Experienced Laboratory Technicians Research Articles

Comparative evaluation of automated reading versus visual interpretation with the BBL Crystal enteric/nonfermenter identification system in a clinical setting

Comparative evaluation of automated reading versus visual interpretation with the BBL Crystal enteric/nonfermenter identification system in a clinical setting

Association between intestinal parasitic infections and type of sanitation system in rural El Salvador

To identify demographic, behavioural and environmental determinants of intestinal parasitic infection, evaluate the impact of a variety of dry sanitation systems on intestinal parasitic infection, and evaluate the safety of using stored biosolids in agriculture in order to guide future sanitation interventions in rural areas of El Salvador. Interviews were conducted with 109 households in eight communities where double-vaulted and solar urine-diverting desiccating latrines, pit latrines or no latrines were used. Faecal samples from 499 individuals were tested for enteric helminths and protozoa. Users of solar desiccating latrines had the lowest prevalence of enteric parasite infection. Double-vault, urine-diverting desiccating latrines effectively reduced the transmission of some pathogens, but may not achieve the conditions sufficient for the complete destruction of the more environmentally persistent pathogens, Ascaris lumbricoides and Trichuris trichiura. Contact with inadequately treated latrine biosolids was associated with an increased risk of Ascaris infection. Solar latrines were associated with the overall lowest prevalence of enteric parasitic infections. Members of households where latrine biosolids were used in agriculture had a higher prevalence of infection than those where biosolids were buried. We therefore recommend the promotion of solar latrines in rural areas of El Salvador over other dry sanitation systems, and recommend that stored biosolids not be used in agriculture.

Evaluation of the proficiency of trained non-laboratory health staffs and laboratory technicians using a rapid and simple HIV antibody test

In Cambodia, nearly half of pregnant women attend antenatal care (ANC), which is an entry point of services for prevention of mother-to-child transmission of HIV (PMTCT). However, most of ANC services are provided in health centres or fields, where laboratory services by technicians are not available. In this study, those voluntary confidential counselling and testing (VCCT) counsellors involved in PMTCT were trained by experienced laboratory technicians in our centre on HIV testing using Determine (Abbot Laboratories) HIV1/2 test kits through a half-day training course, which consisted of use of a pipette, how to process whole blood samples, and how to read test result. The trained counsellors were midwives working for ANC and delivery ward in our centre without any experience on laboratory works. The objective of this study was to assess the feasibility of the training by evaluating the proficiency of the trained non-laboratory staffs. The trained counsellors withdrew blood sample after pre-test counselling following ANC, and performed the rapid test. Laboratory technicians routinely did the same test and returned reports of the test results to counsellors. Reports by the counsellors and the laboratory technicians were compared, and discordant reports in two groups were re-tested with the same rapid test kit using the same blood sample. Cause of discordance was detected in discussion with both groups. Of 563 blood samples tested by six trained VCCT counsellors and three laboratory technicians, 11 samples (2.0%) were reported positive in each group, however four discordant reports (0.7%) between the groups were observed, in which two positive reports and two negative reports by the counsellors were negative and positive by the laboratory technicians, respectively. Further investigation confirmed that all the reports by the counsellors were correct, and that human error in writing reports in the laboratory was a cause of these discordant reports. These findings lead us the conclusion that the half-day training using the rapid and simple test was feasible for non-laboratory staffs to attain enough proficiency to implement VCCT services for PMTCT in resource-limited settings, and that human error was more likely to occur in laboratory before giving reports to counsellors.

Xanthrochromia? By What Method? A Comparison of Visual and Spectrophotometric Xanthrochromia

Most US hospitals use visual inspection for the detection of cerebrospinal fluid xanthrochromia. We compared visual inspection with spectrophotometric xanthrochromia and studied the effect of tube diameter on the sensitivity of visual inspection. Blinded, experienced laboratory technicians visually examined unmarked samples to determine the presence or absence of xanthrochromia. Samples were prepared by lysing RBCs in distilled water. Serial dilutions were placed in clear polystyrene tubes obtained from standard lumbar puncture trays. Laboratory technicians were asked to examine each sample for xanthrochromia using visual inspection. Next, they were asked to interpret the same set of samples with the assistance of a threshold standard. Last, they were asked to interpret the same dilutions, but this time presented in a larger-diameter tube. The absorbance of each sample was measured in a double-beam spectrophotometer at wavelengths between 300 and 700 nm. Samples were said to demonstrate spectrophotometric xanthrochromia if they had an absorbance greater than 0.023 at 415 nm. Sixteen laboratory technicians were shown a total of 160 samples, of which 64 (40%) demonstrated spectrophotometric xanthrochromia. Visual inspection of the samples was 26.6% sensitive (95% confidence interval [CI] 16% to 38%) and 97.9% specific (95% CI 95% to 100%) for spectrophotometric xanthrochromia. Using a reference standard did not improve the performance of visual inspection, but increasing collection-tube diameter increased the sensitivity to 55% (95% CI 43% to 68%). Visual inspection is not sensitive for the detection of spectrophotometric xanthrochromia. Increasing the diameter of the collection tubes did improve sensitivity. Emergency physicians should be aware of how xanthrochromia is determined at their institutions and understand the implications of using visual detection to determine the presence or absence of xanthrochromia.

