# Standard DiskRecently Published Documents

64
(FIVE YEARS 37)

## H-INDEX

9
(FIVE YEARS 4)

2021 ◽
Vol 2021 ◽
pp. 1-5
Author(s):
Ândrea Celestino de Souza ◽
Luciano Z. Goldani ◽
Eliane Würdig Roesch ◽
Larissa Lutz ◽
Patricia Orlandi Barth ◽
...
Keyword(s):

Determination of the susceptibility profile of isolates of Candida from blood culture bottles is extremely important for correctly guiding patient pharmacotherapy. The aim of this study was to compare the results of analysis of Candida isolated directly from blood culture bottles by the VITEK MS MALDI-TOF identification system and the fluconazole disk diffusion assay with those of standard identification methods. Testing directly from the bottle allowed results 24 to 48 hours quicker than the standard method. There was a categorical agreement of 51.64% (47 of 91 samples) between the results of analysis directly from the bottle and analysis by the standard method. Regarding species identification, there was 96.15% agreement for Candida parapsilosis (25 of 26 samples). Categorical agreement between the rapid and standard disk diffusion methods was 95%, and the agreement between the rapid disk diffusion method and the broth microdilution method was 97%. Only minor errors in the rapid method were observed: 3 (5%) in the standard disk diffusion method and 2 (3%) in the broth microdilution method. Our study concluded that the rapid disk diffusion method for fluconazole is a fast, easy, reproducible, and consistent method. Its timely implementation for testing antifungal agents in the clinical microbiology laboratory can help reduce profile release times, thus helping to determine the most appropriate antifungal treatment.

Author(s):
Marcella C. B. Malta ◽
Márcia R. T. C. Andrade ◽
Mirian de W. S. de Marsillac ◽
Luiz H. M. Prates ◽
Ricardo de S. Vieira
Keyword(s):

Objective: This study aimed to evaluate surface dye penetration of two conventional glass ionomer cements (GIC), one of them a high viscous ionomer. Methods: 20 standard disk samples measuring 2 mm thick and 4 mm in diameter were made for each conventional GIC. The high viscous ionomer was used as the control (Group 1). Samples were embedded in wax and submitted to pH cycling for 7 days simulating a high cariogenic challenge in a kiln (37ºC). All samples were brushed with an extra-soft bristles infant toothbrush to mimic oral hygiene after exposure to a demineralizing solution for 6 hours. The samples were immersed in a 1% methylene blue solution for 2 hours at the end of cycling. The Mann-Whitney Rank Sum Test was used to analyze the difference between the two GIC. Results: All samples disclosed a superficial dye penetration of 0.6 to 1.5 mm depth. There was no statistical d ifference b etween t he G IC t ested ( p = 0.883). Conclusion: Both GIC tested in this study exhibited superficial dye penetration to depths of at least until their superficial third.

Author(s):
Saeedeh HASANVAND ◽
Reyhaneh PIRJANI ◽
Davoud AFSHAR ◽
...
Keyword(s):

Background: Listeria monocytogenes show high mortality among pregnant women and newborns. This study aimed to detect L. monocytogenes in pregnant women with a history of abortion and assess the serotypes, antibiotic susceptibility patterns, and its resistance genes. Methods: Overall, 400 vaginal swabs were taken from pregnant women with a history of abortion in the past few years in a tertiary care hospital in Tehran, Iran, during 2015-2018. Antibiotics susceptibility to a panel of 10 antibiotics was determined using the standard disk diffusion method and the isolates serotyped by the agglutination method. The antimicrobial-resistant isolates were also screened for the presence of tetM, ermB and dfrD genes by PCR. Results: Overall, 22 L. monocytogenes isolates were identified. High rates of resistance were observed for trimethoprim (50%; n=11), sulphamethoxazole (50%; n=11), tetracycline (45.45%; n=10) and gentamicin (36.36%; n=8). From 22 L. monocytogenes isolates, 13 (59.10 %), 5 (22.73%), 3 (13.63%) and 1 (4.54%) belonged to serotypes 4b, 1/2a, 1/2b, and 3c, respectively. The genetic determinant tetM was detected in 70% of the tetracycline-resistant isolates. Out of 11 trimethoprim-resistant isolates, 27.27% isolates contained dfrD. Moreover, the ermB gene was found in 83.33% of the erythromycin-resistant isolates. Conclusion: Ampicillin and partly penicillin consider to be suitable antimicrobial agents to treat human listeriosis. Moreover, due to resistance against many antibiotics, it is necessary to continue monitoring and managing antimicrobial resistance.

