Evaluation of a novel triplex immunochromatographic test for rapid simultaneous detection of norovirus, rotavirus, and adenovirus on a single strip test

BACKGROUND

Acute gastroenteritis is one of the major causes of morbidity and mortality in young children worldwide. Among these, rotavirus, norovirus, and adenovirus have been reported as the primary viral pathogens associated with the disease. Rapid diagnosis of viral pathogens is crucial when diarrhea outbreaks occur to ensure the timely administration of appropriate treatment and control measures.

METHODS

We evaluated three immunochromatographic test kits designed for the detection of norovirus, rotavirus, and adenovirus in 71 stool specimens collected from children with diarrhea who visited clinics in Japan. The first kit is a triplex immunochromatographic test kit designed for simultaneous detections of norovirus, rotavirus, and adenovirus on a single strip (this kit was referred to as IC-A). The other two immunochromatographic test kits are a dual detection kit for rotavirus and adenovirus, and a single detection kit for norovirus (IC-B). The RT-PCR/PCR was used as the gold standard method.

RESULTS

The results revealed that both IC-A and IC-B kits exhibited the same level of sensitivity of detection for rotavirus (72.7%) and adenovirus (22.7%), although the detection rate was lower than that of the RT-PCR/PCR method. However, there was a slight difference in the sensitivity of detection for norovirus between IC-A and IC-B, at 86.7% and 93.3%, respectively. The sensitivity of detection for adenovirus of both kits was relatively lower than those of RT-PCR method. This could be due to low viral load of adenovirus in clinical specimens below the detection limit of IC-A and IC-B kits. However, both immunochromatographic test kits (IC-A and IC-B) exhibited 100% specificity for norovirus, rotavirus, and adenovirus.

CONCLUSIONS

The triplex immunochromatographic test kit (IC-A) designed for simultaneous detection of norovirus, rotavirus, and adenovirus has been proved to be more practical and convenient than the use of single or dual detection kits with more or less the same sensitivity and specificity of detections.

Diagnostic performance of a rapid immunochromatographic test for the simultaneous detection of antibodies to Theileria equi and Babesia caballi in horses and donkeys

BACKGROUND

Equine piroplasmosis is caused by two tick-borne protozoan parasites, Theileria equi and Babesia caballi,, which are clinically relevant in susceptible horses, donkeys, and mules. Moreover, equine piroplasmosis significantly constrains international trading and equestrian events. Rapidly diagnosing both parasites in carrier animals is essential for implementing effective control measures. Here, a rapid immunochromatographic test for the simultaneous detection of antibodies to T. equi and B. caballi was evaluated using samples from horses and donkeys collected in Greece, Israel, and Italy. The results were compared with an improved competitive enzyme-linked immunosorbent assay (cELISA) for detecting antibodies to both parasites using the same panel of samples.

METHODS

Blood samples were collected from 255 horses and donkeys. The panel consisted of 129 horses sampled at four locations in northern Greece, 105 donkeys sampled at four locations in Sicily, and 21 horses sampled at two locations in Israel. The rapid test and the cELISA were performed according to the manufacturer's instructions, and the results were subjected to a statistical analysis to determine the sensitivity and specificity of both tests and their association.

RESULTS

The immunochromatographic test provided a result within 15 min and can be performed in the field, detecting both pathogens simultaneously. The overall coincidence rate between the rapid test and the cELISA for detecting antibodies against T. equi was 93% and 92.9% for B. caballi. The rapid test's sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for T. equi were above 91.5%. Sixteen samples were positive for both parasites in the rapid test and eight in the cELISA. Either test had no significant association between T. equi and B. caballi detection. The detection rates of both parasites were significantly higher in Italy than in Greece or Israel and in donkeys than in horses. The agreement for T. equi between the results of both tests was high in Greece (93.8%) and Italy (95.2%) and moderate in Israel (76.2%). For B. caballi, the specificity and NPV of the rapid test were high (94.2% and 98.3%, respectively), although the sensitivity and PPV were moderate (69.2% and 39.1%, respectively) due to the small sample size. However, for B. caballi, the sensitivity was higher with the rapid test.

CONCLUSIONS

The rapid test detected T. equi and B. caballi simultaneously in the field, potentially replacing laborious cELISA testing and is recommended for import/export purposes. The test can also be helpful for the differential diagnosis of clinical cases, since seropositivity may rule out equine piroplasmosis since it does not indicate current or active infection.

Assessment of the performance regarding confirmatory diagnosis and initiation of antiretroviral therapy under a modified national HIV testing algorithm and pay-for-performance program in Taiwan

BACKGROUND

A pay-for-performance plan for rapid antiretroviral therapy (ART) commencement was initiated in 2018, while a modified testing algorithm offers immunochromatographic test (ICT) to replace Western blot (WB), and simultaneous testing with ICT and Nucleic Acid Amplification Test (NAAT) for HIV-positive sera was adopted in 2019 in Taiwan.

METHODS

Serum specimens collected from 1117 suspected or confirmed HIV infection cases in 2016-2019 were reassessed the performance of WB, ICT, and NAAT. We reviewed the medical records of 10,732 individuals diagnosed with HIV in 2015-2021 to determine the time from screening to confirmatory diagnosis, followed by ART commencement.

RESULTS

All 860 WB-positives were also positive by ICT and NAAT. The positive detection percentages were 37.0% by ICT and 51.4% by NAAT for 257 WB-indeterminate and -negative sera. The sensitivity for WB and ICT was 93.8% and 95.5%, respectively. In the people living with HIV (PLHIV) cohort, the median time from initial positive to confirmatory diagnosis decreased from 5 to 6 days before 2019 to 1 day in 2021. The median time from initial positive to ART initiation decreased from 37 days in 2015, 14 days in 2018, to 6 days in 2021. Compared to 2015-2017, the time to ART initiation was 91.48 days lower in 2018 (P < 0.001) and 100.66 days lower in 2019-2021 (P < 0.001) by the adjusted linear regression model.

CONCLUSION

A significant decrease in the time to ART initiation was observed after initiation of the pay-for-performance program and optimized testing algorithm in Taiwan.

Performances of ICT Toxoplasma IgG-IgM test in comparison with Vidas® toxo competition to determine the immune status against Toxoplasma gondii

Toxoplasmosis is a ubiquitous parasitic infection caused by Toxoplasma gondii (Tg). In immunocompetent people, the infection may be asymptomatic with the induction of an immune response that may prevent reinfection or transmission to the fetus in immune pregnant woman. In immunocompromised persons or seronegative pregnant woman with a primary infection during pregnancy, the infection may result in the loss of life, sight, cognition, and motor function in the immune-compromised person or immunologically immature fetus. The objective of this study was to evaluate a new immunochromatographic test Toxoplasma ICT IgG-IgM (ICT) that allows detection of specific anti-Tg immunoglobulins G (Ig G) and M (Ig M). We included 1145 prospectively obtained sera and 376 samples selected for specificity or sensitivity studies. The performance of ICT was compared using Vidas® Toxo Competition (TXC) and Toxoscreen®. In case of discrepancy, Vidas® Toxo Ig G or Ig M and LDBIO Toxo II IgG western blot were used to establish definitive results by additional methods. Sensitivity and specificity of ICT were respectively 99.3% and 100%. In comparison, Toxoscreen®'s sensitivity was 100% and the specificity was 99.8%. TXC had a sensitivity of 98.7% with a specificity of 99.1%. ICT has excellent performance even for low Ig G titers, especially in immunocompromised patients, and confirms the specificity of isolated Ig M. This ICT provides reliable results easily and quickly. This screening technique is not designed to differentiate the Ig M from Ig G. When positive, additional tests may be necessary.

Colloidal gold based immunochromatographic detection of Mycoplasmopsis synoviae infection and its prevalence in avian species of Karachi, Pakistan

Avian mycoplasmosis is an infection that commonly prevails in birds, particularly in poultry chickens. Among mycoplasmosis causing organisms, Mycoplasmopsis synoviae is a predominant and lethal pathogen to the aves. Considering the increased incidence of infections by M. synoviae, the prevalence of M. synoviae was deduced in poultry chickens and fancy birds of Karachi region. The lungs and tracheal samples from chicken and dead fancy birds and swab samples from live fancy birds were collected and investigated by amplifying 16 s rRNA gene of M. synoviae. Biochemical characteristics of M. synoviae was also evaluated. Furthermore, surface-associated membrane proteins, that represent key antigens for diagnosis of M. synoviae infection was extracted by Triton X- 114 method. Results showed that M. synoviae was detected more frequently in lungs than in trachea, that could be due to its invasion capacity and tissue affinity. SDS PAGE analysis of extracted membrane proteins showed two prominent hydrophobic proteins of different molecular mass including proteins of 150 and 50 kDa. Protein of 150 kDa was purified by size exclusion chromatography and it exhibited agglutinogen activity. Purified protein was used in the development of one-step immunochromatographic (ICT) assay for the detection of antibodies against M. synoviae using gold nanoparticles coated with polyclonal antibodies. Low levels of antibodies were detected by the developed ICT kit, which has 88% sensitivity with 92% specificity.

