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Evaluation of a monoclonal antibody-based enzyme-linked immunosorbent assay for detection of Campylobacter fetus in bovine preputial washing and vaginal mucus samples.

A monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) was described and evaluated for use as a presumptive screening test for detection of Campylobacter fetus in bovine preputial washing and vaginal mucus samples. A total of 725 diagnostic samples collected in the field and submitted in Clark's transport enrichment medium (TEM) were analyzed. Cultural isolation of C. fetus was used as the standard for comparison. After incubation of the TEM vials for 4-5 days, fluid was removed for culture and ELISA testing. A sandwich ELISA format was used and the target antigen was C. fetus lipopolysaccharides (LPS). A rabbit anti-C. fetus polyclonal antiserum was used as the capture antibody. Murine monoclonal antibodies (MAbs) to C. fetus serotype A and B LPS core and O-polysaccharides and a goat anti-mouse horseradish peroxidase conjugate were used as detection antibodies. ELISA and culture results for the diagnostic samples were in complete agreement. Seven hundred and eight samples were negative by both tests. All 17 culture positive samples were positive by ELISA with a MAb to LPS core. The ELISA with MAbs to LPS O-polysaccharides detected all culture positive samples with the homologous C. fetus serotype. Sixty-six preputial wash samples from three known C. fetus culture positive bulls were also analyzed. Forty-nine of these samples were positive by both ELISA and culture, 16 were positive by ELISA only, and one was negative by both ELISA and culture. The results indicate that this ELISA is useful as a screening test for the detection of C. fetus in diagnostic samples.

Animals↗

Development of a sensitive detection system for Cryptosporidium in environmental samples.

The identification of Cryptosporidium species and genotypes is necessary to determine sources of infection in outbreaks and the risk factors associated with their transmission. Few studies have applied isolation methods to field samples because of difficulties with detection of oocysts in environmental samples, particularly in soil and manure. The objective of this study was to develop an easy to use method which can be applied to field samples to rapidly detect the presence of Cryptosporidium parasites and identify their species. The assay included an oocyst recovery method combined with spin column DNA extraction, followed by PCR-hybridization for detection and a real-time PCR-melting curve analysis for species assignment. An internal positive control (IPC) was developed to determine the presence of PCR inhibitory substances. Two oocyst recovery methods, sodium chloride and sucrose flotation techniques were compared. Two commercial DNA extraction kits were performed using feces, soil and water samples each inoculated with different concentration of Cryptosporidium oocysts. Subsequently, methods were used to test field samples. The sucrose flotation method provided the greatest analytical sensitivity detecting as few as 10 oocysts. The PCR-hybridization detection limit was 10 oocysts for feces and soil, and less than 10 oocysts for water samples. IPC was positive for all inoculated and field samples indicating 0% PCR inhibition. Cryptosporidium species DNA samples were detected with the real-time PCR and were differentiated by the melting curve analysis. The results of this study demonstrate the potential of the assay system for rapid detection of Cryptosporidium parasites in environmental samples.

Animals↗

Triple-tissue sampling at ERCP in malignant biliary obstruction.

BACKGROUND: Procurement of cytologic samples by brushing is common practice at endoscopic retrograde cholangiopancreatography (ERCP) but has low sensitivity for cancer detection. Limited data are available on other techniques, including endoluminal fine-needle aspiration and forceps biopsy. This series reviews the yield of these three stricture sampling methods. METHODS: In this prospective study, patients with biliary obstruction with a clinical suspicion of malignancy underwent triple-tissue sampling at one ERCP session. Final cancer diagnosis was based on all sampling methods plus surgery, autopsy, and clinical follow-up. Tissue specimens were reported as normal, atypia, or malignant. RESULTS: A total of 133 patients were evaluated: 104 had cancer and 29 had benign strictures. Tissue sampling sensitivity varied according to the type of cancer; the highest yield was seen in ampullary cancers (62% to 85%). The cumulative sensitivity of triple-tissue sampling in the cancer patients was as follows: sensitivity was 52% if atypia was considered benign and 77% if it was considered malignant. The addition of a second or third technique increased sensitivity rates in most instances. No serious complications occurred from the tissue sampling methods. CONCLUSIONS: Tissue sampling sensitivity varied according to the type of cancer. Combining a second or third method increased sensitivity; general use of at least two sampling methods is therefore recommended.