Author(s):
Nicolas Scepi ◽
Mitchell C Begelman ◽
Jason Dexter
Keyword(s):

Abstract Dwarf novæ (DNe) and low mass X-ray binaries (LMXBs) are compact binaries showing variability on time scales from years to less than seconds. Here, we focus on explaining part of the rapid fluctuations in DNe, following the framework of recent studies on the monthly eruptions of DNe that use a hybrid disk composed of an outer standard disk and an inner magnetized disk. We show that the ionization instability, that is responsible for the monthly eruptions of DNe, is also able to operate in the inner magnetized disk. Given the low density and the fast accretion time scale of the inner magnetized disk, the ionization instability generates small, rapid heating and cooling fronts propagating back and forth in the inner disk. This leads to quasi-periodic oscillations (QPOs) with a period of the order of 1000 s. A strong prediction of our model is that these QPOs can only develop in quiescence or at the beginning/end of an outburst. We propose that these rapid fluctuations might explain a subclass of already observed QPOs in DNe as well as a, still to observe, subclass of QPOs in LMXBs. We also extrapolate to the possibility that the radiation pressure instability might be related to Type B QPOs in LMXBs.

2020 ◽
Vol 8 (4) ◽
pp. 163-170
Author(s):
Masoumeh Kiani ◽
◽
Abazar Pournajaf ◽
Thelma Zareh ◽
Mohsen Karami ◽
...
Keyword(s):

Background: The increasing resistance of human microbial pathogens to the available antibacterial compounds is a significant threat, resulting in the search for new antibiotic resources such as plants and probiotics. Therefore, this study aimed to evaluate the antibacterial effect of ethanolic and methanolic extracts of Urtica dioica, Mentha longifolia, and bacteriocin purified from a probiotic bacteria using the standard disk diffusion method against some pathogenic strains. Materials and methods: Ethanolic/methanolic extract of U. dioica, M. longifolia, and bacteriocin from probiotic bacteria were prepared by the standard methods. The effect of different concentrations of the extracts on some antibiotic-resistant bacteria was evaluated using the standard disk diffusion method by measuring the diameter of the growth inhibition zone. Results: The disk diffusion test showed that the bacteriocin Lactobacillus casei had more growth inhibitory effects on the tested bacterial strains than the methanolic and ethanolic extracts of U. dioica and M. longifolia. Bacteriocin extract of L. casei exhibited significant antibacterial activity at the concentrations of 12 and 18 mg/mL (P≤0.05) against antibiotic-resistant bacteria, while a 12 mm zone of inhibition was observed in the concentration of 1.5 mg/mL against Salmonella enterica serovar Typhimurium (S. Typhimurium). Conclusion: According to the agar well diffusion method results, the bacteriocin producing L. casei has an extensive range of antibacterial spectrum against resistant bacteria. It can be used as an alternative to antimicrobia agents for the treatment of infections caused by resistant bacteria. It is suggested that in future research, the cytotoxicity of the extracts be evaluated in vitro/in vivo studies.

2020 ◽
Vol 2020 ◽
pp. 1-6
Author(s):
Amirhossein Heidari ◽
Ali Mehri ◽
Matin Shirazinia ◽
Fereshte Sheybani ◽
...
Keyword(s):