The proportion of false-positives in positive Seratec® prostate-specific antigen SemiQuant test results in postmortem screening for seminal fluid

Prostate-specific antigen (PSA) tests are used in forensics to conduct rapid screening for semen in vaginal swab samples from alleged victims of sexual abuse. Although PSA membrane tests have been applied to autopsy specimens, no study has evaluated predictors of false-positive test results in relation to factors such as age, cause of death, postmortem interval, drugs, and alcohol. This study describes the results obtained with the Seratec® PSA SemiQuant Kit test in 283 deceased women, with or without a history of sexual assault. Overall, 18.4% (52/283) of the vaginal swab samples tested positive for PSA. However, 63.5% (33/52) of the PSA-positive vaginal swab samples had no sperm detected. The proportion of false-positives in positive PSA results was 94.4% in those aged over 60 years. Multivariate logistic regression for PSA-positive samples showed that the proportion of false-positives in positive PSA results increased with the age of the deceased. However, the cause of death, postmortem interval, and presence of drugs or alcohol in the blood or urine of the deceased did not affect the PSA determination. These results show that PSA membrane tests are relatively unreliable and can be misleading, especially when derived from vaginal swab samples of older women, obtained at autopsy. In forensic cases, positive PSA screening test results may have an impact on subsequent legal actions and criminal charges brought against the accused. These findings are important for both forensic pathologists and the police to ensure accurate screening of older women in cases of suspected sex crimes.

Subtyping of Cryptosporidium parvum Obtained from Humans and Calves in Van, Turkey

BACKGROUND

We aimed to investigate the prevalence of Cryptosporidium species detected in humans and calves in the Van region of Turkey.

METHODS

A total of 150 patients, comprising 60 who were immunosup-pressed, 50 who were immunosuppressed and had diarrhea, and 40 who had only diarrhea, were enrolled in this study in the Department of Medical Parasitology, Van Yuzuncu Yıl University Faculty of Medicine, Turkey. Stool samples were taken from the rectums of a total of 50 calves that had 30 diarrhea and 20 that did not have diarrhea, from the stables and farms of 10 central villages of Van, Turkey. All samples were analyzed using modified acid-fast staining, immunochromatographic test, and PCR. Cryptosporidium positive samples were also subtyped.

RESULTS

Only C. parvum subtypes were detected in all positive samples. C. parvum was detected in 30 (20%) of the 150 human stool samples, while it was detected in 5 (10%) of the 50 samples from the calves. The GP60 gene region was amplified and sent for sequence analysis to identify the C. parvum subtypes.

CONCLUSION

As a result, C. parvum is found to be an active species that caused cryptosporidiosis is in the Van region. IIdA24G1 subtype of C. parvum were found in both human and calf. Therefore, due to the zoonotic feature of the C. parvum IIdA24G1 subtype, it has been shown that the calves in the region are a significant risk for humans.

Carbapenemase investigation with rapid phenotypic test (RESIST-4 O.K.N.V) and comparison with PCR in carbapenem-resistant Enterobacterales strains

Background and Objectives

RESİST-4 O.K.N.V. assay is a lateral immunochromatocraphic test for the identification of oxacillinase (OXA)-48-like, Klebsiella pneumoniae carbapenemase (KPC), New Delhi metallo-β-lactamase (NDM), and Verona integron-encoded metallo-β-lactamase (VIM) producing strains. It was aimed to evaluate the performance of the RESIST-4 O.K.N.V. test and to compare it with the reference method polymerase chain reaction (PCR). Also, the objective was to determine the distribution of carbapenemase types of CRE strains isolated in our hospital.

Materials and Methods

Between January 2016-October 2019, 187 strains isolated from clinical samples were included in this study. Bacterial identification was done using MALDI-TOF MS. Antibiotic susceptibility tests were studied with the VITEK-2 automated system. Meropenem minimum inhibitory concentrations (MICs) were determined by the gradient test. All strains were studied with the RESIST-4 O.K.N.V. test and then the strains were selected for the PCR test. bla _OXA-48, bla _NDM, bla _KPC, and bla _VIM were investigated with PCR. K. pneumoniae NCTC® 13438 (KWIKSTIKTM, Microbiologics®, USA) was used as the positive control, E. coli ATTC® 25922 TM (Microbiologics®, USA) and three carbapenem-sensitive clinical isolates were also used as the negative control.

Results

Meropenem MIC₅₀ and MIC₉₀ values were determined to be >32 mg/L. With PCR bla _OXA-48, bla _NDM, bla _KPC and bla _VIM were detected in 79, 63, 20, and 4 strains, respectively. bla _OXA-48 and bla _NDM were found together in 51 of the isolates. bla _OXA-48, bla _NDM, bla _KPC, and bla _VIM were not detected in two strains with carbapenem resistance in susceptibility tests. The sensitivity of the immunochromatographic test was 100% for OXA-48, KPC, and VIM but 84.1% for NDM. Specificity was determined as 100% for OXA-48, NDM, KPC, and VIM.

Conclusion

RESIST-4 O.K.N.V. test showed high sensitivity and specificity in detecting OXA-48, KPC, NDM, and VIM type carbapenemases. However, it should be kept in mind that there may be false-negative results related to NDM.

Evaluation of five different rapid immunochromatographic tests for canine leishmaniosis in Spain

Canine leishmaniosis is a vector-borne disease caused by Leishmania parasites. Serological methods are the most common tests used for the diagnosis. This study aimed to evaluate and compare different serological commercial immunochromatographic rapid tests available in Spain to detect anti-Leishmania canine antibodies. The immunochromatographic tests were evaluated in different groups of dogs (healthy seronegative dogs (n = 21), naturally-sick dogs with moderate anti-Leishmania antibodies (n = 39), naturally-sick dogs with high anti-Leishmania antibodies (n = 37), dogs with the serological result of other pathogens infection (n = 20) and exposed dogs (n = 33)) admitted to the Veterinary Teaching Hospital of the University of Zaragoza (Spain) according to the clinical information sent with the sample to the laboratory for diagnostic purposes. The serology status was also routinely recorded through an in-house enzyme-linked immunosorbent assay (ELISA) and an in-house indirect immunofluorescence test (IFAT). The qualitative commercial serological immunochromatographic tests used were: FASTest LEISH, Uranotest Leishmania, Uranotest Leishmania 2.0, Speed Leish K, Witness Leishmania, and DFV Test Leishmania. Performance measures analyzed for each test were: sensitivity, specificity, and area under the receiver-operating (ROC) curve. The maximum specificity (1.00) was attained for Uranotest Leishmania and DFT Test Leishmania, followed by FASTest LEISH (0.98), Uranotest Leishmania 2.0 (0.98), Speed Leish K (0.98), and Witness Leishmania (0.95). The maximum sensitivity was attained for FASTest LEISH (1.00), followed by Uranotest 2.0 (0.97), Speed Leish K (0.97), Uranotest (0.96), and the lowest results with Witness (0.84) and DFV Test (0.59). Regarding the ROC curve, the maximum value was attained with the FASTest LEISH (0.99), followed by Uranotest (0.98), Uranotest 2.0 (0.97), Speed Leish K (0.97), Witness (0.90), and the lowest result with DFV Test (0.79). Efforts in the field of diagnosis should focus on establishing a commercial immunochromatographic test with high sensitivity and specificity with a reasonable cost-benefit balance.

The accuracy of a recombinant antigen immunochromatographic test for the detection of Strongyloides stercoralis infection in migrants from sub-Saharan Africa

Background

Strongyloidiasis, a nematode infection which is mainly caused by Strongyloides stercoralis in humans, can lead to a fatal syndrome in immunocompromised individuals. Its diagnosis is challenging due to the absence of a diagnostic gold standard. The infection is highly prevalent in migrants from endemic countries in tropical and subtropical areas, and a rapid diagnostic test would be helpful for screening purposes. The aim of this study was to estimate the accuracy of a novel immunochromatographic test (ICT) for the diagnosis of S. stercoralis infection.

