Journal of Ardabil University of Medical Sciences, 2019
Background & objectives: In recent years, Acinetobacter baumannii has been shown to be associated... more Background & objectives: In recent years, Acinetobacter baumannii has been shown to be associated with several nosocomial infections, including pneumonia, bacteraemia, urinary tract infections, wound infection and meningitis. This organism can survive in the hospital environment and rapidly develops resistance to many antibiotics. The molecular genotyping can increase our knowledge about the spread of A. baumannii strains from one hospital to another and their drug resistance. Therefore, this study aimed to determine the prevalence of antibiotic resistance profile as well as phylogenetic relationships of A. baumannii strains in Shahrekord teaching hospitals. Methods: In this study, antibacterial susceptibility patterns of A. baumannii strains isolated from different clinical specimens (urine, blood, sputum) to amikacin, ampicillin/sulbactam, aztreonam, cefepime, ceftazidime, ciprofloxacin, gentamycin, imipenem, meropenem, norfloxacin, ofloxacin, piperacillin/tazobactam, tobramycin were tested using disk diffusion (Kirby-Bauer) method. Finally, genotyping of A. baumannii strains was performed using REP-PCR method. Results: During this study, 50 samples of patients were identified as A. baumannii (71%), and their drug resistance rates were assessed. All A. baumannii strains were resistant to ceftazidime and cefepime and also a high rate of resistance to aztreonam, norfloxacin, ciprofloxacin, amikacin, imipenem, gentamycin, and ampicillin-sulbactam were observed. On the other hand, our results demonstrated nine genotype groups among A. baumannii strains based on REP-PCR method. Conclusion: Due to the high prevalence of antibiotic resistance among isolated A. baumannii strains, similarities between different genotypes and the dispersion of these genotypes in different parts of Shahrekord hospitals, the implementation of infection control programs in different parts of the hospital is necessary.
The Mycobacterium Ag85 complex is the major secretory protein of M. tuberculosis. It is a potenti... more The Mycobacterium Ag85 complex is the major secretory protein of M. tuberculosis. It is a potential marker for early diagnosis of tuberculosis (TB). The authors have identified specific aptamers for Ag85A (FbpA) via protein SELEX using magnetic beads. After twelve rounds of selection, two aptamers (Apt8 and Apt22) were chosen from different groups, and their binding constants were determined by flow cytometry. Apt22 (labeled with Atto 647N) binds to FbpA with high affinity (K d = 63 nM) and specificity. A rapid, sensitive, and low-cost fluorescent assay was designed based on the use of Apt22 and graphene oxide, with a limit of detection of 1.5 nM and an analytical range from 5 to 200 nM of FbpA.
The authors describe a colorimetric method for the sensitive and selective detection of Pb(II). I... more The authors describe a colorimetric method for the sensitive and selective detection of Pb(II). It is based on the use exonuclease I (Exo I), a Pb(II)-binding aptamer bound to gold nanoparticles (AuNPs), and a DNA strand that complementary to the aptamer. In the absence of Pb(II), the dsDNA on the AuNPs prevents aggregation of the AuNPs in the presence of NaCl. In the presence of Pb(II), however, the aptamer binds Pb(II) and complementary strand is released and digested by Exo I. As a result, the solution of AuNPs undergoes a color change from red to purple if salt is added to the sample. The assay is selective for Pb(II) and has a limit of detection as low as 2.4 nM. It was successfully applied to the determination of Pb(II) in spiked tap water.
Salmonella is one of the most frequent causes of food borne infectious disease. Among nearly 2500... more Salmonella is one of the most frequent causes of food borne infectious disease. Among nearly 2500 documented serotypes are reported, Salmonella typhimurium is the number one serotype associated with salmonellosis worldwide. Many different methods have been developed for the detection and quantification of S. typhimurium. Most of these assays are usually expensive, time consuming and require difficult sample preparation steps. Therefore, it is necessary to develop rapid, robust, cost-effective and sensitive alternative detection methods. In the last years, aptasensors, used for detection of S. typhimurium in different samples. In this review, recent advances and applications of aptasensors for the detection and quantification of S. typhimurium in details have been summarized.
Programmed death-ligand 1 (PD-L1) is overexpressed in a variety of cancer cells. Using protein SE... more Programmed death-ligand 1 (PD-L1) is overexpressed in a variety of cancer cells. Using protein SELEX, aptamers against PD-L1 were identified. After 10 rounds of selection, 2 aptamers (Apt5 and Apt33) were chosen. Due to the higher specificity and affinity of Apt5 for PD-L1, this aptamer was characterized in detail. The ATTO 647 N-labeled aptamer readily internalizes into PD-L1 positive A2780 cells where it can detect human ovarian carcinoma. Hence, fluorometry provides a rapid and sensitive quantitative tool for the detection of these cancer cells with limit of detection (LOD) as low as 10 cells.mL −1 and linear response in the range between 50 and 1000 cells.mL −1. In our perception, the Apt 5 aptamer holds great promise for use in cancer diagnosis and therapy.
Staphylococcus aureus (S. aureus) is most common causes of hospital-acquired infections and food-... more Staphylococcus aureus (S. aureus) is most common causes of hospital-acquired infections and food-associated disease, also staphylococcal food poisoning (SFP) are known as the one of the most important foodborne illnesses worldwide. Many different methods have been developed for the detection and quantification of S. aureus and Staphylococcus aureus enterotoxins (SEs). But most of these methods are usually time-consuming and need complicated sample preparation steps. Therefore, it is of great interest to develop a rapid, simple, and sensitive detection method. In the last years, aptamers, are used as a new biosensor platform for detection of S. aureus in different samples. In this review, recent advances and applications of optical and electrochemical aptamer-based biosensors for the detection and quantitative of S. aureus and enterotoxins in details have been discussed.
Introduction: Acinetobacters especially Acinetobacter baumannii causing nosocomial infections in ... more Introduction: Acinetobacters especially Acinetobacter baumannii causing nosocomial infections in hospitals intensive care units and can cause a variety of hospital infections such as bacteremia, meningitis, pneumonia and urinary tract infections. There are several molecular techniques for microbial genotyping, among them Pulsed-Field Gel Electrophoreses is introduced as the gold standard for sub typing of bacteria. The aim of this study was investigating the molecular typing of A. baumannii strains with PFGE as well as the relationship between common types available and their antibiotic resistance. Methods: In this descriptive-analysis study, 50 Acinetobacter baumannii were confirmed with cultivation methods and biochemical tests. Then, bacteria were detected using PFGE typing and the results were compared with the results of antibiotic resistance. Results: The results showed that all isolates had multiple resistance. The highest sensitivity was observed for tobramycin (52%), gentamicin (36%) and moropenem (32%).The results of this study showed that A. baumannii strains isolated from Shahrekord hospitals were in seven different genetic patterns that two of these patterns were sporadic and the genetic patterns were different in each hospital. Conclusion: Although variations among strains of Acinetobacter baumannii were observed by using PFGE in Shahrekord, but no epidemic strain was detected among them. In terms of resistance to commonly used antibiotics were also different patterns.
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Papers by Najmeh Ansari