Background. Antimicrobial resistance among community-acquired uropathogens is an emerging concern over the past decades that warrants a continuing reevaluation of the appropriateness of recommended empiric antimicrobial regimens for treatment of urinary tract infections (UTIs). Aims. To describe the microbial spectrum and resistance profile of community-acquired uropathogens and predictors of isolation of resistant strains. Methods. Between October 2017 and June 2019, individuals who visited the outpatient clinics for diagnosis of UTIs or screening of asymptomatic bacteriuria were included in the study if they were tested for urine culture in one of the three main medical diagnostic laboratories of Mashhad, Iran. The standard disk diffusion antimicrobial susceptibility testing was used, with the Clinical and Laboratory Standards Institute (CLSI) threshold cutoffs for susceptibility of isolated uropathogens. Results. Three hundred thirty cases were included with a median age of 47 years. Two hundred seventy-six (83.6%) were female. The most common isolated uropathogens were Escherichia coli in 201 (60.9%) cases and Klebsiella species in 46 (13.9%) cases. E. coli isolates showed the highest rates of susceptibility to nitrofurantoin (89.3%), cefixime (75%), and gentamicin (72.4%). Exposure to antibiotics in the past 3 months was a predictor of resistance to ciprofloxacin (OR: 2.8, 95% CI: 1.33–6.28), and older age was a predictor of resistance to TMP-SMX (OR: 2.1, 95% CI: 1.07–3.97) among E. coli isolates. Conclusion. E. coli and Klebsiella species accounted for about two-thirds of community-acquired uropathogens. In regard to the high susceptibility rates, nitrofurantoin was identified as the first-choice agent for empiric treatment of community-acquired cystitis, while cefixime and gentamicin might be the second-choice alternatives. Ciprofloxacin and TMP-SMX, on the other hand, cannot be considered appropriate agents for empiric therapy of community-acquired UTIs, particularly in those who had exposure to antibiotics in the past 3 months and the elderly.

2020 ◽
Vol 8 (9) ◽
pp. 1423
Author(s):
Elena Marusich ◽
Heakal Mohamed ◽
Yuriy Afanasev ◽
Sergey Leonov
Keyword(s):

The rapid increase of plant diseases caused by bacterial phytopathogens calls for an urgent search for new antibacterials. Antimicrobial compounds of natural origin stand up as frontiers in the attempts of the antibiotic overuse replacement. With this in mind, the Hermetia illucens (H. illucens) larvae have recently gained attention as a promising approach to fulfill this need. This study aimed to isolate the active constituents of H. illucens larvae fat and to estimate its antimicrobial capacity. We discovered the best composition of extracting solution retaining the pronounced antimicrobial activity of the extract. Using gas chromatography-mass spectrometry (GC-MS), we identified the unique natural array of fatty acids as the major constituents of the acidified water-methanol extract (AWME) as having new antimicrobial potency. In standard turbidimetric assay, the minimum inhibitory concentration (MIC) of the AWME was 0.78 mg/mL after 24 h of incubation for all five tested phytopathogenic bacteria strains: Pantoea agglomerans, Xanthomonas campestris, Pectobacterium carotovorum subsp. carotovorum, Pectobacterium atrosepticum, and Dickeya solani. The minimum bactericidal concentration (MBC) ranged from 0.78 to 1.56 mg/mL against all tested strains after 24 h of incubation. The inhibition zone size of AWME (INZ) at 50 mg/mL concentration was in the range 12.2 ± 0.56 to 19.0 ± 0.28 mm, while zone size for the positive control (penicillin-streptomycin) (5000 IU/mL–5000 µg/mL) was in the scale of 20.63 ± 0.53 to 24.0 ± 0.35 mm as revealed by standard disk diffusion assay. For the first time, our findings indicated the substantial antibacterial potential of AWME of H. illucens larvae fat against these actual phytopathogens, thus paving the way for further research to determine the mechanism of action in crop protection.

2020 ◽
Vol 72 (3) ◽
Author(s):
Shuntaro Ide ◽
Kiyoshi Hayashida ◽
Hirofumi Noda ◽
Hiroyuki Kurubi ◽
Tomokage Yoneyama ◽
...
Keyword(s):

Abstract We report the serendipitous discovery of a transient X-ray source, Suzaku J1305−4930, ∼3 kpc southwest of the nucleus of the Seyfert 2 galaxy NGC 4945. Among the seven Suzaku observations of NGC 4945 from 2005 to 2011, Suzaku J1305−4930 was detected four times in July and August in 2010. The X-ray spectra are better approximated with a multi-color disk model than a power-law model. At the first detection on 2010 July 4–5, its X-ray luminosity was $(8.9^{+0.2}_{-0.4}) \times 10^{38}\:$erg s−1 and the temperature at the inner-disk radius (kTin) was 1.12 ± 0.04 keV. At the last detection with Suzaku on 2010 August 4–5, the luminosity decreased to $(2.2^{+0.3}_{-0.8}) \times 10^{38}\:$erg s−1 and kTin was 0.62 ± 0.07 keV. The source was not detected on 2011 January 29, about six months after the first detection, with a luminosity upper limit of 2.4 × 1038 erg s−1. We also find an absorption feature which is similar to that reported in Cyg X-1. Assuming the standard disk, we suggest that Suzaku J1305−4930 consists of a black hole with a mass of ∼10 $M_\odot$. The relation between the disk luminosity and kTin is not reproduced with the standard model of a constant inner radius but is better approximated with a slim-disk model.