An indigenous malaria transmission in the outskirts of Addis Ababa, Akaki Town and its environs

Background: In recent years malaria is becoming endemic in highland areas beyond its previously known upper limit of transmission. Assessment of the situation of the disease in such areas is necessary in order to institute appropriate control activities. Objectives: The objectives of the study were to determine the prevalence of malaria, the parasite species involved and Anopheles species responsible in local malaria transmission. Methods: A systematic sampling technique was used to select survey households. Blood films were collected monthly between October and December 1999 from all household members by a trained and experienced laboratory technician. Larval and adult mosquitoes were monthly collected using different methods from September 1999 to October 2000. Results: Among 2136 examined blood films, 78(3.7%) of them were malaria positive of which 54(69%) were due to Plasmodium vivax and 24 (31%) due to P. falciparum. Anopheles gambiae s. l. (presumably An. arabiensis) and An. christyi were the dominant man-biting species, with the former being the major vector in the area. Both these species were found to be more of exophagic and active in the early evening, unlike An. pharoensis, which showed an endophagic tendency. Conclusion: This study indicated that indigenous transmission of malaria occurs in the study area. Transmission is reckoned to be maintained by low density of vector species for short period of time under favorable conditions. Therefore, the acquisition of communal immunity is interrupted by long duration of non-malaria season leading to the occurrence of recurrent malaria epidemics. [Ethiop.J.Health Dev. 2004;18(1):2-7]

Best catch from NANOSNET.

Best catch from NANOSNET.

European Scientific Working Group on Influenza (ESWI)

Crete, Greece. We hope that they will be instrumental in encouraging international health authorities to endorse and stimulate effective influenza control programmes, possibly leading to a reduced impact of the disease on a global scale. For the first time, ESWI is organising a course on basic laboratory techniques, to be held at the Pasteur Institute in Paris, from 17‐21 July (course director: Professor van der Werf). The aim is to teach the latest techniques to less experienced laboratory technicians and researchers from influenza research institutes, surveillance centres and laboratories. The course ‐ ‘Basic laboratory techniques in influenza diagnostics’ ‐ was first announced in Influenza bulletin number 11 and on ESWI’s website (www.eswi.org). Late applications for the few remaining places on the course can be made via ESWI’s website. Preparations for the ‘Options for the Control of Influenza IV’ meeting in September are progressing well. ESWI is honoured to organise this prestigious international meeting, in which there is a tremendous interest. We would like to acknowledge the efforts of many people in the organisation of the meeting. The professional support from Biomedia and the active help of coordinators, organising and scientific committee members, advisors, chairpersons, invited speakers, and all those who have submitted abstracts, are ensuring that the 4th meeting in the series will again be a successful event.

Helicobacter Pylori Antibodies in a Saudi Population

The authors determined the sensitivity and specificity of a rapid latex-agglutination test (Pylori-set) to detect Helicobacter pylori infection and screened an asymptomatic Saudi population in different age groups for H. pylori seroprevalence. The study was designed as a blind comparison of a commercial serologic test kit for serologic diagnosis of H. pylori with a standard biopsy-related test in a tertiary referral center and teaching hospital. We included 70 symptomatic male and female Saudi patients, as well as 90 randomly collected sera from asymptomatic Saudi patients. The sensitivity of the Pylori-set was 59%, with a specificity of 89%. Screening of the asymptomatic Saudi population showed an age increase in antibody prevalence. Because of the limited sensitivity in the investigated population, the use of this latex-agglutination test alone cannot be recommended for the serological diagnosis of H. pylori infection in the Saudi population.

Standardizing the Babcock Test for Milk by Increasing the Volume of the Sample and Eliminating the Meniscus on the Fat Column

Summary Standardizing the Babcock test for milk by increasing the volume of the sample and eliminating the meniscus on the fat column is simple, fundamentally sound and accurate as indicated by comparisons with the Mojonnier method on 135 samples of unpreserved milk by five experienced laboratory technicians. It is the judgment of the Committee that the modified Babcock method is better than the method now in use.