Methods

A single-centre diagnostic accuracy study was undertaken using well-characterized frozen sera available from the biobank of a referral hospital for parasitic diseases in Italy. The included sera were from migrants from sub-Saharan Africa, and matching results were available for agar plate culture and/or polymerase chain reaction for S. stercoralis; moreover, the results of both a commercial enzyme-linked immunosorbent assay test and an in-house immunofluorescence test for strongyloidiasis were made available. Laboratory staff who read the ICT results were blinded as regards the results of the other tests. Two readers independently read the ICT, and a third one was involved when results were discrepant. The accuracy of the ICT was assessed both against the results of the panel of faecal tests and by latent class analysis (LCA).

Results

Agreement between the readers was excellent [Cohen’s κ = 92.7%, 95% confidence interval (CI) 88.3–97.1%]. When assessed against the results of the faecal tests, the sensitivity and specificity of the ICT were 82.4% (95% CI 75.7–89.0%) and 73.8% (95% CI 66.8–80.9%), respectively. According to the LCA, the sensitivity and specificity were 86.3% (95% CI 80.1–92.5%) and 73.9% (95% CI 67.0–80.8%), respectively.

Conclusions

The results of the ICT demonstrated ease of interpretation. The accuracy proved good, though the sensitivity might be further improved for screening purposes.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05249-z.

Hapten-labeled fusion-polymerase chain reaction of multiple marker genes for the application of immunochromatographic test

A variety of methods have been reported using polymerase chain reaction (PCR)-based nucleic acid testing (NAT) because of its potential to be used in highly sensitive inspection systems. Among these NATs, fusion-PCR (also called as overlap-extension-PCR) has been focused on this study and adopted to generate the fused amplicon composed of plural marker gene fragments for detection. Generally, conventional agarose gel electrophoresis followed by gel staining is employed to check the PCR results. However, these are time-consuming processes that use specific equipment. To overcome these disadvantages, the immunochromatographic test (ICT) for the detection of PCR amplicons with hapten-labels that were generated by PCR using hapten-labeled primers was also adopted in this study. Based on these concepts, we constructed the systems of hapten-labeled fusion-PCR (HL-FuPCR) followed by ICT (HL-FuPCR-ICT) for the two and three marker genes derived from pathogenic microbe. As a result, we successfully developed a two marker genes system for the pathogenic influenza A virus and a three marker genes system for the penicillin-resistant Streptococcus pneumoniae. These detection systems of HL-FuPCR-ICT are characterized by simple handling and rapid detection within few minutes, and also showed the results as clear lines. Thus, the HL-FuPCR-ICT system introduced in this study has potential for use as a user-friendly inspection tool with the advantages especially in the detection of specific strains or groups expressing the characteristic phenotype(s) such as antibiotic resistance and/or high pathogenicity even in the same species.

DIRECT2: A novel platform for a CRISPR-Cas12-based assay comprising universal DNA-IgG probe and a direct lateral flow test

CRISPR-Cas12-based biosensors are a promising tool for the detection of nucleic acids. After dsDNA-target-activated Cas12 cleaves the ssDNA probe, a lateral flow test (LFT) is applied for rapid, simple, and out-of-laboratory detection of the cleaved probe. However, most of the existing approaches of LFT detection have disadvantages related to inverted test/control zones in which the assay result depends not only on the cleavage of the probe but also on the second factor: the binding of the non-cleaved probe in the control zone. We proposed a novel platform for the detection of trans-cleaved DNA using a universal DNA-IgG probe and LFT with the sequential direct location of test and control zones. The advantage of the platform consists of the assay result depending only on the cleaved probe. For this, we designed a composite probe that comprise two parts: the DNA part (biotinylated dsDNA connected to ssDNA with fluorescein) (FAM), and the antibody part (mouse anti-FAM IgG). The Cas12, with guide RNA, was activated by the dsDNA-target. The activated Cas12 cleaved the probe, releasing the ssDNA-FAM-IgG reporter that was detected by the LFT. The sandwich LFT was proposed with anti-mouse IgG adsorbed in the test zone and on the surface of gold nanoparticles. We called the platform with direct location zones and direct analyte-signal dependence the DNA-Immunoglobulin Reporter Endonuclease Cleavage Test (DIRECT²). Therefore, this proof-of-concept study demonstrated that the combination of the proposed DNA-IgG probe and direct LFT opens new opportunities for CRISPR-Cas12 activity detection and its bioanalytical applications.

Development of an immunochromatographic test for the detection of Mycoplasma pneumoniae GroES antigen

Mycoplasma pneumoniae frequently causes community-acquired pneumonia in children; β-lactam antibiotics are ineffective against this bacterium because of its lack of a cell wall. Hence, a rapid and simple detection method is required to ensure appropriate treatment. In this study, we developed a rapid and simple immunochromatography-based detection method using monoclonal antibodies that react with the co-chaperone GroES of M. pneumoniae. Mice were immunized with recombinant GroES, and hybridoma cells producing anti-GroES monoclonal antibodies were established. For the development of the immunochromatographic test, antibody pairs with superior reactivity and specificity were selected. The developed immunochromatographic test could detect 0.1 ng/mL of recombinant GroES within 20 min. Moreover, no cross-reaction was observed with other microorganisms, including six Mycoplasma species, 20 other bacterial species, and one yeast species. Macrolide-resistant and -susceptible M. pneumoniae clinical isolates were detected at approximately 10⁴ to 10⁵ colony-forming units/mL. The study indicates that immunochromatographic tests targeting GroES are useful for rapid and simple detection of M. pneumoniae.

A rapid test for the environmental detection of pigeon antigen

INTRODUCTION

Avoidance of inhaled bird antigens is essential to prevent hypersensitivity pneumonitis disease progression. The aim of the present study was to develop a sandwich enzyme link immunoassay (ELISA) and an immunochromatographic test (ICT) and compare their ability to detect pigeon antigens in environmental samples.

METHODS

An amplified sandwich ELISA using pigeon serum as a calibration standard and a ICT using gold-labeled anti-pigeon serum antibodies for the rapid detection of pigeon antigens in environmental samples were developed. Twenty-two different airborne samples were collected and analysed using both methods. Strip density values obtained with ICT were calculated and compared with the concentrations determined by the ELISA method for pigeon antigens. Strips results were also visually analysed by five independent evaluators.

RESULTS

The ELISA method to quantify pigeon antigen had a broader range (58.4 and 10,112.2 ng/ml), compared to the ICT assay (420 to 3360 ng/ml). A kappa index of 0.736 (p < 0.0001) was obtained between the observers evaluating the ICT strips. The results of the ELISA and the relative density of the ICT showed a highly significant correlation (rs:0.935; p < 0.0001). Bland-Altman plot also confirmed excellent agreement between the two methods (mean difference: -1.626; p < 0.0001).

CONCLUSIONS

Since there was a good correlation between both assays, we can conclude that the rapid and simple ICT assay is a good and valid alternative, which does not require expensive equipment, for the validated ELISA technique.

Development of an immunochromatographic point-of-care test for detection of IgG antibody in serodiagnosis of human trichinellosis

OBJECTIVE

Trichinellosis is a globally distributed food-borne parasitic disease. Initially, diagnosis is usually made based on clinical signs, symptoms, and history of eating raw or undercooked meat. In the present study, an immunochromatographic test (ICT) kit was developed to diagnose trichinellosis by detecting IgG antibodies in sera of infected humans.

METHODS

Somatic extract from Trichinella spiralis larvae was used as the antigen for the ICT kit development. Diagnostic efficacy was evaluated using human serum samples from proven trichinellosis patients, healthy persons, and those with other parasitic infections.

RESULTS

The diagnostic sensitivity, specificity, positive and negative predictive values and accuracy of the ICT kit were 100.0% (95%; CI 88.8 to 100.0%), 92.5% (95% CI; 86.9 to 96.2%), 73.8% (95% CI; 58.0 to 86.1%), 100.0% (95% CI; 97.3 to 100.0%) and 93.8% (95% CI; 89.2 to 96.9%), respectively.

CONCLUSIONS

This ICT diagnostic kit can be used as a testing tool for human trichinellosis. This test should permit rapid detection of infection to enable prompt anthelminthic treatment. It can also be used for retrospective diagnoses and field surveys based at laboratories where sophisticated equipment is lacking.