Adult↗

Comparison of various liquid chromatographic methods involving UV and atmospheric pressure chemical ionization mass spectrometric detection for the efficient trace analysis of phenylurea herbicides in various types of water samples.

The performance of mass spectrometric (MS) detection and UV detection in combination with reversed-phase liquid chromatography without and with the use of coupled column RPLC (LC-LC) has been compared for the trace analysis of phenylurea herbicides in environmental waters. The selected samples of this comparative study originated from an inter-laboratory study. For both detection modes, a 50 mm x 4.6 mm I.D. column and a 100 mm x 4.6 mm I.D. column packed with 3 microm C18 were used as the first (C-1) and second (C-2) column, respectively. Atmospheric pressure chemical ionization mass spectrometry was performed on a magnetic sector instrument. The LC-LC-MS analysis was carried out on-line by means of direct large volume (11.7 ml) injection (LVI). The performance of both on-line (LVI, 4 ml of sample) and off-line LC-LC-UV (244 nm) analysis was investigated. The latter procedure consisted of a solid-phase extraction (SPE) of 250 ml of water sample on a 500 mg C18 cartridge. The comparative study showed that LC-LC-MS is more selective then LC-LC-UV and, in most cases, more sensitive. The LVI-LC-LC-MS approach combines direct quantification and confirmation of most of the analytes down to a level of 0.01 microg/l in water samples in less then 30 min. As regards LC-LC-UV, the off-line method appeared to be a more viable approach in comparison with the on-line procedure. This method allows the screening of phenylurea's in various types of water samples down to a level of at least 0.05 microg/l. On-line analysis with LVI provided marginal sensitivity (limits of detection of about 0.1 microg/l) and selectivity was sometimes less in case of surface water samples. Both the on-line LVI-LC-LC-MS method and the LC-LC-UV method using off-line SPE were validated by analysing a series of real-life reference samples. These samples were part of an inter-laboratory test and contained residues of herbicides ranging from 0.02 to 0.8 microg/l. Beside good correlation between the methods the data agreed very well with the true values of the samples.

Atmospheric Pressure↗

Large-bore coated columns for sampling and concentration of organic volatiles in air, headspace and water analysis.

Large-bore coated (LBC) columns were used as sampling and concentrating traps in analyses for traces of organic volatiles in air and water. This simple technique utilizes long metal columns thinly coated with SE-30 for direct trapping of the organics. The sample is simply passed through the LBC column; the trapped organics are then thermally desorbed onto a conventional porous polymer pre-column or onto a second LBC column. If desired, this can be shorter or narrower bore than the initial LBC sampling column. The sample is finally desorbed onto the gas chromatographic column for analysis. Multiple transfers between LBC columns are possible, with increased concentration at each transfer, resulting in a "concentration pump" effect. The technique offers the advantages of great simplicity, efficiency and ease of sample transfer. Samples are obtained with low back-pressure and minimal interfering artifacts. The system shows almost complete imperturbability to moisture. Indifference to moisture and the low back-pressure enable direct sampling of very large volumes of air and even breath. Direct sampling of aqueous systems was also possible. The latter area was not fully investigated but offers potential for water pollution analysis and in direct examination of biological fluids and aqueous flavor extracts where heat sensitivity is a problem. With LBC columns the sampling and concentration sequence exposes the substances sought to no more drastic conditions than those they will be subjected to in the process of gas chromatographic analysis.

Air↗

Investigation of the storage stability of selected volatile sulfur compounds in different sampling containers.

The suitability of various sample containers (i.e. standard Tedlar sample bags, black/clear layered Tedlar sample bags and Silcosteel sample cylinders) was examined for a gaseous multicomponent standard containing methylmercaptan, ethylmercaptan, dimethyl sulfide, ethylmethyl sulfide, 2-propylmercaptan, 1-propylmercaptan, 2-butylmercaptan, diethyl sulfide and 1-butylmercaptan (1 mg/m3 each in nitrogen). In the black/clear layered Tedlar sample bags, significant losses (up to 10% for methylmercaptan as the most critical component) were observed after 2 days, whereas in the standard Tedlar sample bags the recovery of methylmercaptan was approximately 90% even after 1 week. The Silcosteel sample cylinders were suitable for sampling of volatile sulfur compounds with respect to the stability of the analytes, but the recoveries exceeded 100% especially for the higher boiling compounds, which was attributed to enrichment effects on parts of the sampling system.

