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PubMed1996

Laboratory diagnosis of acute lower respiratory tract viral infections in children.

This report summarizes and compares the results of complement fixation test (CFT), virus isolation (VI), and direct immunofluorescence test (DIF) for the antigen detection of respiratory syncytial virus (RSV), influenza A virus (Flu A), and adenovirus in 62 children with acute lower respiratory tract infections (ALRI) in Kuwait. It includes, as well, CFT results for parainfluenza virus and Mycoplasma pneumoniae. Combining the three methods, a potential causative agent was identified in 56 (90 per cent) children, of whom 14 (22 per cent) had evidence of infection with more than one pathogen. RSV was most frequently identified followed by Flu A, parainfluenza, Mycoplasma pneumoniae and adenovirus. Virus isolation proved the best method for identification of RSV, Flu A, and adenovirus [identified 52 (84 per cent) cases]. DIF was sensitive for RSV detection (sensitivity 84 per cent, specificity 94 per cent), and less sensitive for Flu A (sensitivity 62 per cent, specificity 98 per cent). However, DIF was completely insensitive to adenovirus (no positives). CFT was positive for the five pathogens in 44 (71 per cent) of the population studied; therefore, almost 20 per cent of positive identifications would have been missed if VI and DIF were not done. The sensitivity and specificity of CFT for RSV, adenovirus and Flu A were 71, 75, and 31 per cent, and 94, 96, and 94 per cent, respectively. Based on the results of this pilot study, it appears that a combination of the three tests yields the best rate of virus detection. Cell culture cannot be discarded for the identification of some respiratory viruses, especially adenovirus, until better techniques, or more sensitive reagents are applied. However, since RSV is the virus most commonly involved in children with ALRI, we recommend using DIF on routine basis for diagnosis. Its results compare well with virus isolation; it is simple, rapid, and inexpensive.

Acute Disease↗

PubMed1995

Laboratory diagnosis and interpretation of tests for syphilis.

The lack of a method for demonstrating the presence of Treponema pallidum by growth necessitates the use of alternative methods. Traditionally, these methods are divided into direct detection methods (animal inoculation, dark-field microscopy, etc.) and serologic tests for the presence of patient antibody against T. pallidum. Serologic methods are further divided into two classes. One class, the nontreponemal tests, detects antibodies to lipoidal antigens present in either the host or T. pallidum; examples are the Venereal Disease Research Laboratory and rapid plasma reagin and tests. Reactivity in these tests generally indicates host tissue damage that may not be specific for syphilis. Because these tests are easy and inexpensive to perform, they are commonly used for screening, and with proper clinical signs they are suggestive of syphilis. The other class of test, the treponemal tests, uses specific treponemal antigens. Confirmation of infection requires a reactive treponemal test. Examples of the treponemal tests are the microhemagglutination assay for antibodies to T. pallidum and the fluorescent treponemal antibody absorption test. These tests are more expensive and complicated to perform than the nontreponemal tests. On the horizon are a number of direct antigen, enzyme-linked immunosorbent assay, and PCR techniques. Several of these techniques have shown promise in clinical trials for the diagnosis of congenital syphilis and neurosyphilis that are presently difficult to diagnose.

Bacteriological Techniques↗

PubMed1993

Evaluation of four commercially available enzyme immunoassays for laboratory diagnosis of Clostridium difficile-associated diseases.

Four commercial enzyme immunoassays (EIAs) for the detection of Clostridium difficile toxin A have recently been developed and marketed (Premier, Meridian Diagnostics, Cincinnati, Ohio; VIDAS, bioMerierux Vitek, Inc., Hazelwood, Mo.; Tox-A-Test, TechLab, Blacksburg, Va.; and Bartels, Baxter Diagnostics, McGaw Park, Ill.). The performances of these EIAs were compared with those of the tissue culture cytotoxicity assay and a definition of C. difficile-associated disease based on both laboratory and clinical criteria for 329 clinical specimens. Two EIAs (Premier and VIDAS) showed good overall agreement (96 and 95%, respectively) with the cytotoxicity assay. However, they were less sensitive (84 and 71%, respectively) than the Bartels (94%) or Tox-A-Test (93%) EIAs. The Bartels and Tox-A-Test assays were much less specific, resulting in poor positive predictive values (56%) of the two assays when compared with that of the cytotoxicity assay. Tox-A-Test had the added drawback of having a significant number of indeterminate results (6.4%). These data indicate that the four EIAs all have specific shortcomings. When using these EIAs, testing strategies that take these shortcomings into consideration should be developed.

