High Resolution Melting Curve Analysis Method for Detecting of Carbapenemases Producing Pseudomonas aeruginosa

Background: The, carbapenems have the broadest spectrum of activity among all β-lactam antibiotics, and also, carbapenem resistant P. aeruginosa may be susceptible to other β-lactam antibiotics. There are several methods for detecting to Carbapenems resistance of Pseudomonas aeruginosa (P. aeruginosa) strains. Aim and Objectives: In the current study, High Resolution Melt curve analysis (HRM) is evaluated to detect carbapenem resistant P. aeruginosa. Material and Methods: This experimental study was done on standard isolates of P. aeruginosa and carbapenemase producing strains in Hamadan. 16srRNA of P. aeruginosa and KPC gene of carbapenemase producing strains were applied to detect by HRM. Also, sensitivity and specificity of primers have been evaluated and carbapenemase producing P. aeruginosa were determined based on melt curve temperature range. Finally, melt curve profiles were assessed and analyzed using StepOne Software v2.3 and HRM Software v3.0.1 software. Results: According to dilutions ratios of 108 to 10-4 it was found that the designed primers have the ability to identify 10-3 CFU/ml of bacteria for P. aeruginosa and 10-1 CFU/ml for carbapenemase producing strains. The melt curve was also shown at 80.9±0/5 °C for all DNA dilutions of P. aeruginosa and 82.4±0/5 °C for all DNA dilutions of Carbapenemases strains. Conclusion: The sensitivity and specificity of HRM method indicated that it is highly reliable, rapid and cost-effective to detect carbapenemase producing P. aeruginosa

Miniaturizing electromagnetic invisibility cloaks using double near zero slabs

A novel method to miniaturize electromagnetic invisibility cloaks is introduced using Double Near Zero (DNZ) slabs, in which both the permittivity and permeability are close to zero. Based on the proposed technique, the phase pattern tailoring property of DNZ materials is utilized to miniaturize electromagnetic devices. The concept is applied to both types of internal and external cloaks, where their sizes are reduced by 50% by changing their structure from a cylindrical shape to a half cylinder shell. The half-sized internal and half-sized external cloaks can still conceal any object with any shape and material, inside and outside the cloaks, respectively. To illustrate that, the results show that an arbitrary shape of dielectric with arbitrary high value of relative permittivity of 20 is concealed by the half-sized internal cloak. For the half-sized external cloak, the presented results show that it can conceal an external half ring dielectric with high relative permittivity of 20 using anti-object in the structure of the cloak. For the analysis, the transverse electric (TE) Z-polarization is used. For the transverse magnetic (TM) Z-polarization, the duality principal can be applied

Ultra wideband Epsilon-Near-Zero metamaterial

An ultra-wideband Epsilon-Near-Zero (ENZ) metamaterial, which has a close to zero permittivity, is introduced. The proposed structure functions as ENZ within the frequency range of 10.5-20 GHz. The loss is almost zero within this frequency range. It also acts as a negative index material (NIM), which has a negative refractive index, within 7-8.5 GHz with zero loss. The structure is composed of a Split Ring Resonator (SRR) and a rod. Unlike our structure that is an ENZ in a very wide frequency range, the conventional SRR-rod structure has wideband Mu-Near-Zero (MNZ) property within the 11-20 GHz and it's ENZ just at 12.5 GHz. Therefore, our wideband ENZ structure could be complementary for that conventional wideband MNZ structure. We obtain the S-parameters of the structure from HFSS scattering simulation results. Then, an electromagnetic parameters retrieval method is used to extract the effective constitutive parameters of the structure from the S-parameters to show that the structure is an ultra-wideband ENZ material

Half-sized cylindrical invisibility cloaks using double near zero slabs with realistic material size and properties