Validity of urine-CCA cassette test and indirect haem-agglutination assay (IHA) in the detection of schistosomiasis-mansoni infection relative to microscopic examination

Several immunodiagnostic assays have been commercially presented over the last years as easy diagnostic methods for schistosomiasis using serum or urine samples. The performance of immunochromatographic test (ICT) and indirect hemagglutination assay (IHA) was validated in the identification of active schistosomiasis infection. Detection of circulating cathodic antigen (CCA) of the parasite in urine samples and anti-Schistosoma antibodies in serum using ICT (Urine-CCA Cassette test) and IHA respectively. Proved diagnosis of Schistosoma mansoni infection was defined by the sum of positive results from microscopic examination (Gold standard) and Kato-Katz method. Out of 173 (mean age, 45 ± 10 years; 70 from Giza, 103 from different Egyptian governorates), 9 4 adult patients were infected. Urine-CCA cassette test despite showing high specificity (91.14%) it was of low sensitivity (23.40%). PPVs was 75.86% and NPV was 50.00% and diagnostic accuracy of 54.34%. The IHA showed a sensitivity of 57.45% and specificity of 48.10%. PPVs was 56.84% whereas NPVs was 48.72%. As for diagnostic accuracy, it was 53.18%. Urine-CCA Cassette test had lower sensitivity than expected for detection of circulating antigen and the IHA kit is generally more expensive than microscopic examination and Urine-CCA cassette test with low sensitivity and specificity. On the basis of this diagnostic performance none of the two tested immune-assays can be a sole tool in the principal diagnosis of active schistosomiasis infections.

Clostridioides difficile laboratory diagnostic techniques: a comparative approach of rapid and molecular methods

Clostridioides difficile infection is a public health problem because of it is easily spread; with harmful consequences, it is essential to reduce hospital costs and prevent its dissemination by having a precise diagnosis. The gold standard for its diagnosis is polymerase chain reaction (PCR); however, the technique is not available for all laboratories due to the high cost. New approaches using non-molecular tests to detect C. difficile and toxin A/B production has been proposed to improve cost benefits. The objective of this study is to compare molecular methods (PCR) and rapid methods (immunochromatographic test and enzymatic immunoassay). A series of tests comprising these diagnostic techniques was performed with 50 patients with a clinical diagnosis for Clostridioides difficile on GeneXpert® devices test; a calculation of the sensitivity was executed, followed by a comparison of the efficiency of all techniques. Greater sensitivity was observed in the PCR-based methods (BD MAX™ and BioFire FilmArray®) and the GDH-based assays (RIDASCREEN® and Alere Techlab®). The proposed algorithm represents minor monetary disadvantages but a significant temporal optimization of 10%. Future studies concerning both positive and negative results could be advantageous because of the possibility of calculating more method concordance indexes, such as the specificity and Kappa index, in addition to being able to indicate a monetary profit if the proposed algorithm was applied due to the nonproceeding PCR cases.

Evaluation of a rapid immunochromatographic test for the detection of Candida species from oropharyngeal samples

Oropharyngeal candidiasis is the most common opportunistic fungal infectious disease. Culture methods and microscopy are used to detect the presence of Candida species in clinical specimens. We have previously developed an immunochromatographic test (ICT) to enable the simple and rapid diagnosis of candidiasis. In this study, we evaluated the performance of the ICT for the detection of Candida species from pharyngeal swabs and compared the results with those of the culture method. The isolated Candida species were identified using polymerase chain reaction-restriction fragment length polymorphism, and viable cell counts were determined using selective chromogenic agar. The detection rate of C. albicans was 63.3% and 0% among ≤10² and ≥ 10⁶ colony-forming units (CFU)/mL of viable Candida cells from pharyngeal swabs, respectively. The detection rate of nonC. albicans Candida species, especially C. glabrata, increased commensurately from 16.7% at ≤10² CFU/mL to 75.0% at ≥10⁶ CFU/mL. Among the 300 pharyngeal swabs analyzed, 59 cultures detected Candida species at a count of >10³ CFU/mL (53 were ICT-positive). Of the remaining 241 culture-negative specimens, 219 were ICT-negative. The sensitivity, specificity, and accuracy of the ICT were 89.8%, 90.9%, and 90.7%, respectively. Taken together, the ICT evaluated can be made readily available for clinical use in detecting Candida.

Effectiveness of Fasciola gigantica excretory-secretory and recombinant cathepsin L antigens for rapid diagnosis of human fascioliasis using immunochromatographic devices

Fascioliasis, a food- and water-borne trematodiasis, has been identified as a public health threat by the World Health Organization, with millions of people estimated to be infected or at risk of infection worldwide. We developed an immunochromatographic test (ICT) as a point-of-care (POC) tool for the rapid serodiagnosis of human fascioliasis caused by Fasciola gigantica and evaluated their diagnostic ability. Two tests were developed using antigens from adult F. gigantica excretory-secretory (ES) product and recombinant F. gigantica cathepsin L (rFgCL). Sera from 12 patients with parasitologically proven fascioliasis caused by F. gigantica, 18 with clinically suspected fascioliasis, 65 with other parasitic infections, and 30 healthy controls were used. Using a cutoff of > 0.5 for antibody detection, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the ES-based ICT method were 100%, 98.9% 96.8%, 100%, and 99.2%, respectively, and those of the rFgCL-based ICT method were 86.7%, 93.7%, 81.3%, 95.7%, and 92.0%, respectively. The concordance between the two methods was 91.2%. Tests using F. gigantica ES and rFgCL antigens can be employed quickly and easily as POC diagnostic tools. They can be used to support the clinical diagnosis of human fascioliasis gigantica and in large-scale surveys in endemic areas throughout tropical regions without necessitating additional facilities or ancillary supplies.

Diagnosis of scrub typhus: recent advancements and challenges

Scrub typhus is a mite-borne, acute febrile illness caused by the bacterium Orientia tsutsugamushi. It is a re-emerging infectious disease of the tsutsugamushi triangle. Scrub typhus is transmitted through bites of contaminated chiggers (larval stage). Diagnosis of scrub typhus is challenging as its symptoms mimic with other acute febrile illnesses. Several methods are effectual for diagnosis of scrub typhus that includes enzyme-linked immunosorbent assay (ELISA), immunofluorescence assay (IFA), immunochromatographic test (ICT), Weil-Felix, polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP). Weil-Felix test was initially used for the diagnosis of scrub typhus in underdeveloped countries but not preferred due to a lack of both specificity and sensitivity. Other immuno-based methods like IFA and ELISA are most outrank for detection of scrub typhus due to their higher sensitivity and specificity, but not vigorous to lay bare the infection at early stages and need the convalescent sampling for verification of positive samples. On another deed, PCR based methods becoming acceptable over era due to its dexterity of early-stage diagnosis with higher specificity and sensitivity but lack its applicability in circumstances of scrub typhus due to the variegated genetic makeup of Orientia tsutsugamushi among its serotypes. The present review focused on various detection methods along with their advantages and disadvantages used in the diagnosis of scrub typhus. A comparison between available methods of diagnosis with challenges in the detection of scrub typhus is also summarized.

Immunochromatographic detection of human hemoglobin from deteriorated bloodstains due to methamphetamine contamination, aging, and heating

Japanese police conduct highly sensitive and quick blood tests to detect human hemoglobin (Hb), because bloodstains left at a crime scene have probative value of circumstantial evidence in a criminal investigation. Although DNA detection from a bloodstain is a useful tool to identify an individual, doing so requires evidence that the bloodstain is of human origin. Stimulant drug abuse and dependence causes major social problems and crimes in Japan, and bloodstains are often found inside syringes seized from drug abusers. In this case, Hb often cannot be detected by conventional testing as high concentrations of stimulants, such as methamphetamine hydrochloride (MA), in blood trigger polymerization of Hb molecules, which become insoluble under non-reducing conditions and can no longer be detected by immunochromatographic detection kits. To overcome this problem, we analyzed methods to detect denatured Hb from bloodstains contaminated with MA. Reduction of polymerized Hb with a strong denaturing agent was required to solubilize polymers into monomers, suggesting that Hb aggregation is caused by aberrant formation of disulfide bonds. Based on these results, we established a pretreatment method, called Fukui's Reduction and Eiken's Dilution (FRED), that enables highly sensitive detection of human Hb from bloodstains mixed with MA by reducing and refolding of denatured Hb. This powerful method can be applied to blood that has been boiled or has otherwise deteriorated for over 20 years.

Viral gastroenteritis in hospitalized patients: Evaluation of immunochromatographic methods for rapid detection in stool samples

BACKGROUND

. Viral infections are recognized as the most common cause of acute gastroenteritis (AGE). Virus detection by immune analytical methods is recommended for diagnosis because of its simplicity and low cost.

OBJECTIVES

. Two commercial immunochromatographic (ICG) techniques (Materlab) for rapid detection of rotavirus/adenovirus and norovirus respectively, were evaluated by comparison to the results obtained using PCR methods. In addition, clinical and epidemiologic characteristics of AGE infections have been described.

STUDY DESIGN

. A total of 100 faecal samples collected from patients with AGE (84% children) admitted into a Spanish Hospital between February and July 2018, were studied for rotavirus-A, adenovirus and norovirus GI/GII by the ICG tests as well as by PCR and sequencing. Other enteric viruses (enterovirus and astrovirus) were investigated by PCR methods. Gastrointestinal bacteria and parasites were also tested.

