• Parasites, Hosts and Diseases
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• v.51 no.1
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• pp.93-98
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• 2013

A field applicable diagnostic technique, the dipstick assay, was evaluated for its sensitivity and specificity in diagnosing human Schistosoma mansoni infection. A monoclonal antibody (mAb) against S. mansoni adult worm tegumental antigen (AWTA) was employed in dipstick and sandwich ELISA for detection of circulating schistosome antigen (CSA) in both serum and urine samples. Based on clinical and parasitological examinations, 60 S. mansoni-infected patients, 30 patients infected with parasites other than schistosomiasis, and 30 uninfected healthy individuals were selected. The sensitivity and specificity of dipstick assay in urine samples were 86.7% and 90.0%, respectively, compared to 90.0% sensitivity and 91.7% specificity of sandwich ELISA. In serum samples, the sensitivity and specificity were 88.3% and 91.7% for dipstick assay vs. 91.7% and 95.0% for sandwich ELISA, respectively. The diagnostic efficacy of dipstick assay in urine and serum samples was 88.3% and 90.0%, while it was 90.8% and 93.3% for sandwich ELISA, respectively. The diagnostic indices of dipstick assay and ELISA either in serum or in urine were statistically comparable (P>0.05). In conclusion, the dipstick assay offers an alternative simple, rapid, non-invasive technique in detecting CSA or complement to stool examinations especially in field studies.

• Food Science and Biotechnology
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• v.15 no.6
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• pp.990-992
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• 2006

In a previous study, we obtained polyclonal antibodies against the organophosphorus insecticide fenitrothion and developed an enzyme-linked immunosorbent assay (ELISA) for this pesticide. Using these antibodies and an enzyme tracer, a direct competitive ELISA method specific for fenitrothion using a dipstick format was developed. Dipstick ELISA using antibodies to fenitrothion immobilized on an Immunodyne membrane allowed the quick visual detection of fenitrothion at concentrations above $10\;{\mu}g/L$. The $IC_{50}$ value of dipstick ELISA using reflectance detection was $27\;{\mu}g/L$ with a detection limit of $2\;{\mu}g/L$. The recovery of fenitrothion from spiked lettuce and rice samples using the dipstick ELISA ranged from 87-107%.

• Journal of Microbiology and Biotechnology
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• v.16 no.8
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• pp.1316-1319
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• 2006

An antibody displayed phage collection (SBAE-2R), screened from a human synthetic phage antibody library (Fab 21ox), was used for the determination of dextran. The dextran-binding affinity was determined by serologically specific transmission electron microscopy (TEM) and a paper dipstick assay. The phage collection was distributed over the dextrancoated grids with 39$\pm$25 phages/$\mu$m$^2$ on the grids. Phages were not seen on dextran-coated grids exposed to the Fab 2lox phage library. The phage collection (SBAE-2R) produced 54$\pm$3 color normalized intensity (N.I.) from 125 ppm to 1,000 ppm of dextran and 5$\pm$1 (N.I.) for 63 ppm of dextran in a paper dipstick assay. This research extends the analytical options for dextran analysis by antibody displayed phage with a minimum of equipment usage.

• Food Science and Biotechnology
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• v.14 no.6
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• pp.743-746
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• 2005

A dipstick-type immunochemical biosensor for the detection of the organophosphorus insecticide fenthion was developed using a screen-printed electrode system as an amperometric transducer with polyclonal antibodies against fenthion as a bioreceptor. The assay of the biosensor involved competition between the pesticide in the sample and pesticide-glucose oxidase conjugate for binding to the antibody immobilized on the membrane. This was followed by measurement of the activity of the bound enzyme by the supply of the enzyme substrate (glucose) and amperometric determination of the enzyme reaction product ($H_2O_2$). The activity of the bound enzyme was inversely proportional to the concentration of pesticide. The optimized sensor system showed a linear response against the logarithm of the pesticide concentration ranging from $10^{-2}$ to $10^3\;{\mu}g/L$.

• Journal of Microbiology and Biotechnology
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• v.31 no.12
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• pp.1672-1683
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• 2021

Vibrio parahaemolyticus is recognized as one of the most important foodborne pathogens responsible for gastroenteritis in humans. The bla_CARB-17 gene is an intrinsic β-lactamase gene and a novel species-specific genetic marker of V. parahaemolyticus. In this study, a loop-mediated isothermal amplification (LAMP) assay combined with a lateral flow dipstick (LFD) was developed targeting this bla_CARB-17 gene. The specificity of LAMP-LFD was ascertained by detecting V. parahaemolyticus ATCC 17802 and seven other non-V. parahaemolyticus strains. Finally, the practicability of LAMP-LFD was confirmed by detection with V. parahaemolyticus-contaminated samples and natural food samples. The results showed that the optimized reaction parameters of LAMP are as follows: 2.4 mmol/l Mg²⁺, 0.96 mmol/l dNTPs, 4.8 U Bst DNA polymerase, and an 8:1 ratio of inner primer to outer primer, at 63℃ for 40 min. The optimized reaction time of the LFD assay is 60 min. Cross-reactivity analysis with the seven non-V. parahaemolyticus strains showed that LAMP-LFD was exclusively specific for V. parahaemolyticus. The detection limit of LAMP-LFD for V. parahaemolyticus genomic DNA was 2.1 × 10^-4 ng/μl, corresponding to 630 fg/reaction and displaying a sensitivity that is 100-fold higher than that of conventional PCR. LAMP-LFD in a spiking study revealed a detection limit of approximately 6 CFU/ml, which was similar with conventional PCR. The developed LAMP-LFD specifically identified the 10 V. parahaemolyticus isolates from 30 seafood samples, suggesting that this LAMP-LFD may be a suitable diagnostic method for detecting V. parahaemolyticus in aquatic foods.