A method is introduced to miniaturize invisibility cloaks by 50% using wave tailoring and finite/ non-zero wave impedance of double near zero (DNZ) slabs. Unlike previous works, which use thick dielectric matching layers to miniaturize internal cloaks, the proposed technique is applied to both internal and external cylindrical cloaks using a thin and short DNZ slab to change cloaks' shapes to half-cylinder shells. Moreover, sets of structures are introduced for the half sized cloaks to enable using feasible-to-fabricate structures with the help of a rigorous theoretical analysis, which is validated via full-wave simulations. All of the presented results show that the proposed half cloaks can function perfectly well. The sensitivity of half-sized cloaks to the length and material properties of the DNZ slab is investigated to find the shortest length and the highest values of the permittivity and permeability for the slab to have small yet realizable structures. The analysis shows that slabs with length as small as the diameter of the cloaks and constitutive parameters (permittivity and permeability) as high as epsilon(slab)= mu(slab) = 0.1-0.1 i and epsilon(slab)= mu(slab) = 0.05-0.04i for half-sized external cloaks and half-sized internal cloaks, respectively, can still considerably reduce the scattered fields. The effect of the loss and incident angle of the field on the performance of the miniaturized cloaks are also analyzed. (C) 2017 Optical Society of Americ

Concealment with near-zero materials and their sensitivity to non-zero material parameters

Slabs with negative material parameters are used to conceal objects with any shape and material. To conceal an object, it is shown that the size of the object should be large compared to the wavelength, whereas subwavelength objects can be detected. Since a TE_z polarized wave is assumed in this work, both mu-near-zero (MNZ) and epsilon-and-mu-near-zero (EMNZ) slabs are used. For the TM_z waves, the epsilon-near-zero (ENZ) slab should be used. We also investigated how the material parameters should be close to zero so that the slab can still considerably reduce the perturbed waves. We found that for the constitutive parameters of the slab, any value within (-0.01, + 0.01) can considerably reduce the perturbed waves. Finally, we proposed a structure to have that effective material range. Within 8.4-8.45 GHz frequency range, the relative permeability of the structure is in (-0.01,0.01) range, hence it can conceal TE_z waves. Within 10.3-10.33 GHz, the relative permittivity is in the range (-0.01, + 0.01) for the structure therefore it can function as an ENZ slab that can conceal TM_z waves

A New Approach to Identify and Determine the Relationship between MecA Gene Mutations Based on HRM with Clinical Species in Staphylococcus aureus Isolates

Background and Aim: Gene mutation in Staphylococcus aureus is one of the most important causes of antibiotic-resistant strains. The High Resolution Melting Curve (HRM) analysis of DNA method can detect these mutations very high quality. The purpose of this study was to evaluate the role of clinical sample type in the occurrence of nucleotide mutations in the mecA gene of S. aureus by HRM method. Materials and Methods: In this experimental study, 43 clinical isolates of S. aureus were used. To detect possible mutations, isolates with mecA gene were replicated and sequenced. Then, analysis was performed using StepOne Software v2.3 and HRM v3.0.1 software. Sequencing results were used as gold-standard. Ethical Considerations: This study with research ethics code IR.UMSHA.REC.1396.637 has been approved by research ethics committee at Hamadan University of Medical Sciences. Findings: Of 43 clinical isolates of S. aureus, 11 isolates (25.58%) had mecA gene and 32 isolates (47.41%) lacked the mecA gene. According to different clinical samples, 3 isolates (27.27%) were resistant to methicillin from blood samples, 2 isolates (18.18%) from urine specimens, 2 isolates (18.18%) from wound samples, 2 isolates (18.18%) of the catheter samples, 1 isolate (9.09%) of the abscess and 1 isolate (9.09%) were separated from the nose swab. In the meanwhile, isolates from the wound and urine had the highest mutation in the adenine amino acid as A → T, A → G, A → C, and A → X. Isolates taken from blood have mutations in Guanine amino acid as G → A. Conclusion: There was a significant relationship between type of mutation and type of clinical specimen in methicillin-resistant Staphylococcus aureus isolates

Association between the accessory gene regulator (agr) locus and the presence of superantigen genes in clinical isolates of methicillin-resistant Staphylococcus aureus

