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PubMed1979

Hemoglobinuria and hematuria: accuracy and precision of laboratory diagnosis.

Five methods of assessing blood in urine were studied and compared: sedimentation count, hemacytometry, "Clini-lab" reagent strip and "N-Multistix" and "ChemStrip-8" dipsticks. The minimum sensitivity of two commercially available urine dip-stick procedures for blood was established. The study includes method association, assay variation among and within technologists, accuracy, precision, and sensitivity. Our results demonstrate generally poor association between results by the dip-stick procedures and the hemacytometer or sedimentation count. Results by the last two procedures also showed very poor association with each other.

Clinical Laboratory Techniques↗

PubMed1994

Laboratory diagnosis of oxacillin resistance in Staphylococcus aureus by a multiplex-polymerase chain reaction assay.

A polymerase chain reaction (PCR) test was developed in which the mecA gene responsible for the intrinsic resistance to oxacillin in Staphylococcus aureus and the gyrA gene, always present in this species, were amplified in one operation. Among the 468 clinical isolates tested, the results obtained for 454 of the isolates (97%) were consistent with those of MIC determination. Discrepant results were noted for strains with low-level oxacillin resistance (MICs, 4-8 micrograms/ml) and mecA gene negative. For these strains, susceptibility to oxacillin was restored in the presence of a beta-lactamase inhibitor, which suggested a resistance by penicillinase hyperproduction. In contrast, all of the high-level resistant strains (MICs, > 8 micrograms/ml) carried the mecA gene. The presence of this gene has frequently been associated with resistance to gentamicin, tetracycline, erythromycin, lincomycin, and pefloxacin. The PCR assay described in this study can be accomplished with ease and total confidence in the clinical microbiologic laboratory for a rapid and effective establishment of antistaphylococcal chemotherapy.

Bacterial Proteins↗

PubMed1994

Serologic methods in the laboratory diagnosis of latex rubber allergy: study of nonammoniated, ammoniated latex, and glove (end-product) extracts as allergen reagent sources.

In the absence of approved natural rubber latex skin testing reagents, serologic methods for the detection of latex-specific immunoglobulin E (IgE) antibody are useful in the definitive diagnosis of latex allergy. In this study we examined extracts from two nonammoniated latex (NAL), two ammoniated latex (AL), and three diverse latex rubber gloves as sources of allergen for their utility in solid phase radioimmunoassays (SPRIAs) for latex-specific IgE. Serum samples were collected from 46 healthcare workers (HCWs), one beautician, two clerks, and seven children with spina bifida who exhibited clinical evidence of latex-associated contact dermatitis (CD, n = 8), contact urticaria (CU) with or without CD (n = 15), or systemic reactions involving respiratory symptoms with or without anaphylaxis (n = 33) and from 10 latex-exposed HCW control subjects with no latex allergy symptoms. Serum samples were coded and analyzed in a blinded manner in two laboratories by three particulate and four nonparticulate SPRIAs with different latex extracts on the allergosorbent. Intraassay coefficient of variation as assessed with 44 split, randomized, blinded serum specimens was < 20%. Agreement within a source of latex (e.g., NAL, AL, or gloves) and between laboratories was > 90% concordant for Glove 1/Glove 2 and NAL1/2. Specific IgE antilatex was detected in one of 10 latex-exposed control serum samples by five of the seven SPRIAs, despite a lack of clinical evidence for latex allergy in this otherwise atopic individual. Latex-specific IgE was detected in the serum of 22% of subjects with CU with or without CD, suggesting that IgE antibody may not be the primary factor involved in the induction of these local reactions. Approximately two thirds of the systemic reactor group had detectable latex-specific IgE in their serum, with levels ranging from 0.7 to 338 ng/ml. The predictive characteristics of these assays will await future provocation testing. We conclude that glove extracts contain as complete a repertoire of allergens as the NAL and AL. Of the three source latex materials, NAL and glove extracts provided the most sensitive and greatest consistency of IgE antibody results between laboratories.

Adult↗

PubMed1979

Glucosuria: accuracy and precision of laboratory diagnosis by dip stick analysis.

