Utility of the Rapid Antigen Detection Test E. histolytica Quik Chek for the Diagnosis of Entamoeba histolytica Infection in Nonendemic Situations

Abstract

Background Entamoeba histolytica infection is an increasingly common sexually transmitted infection in Japan. Currently, stool ova and parasite examination (O&P) is the only approved diagnostic method. Herein, we assessed the utility of the commercially available rapid antigen detection test (QUIK CHEK) for E. histolytica. Methods A multicenter cross-sectional study was conducted. Stool samples that had been submitted for O&P examination were included. The samples were subjected to both QUIK CHEK and polymerase chain reaction (PCR), and the QUIK CHEK results were assessed in comparison with PCR as the reference standard. Results E. histolytica infection was confirmed in 5.8% (38/657) of the samples and comprised 20 diarrheal and 18 non-diarrheal cases. The overall sensitivity and specificity of QUIK CHEK was 44.7% [95% confidence interval 30.1–60.3] and 99.8% [99.1–100], respectively. The sensitivity of QUIK CHEK was higher for diarrheal cases (60.0%) than non-diarrheal cases (27.8%). Further, the combined use of QUIK CHEK with O&P increased the sensitivity (78.9%), especially for diarrheal cases (up to 90%). The E. histolytica burden assessed by quantitative PCR was similar between QUIK CHEK-positive and -negative samples. The QUIK CHEK assay sensitivity was lower for cyst-containing stools than for trophozoite-containing stools, although it was shown that cultured E. histolytica clinical strains from QUIK CHEK-negative cyst-containing stools exhibited antigenicity in vitro. Conclusions The present study confirmed the high specificity of QUIK CHEK for E. histolytica infection. Combined use with O&P increased the sensitivity of detection, facilitating the use of QUIK CHEK in point-of-care settings in non-endemic situations.

Prevalence of Human Intestinal Entamoeba spp. in the Americas: A Systematic Review and Meta-Analysis, 1990–2022

“…Regarding ELISA tests, antigen-based methods have given good sensitivity and specificity, but serology includes limitations such as false negatives in early infections [51]. PCR is the most reliable diagnostic tool for the detection of Entamoeba species, and it is particularly useful for distinguishing pathogenic versus nonpathogenic ones [52]. Although these methods have been implemented since 1990, this review showed that their use is not yet frequent in the Americas.…”

COVID-19 and Corticosteroids: Unfamiliar but Potentially Fatal Infections That Can Arise following Short-Course Steroid Treatment

“…32 Microscopy, which lacks sufficient sensitivity and specificity, is unable to distinguish pathogenic and nonpathogenic amebae, so alternative methods should be used for diagnosis whenever possible. 18,21,38,39 A combination of serology, stool antigen, and/or molecular tests often help establish diagnosis, although serology is more difficult to interpret in endemic settings because it may indicate either past or active infection, and antigen tests may be of low sensitivity, particularly for cyst-containing stool and asymptomatic infection. 38,40,41 Stool PCR is highly sensitive but use is limited in resource-poor settings.…”

“…18,21,38,39 A combination of serology, stool antigen, and/or molecular tests often help establish diagnosis, although serology is more difficult to interpret in endemic settings because it may indicate either past or active infection, and antigen tests may be of low sensitivity, particularly for cyst-containing stool and asymptomatic infection. 38,40,41 Stool PCR is highly sensitive but use is limited in resource-poor settings. 21,42 Those with symptoms should be treated with an amebicidal agent, such as metronidazole, followed by a luminal agent, such as paromomycin.…”