Comparative Assessment of Antibiotic Residues Using Liquid Chromatography Coupled with Tandem Mass Spectrometry (LC-MS/MS) and a Rapid Screening Test in Raw Milk Collected from the North-Central Algerian Dairies

Antibiotic residues in milk are a major health threat for the consumer and a hazard to the dairy industry, causing significant economic losses. This study aims to assess the presence of antibiotic residues in raw milk comparatively by a rapid screening test (BetaStar® Combo) and Liquid Chromatography coupled with Tandem Mass Spectrometry (LC-MS/MS). A total of 445 samples were collected from 3 dairy companies of north-central Algeria (Algiers, Blida, Boumerdes), and they were rapidly screened for β-lactams and tetracyclines; 52 samples, comprising 34 positive tanker-truck milk and 18 negative bulk-tank milk were tested by LC-MS/MS, which revealed 90.4% were contaminated (n = 47) and 55.3% exceeded the Maximum Residue Limit (MRL). The β-lactams as parent compounds and their metabolites were the most frequently detected with maximum value for cloxacillin (1231 µg/kg) and penicillin G (2062 µg/kg). Under field condition, the false-positive results, particularly for tetracyclines, seems to be related to milk samples displaying extreme acidity values (≥19°D) or fat-level fluctuations (2.7 g/100 mL and 5.6–6.2 g/100 mL). Despite a relatively low prevalence (7.64%) of residues using the rapid test, the detection by LC-MS/MS of flumequine (52 µg/kg), cefaclor (maximum 220 µg/kg) and metabolites of β-lactams at high levels should lead to reflections on the control of their human and environmental toxicological effects.

Preliminary Evaluation of Gunshot Residue (GSR) Using 3-Aminophenol as a Substitute in Modified Griess Test

In forensic ballistics, gunshot residue (GSR) particles can be detected using screening or presumptive tests which are mainly focused on the chromophoric reaction. Most tests serve as an initial indication for a forensic investigator at the crime scene before instrumental analysis for definitive identification. The screening methods are known to be convenient, have fast analysis, and minimal preparation. In GSR analysis, the well-known method of detecting GSR known as the Modified Griess Test (MGT) requires acid and heat for the reaction. Therefore, this study demonstrated a new and rapid screening test named the Rapid Griess Test (RGT) for the detection of GSR. This study intends to improve the functionality of previous screening reagents in determining nitrite (NO2–), the composition present after shooting activity. To do this, chemical reagents with an amino group, 3-aminophenol, were substituted with alpha-naphthol. The experiment showed that the reactions were positive color changes using standard NO2– and real GSR samples. The diazotization reactions involving sulfanilic acid and 3-aminophenol produced azo dyes that changed the solution from colorless to orange in the presence of NO2–. The RGT reagent will make it possible to avoid using heat and the addition of acetic acids in a sample to form chromophoric reactions. Moreover, the colorimetric method using Video Spectral Comparator (VSC) showed that RGT had higher intensity of the orange color when compared to MGT.

Methodology of Selecting the Optimal Receptor to Create an Electrochemical Immunosensor for Equine Arteritis Virus Protein Detection

The study reports a methodology of selecting the optimal receptor to create an electrochemical immunosensor for equine arteritis virus (EAV) protein detection. The detection was based on antigen recognition by antibodies immobilized on gold electrodes. Modification steps were controlled by electrochemical impedance spectroscopy and cyclic voltammetry measurements. In order to obtain the impedance immunosensor with the best parameters, seven different receptors complementary to equine arteritis virus protein were used. In order to make the selection, a rapid screening test was carried out to check the sensor’s response to blank, extremely low and high concentrations of target EAV protein, and negative sample: M protein from Streptococcus equi and glycoprotein G from Equid alphaherpesvirus 1. F6 10G receptor showed the best performance.

