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Laboratory Standards (laboratory + standards)
Kinds of Laboratory Standards Selected AbstractsChemical, Mechanical, and Antibacterial Properties of Silver Nanocluster,Silica Composite Coatings Obtained by Sputtering,ADVANCED ENGINEERING MATERIALS, Issue 7 2010Monica Ferraris Abstract Silver nanocluster,silica matrix composite coatings have been deposited by radio frequency (RF) co-sputtering on silica substrates. Field emission scanning electron microscopy and X-ray diffraction spectra of the as deposited and heated samples (150,600,°C) revealed the presence of metal silver nanoclusters, their size depending on the heating treatment. The antibacterial activity of the as deposited and heated samples has been measured in accordance to National Committee for Clinical Laboratory Standards, and it has been demonstrated on samples heated up to 450,°C in contact mode and for samples heated at 600,°C in a liquid environment. Their antibacterial activity was still present after gamma ray and ethylene oxide gas (EtO) sterilization of the samples. Silver leaching tests on the as deposited and heated samples has been measured by graphite furnace atomic absorption spectrometer, revealing an amount ranging from 0.1 to 0.9,µg mm,2, over 28 days. Tape resistance (ASTM D3359-97) and scratch resistance tests have been done on each sample revealing a good adhesion of the coatings on silica. [source] Microbiology of Normal External Auditory Canal,THE LARYNGOSCOPE, Issue 11 2001David W. Stroman PhD Abstract Objectives To isolate and characterize bacteria and fungi from the healthy ear and to obtain susceptibility profiles on each bacterial isolate. Study Design Prospective. Methods Specimens were collected from the external canals and cerumen of healthy subjects. Species-level identification was obtained by combining phenotypic and genotypic data. End-point minimal inhibitory concentration testing was performed using National Committee for Clinical Laboratory Standards recommended methods. Results One hundred sixty-four subjects were cultured. Seventeen canal and 16 cerumen specimens showed no growth. One hundred forty-eight cerumen specimens yielded 314 organisms, including 23 fungi. One hundred forty-seven canal specimens yielded 310 organisms, including 7 fungi. Of 291 bacteria isolated from cerumen, 99% were Gram-positive. Of 302 bacteria isolated from the canal, 96% were Gram-positive. Staphylococci were 63% of both the cerumen bacteria and the canal bacteria. Coryneforms represented 22% of the bacteria in cerumen and 19% in the canal. Turicellaotitidis was the primary coryneform isolated from both the canal and the cerumen. Streptococci-like bacteria were 10% from the cerumen, 7% from the canal. In both cerumen and canal, Alloiococcusotitis was more than 95% of the streptococci-like bacteria. Fifteen gram-negative organisms were isolated from the canal and cerumen, including four Pseudomonas aeruginosa strains. The percentages of Staphylococcus epidermidis isolates that had high-level resistance (,8 ,g/mL) were as follows: to neomycin, 28% from cerumen and 11% from the canal; to oxacillin, 28% from cerumen and 25% from the canal; and to ofloxacin, 15% from cerumen and 19% from the canal. ConclusionsTurcella otitidis and A. otitidis were present with a much higher frequency than previously described, lending evidence that they be considered normal otic flora. Corynebacterium auris, previously reported only in children, was isolated from normal adults. [source] Calibration of fusidic acid disk diffusion susceptibility testing of Staphylococcus aureusAPMIS, Issue 10 2002BARBRO OLSSON-LILJEQUIST Single strain regression analysis, SRA, was used to calibrate disk diffusion fusidic acid susceptibility testing of Staphylococcus aureus in two laboratories using different standard methods but the same interpretative MIC limits. SRA equation constants were calculated using five different fusidic acid disk contents (1.5, 5, 15, 50, 150 ,g). These disks were tested on five separate occasions against quality control strain S. aureus ATCC 29213. The National Committee for Clinical Laboratory Standards (NCCLS) method was employed in Tartu, Estonia (TE) and the Swedish Reference Group for Antibiotics (SRGA) method in Sweden at the Karolinska Hospital (KS). SRA constants obtained were used for calculating zone breakpoints corresponding to MIC breakpoints recommended by the SRGA (S ,0.5 mg/L, R ,1 mg/L). Zone diameter histograms from KS, performed with a 50 ,g disk, and from TE, using a 10 ,g disk, showed a clustering of wild type strains around 41 mm and 30 mm, respectively, reflecting differences in methodology. Zone breakpoints calculated from the equations were validated by comparison with the histograms. Breakpoints were also calculated for a suggested lower disk content in Sweden, 10 ,g, and validated in tests of clinical isolates and by histogram analysis. [source] In vitro antifungal susceptibility patterns of dermatophyte strains causing tinea unguiumCLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 6 2007E. Sarifakioglu Summary Background., Dermatophytes are the major responsible organisms in onychomycosis. Although recent antifungal agents have high success rates in treating this condition, lack of clinical response may occur in 