• Journal of Microbiology and Biotechnology
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• v.29 no.3
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• pp.454-464
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• 2019

Salmonellosis is a highly contagious bacterial disease that threatens both human and poultry health. Tests that can detect Salmonella in the field are urgently required to facilitate disease control and for epidemiological investigations. Here, we combined loop-mediated isothermal amplification (LAMP) with a chromatographic lateral flow dipstick (LFD) to rapidly and accurately detect Salmonella. LAMP primers were designed to target the Salmonella invA gene. LAMP conditions were optimized by adjusting the ratio of inner to outer primers, $MgSO_4$ concentration, dNTP mix concentration, amplification temperature, and amplification time. We evaluated the specificity of our novel LAMP-LFD method using six Salmonella species and six related non-Salmonella strains. All six of the Salmonella strains, but none of the non-Salmonella strains, were amplified. LAMP-LFD was sensitive enough to detect concentrations of Salmonella enterica subsp. enterica serovar Pullorum genomic DNA as low as $89fg/{\mu}l$, which is 1,000 times more sensitive than conventional PCR. When artificially contaminated feed samples were analyzed, LAMP-LFD was also more sensitive than PCR. Finally, LAMP-LFD gave no false positives across 350 chicken anal swabs. Therefore, our novel LAMP-LFD assay was highly sensitive, specific, convenient, and fast, making it a valuable tool for the early diagnosis and monitoring of Salmonella infection in chickens.

• Journal of Yeungnam Medical Science
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• v.8 no.1
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• pp.42-52
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• 1991

Two types of urine dipstick assays, Multistix-SG and Combur-9-test RL, were compared for compatibility, accuracy, specificity and predictive values of a positive and negative test in 501 patients urine and artificially prepared specimen. We found that the results of semiquantitative tests of Multistix-SG and Combur-9-Test RL performed were statistically similar in patients specimen. The urinary leukocyte estrase tests of Combur-9-Test RL assays compared with urine sediment microscopy in regard to compatibility, sensitivity, specificity, and predictive values of a positive and negative test 83.7%, 48.1%, 90.3%, 47.4% and 90.1%, respectively. The urinar nitrite tests of Comber-9-Test RL assays compared with urine culture tests, in regard to compatibility, sensitivity, specificity, and predictive values of a positive and negative tests were 90.3%, 19.4%, 84.7%, 53.8% and 94.1%, respectively. For the urinary protein, the sulfosalicylic acid method was the most sensitive test for any kinds of protein, and Multistix-SG appeared more sensitive than Compur-9-Test RL for the albuminuria. For the urinary bilirubin and glusose, two dipstick assays were similar in their diganostic efficiency. Finally in the urinary occult blood tests, Combur-9-Test RL assays was more sensitive than Multistix-SG.

• Korean Journal of Veterinary Research
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• v.39 no.5
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• pp.951-960
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• 1999

We performed this study to evaluate the potential clinical marker of urinary trypsinogen-2 together with amylase, lipase and urinary amylase creatinine clearance ratio (ACCR) for the diagnosis of acute pancreatitis in dogs. In the experiment on daily changing patterns of amylase, lipase and ACCR measurements in experimentally induced pancreatitis dogs, compared to values measured in pre-induction state, significant difference was seen in amylase until 5th day of induction, and for lipase significant difference was found during the 7th day of observation period (p < 0.05). No significant difference was found in ACCR for the study period (p > 0.05). On SDS-PAGE analysis of urine from experimentally induced pancreatitis dog, The 26kd band was markedly increased compared with that of normal state and that band was confirmed trypsinogen-2 using substrate interaction and isoelectric focusing assay after being eluted. When assessing the appearance of 26kd band on urine SDS-PAGE 87.1% (range: 50~100%) of experimentally induced pancreatitis dogs showed positive results, whereas no corresponding band was seen in dog without pancreatic disorders. With this result, determination of urinary trypsinogen-2 assay was found to have a high diagnostic value with a 70% of sensitivity and 100% of specificity as a routine test for pancreatitis, although the detection of trypsinogen-2 in urine can be varied on the progression stage of pancreatitis at the initial visit to animal clinic. We therefore suggest that the promising results in this study be used for the development of dipstick test for detecting acute pancreatitis in the future research.

• Journal of Microbiology and Biotechnology
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• v.33 no.8
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• pp.1091-1100
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• 2023

Human papillomavirus (HPV) types 16 and 18 are the major causes of cervical lesions and are associated with 71% of cervical cancer cases globally. However, public health infrastructures to support cervical cancer screening may be unavailable to women in low-resource areas. Therefore, sensitive, convenient, and cost-efficient diagnostic methods are required for the detection of HPV16/18. Here, we designed two novel methods, real-time ERA and ERA-LFD, based on enzymatic recombinase amplification (ERA) for quick point-of-care identification of the HPV E6/E7 genes. The entire detection process could be completed within 25 min at a constant low temperature (35-43℃), and the results of the combined methods could be present as the amplification curves or the bands presented on dipsticks and directly interpreted with the naked eye. The ERA assays evaluated using standard plasmids carrying the E6/E7 genes and clinical samples exhibited excellent specificity, as no cross-reaction with other common HPV types was observed. The detection limits of our ERA assays were 10⁰ and 10¹ copies/µl for HPV16 and 18 respectively, which were comparable to those of the real-time PCR assay. Assessment of the clinical performance of the ERA assays using 114 cervical tissue samples demonstrated that they are highly consistent with real-time PCR, the gold standard for HPV detection. This study demonstrated that ERA-based assays possess excellent sensitivity, specificity, and repeatability for HPV16 and HPV18 detection with great potential to become robust diagnostic tools in local hospitals and field studies.