RESULTS

. Evaluated ICG tests yielded high specificity (>97%). Sensitivity values were high for rotavirus/adenovirus (>80%) but lower for norovirus (57%). Overall, and taking into account coinfections, viruses (32%), bacteria (14%) and parasites (1%) could be detected. Rotavirus-A were the most frequently identified viruses (16%), followed by enterovirus (12%), norovirus (4%), adenovirus 41 (4%) and astrovirus (1%). In five vaccinated children, a rotavirus was detected.

CONCLUSIONS

. ICG technique is a useful tool for the routine diagnosis of AGE infections at hospital, but for surveillance and epidemiological studies, it is needed the use of amplification and sequencing methods, which also allow monitoring of new strains or variants emergence. In this study, an etiological pathogen was determined only in 44% of samples.

Prevalence of scrub typhus in a tertiary care centre in Telangana, south India

BACKGROUND AND OBJECTIVES

Scrub typhus is re-emerging as an important cause of acute undifferentiated fever in the last decade from various parts of India. Complexity in performing the "gold standard" immunofluorescent assay and the unreliable nature of Weil Felix test often results in delayed or misdiagnosis in a majority of cases. The present study seeks to integrate the results of rapid diagnostic tests, clinical and laboratory features to aid the diagnosis and management of scrub typhus patients.

MATERIALS AND METHODS

A total of 645 serum samples with suspected scrub typhus sent to the Department of Microbiology were included in the study. Scrub typhus was tested by rapid immunochromatographic test (SD Diagnostics) and IgM ELISA (Inbios International, USA). Clinical features, laboratory parameters and final outcome were analysed from the clinical records of positive patients.

RESULTS

Scrub typhus was diagnosed in 13.7% of patients and majority of them were observed in the month of August. 58.6% of scrub typhus patients presented with fever of one to two weeks duration. Eschar was documented in 13.7% of patients and 24% of patients gave a history of working outdoors or exposure to vegetation. All the patients responded to Doxycycline treatment and there was no mortality.

CONCLUSION

High index of suspicion for scrub typhus is necessary in febrile patients not responding to conventional antibiotics especially during outbreak situations. Rapid immunochromatographic tests with excellent specificity and acceptable sensitivity can be used as potential point of care tests for quick diagnosis of scrub typhus especially in delayed presentation.

Development of immunochromatographic device as a point-of-care tool for serodiagnosis of human strongyloidiasis cases

Human strongyloidiasis is an important gastrointestinal disease with an estimated 30 to 100 million people infected. Prevalence is generally underestimated since many infections are asymptomatic, and traditional diagnostic tests based on parasitological examination of stool samples are not adequately sensitive. Serological tests are useful and supportive but are still only available in a reference research setting. We made an immunochromatographic test (ICT) kit for rapid serodiagnosis of human strongyloidiasis. The antigen used in the ICT kit was extracted from larvae of Strongyloides stercoralis. Diagnostic efficacy of the kit was evaluated using human serum samples from strongyloidiasis patients, healthy persons, and those with other parasitoses. When using a cutoff level of 0.5 or above, the diagnostic sensitivity, specificity, and positive and negative predictive values at the prevalence of infection of 34.4%, were 93.3%, 83.7%, 76.7%, and 95.6%, respectively. This ICT kit is easy to use at the point-of-care and a result can be obtained in 15 min. Sophisticated instruments and highly trained staff are not required. It can be used in several diagnostic and public-health settings, e.g., prevalence surveys in endemic areas, confirmation and monitoring of cure post-treatment, diagnosis and screening of infected but asymptomatic individuals, and populations “at risk” for hyperinfection syndrome or disseminated strongyloidiasis if they are given immunosuppressive treatment for other conditions.

Evaluation of four rapid diagnostic tests for canine and human visceral Leishmaniasis in Colombia

BACKGROUND

Leishmaniasis caused by different species of Leishmania affect 98 countries worldwide. Visceral Leishmaniasis (VL) is the mortal clinical presentation of the disease that causes the dead to more than 90% of the patients who suffer it. The diagnosis of VL is made by the direct observation of the parasite in bone marrow, spleen and/or liver aspirates that requires complex proceedings. Therefore, serum samples are submitted to Indirect Immunofluorescence to identify the presence of anti-Leishmania antibodies. Despite the variability in the diagnostic performance of the Immunochromatographic Tests (ICTs), there are many evidences that suggest that ICTs can be used for epidemiological screening. However, in Colombia there are not any evidence about the performance of the ICTs for VL diagnosis, both for human and canine serum samples. Therefore, this study evaluated the diagnostic performance of 4 ICTs for VL (2 ICTs in human sera and 2 ICTs in canine sera) in samples from endemic areas of Colombia.

METHODS

We selected a total of 156 human serum samples (82 positive and 74 negative for VL) and 126 canine serum samples (71 positive and 54 negative) diagnosed by in house Indirect Immunofluorescence (IIF). The samples were submitted to the ICTs following the manufacturers' instructions. Statistical analysis was performed to evaluate the diagnostic performance of each ICT in comparison with the IIF. PCR for HSP70 gene and sanger sequencing was performed in samples with negative results for both ICTs.

RESULTS

The sensitivity (S) of both ICTs for human samples (Ad-bio Leishmania IgG/IgM Combo Rapid Test and Kalazar Detect™) was 91.5% and specificity (E) were 93.2 and 89.2% respectively, while for the ICTs tested on canine samples (Kalazar Detect™ Rapid Test, Canine and DPP® CVL rapid test) we found S values between 82.9 and 85.7% and E values between 79.6 and 92.6%. We found L. infantum by PCR and sequencing in 2 human samples, and L. braziliensis and L. amazonensis in canine serum samples that were negative by both ICTs.

CONCLUSIONS

We conclude that both tests evaluated on human samples have a similar diagnostic performance, while the Kalazar Detect™ Rapid Test, Canine showed a better diagnostic performance than the DPP® CVL rapid test evaluated on canine samples. Also, we suggest that it is necessary to design tests with antigens of the circulating strains to increase its diagnostic utility.

Detection of prostate specific antigen and salivary amylase in vaginal swabs using SERATEC® immunochromatographic assays

Immunochromatographic assays are used by crime laboratories to conduct simple and quick analyses of bodily fluids. These streamlined tests are ideal for decreasing the sexual assault kit backlog in the United States. A large-scale analysis of the frequency of positive results of amylase and prostate specific antigen (PSA) endogenously found in the vaginal cavity was conducted using the SERATEC PSA Semiquant and Amylase tests. Vaginal swabs were self-collected by participants after 7-10 days of no oral contact or male ejaculation. In this study of 50 participants, 98% were negative for PSA and 92% were negative for amylase. Positive results were confirmed to contain no exogenous DNA by male-specific quantitation, short tandem repeat (STR) typing, and Y-STR typing. These results can be used by crime laboratories to help guide interpretation of immunochromatographic test results from vaginal swabs and aid in decision-making in downstream DNA testing.

Rapid detection of OXA-48-like, KPC, NDM, and VIM carbapenemases in Enterobacterales by a new multiplex immunochromatographic test

The rapid detection of carbapenemase-producing Gram-negative bacteria is indispensable to optimize treatment and avoid the further spread of these organisms. While phenotypic tests are time-consuming and PCR is expensive and not available in many routine laboratories, immunochromatographic tests (ICT) can provide rapid results at moderate cost. The aim of this study was to determine the performance of the new ICT RESIST-4 O.K.N.V. K-SeT (Coris BioConcept, Gembloux, Belgium) which can detect the four most prevalent carbapenemases: OXA-48-like, KPC, NDM, and VIM. Additionally, we analyzed the impact of different culture conditions on the sensitivity. The new ICT was challenged with 169 carbapenem-resistant isolates. Of these, 125 were carbapenemase producers: 43 OXA-48-like, 15 KPC, 29 NDM, and 43 VIM. The ICT correctly detected 129 of the 130 carbapenemases resulting in a sensitivity of 99.2% and specificity of 100% when tested from Mueller-Hinton agar (MHA). The sensitivity of the assay increased to 100% when performed from zinc-supplemented MHA and sheep blood agar (SBA) or when the inoculum was harvested from the inhibition zone of an ertapenem disk. All carbapenemase-negative carbapenem-resistant bacteria tested negative and no cross-reaction was observed. The new ICT is an excellent test for rapid diagnostic of carbapenemase-producing Gram-negatives in the routine laboratory. It is easy to handle and provides rapid results with a high sensitivity. For best results, we recommend to obtain the inoculum from a medium with sufficient zinc or from the inhibition zone of an ertapenem disk.

