in routine on Groupamatic 360: out of 6 079 plasmas of blood donnors examined, 3 per cent of reactions are positive or doubtfull (which stays compatible with the screenings in large number). After confirmation with complementary tests made with manually GAST, RPR with microscopic reading, haemagglutination, and lastly fluorescent method, it appears that the rate of positive reactions is 1,7%. This result is conformable to habitual statistics. In conclusion, the GAST is a well-adapted reagent for Groupamatic technology, and represents a progress compared with classical manually methods. The adaptation of syphilis screening on Groupamatic is a factor of rentability of this equipment, allowing to realize 360 tests in one hour. At last, considering that cardiolipidic reactions are not of an absolute diagnostic value, treponemic complementary tests are necessary in order to confirm positive results picked up on Groupamatic.