Kinetics↗

Flow-through sampling for electrophoresis-based microfluidic chips using hydrodynamic pumping.

This work presents a novel electrophoretic microchip design which is capable of directly coupling with flow-through analyzers for uninterrupted sampling. In this device, a 3 mm wide sampling channel (SC) was etched on quartz substrate to create the sample inlet and outlet and the 75 microm wide electrophoretic channels were also fabricated on the same substrate. Pressure was used to drive the sample flow through the external tube into the SC and the flow was then split into outlet and electrophoretic channels. A gating voltage was applied to the electrophoretic channel to control the sample loading for subsequent separations and inhibit the sample leakage. The minimum gating voltage required to inhibit the sample leakage depended on the solution buffer and increased with the hydrodynamic flow-rate. A fluorescent dye mixture containing Rhodamine B and Cy3 was introduced into the sample stream at either a continuous or discrete mode via an on-line injection valve and then separated and detected on the microchip using laser-induced fluorescence. For both modes, the relative standard deviation of migration time and peak intensity for consecutive injections was determined to be below 0.6 and 8%, respectively. Because the SC was kept floating, the external sampling equipment requires no electric connection. Therefore, such an electrophoresis-based microchip can be directly coupled with any pressure-driven flow analyzers without hardware modifications. To our best knowledge, this is something currently impossible for reported electrophoretic microchip designs.

Electrophoresis↗

Solid-phase microextraction from small volumes of sample in a glass capillary.

A new sampling method is proposed for solid-phase microextraction (SPME), in which the extraction is carried out in a glass capillary containing a few microliters of sample. When an adsorption-type fiber is used for SPME, the equilibrium between aqueous sample and coating can be described by a Langmuir isotherm. Since the total amount of analytes and coexisting substances stays at a low level in a small volume of sample, the linear concentration range of analytes will be extended for SPME to be applied in quantification and the interference caused by sample matrix will be reduced. In addition, sampling in a capillary has a short diffusion distance and extraction equilibrium is established in 5-10 min. It is important in clinical analysis and therapeutic drug monitoring to be able to analyse sample volumes of samples. The feasibility of the new sampling method is demonstrated by the extractions of p-hydroxybenzaldehyde and a synthetic solution containing 1-naphthol, paeonol and 1-naphthylamine.

Chromatography, Gas↗

Determination of phenylurea herbicides in water samples using online sorptive preconcentration and high-performance liquid chromatography with UV or electrospray mass spectrometric detection.

A recently developed method for the extraction of organic micropollutants from aqueous samples based on sorptive enrichment in columns packed with 100% polydimethylsiloxane (PDMS) particles was coupled on-line with HPLC analysis. The sorptive enrichment procedure originally developed for relatively nonpolar analytes was used to preconcentrate polar phenylurea herbicides from aqueous samples. PDMS extraction columns of 5, 10 and 25 cm were used to extract the herbicides from distilled, tap and river water samples. A model that allows prediction of retention and breakthrough volumes is presented. Despite the essentially apolar nature of the PDMS material, it is possible to concentrate sample volumes up to 10 ml on PDMS cartridges without losses of the most polar analyte under investigation, fenuron. For less polar analytes significantly larger sample volumes can be applied. Since standard UV detection does not provide adequate selectivity for river water samples, an electrospray (ES)-MS instrument was used to determine phenylurea herbicides in a water sample from the river Dommel. Methoxuron was present at a level of 80 ng/l. The detection limit of the current set-up, using 10 ml water samples and ES-MS detection is 10 ng/l in river water samples. Strategies for further improvement of the detection limits are identified.

Chromatography, High Pressure Liquid↗

A dynamic loading method for controlling on-chip microfluidic sample injection.

A new technique for controlling discrete sample injection in straight-cross microfluidic chips is presented here. This technique involves a three-part process with a dynamic loading step in between the steady-state loading step and the dispensing step. During the intermediate step, sample is pumped into the intersection and into the three connecting channels. The key features of this technique are the ability to dynamically control the sample size and the ability to inject well-defined samples at the original sample concentration. Injections of these samples with lengths varying from 2 channel widths (100 microm) to 20 channel widths (millimeter-sized) are demonstrated. The sample concentration profiles obtained are compared with those of focused and less-focused pinched-valve injections. In applications such as high-speed capillary zone electrophoresis, this technique can provide an increase in signal with a small increase in sample length. This technique is especially applicable to many large-sample applications in which the offset twin-T microchip has been previously employed.