Adult↗

PubMed2006

Laboratory diagnosis and therapy of invasive fungal infections.

Diagnosing fungal infections remains a problem, particularly in the immunocompromised patient. Symptoms are mostly non-specific and colonization is difficult to distinguish from invasive disease. Existing diagnostic tools often lack sensitivity. Thus, the combination of various diagnostic tools is mandatory to allow earlier diagnosis of systemic fungal infections. Microscopy, culture based methods, antigen detection, and PCR may help to facilitate and accelerate the diagnosis. Galactomannan and glucan are two promising antigens that may be useful for early detection of the infection, but also for therapeutic monitoring. Sensitive and specific PCR assays to detect fungal DNA are an important part of the diagnostic approach. But extensive validation and standardization is strongly needed, before PCR assays can be used in a routine laboratory. The tremendous increase in invasive fungal infections has led to an increased interest in new antifungal agents and the field of antifungal chemotherapy evolved even more rapidly than diagnostic assays. The development of less toxic formulations of amphotericin B, the introduction of improved azoles and the availability of the echinocandins are opening new opportunities for the treatment of fungal infections. However, continuing efforts in the laboratory and well-designed clinical trials are still needed.

Animals↗

PubMed1978

[Pathogenicity of E. coli: biological aspects and problems related to laboratory diagnosis (author's transl)].

The biological properties which may contribute to the pathogenicity of E. coli are reviewed in this article. Specifically the following topics are discussed in detail: 1) adhesion to the intestinal epithelial cells, 2) production of enterotoxins, 3) invasiveness of and ability to multiply within the epithelial cells, 4) insensitivity to complement lysis or inability to activate the alternative pathway of complement, 5) resistance to phagocytic killing. The various techniques which might be of potential usefulness in the clinical laboratory to test the parameters of the pathogenicity of E. coli are briefly outlined. The dissociation between the definition of pathogenicity, as established on the basis of the results of E. coli serotyping, and the criteria of pathogenicity listed above is brought to the attention of the reader. As specificity regards the toxinogenicity, what emerged from a survey of the literature, was that only one of the so called "enteropathogenic" strains of E. coli, according to the serotype classification, was found to produce an enterotoxin.

Clinical Laboratory Techniques↗

PubMed1998

Is food poisoning a clinical or a laboratory diagnosis? A survey of local authority practices in the south Thames region.

An audit of South Thames infectious disease surveillance systems in 1995 revealed large inconsistencies between the numbers of food poisoning records held on local databases and the numbers of food poisoning notifications reported to the Office for National Statistics (ONS), then called the Office of Population Censuses and Surveys. In March 1996 a questionnaire sent to each local authority in South Thames asked what action was usually taken when a laboratory report of cryptosporidium, campylobacter, salmonella, or giardia was received unsupported by a notification of food poisoning. All 51 local authorities responded to the questionnaire. Forty-eight reported salmonella to ONS, 38 reported cryptosporidium, 38 campylobacter, and 37 giardia. Some local authorities considered whether a food or water source was evident or suspected before reporting. Patterns of notification varied between geographical areas. Differences between local authorities' interpretations of the requirement to report to ONS the isolations of food poisoning organisms from patients make it difficult to analyse food poisoning statistics. We would recommend the adoption of a simple approach, in which laboratory reports and notifications are reconciled locally. A case should be reported to ONS only if the doctor who notified or arranged for an examination of stool suspected food or waterborne transmission initially.

Disease Notification↗

PubMed2006

Laboratory diagnosis of norovirus.