20%. Antifungal drug resistance may be one of the causes of treatment failure. The need for in vitro antifungal drug resistance in daily practice is still under discussion. Objective., We aimed to determine the in vitro susceptibility patterns of dermatophytes causing onychomycosis, against the traditionally available systemic antifungal agents terbinafine, itraconazole and fluconazole. Methods., In total, 100 otherwise healthy patients with suspected onychomycosis were included. Nail clippings were cultured on Sabouraud dexrose agar, mycobiotic agar and dermatophyte test medium. Antifungal susceptibility tests were carried out, mainly following The National Committee for Clinical and Laboratory Standards (M38-P) protocol standard for filamentous fungi. Different concentrations of terbinafine (0.008,8 µg/mL), itraconazole (0.015,16 µg/mL) and fluconazole (0.06,64 µg/mL) were tested. Minimum inhibitory concentration end-point determination was chosen as 100% growth inhibition for terbinafine and 80% for azoles. Results., Of the 100 nail samples, 43% grew dermatophytes. The main causative organism was Trichophyton rubrum (91%) followed by Trichophyton mentagrophytes (9%). Terbinafine had the lowest minimum inhibitory concentration (0.008 µg/mL) followed by itraconazole. Fluconazole showed the greatest variation in minimum inhibitory concentration (0.03,2 µg/mL) and had different susceptibility patterns for the two species. Conclusions., Of the three antifungals tested, terbinafine had the most potent in vitro antifungal activity against dermatophytes. Antifungal susceptibility tests would be useful to screen antifungal-resistant dermatophyte strains. [source] In vitro susceptibility of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis: a European multicenter study during 2000,2001CLINICAL MICROBIOLOGY AND INFECTION, Issue 7 2003M. E. Jones Objective, To assess the current (2001) activity of respiratory fluoroquinolones and comparator agents against respiratory pathogens isolated in European countries. Methods, During 2000,2001, we prospectively collected 1995 isolates of Haemophilus influenzae, 1870 isolates of Streptococcus pneumoniae and 649 isolates of Moraxella catarrhalis from hospital laboratories in France, Germany, Greece, Italy, Spain and the UK. National Committee for Clinical Laboratory Standards (NCCLS)-approved broth microdilution antimicrobial susceptibility testing methods and interpretive criteria were used throughout. Results, Of the S. pneumoniae isolates, 99.6% were susceptible to moxifloxacin, gatifloxacin and levofloxacin; the corresponding figure for H. influenzae was 100%. All M. catarrhalis isolates had moxifloxacin MICs ,,0.12 mg/L. For all three pathogens, fluoroquinolone susceptibility remained unchanged from the previous 1997,98 study. The incidence of penicillin non-susceptibility in the S. pneumoniae isolates tested remained similar to or higher than that recorded in previous studies: France, 165/291 (56.7%); Germany, 46/506 (9.1%); Greece, 20/55 (36.4%); Italy, 45/364 (12.4%); Spain, 146/268 (54.5%); and the UK, 26/386 (6.7%). Significant levels of resistance to oral compounds (cefuroxime, cefaclor, cefdinir, clarithromycin, azithromycin, tetracycline, and trimethoprim,sulfamethoxazole) were detected among S. pneumoniae isolates. ,-Lactamase production among H. influenzae isolates ranged from 6.2% to 33.1% per country, and ampicillin, clarithromycin or trimethoprim,sulfamethoxazole resistance were the most common phenotypes detected. ,-Lactamase production among M. catarrhalis isolates ranged from 94.1% to 100% per country. Conclusions, With the exception of a few localized reports, resistance to moxifloxacin and other new fluoroquinolones in common respiratory pathogens is a rare occurrence, despite significant resistance to other compound classes. Surveillance will play a key role in tracking changes in fluoroquinolone susceptibility in European countries. [source] Multicenter evaluation of the reproducibility of the proposed antifungal susceptibility testing method for fermentative yeasts of the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antimicrobial Susceptibility Testing (AFST-EUCAST)CLINICAL MICROBIOLOGY AND INFECTION, Issue 6 2003M. Cuenca-Estrella Objective To evaluate the intra- and inter-laboratory reproducibility of a new standard for susceptibility testing of fermentative yeasts. This standard is based on the M27-A procedure of the National Committee for Clinical Laboratory Standards (NCCLS), but incorporates several modifications, including spectrophotometric growth-dependent endpoint reading. Methods Nine laboratories participated in the study. Common material lots were used to test six Candida species (one each of C. albicans, C. tropicalis, C. parapsilosis, C. glabrata, C. krusei, and C. lusitaniae), and two quality control strains (C. krusei ATCC6258 and C. parapsilosis ATCC22019). Triplicate testing on three separate days was performed in microtiter format with RPMI,2% glucose, pH 7.0. Flucytosine, fluconazole and itraconazole were tested. In total, 3888 MIC values were included in the analyses. Reproducibility was calculated by means of agreement (percentage of MICs within one two-fold dilution of the mode) and intraclass correlation coefficient (ICC, maximum value of 1). Results The average intra-laboratory agreements