Journal Article↗

Identification methods for Legionella from environmental samples.

Laboratories responsible for Legionella diagnostics around the world use a number of different culturing methods of non-equivalent sensitivities and specificities, to detect Legionella species in environmental samples. Specific countries usually standardize and use one approved method. For example, laboratories in Australia use the Australian Standard (AS) method and those in Europe, the International Standard method (ISO). However, no standard culturing methods have been established in South Africa to date. As a result, there is uncertainty about the true prevalence and most common species of Legionella present in the South African environment. In an attempt to provide guidelines for the development of a standard method specific for South Africa, the ISO, AS and a most probable number method were evaluated and compared. In addition, the effect of sample re-incubation with autochthonous amoebae on culture outcome was studied. Samples were collected from four environments, representing industrial water, mine water and biofilm. The samples were concentrated by membrane filtration and divided into three portions and cultured without pretreatment, after acid treatment and after heat treatment, on four culture media namely alphaBCYE, BMPA, MWY and GVPC agar. A selective approach, incorporating heat treatment, but not acid treatment, combined with culture on alphaBCYE and GVPC or MWY, was most appropriate for legionellae detection in the samples evaluated. Legionellae were cultured from 82% of the environmental samples we evaluated. In 54% of the samples tested, legionellae were present in numbers equal to or exceeding 10(2) colony-forming units per milliliter (cfu/ml). Legionella pneumophila serogroups (SGs) 1-14 were the most prevalent species and were present as single, or a combination of two or more SGs in a number of samples tested. Re-incubation of sample concentrates with autochthonous amoebae improved the culturability of legionellae in 50% of cultures on alphaBCYE and 25% on GVPC.

Biofilms↗

Description of the test area and reference sampling at Dornach.

The selected test area for the comparative evaluation of European methods on sampling and sample preparation of soils (CEEM Soil) at Dornach near Basel (Switzerland) is located at approximately 400 m a.S.l. on the north-west rolling footslope of the Jura mountain chain that has a temperate climate. The area is known to be airborne polluted by emissions of a non-ferrous metal recycling plant. The geology is dominated by Jurassic limestone and (decarbonated) loess loam. The land use is deciduous forest (beech, oak) in the upper part and traditional cherry orchards with permanent grassland which have mostly been converted into arable land. The detailed soil survey distinguishes four different soil mapping units in the test area of 0.61 ha. The reference sampling was performed in a 190-m-long and 20-40 m large transect area following four devices: (1) composite samples (0-10 cm and 0-20 cm), each from 25 stratified single samples of 61 squares of 10 x 10 m; (2) hypotheses and soil horizon-based composite samples at nine locations; (3) horizon-related samples from the four described soil profiles representing the mapping units; and (4) three soil cores with 5-cm interval samples taken in the major land use units. Altogether 301 reference soil samples were taken.

Environmental Monitoring↗

Sampling and pre-treatment--some observations from the United Kingdom.

This paper arises from the current discussion in the United Kingdom to develop, under the auspices of the British Standards Institution a 'code of practice for investigation of potentially contaminated sites'. Within this code of practice a key element in the analysis is the sampling strategy for the collection of samples and characterisation of the site. The paper briefly summarises the current status of the development of the ideas on the sampling and pre-treatment of potentially contaminated sites, and emphasises the importance which must be attached to the sampling phase of any investigation if the outcomes are to be valid. A brief reference is made to other studies which have addressed the problem of sampling contaminated sites. These studies have considered both the design of the sampling scheme and the number of samples to be taken in relation to the costs of sampling, the nature of the potential hazard, the potential risks involved and the statistical requirements if samples are to be used to predict within given confidence limits.

Environmental Monitoring↗

Guidelines for sampling in Flanders (Belgium).

