Ultrasensitive and easily reproducible biosensor based on novel doped MoS2 nanowires field-effect transistor in label-free approach for detection of hepatitis B virus in blood serum

An ultrasensitive field-effect transistor (FET) for hepatitis B virus deoxyribonucleic acid (HBV DNA) detection in label free approach and easily reproducible setup was reported. The fabricated FET biosensor was materialized by ZnO doped MoS2 nanowires (NWs). This report introduced a novel structure of the MoS2 in bio-sensing approach. Because of unique electrical and structural properties of MoS2, HBV biosensor could demonstrate the high sensitivity and showed the detection limit of 1 fM. The MoS2 NWs fabrication was materialized through ZnO based vapor-liquid-solid (VLS) technique. The fabricated device could measure the DNA targets in a linear concentration range from 0.5 pM to 50 μM. The dynamic response time of FET biosensor was 25 s. The functionality of the NWs biosensor for label-free measurements could be repeated for several times without any significant malfunction and biosensor could retain 96 of its initial response after eight weeks maintenance. The HBV biosensor showed high selectivity by discrimination the complementary DNA oligonucleotides from non-complementary and the mismatch (1, 2 and 3 bases) oligonucleotides. The materialized platform was desirably reproduced for HBV concentrations in human serum. The specificity of the biosensor was evaluated against several different types of DNAs and the fabricated device showed the outstanding performance. In order to optimize the device functionality, the biosensor was checked for two different human samples and device could distinguish the samples from each other in the same manner. © 2021 Elsevier B.V

Reduction in prevalence of hepatitis B surface antigen among intravenous drug users in Tehran drop-in-centers

Background: Despite the availability of an effective vaccine for more than three decades, HBV (hepatitis B virus) continues to infect many people worldwide, particularly in developing countries of Asia. In older people at higher risk of infection, high prevalence of HBV may exist, particularly among intravenous drug users (IDUs). This group is among groups at higher risk of infection as they share needles for drug injection. Objectives: The current study aimed to determine the prevalence of HBsAg (hepatitis B antigen) among intravenous drug users in drop-in-centers (DICs) of Tehran in 2013. Patients and Methods: This cross sectional study included 129 intravenous drug users recruited from DICs in Tehran in 2013. Socio-demographic characteristics and associated risk factors were recorded during the sample collection. Their serum samples were tested for the presence of HBsAg by enzyme-linked immunosorbent assay (ELISA). Results: HBsAg was detected in 4 of 129 subjects, giving an overall prevalence of 3.1. No significant correlation was observed between HBsAg positivity and socio-demographic and associated risk factors. Conclusions: Undoubtedly, IDUs are one of the most high-risk groups exposed to infection; so the priority of preventive and educational programs would be beneficial for this high-risk group. Screening IDUs at the national level and statistical analysis for HBV in the larger sample size is recommended. © 2013, Shahid Beheshti University of Medical Sciencces

Urinary viral shedding of COVID-19 and its clinical associations: A systematic review and meta-analysis of observational studies

Objectives: To review the current literature on the presence of COVID-19 virus in the urine of infected patients and to explore the clinical features that can predict the presence of COVID-19 in urine.Materials and Methods: A systematic review of published literature between 30th December 2019 and 21st June 2020 was conducted on Pubmed, Google Scholar, Ovid, Scopus, and ISI web of science. Studies investigating urinary viral shedding of COVID-19 in infected patients were included. Two reviewers selected relative studies and performed quality assessment of individual studies. Meta-analysis was performed on the pooled case reports and cohort with a sample size of >= 9.Results: Thirty-nine studies were finally included in the systematic review; 12 case reports, 26 case series, and one cohort study. Urinary samples from 533 patients were investigated. Fourteen studies reported the presence of COVID-19 in the urinary samples from 24 patients. The crude overall rate of COVID-19 detection in urinary samples was 4.5%. Considering case series and cohorts with a sample size of >= 9, the estimated viral shedding frequency was 1.18 % (CI 95%: 0.14 - 2.87) in the meta-analysis. Urinary viral load in most reports were lower than rectal or oropharyngeal samples. In adult patients, urinary shedding of COVID-19 was commonly detected in patients with moderate to severe disease (16 adult patients with moderate or severe disease versus two adult patients with mild disease). In children, urinary viral shedding of COVID-19 was reported in 4 children who all suffered from mild disease. Urinary viral shedding of COVID-19 was detected from day 1 to day 52 after disease onset. The pathogenicity of virus isolated from urine has been demonstrated in cell culture media in one study while another study failed to reveal replication of isolated viral RNA in cell cultures. Urinary symptoms were not attributed to urinary viral shedding.Conclusion: While COVID-19 is rarely detected in urine of infected individuals, infection transmission through urine still remains possible. In adult patients, infected urine is more likely in the presence of moderate or severe disease. Therefore, caution should be exerted when dealing with COVID-19 infected patients during medical interventions like endoscopy and urethral catheterization especially in symptomatic adult patients while in children caution should be exerted regardless of symptoms

Prevalence of β-lactamase-encoding genes and molecular typing of Acinetobacter baumannii isolates carrying carbapenemase OXA-24 in children

Background: β-Lactam antibiotics have been broadly used for the treatment of Acinetobacter baumannii infections, resulting in development of β-lactam inactivating β-lactamases. Here, we described antibiotic resistance rate, prevalence of β-lactamase-encoding genes, and clonal relationships of A. baumannii strains isolated from children referred to Children�s Medical Center in Tehran, Iran, during 2019�2020. Methods: A total of 60 non-replicate A. baumannii isolates were recovered from clinical specimens of pediatric patients. Antibiotic susceptibility testing was done by the disc diffusion method. Colistin susceptibility of isolates was performed by the broth microdilution method. β-lactamase-encoding genes were characterized by PCR. The presence of ISAba1 element upstream of the several oxacillinase genes was also checked. Genetic relatedness of isolates was determined by using random amplification of polymorphic DNA (RAPD) typing. Results: The antimicrobial susceptibility tests showed that 83.3 of A. baumannii isolates were MDR, and 40 XDR. Both MDR and XDR A. baumannii isolates were susceptible to colistin. The frequency of blaOXA-51-like, blaOXA-23-like, blaTEM, blaOXA-24-like, blaPER, blaSHV, blaCTX-M, blaOXA-58-like, and blaIMP was 100, 93.33, 60, 36.67, 28.33, 8.33, 5, 3.33, and 1.67, respectively. Coexistence of ISAba1/blaOXA-23-like and ISAba1/blaOXA-51-like was observed in 65 and 85 of isolates, respectively. RAPD analysis revealed 4 common types and 2 single types of A. baumannii isolates. Conclusions: The multiple clones harboring blaOXA-23-like, ISAba1-blaOXA-51-like, and ISAba1-blaOXA-23-like were responsible for the spread of A. baumannii isolates in our clinical wards. Dissemination of the well-established clones is worrisome and would become therapeutic challenges due to the possible transferring genetic elements associated with resistance. © 2021, The Author(s)