Abstract Objective Methicillin-resistant Staphylococcus aureus cause to a variety of hard to cure infections. MRSA isolates also, produce an arsenal of virulence factors contribute to severe infections. The aim of this study was to find out the relationship between agr locus and presence of S. aureus superantigens (SAgs). Results Clinical isolates in two groups from two different states of Iran were collected. Antibiotic resistance patterns, agr typing, and virulence factor genes prevalence were identified and relationship between them was analyzed using SPSS software version16. Most of the samples were collected from wound 39 isolates in Group 1 and 61 isolates in Group 2. Frequency of MRSA strains was 38.1% in Group 1 and 52.1% in Group 2. Also, the most common resistance among both groups was to penicillin. agr positive isolates were detected in 132 isolates of Group 1 and 104 isolates of Group 2. In Conclusion, a significant relationship between the SAgs frequency and agr locus in both groups has been indicated. The production of superantigens in S. aureus plays an important role in the classification of agr locus, and this locus can affect differently in methicillin-resistant strains

Uniqueness Theorem for Lossy Anisotropic Inhomogeneous Structures with Diagonal Material Tensors

The method of transformation optics (TO) was introduced some time ago to create anisotropic inhomogeneous structures like hyper-lenses and invisibility cloaks which have diagonal material tensors. In this paper, we prove that the uniqueness theorem is valid for anisotropic inhomogeneous structures with diagonal constitutive tensors if all the tensor elements of all regions are lossy. The uniqueness theorem says for a particular sets of boundary conditions the solution to Maxwell equations are unique. The uniqueness theorem is proven for three cases: Single medium, media composed of two materials of our interest, and media composed of two materials which the one with diagonal material tensors is surrounded by the other one which could be an isotropic material. The latter case, is the one that can be considered for the TO-based materials like invisibility cloaks or hyper-lenses that have diagonal anisotropic inhomogeneous constitutive parameters. Because, the cloaks or hyper-lenses are usually surrounded by a free space and also the sources are usually outside of them

Determination of Antimicrobial Resistance Pattern in Methicillin-Resistant Staphylococcus saprophyticus and Staphylococcus epidermidis and Detection of Resistance Genes to Clindamycin and Erythromycin

Background and Aims: Clindamycin is one of the selective drugs for treatment of staphylococcal infections. Molecular methods can complete phenotypic methods to diagnosis induction resistance to clindamycin. The aim of this study was to identify the genes responsible for the resistance to clindamycin and erythromycin, and determine their antibiotic resistance pattern. Materials and Methods: 100 isolates of Staphylococcus epidermidis and Staphylococcus saprophyticus were isolated from 466 different clinical specimens using biochemical tests. Using the disc diffusion method, Antibiogram susceptibility test was conducted to determinate lincosamides and tetracycline resistance pattern. Then  ermA, ermB, ermC and msrA genes were identified and investigated by PCR method. Results: Out of 100 strains of coagulase-negative staphylococci isolated from clinical specimens, 5 isolates were identified as S. saprophyticus (5%) and 55 isolates of S. epidermidis (55%), respectively. Out of the 5 isolated of S. saprophyticus, 2 (40%) isolates were resistant to methicillin and one (20%) isolate had D phenotype. In addition, 1 isolate had ermA gene and 1 isolate had ermB. Out of the 55 isolates of S. epidermidis, 25 (45.45%) isolates were resistant to methicillin, of which nine (36%) isolates had D phenotype. Also, 4 (16%) isolates had ermA gene, 3 (12%) isolates had ermB, 6 (24%) isolates had ermC and 1 (4%) isolate was carrying the msrA.  Conclusions: The phenotypic pattern of resistance to macrolide- lincosamides groups does not have a high degree of accuracy in detecting methicillin-resistant MLSB strains

On the uniqueness of inverse electromagnetic problems for invisibility cloaks

Devices like invisibility cloaks are designed based on the method of transformation optics, which have anisotropic inhomogeneous structures. In this paper, we examine uniqueness of the inverse problem for such structures. We prove all these materials have the same surface field distribution on a surface enclosing the area of interest, while solutions to Maxwell's equations inside them are different. The uniqueness theory suggests that within the surface, the same medium should exactly be present. However, for anisotropic inhomogeneous media of our interest, this paper illustrates that this might not be true, despite the result of a previous study that shows uniqueness could be true for some anisotropic inhomogeneous structures. For the analysis, the transverse electric (TE) Z-polarization is used. The simulation results are obtained by a commercial Finite-Element based simulator