Noroviruses are considered the most common cause of outbreaks of non-bacterial gastroenteritis worldwide, as well as being an important cause of sporadic gastroenteritis. Noroviruses were discovered by electron microscopy and this method played an important role in the diagnosis of noroviruses until the introduction of the reverse transcription-polymerase chain reaction procedure in the 1990's. In recent years, real time reverse transcription-polymerase chain reaction methodology has emerged as a potentially important diagnostic procedure. The recent introduction of commercial enzyme immunoassay kits has further broadened the range of techniques available to the diagnostic laboratory for detection of noroviruses. In addition, the technique of nucleic acid sequence-based amplification shows promise. This review examines the main features of current diagnostic methods for norovirus identification: electron microscopy, reverse transcription-polymerase chain reaction, real time reverse transcription-polymerase chain reaction, nucleic acid sequence-based amplification and enzyme immunoassay detection using a commercial kit.

Base Sequence↗

PubMed1976

Laboratory diagnosis of botulism complicated by pyridostigmine treatment of the patient. A method for selectively removing interfering substances from clinical specimens.

In August 1974, a case of botulism occurred; home-canned potatoes and peas containing Clostridium botulinum, type A, were strongly incriminated as the vehicle of transmission. C. botulinum, type A, was isolated from a stool specimen of the patient, but the mouse neutralization test for botulinal toxin could not be completed because the stool extract contained a highly toxic, heat-stable substance that rapidly killed mice. Historical and laboratory evidence indicated that the substance was pyridostigmine bromide, a low-molecular-weight drug with which the patient had been treated after her disease was misdiagnosed as myasthenia gravis. A generally applicable method employing dialysis by which toxic SUBSTANCED of low molecular weigth could be selectively removed from specimens without diminishing the potency of botulinal toxin contained in them was developed. Dialysis rendered a pyridostigmine solution, a stool extract from the patient with botulism, and a stool extract from a person taking pyridostigmine virtually nontoxic to mice. Dialysis did not significantly alter the toxicity to mice of crude botulinal toxin; it selectively eliminated all or almost all pyridostigmine toxicity from a pyridostigmine-botulinal toxin mixture without altering the toxicity of the botulinal toxin.

Animals↗

PubMed1985

[3H-estradiol-17 beta in laboratory diagnosis].

USSR made [3H]estradiol-17 beta was shown to be no inferior in quality to [3H]estradiol-17 beta produced by Amersham Int., Gr. Britain, for the determination of estrogen protein receptors in target tissues and for radioimmunoassay methods.

Clinical Laboratory Techniques↗

PubMedDate not supplied

[Emergency laboratory diagnosis of diphtheria].

The immune response to diphtheria toxin (clinically pronounced infection or carrier state with the presence of toxigenic bacteria) or toxoid (vaccination) the blood has been found to contain lymphocytes (1.00-5.71%), specifically binding diphtheria toxoid (DTX). The method for the determination of lymphocytes, specifically binding DTX, may serve both for early diagnosis and in the process of the disease, irrespective of the injection of therapeutic serum to the patient. The result of the test is obtained 2-3 days earlier than the positive result of the bacteriological analysis. The set of immune reagents for the rapid diagnosis of diphtheria by the method of rosette formation has been developed.

Antibodies, Bacterial↗

PubMed1980

High performance liquid chromatographic analysis of urinary catecholamines employing amperometric detection: references values and use in laboratory diagnosis of neural crest tumors.

We have developed an high performance liquid chromatographic procedure employing amperometric detection for the measurement of urinary free norepinephrine, epinephrine and dopamine. The between-day precision (C.V.) at various concentrations of the above analytes varied from 4.8-11.6%. There was negligible between-urine difference in the percent recovery of norepinephrine and epinephrine but considerable between-urine difference for dopamine. The procedure has been used to determine reference ranges in infants, children and adults. Its preliminary application to the laboratory detection of neural crest tumors is also described.

Adolescent↗

PubMed2002

Laboratory diagnosis of nontuberculous mycobacteria.

In conclusion, it is important to realize that there is no "stand alone" assay for the identification of NTM. Many new species may not be recognized in all assays. Newer molecular tests are more accurate for identification than phenotypic tests and have significantly improved turnaround time. Clinical significance of an isolate should be determined, however, before committing resources for the identification of a mycobacterial isolate to the species level. In addition, there are significant differences in the range and quality of services provided by different laboratories. Today, techniques and equipment are increasingly complex and costly, making it more difficult to upgrade every local laboratory to perform these assays. But because specimen delivery and communication of results can be rapidly and easily achieved, utilization of reference laboratories for rarely performed sophisticated tests is a more practical approach.