Two urine dip-stick assays for glucose were studied and compared to a quantitative hexokinase procedure. We determined sensitivity, specificity, predictive value of "normal" and "abnormal" dip stick results, assay efficiency, technologist precision, and method association. Precision was poor. Attempts to estimate urine glucose concentration with the dip sticks frequently produced gross inaccuracies. We believe the dip stick glucose assay should be considered qualitative only; as a qualitative test, the dip sticks are fairly efficient at distinguishing glucose concentrations of less than 0.3 g/L from concentrations greater than 0.3 g/L.

Clinical Laboratory Techniques↗

PubMed1987

Value and application of automation in laboratory diagnosis of haemostatic disorders.

There is a bewildering variety of instrumentation available for automation of coagulation procedures. The advantages and draw-backs of the most widely-used types are discussed to help the prospective purchaser to decide the most suitable instrument for his needs. Operator satisfaction is of considerable importance. Anticoagulated plasmas give shorter clotting times on many instruments as compared with the manual method which may necessitate an extrapolation curve or change of therapeutic range. An instrument, carefully selected, can increase the throughput of samples and improve the overall accuracy and precision of results.

Automation↗

PubMed1994

Comparison of techniques and evaluation of three commercial monoclonal antibodies for laboratory diagnosis of varicella-zoster virus in mucocutaneous specimens.

A comparison of direct antigen detection in cell scrapings with culture techniques (tube culture and shell vial method) for diagnosis of varicella-zoster virus (VZV) mucocutaneous infections was done in parallel in two groups of specimens. A total of 100 specimens were from patients with clinical diagnosis of VZV infection (group 1), and 69 were from patients with no suspicion of VZV infection (group 2) but mainly with herpes simplex virus infections. In addition, three commercially available monoclonal antibodies (Whittaker, Biosoft Clone 2013, and Ortho 3B3) directed against VZV antigens were evaluated in parallel in the last 87 group 1 specimens. Overall, 80% of the group 1 specimens were confirmed positive by direct detection, in comparison with 56% positive by tube culture and/or shell vial. None of the group 2 specimens were positive for VZV by any of the methods, and none of the monoclonal antibodies assayed reacted with any herpes simplex virus stock strains. Antiviral therapy and the length of evolution time of lesions affected negatively the performance of all laboratory methods, but to a lesser extent in direct detection techniques than in culture techniques. The Whittaker and Biosoft reagents (indirect immunofluorescence assay) showed statistically significant differences in sensitivity with respect to the Ortho antibody (P = 0.002 and P = 0.039, respectively; two-tailed binomial test). Direct antigen detection is a rapid, easy-to-perform, sensitive, and specific technique and appears to be the method of choice for laboratory confirmation of VZV mucocutaneous infections.

AIDS-Related Opportunistic Infections↗

PubMed1999

Different strategies in the laboratory diagnosis of autoimmune disease: immunofluorescence, enzyme-linked immunosorbent assay or both?

We investigated the clinical utility of different strategies for antinuclear antibodies (ANA) and antibodies to extractable nuclear antigens (ENA) testing. All requests for ANA and ENA (n = 485) in a 20-week period were tested by immunofluorescence (FANA) and immunodiffusion (strategy 1), enzyme-linked immunosorbent assay (ELISA) techniques (strategy 2) or a combination of FANA and ELISA (strategy 3). Results of strategy 1 were positive by FANA in 8% (by immunodiffusion in 2%). By ELISA, 11% of the samples tested positive. In 12% (n = 60) of the cases the two strategies did not agree. The positive predictive value (PPV) for autoimmune disease of strategy 1 was significantly higher than that for strategy 2, but after exclusion of rheumatoid arthritis this difference was abolished. In strategy 2 reagent costs were high but working time comparably shorter. With strategy 3 PPV results were not better, whereas costs and working time were higher. The most frequently occurring reasons for ANA/ENA test requests were: joint symptoms (37%), follow up (30%) or abnormal laboratory result (7%). In a survey of the clinicians 66% replied that the test result did not have any consequences, irrespective of the result or the strategy used. We conclude that FANA and immunodiffusion are superior to ELISA techniques. However, the clinical value of ANA/ENA testing is low and more selective test ordering is strongly recommended.

