Search results for "techniques"
showing 10 items of 4426 documents
Reliable Detection and Smart Deletion of Malassez Counting Chamber Grid in Microscopic White Light Images for Microbiological Applications
2015
AbstractIn biology, hemocytometers such as Malassez slides are widely used and are effective tools for counting cells manually. In a previous work, a robust algorithm was developed for grid extraction in Malassez slide images. This algorithm was evaluated on a set of 135 images and grids were accurately detected in most cases, but there remained failures for the most difficult images. In this work, we present an optimization of this algorithm that allows for 100% grid detection and a 25% improvement in grid positioning accuracy. These improvements make the algorithm fully reliable for grid detection. This optimization also allows complete erasing of the grid without altering the cells, whic…
Aflatoxins and ochratoxin A in stored barley grain in Spain and impact of PCR-based strategies to assess the occurrence of aflatoxigenic and ochratox…
2011
Contamination of barley by moulds and mycotoxins results in quality and nutritional losses and represents a significant hazard to the food chain. The presence of aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1) and G2 (AFG2) and ochratoxin A (OTA) in stored barley in Spain has been studied. Species-specific PCR assays were used for detection of Aspergillus flavus, A. parasiticus, A. ochraceus, A. steynii, A. westerdijkiae, A. carbonarius and A. niger aggregate in mycotoxin-positive barley samples at different incubation times (0, 1 and 2 days). Classical enumeration techniques (CFU/g) in different culture media for evaluation of Aspergillus in sections Flavi, Circumdati and Nigri were also used. O…
Rapid isolation of single microbial cells from mixed natural and laboratory populations with the aid of a micromanipulator.
1999
In order to facilitate the isolation of pure cultures from natural habitats we have developed a method for the isolation of single microbial cell clones from a mixed population, e.g. the flora of the termite gut, with the aid of a modern micromanipulator. The separated single prokaryotic or eukaryotic cells were grown after transfer in culture media or they were used for single cell PCR. The micromanipulator was also applied for the removal of nuclei from protozoa, of which the SSU rDNA was directly amplified.
Approaches to study yeast cell aging and death
2014
For millennia, yeast has been exploited to obtain fermentation products, such as foods and beverages. For c. 50 years, yeast has been an established model organism for basic and applied research, and more specifically, for c. 15 years, this unicellular organism has been applied to dissect molecular mechanisms of cell aging and programmed cell death. In this review, we present an overview of approaches to study cell aging and death in yeast, including lifespan assessments, calorie restriction, cell viability, survival, and death markers.
The role of public biological resource centers in providing a basic infrastructure for microbial research
2009
Public collections of microorganisms have been established since the late 19th century, and currently 573 service collections are registered at the World Data Center for Microorganisms (www.wdcm.org). All together, they hold more than 1.5 million microorganisms. By implementing guidelines compiled by the Organisation for Economic Co-operation and Development (OECD), many public service collections evolve into professional ex situ repositories of biodiversity and distribution nodes for known, validated and precisely identified microbial resources and associated information to legitimate end-users. These Biological Resource Centers (BRCs) may be the preferred mechanism for the appropriate exp…
Fluconazole susceptibility of Italian Candida dabliniensis clinical isolates determined by reference and simplified tests
2001
Candida dubliniensis ia an opportunistic pathogen mainly associated with oral candidiasis in human immunodeficiency virus (HIV)-infected individuals. We recently recovered the first Italian clinical isolates of C. dubliniensis from the oral cavities of seven HIV-seropositive subjects. The in vitro susceptibility to fluconazole (FLCZ) of these isolates was determined according to the National Committee for Clinical Laboratory Standards (NCCLS) M27-A broth microdilution method for yeasts. All seven isolates of C. dubliniensis were susceptible to FLCZ (MICs < or =0.5 microg/ml). Results of this reference method were compared to those obtained with simplified tests, more adapted to routine eval…
Phenotypic study by numerical taxonomy of strains belonging to the genus Aeromonas.
2002
Aims: This study was undertaken to cluster and identify a large collection of Aeromonas strains. Methods and Results: Numerical taxonomy was used to analyse phenotypic data obtained on 54 new isolates taken from water, fish, snails, sputum and 99 type and reference strains. Each strain was tested for 121 characters but only the data for 71 were analysed using the `SSM' and `SJ' coefficients, and the UPGMA clustering algorithm. At SJ values of ≥ 81·6% the strains clustered into 22 phenons which were identified as Aer. jandaei, Aer. hydrophila, Aer. encheleia, Aer. veronii biogroup veronii, Aer. trota, Aer. caviae, Aer. eucrenophila, Aer. ichthiosmia, Aer. sobria, Aer. allosaccharophila, Ae…
Use of ATP bioluminescence for assessing the cleanliness of hospital surfaces: A review of the published literature (1990–2012)
2014
Summary: Hospital cleanliness tends to be considered by patients and the public as an important indicator of the general quality of healthcare. Tests for detecting the presence of adenosine triphosphate (ATP) as a proxy of microbial contamination are increasing in popularity, and several studies have been conducted on this topic in the last few decades. The aim of the present study was to review the published literature on this topic and summarize and discuss the available results. The review focused on relevant English-language articles that were identified through searches of two databases [PubMed and Scopus (1990–2012)] by using the keywords “ATP”, “bioluminescence”, “hospital”, and “sur…
One-step polymerase chain reaction-based typing of Helicobacter pylori vacA gene: association with gastric histopathology.
2000
Heterogeneity of the Helicobacter pylori vacA gene may be associated with bacterial virulence and presentation. In this study, the possible correlation between vacA genotypes and gastric histopathology was investigated. Using a modified one-step polymerase chain reaction (PCR)-based method, 122 of 131 H. pylori isolates obtained from 63 of 67 patients from Germany were classified into distinct vacA genotypes according to their signal sequence (s1 or s2) and their midregion alleles (m1 or m2). A possible subtype of m1, now alluded to as m3, was identified in one-third of the isolates. Signal sequence s1 was significantly associated with higher H. pylori density but not with gastric inflammat…
Diagnóstico microbiológico de las infecciones gastrointestinales
2009
Resumen Las infecciones agudas del tracto gastrointestinal figuran entre las enfermedades infecciosas más frecuentes. En esta revisión se examinan diversas técnicas para diagnosticar las gastroenteritis que ocasionan bacterias, virus y parásitos. El coprocultivo es el método de elección para el diagnóstico de las infecciones bacterianas intestinales, aunque las infecciones por Clostridium difficile se pueden diagnosticar mediante la detección de las toxinas A y B en las heces y las infecciones por Escherichia coli diarreagénicas se pueden diagnosticar mediante la detección por reacción en cadena de la polimerasa de factores de virulencia específicos de los diversos enteropatotipos. Las técn…