However, real false positives in industrialized countries are rare. Among 1000 amebic

serologies, Laverdant and colleagues reported only two cases of false positives concerning patients with hepatocarcinoma.[6] Thus, in industrialized countries, amebic serology must be performed only on patients with a hepatic abscess who have stayed in an endemic area. False negatives decrease sensitivity and negative predictive value. They can be due to patients’ immune response, the type of serologic test, or the pathogen strain. Sensitivity seems to be less important with PLX-4720 supplier serums obtained during acute illness (70%–80%) than those obtained during convalescence (>90%).[4] Indeed, a false-negative result can be obtained with a serologic test done within the first 7 to 10 days of the infection, but when repeated later, the test usually becomes positive: most of the time, seroconversion occurs before the 15th day. Furthermore, discrepant results can be seen between different assays done on the same sample. It has been described between LAT (negative) and IHAT (positive) in several publications (1/15 for Cummins[7] and 4/42 for Kraoul[8]), although these two assays use the same antigen. A similar result has been obtained between LAT and EIA (2/27 for van Doorn[9]). In this last case, initially negative samples

in LAT became positive 3 to 6 days later. Furthermore, E histolytica wild-type Cepharanthine strains compared to strains developed in cultures used to make serologic tests could present differences in their antigenic profile. selleck kinase inhibitor Tanyuksel and colleagues pointed out

that the lack of an accurately defined “gold standard” has impeded an objective assessment of the sensitivity of the antibody detection tests currently in use.[10] The accuracy of serology may be overestimated and the use of PCR methods tends to confirm this hypothesis.[11] Furthermore, no studies have been found concerning evaluation of amebic serology performance compared to a “gold standard” with likelihood-ratio test that limit the impact of prevalence. These observations lead to the conclusion that, in a highly evocative context with negative blood cultures, ALA should be considered despite a first negative amebic serology. Several propositions can be made to confirm the hypothesis of ALA. First, two or more screening serologic tests must be made. Second, if the initial serologic tests are negative, it is necessary to repeat the assay 7 to 10 days later. Third, the direct detection methods based on PCR gene amplification techniques realized in the abscess liver pus (when the aspiration is required) and also in blood, saliva, and urine samples appear to be very helpful and should be more systematically performed.[12] The authors state that they have no conflicts of interest to declare.