Adolescent↗

PubMed2001

Laboratory diagnosis of von Willebrand disorder (vWD) and monitoring of DDAVP therapy: efficacy of the PFA-100 and vWF:CBA as combined diagnostic strategies.

We have coevaluated a combination of test processes for diagnosing von Willebrand disease (vWD) and monitoring deamino-delta-D-arginine vasopressin (DDAVP) therapy. Using normal controls (n = 23), closure time (CT) ranges measured by PFA-100(R) were (mean +/- 2SD): (i) collagen/ADP cartridge (C/ADP): 67-127 s (ii) collagen/epinephrine (C/Epi): 94-162 s. From a panel of 125 patients undergoing evaluation for clinical haemostatic defects, 29/30 samples from patients with vWD [17/18 type 1, 1/1 type 3, 3/3 type 2A, 7/7 type 2B and 1/1 pseudo-vWD] gave prolonged CTs using C/Epi. The C/ADP was less sensitive, being normal in 7/18 of the type 1 vWD individuals, with higher sensitivity to more severe vWD. Individuals with haemophilia (six factor VIII-deficient, one factor XI-deficient) gave normal CTs, while those with clinical thrombocytopenia (n=13) gave normal or prolonged CTs, somewhat dependent on platelet count. The PFA-100 was also evaluated as a part of the laboratory monitoring procedure in patients with either vWD or haemophilia undergoing a DDAVP trial as a therapeutic management process. For vWD, correction of an initially prolonged CT by DDAVP, accompanied by normalization of von Willebrand factor (vWF) measurable by von Willebrand factor antigen, vWF collagen binding activity and vWF ristocetin cofactor assays (vWF:Ag, vWF:CBA and vWF:RCof), was achieved in type 1 vWD (n=5). In an individual with type 2A vWD, DDAVP normalized vWF:Ag and vWF:RCof, but had no apparent effect on the baseline maximally prolonged CT. In an individual with type 2B vWD, factor VIII/vWF concentrate also normalized vWF:Ag and vWF:RCof, but similarly had no apparent effect on the baseline maximally prolonged CT. vWF:CBA did not normalize for either of these individuals, potentially suggesting that normalization of vWF:CBA might be required for normalization of CT. This concept is supported by correlation analysis undertaken between CT and various vWF parameters. Among these, vWF:CBA held the strongest relationship in our data set, which showed an inverse progressive rise in CT for falling vWF:CBA. Based on these results, we would conclude that the PFA-100 is highly sensitive to the presence of vWD, and may thus provide a valuable screening test for vWD. Furthermore, the combined utility of the PFA-100 and vWF:CBA as markers of DDAVP responsiveness may prove to be simple, quick but powerful, predictors for its clinical efficacy.

Blood Protein Disorders↗

PubMed1958

Laboratory diagnosis of typhoid fever with notes on treatment.

As indicated by a study of 41 cases of typhoid fever treated in three years, blood culture alone is often sufficient for the diagnosis of the disease if a large (30 cc.) specimen is used. Demonstration of the organism is the only completely diagnostic measure, but this was also achieved by the Widal reaction, by fecal or urine culture, or by aspirated bile culture, which in one case gave the only positive response. Chloramphenicol is the drug of choice in treating typhoid fever. Since only 25 per cent of patients develop immunity, immunizing injections should be started a week after therapy is discontinued.

Adult↗

PubMed1993

Hepatitis E virus infection in Europe: regional situation regarding laboratory diagnosis and epidemiology.