Evaluation of an in-house LipL32 polymerase chain reaction for diagnosis of leptospirosis and its correlation with various serological diagnostic techniques

Background

Leptospirosis is a zoonotic disease of ubiquitous distribution. During rainy seasons, in spring and summer and also during harvest times, the risk of leptospirosis increases as there are chances of frequent contact with infected rat population which is common in Karnataka as farming is a main source of income to the people here. There is a paucity of data regarding the prevalent serovars from Karnataka. This study was undertaken as an attempt to compare a battery of tools such as immunochromatographic test (ICT), microscopic agglutination test (MAT), immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) and in-house polymerase chain reaction (PCR) to detect leptospirosis.

Settings and Design

This study using consecutive sampling technique was conducted in a tertiary care centre, Mysore, Karnataka.

Subjects and Methods

Samples from 783 suspected cases of leptospirosis in and around Mysore between April 2013 and April 2016 were processed. Samples from 783 patients suspected of leptospirosis were subjected to ICT, IgM ELISA, MAT and in-house PCR.

Statistical Analysis Used

The statistical analysis was carried out using SPSS software version.

Results

Among 783 samples tested, only 14 (1.7%) were positive by ICT, 341 (44%) were positive by IgM ELISA, 368 (47%) were positive by MAT and 393 (50.2%) were positive by in-house PCR.

Conclusions

Mysore can be considered endemic for leptospirosis. The in-house PCR based on LipL32 gene proved to be useful in the early diagnosis of leptospirosis.

A versatile and sensitive lateral flow immunoassay for the rapid diagnosis of visceral leishmaniasis

Visceral leishmaniasis (VL) is a zoonotic infectious disease with a severe impact on humans and animals. Infection is transmitted by phlebotomine sand flies, and several domestic and wild mammals act as reservoirs for the infection, so the prompt detection of infected hosts is crucial to preventing and controlling the spread of the disease and its transmission to humans. A rapid and portable tool for VL diagnosis based on the lateral flow immunoassay (LFIA) technology is described herein. The device exploits a highly specific chimeric recombinant antigen as the recognition element for capturing anti-leishmanial antibodies, and protein A labelled with gold nanoparticles as the signal reporter. The LFIA shows excellent diagnostic sensitivity (98.4%), specificity (98.9%), and agreement with serological reference methods for diagnosing canine VL. The long-term stability of the LFIA device was confirmed based on six months of storage at room temperature or 4 °C, and the qualitative response of the device was not affected by limited thermal stress. The use of the broadly specific protein A means that the LFIA can be readily adapted to diagnose VL in dogs (the main reservoir for human infection) and other mammals, thus further assisting efforts to control the spread of VL. Graphical abstract A rapid and portable diagnostic tool for visceral leishmaniasis (VL) based on lateral flow immunoassay (LFIA) technology. The presence of anti-leishmanial antibodies is revealed through the binding of these antibodies to a highly specific chimeric antigen. Employing a broadly specific signal reporter (protein A labelled with gold nanoparticles) enables the LFIA to be easily adapted to diagnose VL in different animals.

Performance of "RESIST-3 O.K.N. K-SeT" immunochromatographic assay for the detection of OXA-48 like, KPC, and NDM carbapenemases in Klebsiella pneumoniae in Turkey

In this study, the performance of the “RESIST-3 O.K.N. K-SeT” (Coris BioConcept, Gembloux, Belgium) immunochromatographic assay was evaluated in 132 Klebsiella pneumoniae comprising 102 carbapenem resistant and 30 carbapenem susceptible isolates. Genotypically known isolates of Gram negative bacteria (n = 22) including various species were also tested by the assay as controls. The isolates tested by the immunochromatographic assay and also were run PCR for bla_KPC, bla_IMP, bla_VIM, bla_NDM, and bla_OXA-48. The rates of bla_NDM, bla_OXA-48, and bla_KPC in carbapenem resistant isolates were found at 52.9%, 39.2%, and 2.0%, respectively. Both bla_NDM and bla_OXA-48 were found in six (5.9%) isolates. The results of the assay showed 100% concordance with those obtained by PCR in 132 K. pneumoniae. The agreement between the two methods was found to be identical at the isolate level. The assay also correctly detected all genotypically known isolates of Escherichia coli, Serratia marcescens, Citrobacter freundii, Enterobacter cloacae, K. pneumoniae carrying bla_KPC, bla_NDM, and/or bla_OXA-48. On the other hand, the assay did not exhibit any cross-reaction in control isolates harboring bla_IMP and bla_VIM. We conclude that the RESIST-3 O.K.N. K-SeT is a reliable, rapid, and user friendly test and we recommend it for routine diagnostic laboratories.

Large-scale evaluation of a rapid diagnostic test for diarrhea caused by enterotoxigenic Escherichia coli targeting the heat-labile toxin

We standardized an immunochromatographic test (IC) for heat-labile toxin I (LT-I) detection using LT-I antibodies and a specific platform containing the apparatus for application, assembly and cutting. IC detected as little as 62.5ng/mL of purified LT-I toxin and presented 91% sensitivity, 99.5% specificity and 96.0% accuracy, thereby proving to be an excellent point-of-care test for the diagnosis of enterotoxigenic E. coli infection in low-income countries.

The evaluation of GM6-based ELISA and ICT as diagnostic methods on a Mongolian farm with an outbreak of non-tsetse transmitted horse trypanosomosis

Trypanosoma equiperdum, which is the etiological agent of dourine, spreads through sexual intercourse in equines. Dourine (T. equiperdum) has been reported in Mongolia, where it is considered an economically important disease of horses. T. evansi has also been reported in Mongolian domestic animals. The objective of this study was to evaluate the potential application of recombinant T. evansi GM6 (rTeGM6-4r)-based diagnostic methods on a farm with an outbreak of non-tsetse transmitted horse trypanosomosis. Ninety-seven percent homology was found between the amino acid sequences of T. equiperdum GM6 and the GM6 of another Trypanozoon, which also shared the same cellular localization. This finding suggests the utility of rTeGM6-4r-based serodiagnostic methods for epidemiological studies and the diagnosis of both surra and dourine in Equidae. Fifty blood samples were examined from a herd of horses. The diagnostic value of an rTeGM6-4r-based ELISA and an rTeGM6-4r-based immunochromatographic test (ICT) were measured in comparison to a T. evansi crude antigen-based ELISA, which is a diagnostic method recommended by the OIE. However, this is not a perfect diagnostic method for trypanosomosis. Positive serum samples were detected in 46%, 42% and 28% of the tested horses using an rTeGM6-4r-based ELISA, crude antigen-based ELISA and rTeGM6-4r-based ICT, respectively. The sensitivity of rTeGM6-based ELISA was 81%, the specificity was 79%, and the agreement was moderate. We conclude that rTeGM6-4r-based ELISA and ICT represent alternative options for baseline epidemiological studies and the on-site diagnosis of horse trypanosomoses in the field, respectively.

Development and evaluation of a rapid diagnostic immunochromatographic device to detect antibodies in sera from intestinal capillariasis cases

Intestinal capillariasis, a fish-borne nematodiasis, is an important emerging zoonotic disease. Patients present clinical symptoms of borborygmus chronic diarrhea, intermittent abdominal pain, weight loss, and several degrees of painless lower-leg edema. Death may occur in cases of misdiagnosis and improper treatment. Diagnosis is difficult because of the atypical clinical symptoms and diagnostic confusion with diarrhea caused by gastrointestinal cancer, opportunistic infections in human immunodeficiency virus patients, and hyperthyroidism. In addition, parasite eggs are not always found in stool examination. Serology can provide a supportive diagnostic tool. We have produced a rapid and simple immunochromatographic test (ICT) kit for diagnosis of intestinal capillariasis by detection of diagnostic antibodies in human sera. Serum samples from healthy volunteers and patients with proven intestinal capillariasis and other parasitic diseases were evaluated with the Trichinella spiralis larval extract antigen absorbed ICT strips. The diagnostic sensitivity, specificity, and positive and negative predictive values were 100, 96.6, 90.2, and 100%, respectively. The ICT kit is simple and rapid to use and can supplement stool examination in clinical diagnosis of intestinal capillariasis. The test can be completed in 15 min without a need for any sophisticated instruments or reagents.

Development of a prototype immunochromatographic test for rapid diagnosis of respiratory adenovirus infection

Human adenoviruses comprise an important group of etiologic agents that are responsible for various diseases in adults and children, such as respiratory, ocular, gastroenteric, and urinary infections. In immunocompromised and organ-transplanted individuals, these agents can cause generalized infections. Rapid diagnostic methods for detecting these infectious agents are not widely available.

