Latent listeriosis--its diagnosis by bacteriology and serology in five cases.

The failure of agglutination tests in the diagnosis of latent listeriosis (chronic and asymptomatic) are partly due to the fact that deficient antigens in general use have discredited the serology in this infection. However, using good live antigens or antigens devitalized at moderate temperature and conserved by lyophilization, excellent diagnostic results may be obtained by indirect immunofluorescence (IIF). We could confirm this again in five women with a history of pregnancy disorders. All had a positive or strongly positive IIF. Listeria monocytogenes could be isolated by cultivation of the cervico-vaginal exudate, cerebrospinal fluid and from the placenta. After one year and more, these mothers continued to have positive IIF, proving that L. monocytogenes does not disappear from infected persons, even after a long-lasting treatment.