False positive results with the use of chlamydial antigen detection tests in the evaluation of suspected sexual abuse in children

The role of the microbiology laboratory in the investigation of child sexual abuse

“…However, this approach is traumatic for children and the achievable level of sensitivity remains unacceptable in the investigation of suspected CSA. The specificity of the test is higher than its sensitivity [34, 351. However, the positive predictive value is reduced in a low prevalence population; this renders the test unacceptable in low risk cases [36]. False-positive results may result from the presence in the anogenital flora of organisms (Escherichia coli, Acinetobacter calcoaceticus, N. gonorrhoeae, group B streptococci and G. vaginalis) that cross-react with chlamydiae [34].…”

“…Cell culture is more specific than antigen detection tests and is the method of choice in CSA cases, given the medico-legal dimension to these cases [36]. Antigen detection tests should not be used alone in this context; low test specificity means that positive results would not be acceptable in a Court of Law [36].…”

“…Antigen detection tests should not be used alone in this context; low test specificity means that positive results would not be acceptable in a Court of Law [36]. However, use of the DIF test, in conjunction with cell culture, is justified because the adequacy of the specimen can be noted readily during microscopic visualisation of the smear.…”

Medical and Legal Implications of Testing for Sexually Transmitted Infections in Children

“…The use of a genusspecific antibody for culture confirmation can lead to a misidentification of Chlamydia pneumoniae as C. trachomatis in pharyngeal specimens (6). Enzyme immunoassays (EIAs) are not acceptable as confirmatory tests and have been associated with false-positive results, especially when used on vaginal and rectal specimens (12,32,33,61). Currently available EIAs are based on polyclonal antibodies that will cross-react with bacteria present in the anogenital tract and nonspecifically react with fecal material (12,32,33,61).…”

“…Enzyme immunoassays (EIAs) are not acceptable as confirmatory tests and have been associated with false-positive results, especially when used on vaginal and rectal specimens (12,32,33,61). Currently available EIAs are based on polyclonal antibodies that will cross-react with bacteria present in the anogenital tract and nonspecifically react with fecal material (12,32,33,61). The methods used for culture confirmation became an issue when several large commercial laboratories started using an EIA instead of fluorescent-antibody (FA) staining and visual identification of inclusions for culture confirmation.…”