The aim of this work was to produce monoclonal and polyclonal anti-adenovirus antibodies to be used in a rapid diagnostic test for respiratory infections.

Adenovirus hexons were satisfactorily purified by ultracentrifugation and chromatography. After virus purification, anti-hexon monoclonal antibodies were produced and characterized, following classical methods. Antibodies were specific for adenoviruses 2, 3, 5, and 41. The proposed immunochromatographic test was standardized using colloidal gold.

The standardization of the rapid test was sufficient to detect adenovirus antigens (in nasopharyngeal lavage samples) with sensitivity of 100% and specificity of 85% when compared to direct immunofluorescence.

The immunochromatographic assay prototype was sufficiently sensitive to detect B (3), C (2 and 5), and F (41) adenovirus samples. Although based on preliminary data, the test demonstrated the same performance as direct immunofluorescence, but with the advantage of being a point-of-care test. Further studies are still needed to confirm its effectiveness in clinical practice.

[Progress and application of immunodiagnostic methods of giardiasis]

Giardia lamblia is an important intestinal protozoan which can cause diarrhea in humans. The detection of Giardia infection is performed through the detection methods of pathogen, immunoassay and molecular biology. Currently, the immunodiagnostic methods have good application and development prospect because of high sensitivity and specificity, simple and convenient, and time saving. In this article, we review the main progress and application of immunodiagnostic methods for Giardia infection.

Improved Serodiagnostic Sensitivity of Strip Test for Latent Tuberculosis

INTRODUCTION

Diagnosis of Latent Tuberculosis Infection (LTBI) is difficult due to no clinical manifestations. Cases of LTBI are mostly sputum negative. The World Health Organization recommends the Tuberculin Skin Test (TST) as the current diagnostic standard for LTBI. Our previously developed serologic strip test for LTBI detection had suboptimal sensitivity. Additional Mycobacteriumtuberculosis (MTB) latency-associated antigens may improve the detection rate of LTBI.

AIM

The present study aimed to optimize sensitivity of existing strip test.

MATERIALS AND METHODS

A combination of recombinant latency proteins Rv2029c, Rv2031c, Rv2032, Rv2627c, Rv3133c, and Rv3716c was used to prepare the strips and evaluate the performance with the sera of patients in four well-classified categories: LTBI, active pulmonary TB, healthy TB contacts and other non-TB diseases.

RESULTS

A total of 91 serum samples from various clinical categories were screened with the strips. Among clinically diagnosed LTBI patients, strip test yielded a sensitivity of 75.0%. Among clinically diagnosed non-LTBI subjects, strip test yielded 88.1% specificity. The diagnostic positive and negative predictive values for strip test in reference to various clinical contexts were 77.4% and 86.7%, respectively.

CONCLUSION

Addition of the six potential latency proteins could improve the diagnostic performance of existing strip test for LTBI. The use of suitable immunodominant antigens could maximize sensitivity in the diagnosis and differentiate MTB infection status.

Does 24bp Duplication of Human CHIT1 Gene (Chitotriosidase1) Predispose to Filarial Chyluria? A Case-Control Study

INTRODUCTION

Chyluria which is endemic in many parts of the world is mainly caused by Wuchereria bancrofti. CHIT1 (chitotriosidase) is produced by macrophages and plays an important role in the defense against chitin containing pathogen such as filarial parasite. Variation in the coding region with 24 bp duplication allele results in reduced CHIT1 activity that enhance the survival of parasite which may play a role in the occurrence of disease.

AIM

To examine the role of 24bp duplication of CHIT1 gene in patients of filarial chyluria (FC).

MATERIALS AND METHODS

A case-control study was carried out where 155 confirmed FC patients and equal number of age-, sex- and residence-matched controls without any symptoms or signs of lymphatic filariasis, confirmed by negative immunochromatographic card test (ICT) and IgG/IgM combo rapid antibody test, from a hospital-based population were enrolled. Filarial aetiology was confirmed on the basis of DEC-provocative test (Giemsa staining), ICT and IgG/IgM- antifiarial antibody test. The patients positive by either of these tests were enrolled as FC cases. 24bp duplication in CHIT1 gene in FC was detected by the product size 99bp of amplified gene using polymerase chain reaction.

RESULTS

The mean ages of patients and controls were 38.25±12.09 and 35.45±12.53 years, respectively while male: female ratio was 2.4:1. The mean duration of illness in chyluria patients was 62.81±60.83 months and mean number of episodes was 2.54±1.11. Homozygous wild type, heterozygous and homozygous mutant frequencies were 10.3%, 81.3% and 8.4% in FC patients and 18.7%, 75.5%, and 5.8% in controls, respectively. The 24bp duplication in CHIT1 gene showed a significant association in Heterozygous (HT) genotype with Odd Ratio (OR) of 1.95, 95% Confidence Interval (CI) (1.01-3.77); p=0.04. However, the homozygous mutant genotype (TT) was found to be non-significant with OR of 2.61, 95% CI (0.91-7.45); p=0.07. The combination of both HT+TT was also found to be significant with OR of 2.00, 95% CI (1.03-3.85); p=0.03.

CONCLUSION

In this study from Northern India, CHIT1 gene polymorphism showed an influence as a possible risk factor for susceptibility to FC. Further studies need to be done on a larger number of FC patients in different regions of the country.

Utility of a lateral flow assay for culture confirmation of Mycobacterium tuberculosis complex

BACKGROUND

Therapy for the clinical management of patients with Mycobacterium tuberculosis complex (MTBC) and non tuberculous mycobacteria (NTM) is different. Prompt detection and discrimination is necessary for administration of suitable therapy.

METHODS

The aim of the study was to evaluate the performance of a Immunochromatographic Test (ICT) in rapid differentiation of MTBC from NTM grown in Lowenstein-Jensen medium and MGIT broth in comparison to molecular methods.

RESULTS

Of the 106 isolates in this study, 96 and 95 were identified as MTBC by 16S rRNA PCR and MPT64 respectively. The sensitivity and specificity of MPT64 was found to be 99% and 100% respectively.

CONCLUSION

The Lateral Flow Assay Test is a useful and specific tool in rapid differentiation of M. tuberculosis complex from culture. Therefore proper identification avoids unnecessary ATT to patients infected with NTM.

A TeGM6-4r antigen-based immunochromatographic test (ICT) for animal trypanosomosis

Animal trypanosomosis is a disease that is distributed worldwide which results in huge economic losses due to reduced animal productivity. Endemic regions are often located in the countryside where laboratory diagnosis is costly or inaccessible. The establishment of simple, effective, and accurate field tests is therefore of great interest to the farming and veterinary sectors. Our study aimed to develop a simple, rapid, and sensitive immunochromatographic test (ICT) for animal trypanosomosis utilizing the recombinant tandem repeat antigen TeGM6-4r, which is conserved amongst salivarian trypanosome species. In the specificity analysis, TeGM6-4r/ICT detected all of Trypanosoma evansi-positive controls from experimentally infected water buffaloes. As expected, uninfected controls tested negative. All sera samples collected from Tanzanian and Ugandan cattle that were Trypanosoma congolense- and/or Trypanosoma vivax-positive by microscopic examination of the buffy coat were found to be positive by the newly developed TeGM6-4r/ICT, which was comparable to results from TeGM6-4r/ELISA (kappa coefficient [κ] = 0.78). TeGM6/ICT also showed substantial agreement with ELISA using Trypanosoma brucei brucei (κ = 0.64) and T. congolense (κ = 0.72) crude antigen, suggesting the high potential of TeGM6-4r/ICT as a field diagnostic test, both for research purposes and on-site diagnosis of animal trypanosomosis.

Direct Identification of Staphylococcus aureus and Determination of Methicillin Susceptibility From Positive Blood-Culture Bottles in a Bact/ALERT System Using Binax Now S. aureus and PBP2a Tests

Staphylococcus aureus bacteremia is associated with high mortality and morbidity, requiring prompt and appropriate antimicrobial treatment. Therefore, it is important to detect methicillin-resistant S. aureus (MRSA) rapidly from blood cultures. Two immunochromatographic tests, BinaxNow S. aureus and BinaxNow PBP2a, were directly applied to 79 Bact/Alert bottles that were positive for Gram positive cocci in cluster aggregations. Sensitivity and specificity for the identification of S. aureus and determination of methicillin resistance were 94% and 87%, and 100% and 100%, respectively, with less than 30 min of performance time. These tests are efficient and rapid; these tests are valuable alternatives to more sophisticated and expensive methods used in the diagnosis of MRSA bacteremia.