Hepatitis E virus (HEV) was first identified in the excreta of an experimentally infected human volunteer and further confirmed by similar findings in clinical specimens from patients with acute jaundice disease different from hepatitis A and B. The HEV is a 27- to 34-nm spherical non-enveloped virus obviously represented by a single serotype; however, its final taxonomic definition remains to be established. Studies on molecular biology of this virus revealed some peculiar characteristics showing no homologies in its nucleotide sequence to any entries in the Genbank database. The HEV infection was experimentally transmitted to non-human primates producing a disease in many features similar to that occurring in humans. Recently cell lines persistently infected with the HEV have also been obtained. These studies provided valuable virus-specific reagents which were used in diagnostic tests. Currently immune electron microscopy, fluorescent antibody technique, latex agglutination, cDNA hybridization, and Western blotting are employed to prove the etiological involvement of HEV in suspected hepatitis cases; serological tests with synthetic substances analogous to HEV antigens are expected to be available soon. Reliable diagnostic procedures can be carried out in a number of laboratories with the locally produced reagents. The HEV infection is common in many hot climate countries being responsible for more than 50% of jaundice cases among young adults. The European region is considered to be free of natural foci of this infection, however, several sporadic cases of HEV disease were reported to occur in Europeans who developed jaundice shortly after returning from endemic areas. It is suspected that in the Mediterranean countries (Italy and Spain) the cases of HEV infection could be causatively related to the consumption of shell-fish cultivated in sewage-polluted waters.

Journal Article↗

PubMedDate not supplied

[The status and outlook of the laboratory diagnosis of rotavirus infection].

Rotavirus infection is not only the most distributed disease of children but a widely spread cause of their death. Nowadays considerable methodical potential which permits effectively detecting the whole virions, group A, antigens of human rotaviruses, virus-specific RNA in the clinical material is accumulated. There is a tendency to an increase of sensitivity and expressivity of the methods based on the use of immunological principles for detection and calculation of the antigen-antibody complex. Molecular-biological methods of the study are developed, which is important for the theory and practice of this infection control.

Antibodies, Viral↗

PubMed1993

Laboratory diagnosis of human immunodeficiency virus infection.

HIV infection and AIDS will continue to grow as a major medical and social problem. The incidence of heterosexual transmission is rising, and it will become increasingly difficult for physicians and counselors to assess an individual's risk of infection. In coming years, physicians can expect to see patients who are infected, but whose risk may not be apparent, and who may not present with conditions immediately suggestive of their infection. The majority of these patients may not even suspect they are infected. Many of the tests currently available for diagnosing HIV infection are very good. They are both highly sensitive and highly specific and their predictive values are good when their limits are understood. But, as HIV infection expands to an ever larger number of women and children and as the ability to sharply define risk groups fades, demand for a broader range of tests that can reliably confirm infection and are easy to perform can only increase. We have attempted to describe some of the common serologic tests currently used to diagnose HIV infection and some of the limitations of these tests. We also have pointed out that criteria used by laboratories for interpreting tests such as the Western blot may not always be uniform, and physicians should know the criteria used by their reference laboratory and the quality control measures taken. We also have attempted to describe some of the tests available to detect the virus, its genes, or its gene products. PCR and other rapidly evolving gene amplification techniques hold great promise as highly sensitive and specific tests for the diagnosis/confirmation of HIV infection. As with the serologic tests, it is important for those who may use these tests to understand their value as well as their limitations.

Blotting, Western↗

PubMed2000

Completeness and timeliness of treatment initiation after laboratory diagnosis of tuberculosis in Gaborone, Botswana.

SETTING: Gaborone, the capital of Botswana. OBJECTIVE: To determine the time from positive sputum smear microscopy for acid-fast bacilli (AFB) to initiation of therapy, and to identify risk factors for delays. DESIGN: Retrospective cohort study of medical records and surveillance data for patients with positive smear microscopy and newly diagnosed tuberculosis (TB) from January to May 1997. Treatment delay was defined as more than 2 weeks from the first positive sputum smear to the initiation of TB treatment. RESULTS: Of 127 patients identified, 15 (11.8%) had treatment delay, 13 (10.2%) had an incomplete workup (only one smear performed) and were not registered for TB treatment, and six (4.5%) had two or more positive smears but were not registered for TB treatment. Risk factors for treatment delay or non-registration included TB patients who had been diagnosed in a hospital outpatient setting vs. a clinic (RR 2.9, 95% CI 1.2-3.6, P = 0.02), or in a high volume vs. low volume clinic (RR 2.2, 95% CI 1.2-5.3, P = 0.01). CONCLUSION: More than a quarter of the smear-positive TB patients identified had treatment delay or no evidence of treatment initiation. Proper monitoring of laboratory sputum results and suspect TB patient registers could potentially reduce treatment delays and patient loss.

