Laboratory evaluation of the new Access ® cytomegalovirus immunoglobulin IgM and IgG assays.

BACKGROUND

Reliable laboratory methods for detecting congenital CMV infection are valuable since CMV infections are asymptomatic and because early detection is important for correct management and counseling of expectant mothers.

OBJECTIVES

Compare the Beckman Coulter Access(®) method for the Unicel(®) DxI 800 analyzer with the bioMérieux VIDAS(®) method for two serological markers: CMV IgG and CMV IgM.

STUDY DESIGN

Precision was determined with CLSI EP5-A2 protocol. Linearity of the Access CMV IgG was evaluated using selected high positive samples. Performance was assessed by testing non-selected pregnant women, frozen negative and positive samples with recent and old infections. Kinetics of the anti-CMV antibodies response was studied using samples from pregnant women with a recent infection. In a prospective study, 3992 pregnant women were screened for determining prevalence of a primo-infection and CMV IgM non-specific rate.

RESULTS

Total CV is lower than 10% and 12% for Access CMV IgG and CMV IgM. The IgG method is linear (R(2)=0.999) with recoveries between 85% and 108%. Correlation between Access and VIDAS CMV IgG is highly significant (P<0.001). Observed agreement was 97.4% for CMV IgG and 93.7% for CMV IgM. Relative sensitivity and specificity was 97.2% and 100% for IgG and 100% and 97.4% for IgM. Kinetics of the antibody response measured with Access methods is significantly higher (P<0.02) when compared with VIDAS and probably easier to interpret. Prevalence of a recent infection was 0.85% and CMV IgM non-specific rate was 2.9%.

CONCLUSION

Good sensitivity and specificity and pronounced anti-CMV antibody response make the Access CMV IgG and IgM tests suitable for screening prenatal CMV infections.