Evaluation of modified nitrite test for diagnosing urinary tract infection in pediatrics

Background: Urinary tract infection (UTI) is a common bacterial infection causing illness in children. It may be difficult to recognize UTI in children because the presenting symptoms and signs are non-specific, particularly in younger children. In addition, urine collection and interpretation of urine tests in children are not easy, and therefore, it may not always be possible to confirm the diagnosis unequivocally. The study was conducted to evaluate the value of the modified nitrite test in diagnosing urinary tract infection (UTI) in children.Methods: The study included 150 children of both sexes, aged below 5 years, who were examined due to suspicion of UTI. The efficacy of the modified nitrite test to predict culture positivity was studied.Results: Modified nitrite test was positive in 14 out of the 26 culture-positive urine samples (sensitivity 53.85%). The specificity, positive predictive value, and negative predictive value were 96.77%, 77.78%, and 90.91%. The overall diagnostic accuracy was 89.33%.Conclusions: Modified nitrite test is an effective rapid screening test for diagnosing pediatric UTI.

A Simple and Rapid Spectrophotometric Method for Nitrite Detection in Small Sample Volumes

A simple, rapid, and environmentally-friendly spectrophotometric method for nitrite detection was developed. Detection was based on a redox reaction with iodide ions in an acidic condition. The reaction was evaluated by detecting the increase in absorbance of the colored product of iodine at 362 nm wavelength. To obtain a good spectrophotometric performance, the iodide ions concentration, hydrochloric acid concentration, and reaction time were optimized. In the optimal condition, the developed spectrophotometric method provided a linear range of 0.0625 to 4.00 mg L−1 (r = 0.9985), reaction time for 10 min, a limit of detection of 25 µg L−1, and a limit of quantitation of 85 µg L−1. This method showed good repeatability (RSD < 9.21%), high sample throughput (9 samples min−1), and good accuracy (recovery = 88 ± 2 to 99.5 ± 0.4%). The method has the potential to be used in crime scene investigations as a rapid screening test for gunshot residue detection via nitrite detection.

Molecular Comparison of Screening Technique for Hepatitis B Virus Infection among Blood Donors in Ibadan, South West, Nigeria

Hepatitis B infection has been a great threat to transfusion medicine and public medicine, especially Nigeria where approximately 18 million Nigerians are chronic carriers. The blood donors in Ibadan are routinely screened with rapid technique or enzyme-linked immunosorbent assay (ELISA) for the detection of Hepatitis B surface antigen (HBsAg), there is paucity of information on the use of Nested Polymerase Chain Reaction (Nested PCR) for the detection of Hepatitis B virus deoxyribonucleic acid (DNA) for the screening of blood donors. This study was aimed at carrying out molecular comparison of the screening techniques for the detection of HBV infection among blood donors in Ibadan, South West, Nigeria. Blood samples were collected from 150 potential blood donors at the blood bank, University College Hospital, Ibadan. Rapid immune-chromatographic technique and nested PCR using primer SF, 979 and MF specific for DNA polymerase genome was used to screen the serum of the blood donors. Processing and analysis of data were performed using IBM statistical package for social sciences (IBM SPSS version 21.0 computer software). Descriptive statistics were presented using chart and tables while statistical significance was taken as P<0.05 The Rapid Screening test showed that 16 (10.7%) of the blood donors were positive while 134 (89.3%) were negative. The molecular detection of the Hepatitis B virus-DNA using nested PCR showed that 7 (4.7%) of the blood donors were positive while 143 (95.3%) were negative. It was also observed that 5 (71.4%) out of the 16 donors (10.7%) captured by the rapid screening were also detected by the Nested PCR, while the remaining 2 (28.6%) detected by the PCR were negative with the Rapid Screening test. The age range of 30 to 39 years and 40 to 49 years had the higher rate of infection 42.9% respectively. Result of the effects of different risk factors generated with the aid of questionnaire reflected that multiple sex partner have the highest prevalence of 16.7% compared to other risk factors In conclusion, the detection of HBV-DNA using nested PCR among blood donors that was positive in Ibadan South West, Nigeria has public health implication for prevention of Hepatitis B virus and this confirms the practice of improper screening of blood before transfusion. Nested PCR techniques helps in early detection of hepatitis B virus DNA among blood donors, due to its high specificity and sensitivity than Rapid technique hence it serves as a confirmatory technique.