Adult↗

PubMed2000

[Laboratory diagnosis of intoxication in chronic dermatosis].

The content of medium molecular weight (MMW) substances in the blood and urine was studied in patients with chronic dermatoses (psoriasis and atopic dermatitis). Intoxication was detected in all these patients, which was confirmed by clinical symptoms and a high level of plasma MMW substances, indicating pronounced catabolic processes in this condition. The distribution of MMW substances in biological media and the absence of positive changes after treatment in patients with atopic dermatitis in comparison with psoriasis patients may be indicative of different mechanisms of biochemical homeostasis and different adaptation potential, which should be taken into consideration when prescribing correction.

Blood Proteins↗

PubMed1987

Laboratory diagnosis of megaloblastic anaemia: current methods assessed by external quality assurance trials.

The results of an Interregional quality assurance scheme for tests in the diagnosis of megaloblastic anaemia were reviewed to assess the methods used. Serum folate assays showed great variation between methods, partly due to limitations in assessment by external quality assurance. Red cell folate assays yielded widely different results and much imprecision due both to the differences in preparation of the haemolysate and to the problems inherent in radioassay of a mixture of folate compounds. Intrinsic factor antibody tests showed appreciable variation in sensitivity. There was considerable inconsistency in the detection of polymorph nuclear hypersegmentation.

Anemia, Macrocytic↗

PubMed1978

The laboratory diagnosis of megaloblastic anemias.

The diagnostic approach to megaloblastic anemia involves four usually sequential steps. The first step, recognition of megaloblastosis, requires attention to altered blood cell size and morphology. These changes may sometimes be subtle or masked. The cornerstone of the second step, identification of the specific vitamin deficiency, is assay of serum vitamin B(12) and folic acid levels, although they may occasionally be misleading. The third step, identification of the specific disease entity responsible for the vitamin deficiency, generally revolves around tests of absorption and gastric function. The fourth step, reevaluation after replacement therapy, is often not thought of as a diagnostic step but carries important diagnostic implications and is sometimes the only way in which coexisting abnormalities can be unmasked and identified.

Anemia, Macrocytic↗

PubMed2000

[Laboratory diagnosis of toxoplasmosis].

Toxoplasmosis is a world-wide spread parasitosis. The disease potentially highly affects two groups of patients: foetus and immunosuppressed patients. The determination of diagnosis and therapy on the basis of a single serum examination is very important; possible on the basis of a single serum sample. In most cases, it is possible to differentiate between recent and latent infections using a combination of suitable methods, which permit us to confirm particular antibody classes. In the presented paper the authors suggest diagnostic procedures for 4 groups of patients: pregnant, neonates with suspected congenital toxoplasmosis, immunodeficient patients and immunocompetent patients. The diagnostic methods consist of a combination of basic and supplemented diagnostic methods. Each patient's serum should be tested by basic tests which include the detection of total antibodies with CFT or IFT and specific classes of IgM and IgG antibodies by ELISA. The potential activity of toxoplasma infection can be determined by supplementary methods of e.g. IgG avidity antibodies, establishment of IgA antibodies, western blotting method and monitoring of antibodies production. For each situation the authors present interpretations of suspected cases including proposals for clinicians. These procedures are suggested for practical use in laboratories of various diagnostic levels in order to help to the diagnostic procedures in a particular situation as well as for clinical evaluation of established results. (Fig. 4, Ref. 65).

Female↗

PubMed2004

Laboratory diagnosis of a compound heterozygosity for Hb Hekinan [alpha27(B8) Glu-Asp] and a deletional alpha-thalassaemia 2 in Thailand.

We report the haematological and molecular characterization of a previously undescribed condition of compound heterozygosity for haemoglobin (Hb) Hekinan [alpha27(B8) Glu-Asp] and a deletional alpha-thalassaemia 2 detected in a Thai individual. Hb analysis demonstrated that although this Hb variant co-migrates with Hb A on cellulose acetate electrophoresis and cation-exchange high-performance liquid chromatography (HPLC), the HPLC procedure using a weak cation-exchange material with polyaspartic acid could clearly differentiate the two Hb. The variant could then be confirmed using the polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) analysis of the amplified alpha1-globin gene.

Adult↗