were 99% and 96% after 24 h and 48 h of incubation, respectively, with ICCs of 0.98 and 0.97 (P < 0.05). Two strains exhibiting a trailing effect showed intra-laboratory agreement of 92% and ICCs of <,0.91 at 48 h. The inter-laboratory agreement was 94% and 88% after 24 h and 48 h, respectively, with ICCs of 0.93 and 0.91 (P < 0.05). Lower values of agreement and ICCs were obtained for strains exhibiting trailing after 48 h of incubation. Itraconazole yielded the lowest values of reproducibility. Conclusion The new procedure of EUCAST for antifungal susceptibility testing is a reproducible method within and between laboratories and offers several advantages over the NCCLS approved method. [source] CPA assessment , the regional assessors' experienceCYTOPATHOLOGY, Issue 2007E. Welsh Many individuals within Laboratory Medicine will be unaware that CPA conducts assessments to two different sets of CPA Standards. There are the Standards for the Medical Laboratory and the Standards for EQA Schemes in Laboratory Medicine. The style and format of both sets of standards is very similar with each being presented in eight sections A , H. The EQA standards are almost identical to the laboratory standards with the exception of the E.F and G standards which are specific to EQA schemes. There are approximately 40 EQA Schemes registered with CPA compared with almost 2 500 laboratories. These EQA schemes vary from very large national/international schemes with numerous analytes to small interpretive schemes run by one individual with a personal interest in that specific subject. The large schemes usually come under the UKNEQAS consortia banner and due to their size and configuration do not present undue problems in the assessment process. Smaller interpretive EQA schemes present a challenge both for the scheme and CPA in gaining accreditation. These schemes are usually within the discipline of Histopathology and are regarded as educational rather than proficiency testing schemes. Very frequently, the scheme is organized by a single individual with a collection of microscope slides, storage facilities for the slides and a computer. This presents the Scheme Organizer with great difficulty in complying with the Quality Management System requirements of the CPA Standards. There are a number of models which can be applied in order to satisfy the requirement of the Quality Management System, but ultimately it must be recognized that in some circumstances it is not possible to accredit these small schemes. The NHSCSP Gynae Cytology EQA Scheme is probably the largest EQA scheme within the UK, in respect of the number of participants and the number of staff supporting the scheme. Scheme Management decided that all nine regions of England would apply for accreditation under one CPA Reference Number. This process meant that the scheme would be assessed as a Managed Pathology Network. This is unique in terms of EQA schemes and presented a number of problems not previously encountered in EQA scheme accreditation. This decision meant that all nine regions must comply with a single Quality Management System and other CPA standards whilst allowing flexibility within the system for each region to facilitate the assessment process specific to their user's requirements. The process worked in a satisfactory manner and the overall outcome was not dissimilar to that of other large EQA schemes. The assessment to the current EQA Standards only commenced in April 2006 whilst the Standards for Medical Laboratories commenced in 2003, and it is perhaps not surprising to find that the principal non-conformities are related to the Quality Management System. This parallels the findings encountered in laboratory accreditation. There is an ongoing educational process for Scheme Management and the Facilitators in each region in how to comply fully with the standards and a commitment to quality improvement which ultimately is beneficial to the participant's of the scheme and to patient safety. [source] The periodontal abscess (I).JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 6 2000Clinical, microbiological findings Background/aims: Little information is available regarding the diagnosis and microbiology of periodontal abscesses. The aim of this descriptive clinical and microbiological study was to provide more information in order to help in the characterisation of the periodontal abscess associated to periodontitis. Method: 29 consecutive patients with a periodontal abscess were studied by the assessment of clinical variables, including both subjective (pain, edema, redness and swelling) and objective (bleeding on probing, suppuration, probing pocket depth, tooth mobility and cervical lymphadenopathy) parameters. Microbiological samples were taken for anaerobic microbiology and processed by means of culture. Systemic involvement was also studied through the analysis of blood and urine samples using conventional laboratory standards. Results: 62% of the abscesses affected untreated periodontitis patients, and 69% were associated with a molar tooth. More than 75% of the abscesses had moderate-severe scores related to edema, redness and swelling, and 90% of the patients reported pain. Bleeding occurred in all abscesses, while suppuration on sampling was detected in 66%. Mean associated pocket depth was 7.28 mm, and 