SEROPREVALENCE OF HEPATITIS B IN PATIENTS ADMITTED IN SURGICAL UNITS IN A TEACHING HOSPITAL OF SEMI URBAN SETUP.

BACKGROUND: st st This was a prospective observational study carried over a period of one years(1 . Jan 2019 to 31 . Dec 2019).The aim of this study was screening of Hepatitis B infection in patients admitted to undergo selective/emergency surgery in order to provide both preventive and treatment services and to reduce the transmission to the attending healthcare workers. PATIENTS AND METHODS: The patients dated for elective surgery were taken up for this study. These patients were screened for HBsAg using a commercial rapid screening test kit of lateral ow immunochromatographic method. RESULTS:In our Study we have found that the prevalence of HBVinfection was 1.23%. The male female ratio was 1.3:1. Males are more infected than females. Patients in 20-39 years age group showed highest positivity (1.99%) and least (1.00%) in ≥ 60 years. CONCLUSION: For all surgical procedures, routine pre-operative screening has been recommended for HBV. We therefore recommend screening for hepatitis B infection for all patients who are undergoing surgical procedures to reduce the risk of infection to the surgical team so sas to reduce the prevalence rate in a developing country like India.

D-karyo—A New Prenatal Rapid Screening Test Detecting Submicroscopic CNVs and Mosaicism

Chromosomal microarray analysis (CMA), recently introduced following conventional cytogenetic technology, can detect submicroscopic copy-number variations (CNVs) in cases previously diagnosed as “cytogenetically benign”. At present, rapid and accurate chromosomal analysis is required in prenatal diagnostics, but prenatal CMA is not widely used due to its high price and long turnaround time. We introduced a new prenatal screening method named digital karyotyping (D-karyo), which utilizes a preimplantation genetic test for the aneuploidy (PGT-A) platform. First, we conducted a preliminary experiment to compare the original PGT-A method to our modified method. Based on the preliminary results, we decided to implement the modified strategy without whole-genome amplification (WGA) and combined it with three analytical software packages. Next, we conducted a prospective study with 824 samples. According to the indication for invasive tests, the D-karyo positive rates were 2.5% and 5.0%, respectively, in the screening positive group with NT ≥ 3.5 mm and the group with fetal abnormalities by ultrasound. D-karyo is a breakthrough modality that can detect submicroscopic CNVs ≥ 1.0 Mb accurately in only 10.5 h for 24 samples at a low cost. Implementing D-karyo as a prenatal rapid screening test will reduce unnecessary CMA and achieve more accurate prenatal genetic testing than G-banding.

The Challenge of Environmental Samples for PCR Detection of Phytopathogenic Bacteria: A Case Study of Citrus Huanglongbing Disease

Huanglongbing (HLB) is the most devastating citrus disease and is associated with three bacterial species of the genus ‘Candidatus Liberibacter’ transmitted by insect vectors. The early detection of HLB is based on PCR methods, and it is one of the cornerstones for preventing incursion into disease-free countries. However, the detection of phytopathogenic bacteria with PCR-based methods is problematic in surveys that include a variety of samples of different origins. Here, we first report the proportion of amplifications obtained by two standardized real-time PCR methods for the diagnosis of HLB in various environmental samples that include plants, psyllid vectors, and parasitic wasps of the psyllids. The results of 4915 samples showed that 9.3% of them were amplified by the first rapid screening test and only 0.3% by the more specific tests. Most of the amplifications were associated with parasitic wasps. We designed the primers external to the target regions of both real-time PCR protocols to determine if amplifications belonged to one of three ‘Ca. Liberibacter’ species associated with HLB. The bioinformatic analysis of the sequences obtained with these primers revealed that all these amplifications came from the presence of other prokaryotic organisms in the samples. The primers developed in this study overcome the problem of undesired amplification in environmental samples. Thus, they could be used in future survey protocols to prevent the eradication of negative trees and the generation of unjustified alarms.