2020 ◽
Vol 10 (3) ◽
pp. 422 ◽
Author(s):
Enas M. Ali ◽
Basem M. Abdallah
Keyword(s):

The approaches used for the green biosynthesis of nanoparticles with clinical applications have been widely used in nanotechnology due to their potential to provide safe, eco-friendly, cost effective, high-stability, and high-loading-capacity nanoparticles. This study aimed to evaluate the anti-candidal activity of silver nanoparticles (AgNPs) biosynthesized using the aqueous leaf extract of Calotropis gigantea (CG) alone or in a combination with the plant extract of CG (AgNPs/CG). AgNPs were characterized using UV-Vis spectrophotometry, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The results of the standard disk diffusion method revealed that AgNPs alone displayed anti-candidal activity (11.33-mm inhibition zone), while AgNPs/CG displayed a strong synergistic anti-candidal activity (17.76-mm inhibition zone). Similarly, AgNPs/CG completely inhibited the growth of C. albicans after 4 h of incubation, as measured using the time-kill assay. In addition, AgNPs/CG inhibited the dimorphic transition of C. albicans and suppressed both the adhesion and the biofilm formation of C. albicans by 41% and 38%, respectively. The treatment of Candida. albicans with AgNPs/CG showed a significant inhibition of the production of several antioxidant enzymes. Interestingly, AgNPs/CG did not show any cytotoxicity in animal cells, including the MCF-7 cell line and primary mouse bone marrow-derived mesenchymal stem cells (mBMSCs), at the concentration used to completely inhibit the dimorphic transition of C. albicans. In conclusion, we identified AgNPs/CG as a promising natural-product-based nanoparticle that can potentially be used as an anti-candidal drug.

2020 ◽
Vol 13 (2) ◽
pp. 1-8
Author(s):
Aleruchi Chuku ◽
Godwin Attah Obande ◽
Sani Bashir Eya
Keyword(s):

Background and objective: Listeria sp. is a ubiquitous and frequently isolated foodborne pathogen. The prevalence of Listeria sp in raw beef and chevon sold in Lafia Nigeria, as well as their antibiotic susceptibility profile was evaluated. Methods: A total 104 samples comprising of 52 raw beef and 52 chevon were obtained from street vendors (hawkers), Shinge abattoir, Lafia old market and Lafia Modern Market. Isolation of Listeria sp. was performed on Listeria Selective Agar, following enrichment in supplemented Listeria Selective Broth. Identification of Listeria sp. was carried out by cultural and biochemical methods. Antimicrobial susceptibility of isolated L. monocytogenes was performed by standard disk diffusion method. Chi-square test was used to determine association between contamination levels at p=0.05. Results: Seven types of Listeria sp. were isolated. L. monocytogenes and L. ivanovii were the most frequently isolated contaminants in all meat types and from all sample sources. L. monocytogenes was isolated with a frequency of 64.4% (67/104) in the meat samples. Beef samples had the highest listerial contamination with a frequency of 58.2% (78/134) compared to chevon which had a listerial frequency of 41.8% (56/134). Resistance of L. monocytogenes to streptomycin and sparfloxacin was 58.2% and 55.2% respectively. Resistance to ampicillin (34.3%) and gentamicin (20.9%) was also observed. Resistances to multiple antimicrobials were detected in 11 L. monocytogenes isolates. Conclusion: The study demonstrated that the raw meat sold in Lafia was contaminated with several Listeria sp. L. monocytogenes showed high rate of resistance to several antimicrobial agents used for the treatment of listerial infection. Appropriate regulation and monitoring of livestock rearing and meat retailing practices are advocated to safeguard the health of consumers. Ibrahim Med. Coll. J. 2019; 13(2): 1-8