Abstract

Objective: Between January 2008 and December 2009 the Microbiology and Clinical Microbiology Department, Serology/ELISA Laboratory evaluated the detection of three infectious agents and we aimed to evaluate the algorithmic position of avidity index (AI) test results in the clinician-laboratory collaboration.

Methods: Toxoplasma gondii, cytomegalovirus (CMV) and rubella serological tests were evaluated retrospectively in the serum samples of the 126 cases between January 2008 and December 2009. IgM and IgG antibodies and IgG AI were investigated in the serum samples of the cases by ELISA method. 

Results: T. gondii, CMV and rubella IgG AI tests were performed in 40, 53 and 33 of 126 cases, respectively. Low AI results were detected in 7 T. gondii, 5 CMV and 1 rubella tests and high AI test results were detected in 29 (72.5%), 45 (84.9%) and 30 (90.9%) of Toxoplasma, CMV and rubella tests, respectively. We detected low avidity test results in 8 (7.3%) of 110 cases which required the triple test. IgM and IgG were positive in 2 of 8 cases. IgM was negative and IgG was positive in 6 of 8 cases. We detected high AI test results in 96 (87.3%) cases. Primarily, direct dual test (IgM and IgG) was required and 90 cases were IgM-negative and IgG-positive, and 6 cases were both IgG and IgM-positive. Later the dual test and AI test were required. Of 16 cases, 5 (31.3%) showed low AI, and 8 showed high AI. 

Conclusions: With respect to clinician-laboratory collaboration, avidity tests were required primarily together with serologic tests for the detection of these three infectious agents. Although avidity tests have a high cost, it is advisable to perform them if there is a potentially high clinical risk.