In Flanders, sampling guidelines for investigations on contamination of soils are in development. One detailed sampling guideline is currently available with respect to the prospective investigation in the frame of the decree related to soil sanitation. Four strategies for sampling may be followed as a function of available information about pollution sources. Guidelines indicate what has to be sampled (top soil, deeper soil, soil water), how sampling points must be determined, how the number of samples and analyses is determined and what parameters need to be analysed. The example given shows that sampling guidelines will strongly depend on the ultimate goal of a particular sampling. A sampling procedure should be developed with close consideration of practical aspects and limitations, in order to be practical, realistic and cost-effective.

Accreditation↗

Storage effects on bacterial concentration: determination of impinger and filter samples.

Effects of storage on the colony recovery of airborne bacterial samples were evaluated in a laboratory test chamber. Escherichia coli cells and Bacillus subtilis spores were generated by a Collison three-jet nebulizer. Bioaerosol samples were collected by three sampling methods, AGI-30 impingers, Nuclepore filtration and elution methods, and gelatin filters. Effects of storage time was determined by the ratio, Ct/C0, where Ct and C0 were the CFU concentrations of the simultaneously collected samples stored for t and 0 h, respectively. The effect of storage temperature was also studied for AGI-30 samples stored at 25 and 4 degrees C. For impinger samples, it was demonstrated that the bioefficiency of bacterial bioaerosols could survive in the impinger fluid, and even bud more cells at room temperature. In addition, the inhibition effect of refrigerated samples was observed. Therefore, we suggest that samples collected by an impingement method should be refrigerated and processed as soon as possible to avoid the increase of bacterial culturability. Moreover, the effect of storage time on filtration collection for B. subtilis spores was demonstrated to be insignificant. However, E. coli recovery from filters was demonstrated to decrease as storage time increased. It was concluded that the recovery would not decrease during storage if bioefficiencies of the sampling methods were excellent, for example, using filters to collect B. subtilis spores or impingers to collect E. coli cells.

Aerosols↗

An analytical protocol for the determination of total mercury concentrations in solid peat samples.

Traditional peat sample preparation methods such as drying at high temperatures and milling may be unsuitable for Hg concentration determination in peats due to the possible presence of volatile Hg species, which could be lost during drying. Here, the effects of sample preparation and natural variation on measured Hg concentrations are investigated. Slight increases in mercury concentrations were observed in samples dried at room temperature and at 30 degrees C (6.7 and 2.48 ng kg(-1) h(-1), respectively), and slight decreases were observed in samples dried at 60, 90 and 105 degrees C (2.36, 3.12 and 8.52 ng kg(-1) h(-1), respectively). Fertilising the peat slightly increased Hg loss (3.08 ng kg(-1) h(-1) in NPK-fertilised peat compared to 0.28 ng kg(-1) h(-1) in unfertilised peat, when averaged over all temperatures used). Homogenising samples by grinding in a machine also caused a loss of Hg. A comparison of two Hg profiles from an Arctic peat core, measured in frozen samples and in air-dried samples, revealed that no Hg losses occurred upon air-drying. A comparison of Hg concentrations in several plant species that make up peat, showed that some species (Pinus mugo, Sphagnum recurvum and Pseudevernia furfuracea) are particularly efficient Hg retainers. The disproportionally high Hg concentrations in these species can cause considerable variation in Hg concentrations within a peat slice. The variation of water content (1.6% throughout 17-cm core, 0.97% in a 10 x 10 cm slice), bulk density (40% throughout 17-cm core, 15.6% in a 10 x 10 cm slice) and Hg concentration (20% in a 10 x 10 cm slice) in ombrotrophic peat were quantified in order to determine their relative importance as sources of analytical error. Experiments were carried out to determine a suitable peat analysis program using the Leco AMA 254, capable of determining mercury concentrations in solid samples. Finally, an analytical protocol for the determination of Hg concentrations in solid peat samples is proposed. This method allows correction for variation in factors such as vegetation type, bulk density, water content and Hg concentration in individual peat slices. Several subsamples from each peat slice are air dried, combined and measured for Hg using the AMA254, using a program of 30 s (drying), 125 s (decomposition) and 45 s (waiting). Bulk density and water content measurements are performed on every slice using separate subsamples.

Environmental Monitoring↗

Cell cycle perturbations in acute myeloid leukemia samples following in vitro exposures to therapeutic agents.

