Introduction: Syphilis consists in a systemic infect contagious pathology with a chronic character. The etiological agent consists of an anaerobic spirochete bacterium, Treponema pallidum. Laboratory diagnosis can be ...Introduction: Syphilis consists in a systemic infect contagious pathology with a chronic character. The etiological agent consists of an anaerobic spirochete bacterium, Treponema pallidum. Laboratory diagnosis can be made through a direct investigation of the etiologic agent or non-treponemal (VDRL) and treponemal (FTA-Abs) serological tests. False-negative results are rare. Objectives: The present report presents a rare case of a man with a secondary syphilis syndrome who was initially undiagnosed due to the prozone effect, since he presented VDRL in low titers, and was later confirmed with a new diluted serum sample and VDRL and FTA-Abs, which were positive. Conclusion: A close look should be given to patients who, although the clinical condition is compatible, complementary exams may not be, and clinical cases should be carefully evaluated so that the patient is not treated late.展开更多
The hook effect is best explained by how the analyte signal generated from the assay is compromised due to either antibody excess or antigen excess.Reporting false negatives can also impact clinical decisions that may...The hook effect is best explained by how the analyte signal generated from the assay is compromised due to either antibody excess or antigen excess.Reporting false negatives can also impact clinical decisions that may have adverse effects on the patient.The clinical impact of the hook effect will lead to reporting either inaccurately low or false-negative results.Six different patient pools were tested using immunoassay screening methods and also the LC-MS/MS confirmation method.For the immunoassay screening method,50μL of each patient sample is pooled together for every 100 patient samples.If there is a sample with the hook effect,it would give a very low or a negative result when the pool is tested neat and it would give a positive result when the pool is tested in a 1∶100 dilution.The drugs tested included Cannabinoids,Benzodiazepines,Amphetamines,Ecstasy,EDP,Opiates,Heroin,Cocaine,Fentanyl,Oxycodone and a combined method for Buprenorphine/Norbuprenorphine.Patient Pool number 6 showed a positive Buprenorphine and Norbuprenorphine that was traced back to the sample with the hook effect based on the suggested protocol.The random and different patient pools were prepared by using a Gilson GX241 liquid handler.The neat result for Pool number 6 showed the immunoassay for Buprenorpone and Norpuprenorphine was“Not Detected”at 2.1μg/L while the LC-MS/MS result was 2,780μg/L(cut-off<10μg/L).However,the result for the 1 in 100 dilutions of the pool for the immunoassay was“Detected”at 37μg/L without multiplying by the dilution factor.The result for the LC-MS/MS was 2,970μg/L.The suggested protocol is practical and cost-effective to avoid the clinical impact of reporting either inaccurately low or false-negative results.Also,can be used for testing when suspected samples with the hook effect are investigated.展开更多
文摘Introduction: Syphilis consists in a systemic infect contagious pathology with a chronic character. The etiological agent consists of an anaerobic spirochete bacterium, Treponema pallidum. Laboratory diagnosis can be made through a direct investigation of the etiologic agent or non-treponemal (VDRL) and treponemal (FTA-Abs) serological tests. False-negative results are rare. Objectives: The present report presents a rare case of a man with a secondary syphilis syndrome who was initially undiagnosed due to the prozone effect, since he presented VDRL in low titers, and was later confirmed with a new diluted serum sample and VDRL and FTA-Abs, which were positive. Conclusion: A close look should be given to patients who, although the clinical condition is compatible, complementary exams may not be, and clinical cases should be carefully evaluated so that the patient is not treated late.
文摘The hook effect is best explained by how the analyte signal generated from the assay is compromised due to either antibody excess or antigen excess.Reporting false negatives can also impact clinical decisions that may have adverse effects on the patient.The clinical impact of the hook effect will lead to reporting either inaccurately low or false-negative results.Six different patient pools were tested using immunoassay screening methods and also the LC-MS/MS confirmation method.For the immunoassay screening method,50μL of each patient sample is pooled together for every 100 patient samples.If there is a sample with the hook effect,it would give a very low or a negative result when the pool is tested neat and it would give a positive result when the pool is tested in a 1∶100 dilution.The drugs tested included Cannabinoids,Benzodiazepines,Amphetamines,Ecstasy,EDP,Opiates,Heroin,Cocaine,Fentanyl,Oxycodone and a combined method for Buprenorphine/Norbuprenorphine.Patient Pool number 6 showed a positive Buprenorphine and Norbuprenorphine that was traced back to the sample with the hook effect based on the suggested protocol.The random and different patient pools were prepared by using a Gilson GX241 liquid handler.The neat result for Pool number 6 showed the immunoassay for Buprenorpone and Norpuprenorphine was“Not Detected”at 2.1μg/L while the LC-MS/MS result was 2,780μg/L(cut-off<10μg/L).However,the result for the 1 in 100 dilutions of the pool for the immunoassay was“Detected”at 37μg/L without multiplying by the dilution factor.The result for the LC-MS/MS was 2,970μg/L.The suggested protocol is practical and cost-effective to avoid the clinical impact of reporting either inaccurately low or false-negative results.Also,can be used for testing when suspected samples with the hook effect are investigated.