79% of teeth presented some degree of mobility. Cervical lymphadenopathy was seen in 10% of patients, while elevated leucocyte counts were observed in 31.6%. The absolute number of neutrophils was elevated in 42% of the patients. High prevalences of putative periodontal pathogens were found, including Fusobacterium nucleatum, Peptostreptococcus micros, Porphyromonas gingivalis, Prevotella intermedia and Bacteroides forsythus. Conclusions: The periodontal abscess has clear clinical characteristics and is usually associated with severe periodontal destruction. This condition may cause systemic involvement and the lesion generally has a large bacterial mass with a high prevalence of well-recognised periodontal pathogens. [source] Comparison of traceable calibration methods for primary photovoltaic reference cellsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 8 2005Harald Müllejans Abstract The calibration of photovoltaic reference cells used as primary laboratory standards for the calibration of photovoltaic devices needs to be traceable to international radiometric standards and SI units. As a contribution to the development of an international standard this paper describes three methods for the calibration of primary photovoltaic reference cells, establishing two independent traceability chains. The solar simulator method is traceable via a standard lamp to the international irradiance scale whereas the global sunlight method and the modified global sunlight method are traceable to the world radiometric reference. The calibration values obtained by the three methods agree with each other within their respective uncertainties and with the world photovoltaic scale within ±,0·8%. Copyright © 2005 John Wiley & Sons, Ltd. [source] Imaging of uranium on rat brain sections using laser ablation inductively coupled plasma mass spectrometry: a new tool for the study of critical substructures affined to heavy metals in tissuesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2008J. Sabine Becker The specific toxicity of trace metals and compounds largely depends on their bioavailability in different organs or compartments of the organism considered. Imaging mass spectrometry (IMS) using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) with a spatial resolution in the 100,µm range was developed and employed to study heavy metal distribution in brain tissues for toxicological screening. Rat brain post-mortem tissues were stained in an aqueous solution of either uranium or neodymium (metal concentration 100,µg,g,1) for 3,h. The incubation of heavy metal in thin slices of brain tissue is followed by an imaging mass spectrometric LA-ICP-MS technique. Stained rat brain tissue (thickness 30,µm) were scanned with a focused laser beam (wavelength 266,nm, diameter of laser crater 100,µm and laser power density 3,×,109,W,cm,2). The ion intensities of 235U+, 238U+, 145Nd+ and 146Nd+ were measured by LA-ICP-MS within the ablated area. For quantification purposes, matrix-matched laboratory standards were prepared by dosing each analyte to the pieces of homogenized brain tissue. Imaging LA-ICP-MS allows structures of interest to be identified and the relevant dose range to be estimated. Copyright © 2008 John Wiley & Sons, Ltd. [source] Prediction of congenital toxoplasmosis by polymerase chain reaction analysis of amniotic fluidBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 5 2005L. Thalib Objective To determine the accuracy of polymerase chain reaction (PCR) analysis of amniotic fluid for fetal toxoplasmosis according to clinical predictors of outcome and study centre. Design Prospective cohort study. Setting Nine European centres. Population Women with suspected toxoplasma infection identified by prenatal screening. Methods Logistic regression was used to examine the effects of gestational age at maternal seroconversion, treatment and timing of amniocentesis, on PCR accuracy, and to calculate the post-test probability of congenital toxoplasmosis. Main outcome measures Infants had congenital toxoplasmosis if specific IgG persisted beyond 11.5 months. Uninfected infants had undetectable IgG in the absence of anti-toxoplasma treatment. Results Of 593 PCR results, 64 were positive (57 confirmed infected), and 529 were negative (23 confirmed infected). The likelihood ratio for a positive PCR result decreased significantly with trimester at seroconversion, but did not change significantly for a negative result. Weak associations were detected between sensitivity and, inversely, with specificity, and gestational age at maternal seroconversion. There was no significant association between sensitivity and centre, type or duration of treatment, or timing of amniocentesis. Specificity differed significantly between centres (P < 0.001). The change in pre- to post-test probability of infection was maximal for a positive PCR after first trimester seroconversion, affecting 1% of women tested, and a negative PCR after third trimester seroconversion, affecting half the women tested. Conclusions Prediction of the risk of congenital toxoplasmosis should combine estimates of test accuracy and maternal,fetal transmission, which take account of the gestational age at which the mother seroconverted. Local laboratory standards will affect the generalisability of these results. [source] | ||||||||||