Cell cycle checkpoints establish the timing and strength of arrest, repair and apoptosis responses to damaging treatments. We designed flow cytometric assays to measure cell cycle arrest and apoptosis in acute myeloid leukemia (AML) samples treated in vitro with relevant therapeutic agents so as to functionally characterize checkpoints in these samples and to ask if checkpoint abnormalities are common in AML and contribute to therapeutic failures. We show here that cell cycle responses to daunomycin (DNR), cytosine arabinoside (ARA-C) and gamma irradiation (RAD) were reproducibly treatment agent- and dose-dependent and distinct in different myeloid cell lines. DNR treatments differentially induced cell accumulations in the gap 2 and mitosis (G2/M) phases of the cell cycle and/or in the gap 1 (G1) phase, as did RAD, while ARA-C induced accumulations in the DNA synthesis (S) phase or in the G1 phase. Flow cytometric gates were devised to exclude lymphocytes and mature neutrophils in analyses of primary myeloid cell samples. Cell subsets in bone marrow samples from normal donors were thus enriched for myeloid constituents and used as normal myeloid cell controls. Proliferating cell nuclear antigen (PCNA) immunostaining was used to further identify actively dividing cell subpopulations in primary cell samples. AML samples were similarly analyzed and the majority showed lower DNA synthesis cell cycle phase (S) fractions and lower PCNA-positive fractions than normal myeloid cells, suggesting that AMLs are generally less proliferative in these culture conditions. Exceptional AML samples with high S phase fractions had cytogenetic abnormalities associated with poor prognosis. Most AML samples mounted weak cell cycle responses relative to normal myeloid cells, while a minority showed robust, agent-specific cell cycle arrests. This non-responsiveness was not simply associated with lower cycling indices-neither the response patterns nor the degrees of response were correlated with untreated S phase fractions or with PCNA-positive fractions. Cell cycle responses were also not associated with clinical parameters including patient age, FAB class, or white blood cell count, nor with immunophenotypic features including CD34 status, nor with specific cytogenetic markers. This suggests that functional cell cycle response assays could provide unique diagnostic information in AML. These assays might also have prognostic value as ARA-C induced G1 arrests and DNR-specific G2/M arrests tended to be associated with failure to achieve clinical remission. In addition, G1 arrests after ARA-C and G2/M accumulations after DNR treatments tended to be more robust in samples that had previously been shown to be more highly immunopositive for bcl-2 expression. This data suggests that the association of bcl-2 expression with particular cell cycle responses to therapeutic agents may contribute to the association of bcl-2 with poor clinical responses in AML. These data provide the basis for further laboratory studies aimed at examining specific cell cycle arrests as mechanisms of therapeutic resistance and prospective studies aimed at rigorously assessing the prognostic utility of in vitro assays of checkpoint function.

Acute Disease↗

Usefulness of blood and urine samples collected on filter paper in detecting cytomegalovirus by the polymerase chain reaction technique.

A rapid test for the diagnosis of congenital CMV infection is still needed. This study evaluated the usefulness of dried blood and urine samples collected on filter paper for detecting cytomegalovirus (CMV) by the polymerase chain reaction (PCR) assay compared with the use of liquid urine. Samples were obtained from 332 infants aged 1-7 days. Liquid urine samples were collected into bags, cultured in human fibroblasts, and processed using a multiplex PCR technique. Dried urine samples were obtained by placing a piece of filter paper in contact with the infant's genitals. The heels of neonates were punctured and capillary blood was blotted onto filter paper and dried. Dried blood and urine specimens were analyzed by multiplex PCR and nested-PCR assays. A diagnosis of congenital CMV infection was established by isolating the virus, and by detecting viral DNA in the liquid urine. Of the 332 liquid urine samples collected from 332 neonates, seven (2.1%) were positive for CMV and 325 were negative, by both cell culture and PCR assay. In dried samples, CMV DNA was detectable only with a nested PCR assay. Compared with known CMV infection status, 5/7 (71.4%) neonates were positive for congenital CMV infection using dried blood samples. All 325 uninfected neonates were negative. In the dried urine samples, 4/4 CMV-infected infants gave positive tests, and all 262 uninfected infants were negative. Although further improvements in sample collection and/or processing are still needed, PCR testing on dried urine or blood collected on filter paper is a promising approach in the diagnosis of neonatal CMV infection.

Blood Specimen Collection↗