Diagnostic performance characteristics of a rapid field test for anthrax in cattle

Although diagnosis of anthrax can be made in the field with a peripheral blood smear, and in the laboratory with bacterial culture or molecular based tests, these tests require either considerable experience or specialised equipment. Here we report on the evaluation of the diagnostic sensitivity and specificity of a simple and rapid in-field diagnostic test for anthrax, the anthrax immunochromatographic test (AICT). The AICT detects the protective antigen (PA) component of the anthrax toxin present within the blood of an animal that has died from anthrax. The test provides a result in 15min and offers the advantage of avoiding the necessity for on-site necropsy and subsequent occupational risks and environmental contamination. The specificity of the test was determined by testing samples taken from 622 animals, not infected with Bacillus anthracis. Diagnostic sensitivity was estimated on samples taken from 58 animals, naturally infected with B. anthracis collected over a 10-year period. All samples used to estimate the diagnostic sensitivity and specificity of the AICT were also tested using the gold standard of bacterial culture. The diagnostic specificity of the test was estimated to be 100% (99.4-100%; 95% CI) and the diagnostic sensitivity was estimated to be 93.1% (83.3-98.1%; 95% CI) (Clopper-Pearson method). Four samples produced false negative AICT results. These were among 9 samples, all of which tested positive for B. anthracis by culture, where there was a time delay between collection and testing of >48h and/or the samples were collected from animals that were >48h post-mortem. A statistically significant difference (P<0.001; Fishers exact test) was found between the ability of the AICT to detect PA in samples from culture positive animals <48h post-mortem, 49 of 49, Se=100% (92.8-100%; 95% CI) compared with samples tested >48h post-mortem 5 of 9 Se=56% (21-86.3%; 95% CI) (Clopper-Pearson method). Based upon these results a post hoc cut-off for use of the AICT of 48h post-mortem was applied, Se=100% (92.8-100%; 95% CI) and Sp=100% (99.4-100%; 95% CI). The high diagnostic sensitivity and specificity and the simplicity of the AICT enables it to be used for active surveillance in areas with a history of anthrax, or used as a preliminary tool in investigating sudden, unexplained death in cattle.

Performance of a rapid strip test for the serologic diagnosis of latent tuberculosis in children

BACKGROUND

The serodiagnostic tests for tuberculosis (TB) present a high variability in terms of sensitivity and specificity. Data on patients with latent TB infection (LTBI) and children in high prevalence settings are still limited. The present study aimed to evaluate an in-house strip test for detection of anti-M. tuberculosis antibodies in TB patients, mostly children aged under 15 y, grouped into four diagnostic categories: active TB, LTBI, healthy TB contacts, and other non-TB diseases.

MATERIALS AND METHODS

The diagnostic performance of strip test was compared with the tuberculin skin test (TST) and interferon-gamma release assay (IGRA). Sensitivity and specificity were assessed for all three diagnostic tests. The detection accuracy among the tests was calculated by using a receiver operating characteristic analysis.

RESULTS

TST and IGRA could diagnose the active TB cases correctly (100%). The sensitivity of strip test for active TB was 58.3% and 37.5% for LTBI, while the sensitivities of TST and IGRA for LTBI were 90.3% and 37.5%, respectively. The overall specificities of strip test and IGRA were 91.5% and 95.7%, respectively, which were superior to that of TST (68.1%).

CONCLUSION

The strip test did not appear to be useful for diagnosis of active TB in comparison with the current diagnostic standard. The assay may be particularly significant in situations where TB is clinically difficult to diagnose like LTBI and could be a meaningful tool in terms of high specificity and simplicity for ruling in pediatric TB in countries with high TB infection rate. Further studies are needed to determine whether strip test can be improved in its sensitivity and should be implemented into routine clinical practice.

Immunochromatographic test for detection of adenovirus from respiratory samples: is it a real solution for pediatric emergency department?

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Rapid diagnosis of adenoviral respiratory infections is required in order to decide optimal treatment strategies.

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We evaluated the adenovirus antigen IC test Adeno Respiratory Letitest, versus the shell-vial culture and multiplex PCR.

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Using multiplex-PCR as the reference standard, the overall sensitivity was 77.89% and the specificity was 73.64%.

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It is a simple and rapid method for detection of adenovirus in pediatric respiratory samples.

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It would be necessary to improve the specificity and sensitivity of the test.

Rapid diagnosis of adenoviral respiratory infections is required in order to decide optimal treatment strategies. The adenovirus antigen immunochromatography Adeno Respiratory Card Letitest (Leti diagnostics, Barcelona, Spain), was evaluated versus the shell-vial culture and multiplex PCR (Clart Pneumovir Version 3.0, Genomica, Madrid, Spain), in nasopharyngeal washes and oropharyngeal swabs specimens from subjects with respiratory tract infections.

Between April 2011 and November 2012, 224 patients were included. The IC Adeno Respiratory Card Letitest was positive for 77.9% (74 of 95) of patients diagnosed at bedside. Using multiplex-PCR as the reference standard, the overall sensitivity was 77.9% and the specificity was 73.6%. Taking shell-viral culture as the reference method, the Adeno Respiratory Card Letitest (Leti diagnostics, Barcelona, Spain) sensitivity and specificity values were 80.0% and 60.9%, respectively. Using RT-PCR (Clart Pneumovir Version 3.0, Genomica, Madrid, Spain) as the reference standard, the viral culture sensitivity was 53.2% and the specificity was 100%.

The Adeno Respiratory Card Letitest (Leti diagnostics, Barcelona, Spain) assay could be a simple and rapid method for antigenic detection of adenovirus in pediatric respiratory samples although it would be necessary to improve the specificity and sensitivity of the test.

Bedside immunochromatographic test for enterovirus 71 infection in children

BACKGROUND

Enterovirus 71 (EV71) causes frequent outbreaks worldwide, particularly in the Asia-Pacific area. Its quick spread is a critical challenge for public health and timely preventive measures and clinical management therefore rely on early detection. There is a need for a rapid, easy-to-use, and reliable method for detecting EV71 infections.

OBJECTIVE

The study aimed to evaluate a bedside immunochromatography (ICT) kit for diagnosing acute EV71 infection in children.

STUDY DESIGN

Pediatric patients with herpangina or hand-foot-mouth disease were randomly and prospectively enrolled from hospitals across Taiwan. Throat or rectal swabs were collected for viral culture and reverse-transcriptase polymerase chain reaction (RTPCR). For the ICT kit, whole blood was obtained by ear piercing, finger-sticking, or venipuncture. The results of ICT, virus isolation and RTPCR in clinical samples were compared.

RESULTS

Of the 156 patients enrolled, 91 (58%), 64 (41%) and 72 (46%) had positive results of the ICT kit, viral culture and RTPCR, respectively. Laboratory-confirmed infection with either positive EV71 culture or RTPCR was used as the diagnostic standard. The sensitivity and specificity of the ICT kit was 84% and 77%, respectively. The viral culture and RTPCR had relatively lower sensitivity but higher specificity. The patient's age did not affect the performance of the ICT, viral culture and RTPCR. However, a low sensitivity of ICT kit was noted before the second day of disease onset.

CONCLUSIONS

The ICT kit may serve as a simple, quick and reliable method for the bedside diagnosis of acute EV71 infection in children.

Non-invasive diagnosis of H pylori infection: Evaluation of serological tests with and without current infection marker CIM

AIM: To evaluate the performance of commercially available immunochromatographic (ICT) and immunoblot tests covering the current infection marker CIM and conventional ELISA for the diagnosis of H pylori infection in adult dyspeptic patients.

METHODS: Consecutive non-treated dyspeptic patients undergoing diagnostic endoscopy were tested for H pylori infection by culture, rapid urease test, and histology of gastric biopsy specimens. Serum from 61 H pylori infected and 21 non-infected patients were tested for anti-H pylori IgG antibodies by commercial ELISA (AccuBind^TM ELISA, Monobind, USA), ICT (Assure^®H pylori Rapid Test, Genelabs Diagnostics, Singapore), and immunoblot (Helico Blot 2.1, Genelabs Diagnostics, Singapore) assays. ICT and immunoblot kits cover CIM among other parameters and their performance with and without CIM was evaluated separately.

RESULTS: Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of ELISA were 96.7%, 42.8%, 83.1%, 81.8%, and 82.9%, of ICT were 90.1%, 80.9%, 93.2%, 73.9%, and 87.8%, of ICT with CIM were 88.5%, 90.4%, 96.4%, 73.0%, and 89.0%, of immunoblot were 98.3%, 80.9%, 93.7%, 94.4%, and 93.9%, and of immunoblot with CIM were 98.3%, 90.4%, 96.7%, 95.0%, and 96.3%, respectively.

CONCLUSION: Immunoblot with CIM had the best performance. ICT with CIM was found to be more specific and accurate than the conventional ELISA and may be useful for non-invasive diagnosis of H pylori infection.