DNA, Bacterial↗

PubMed1996

A practical approach to the laboratory diagnosis of dyslipidemia.

Disorders in lipoprotein metabolism (dyslipidemia) can result in premature atherosclerosis or pancreatitis. Dyslipidemias can be classified as hypercholesterolemia, hypertriglyceridemia, combined hyperlipidemia, and low levels of high density lipoprotein (HDL) cholesterol. All of the dyslipidemias can be primary or secondary. Both elevated levels of low density lipoprotein cholesterol and decreased levels of HDL cholesterol predispose to premature atherosclerosis. Triglyceride levels greater than 1,000 mg/dL increase the risk for pancreatitis. In the appraisal of the dyslipidemias, measurement of serum cholesterol, triglycerides, HDL-cholesterol and obtaining the LDL cholesterol by Friedewald equation is usually sufficient in the majority of patients. However, in some cases, such as the diagnosis of the Type III dyslipidemia and when triglycerides are > or = 400 mg/dL, ultracentrifugation is required to determine the VLDL or LDL cholesterol. Lipoprotein electrophoresis can be useful in the diagnosis of Type III dyslipidemia (broad beta band) and also to detect chylomicrons. In young subjects with coronary artery disease with a normal LDL cholesterol an apolipoprotein B-100 level may be a useful test. In children and young adults with severe hypertriglyceridemia, measurement of lipoprotein lipase activity or assaying apolipoprotein C-II levels can be useful in elucidating the cause. Also, laboratory tests are useful in excluding a secondary cause of dyslipidemia (urinalysis, plasma creatinine, TSH, glucose, protein electrophoresis, alkaline phosphatase and transaminases). Thus, laboratory investigations play an important role in the management of dyslipidemia.

Chemistry, Clinical↗

PubMed1991

Laboratory diagnosis of hemoglobinopathies.

Diagnostic tests for most common hemoglobinopathies and recent advances in structural analysis of variant hemoglobins are reviewed. Routine and newly introduced methods that apply to the diagnosis of sickle cell anemia, thalassemia and the hemoglobin E disorders are presented. A brief description of the clinical course for each of these disorders is given, and potential pitfalls in diagnosis are discussed. Application of high-performance liquid chromatography and various mass spectrometric techniques (electrospray ionization mass spectrometry, liquid secondary ion mass spectrometry, and tandem mass spectrometry) for evaluation of hemoglobinopathy is presented.

Clinical Laboratory Techniques↗

PubMed2004

Review: IgA anaphylactic transfusion reactions. Part I. Laboratory diagnosis, incidence, and supply of IgA-deficient products.

Despite yielding a definitive diagnosis in fewer than 20 percent of anaphylactic transfusion reactions, investigation for IgA deficiency and the presence of presumably pathogenic IgG anti-IgA is useful in patient management. Individuals with demonstrated anti-IgA are thereafter committed to receiving IgA-depleted cellular products or IgA-deficient plasma and derivatives to prevent recurrent severe reactions. Unfortunately, in populations of IgA-deficient individuals screened for anti-IgA, the predictive value of the test in the absence of a prior reaction is quite low. Anti-IgA testing is complex and limited to a few reference laboratories, many of which still employ a labor-intensive hemagglutination assay developed in the late 1960s. Timely decisions regarding further transfusion management of patients experiencing anaphylaxis often rely upon more rapidly obtained assays of the IgA concentration as an indicator of the likelihood of subsequent demonstration of anti-IgA. The scarcity of IgA-deficient banked plasma products and dedicated plateletpheresis donors has led to the development of American Rare Donor Program policies designed to appropriately allocate these precious resources. The test methods used to establish the diagnosis of IgA deficiency and identify the approximately one third of these individuals with anti-IgA are discussed, along with the incidence of abnormal tests in various populations. Also presented are testing recommendations for the identification of an IgA-mediated mechanism for transfusion-associated anaphylaxis and qualification of patients to receive rare IgA-deficient plasma-containing products.

Anaphylaxis↗

PubMedDate not supplied

Office laboratory diagnosis of skin and soft tissue infections.

Some skin and soft tissue infections can be treated empirically without culturing. Some infectious sites should be cultured before initiating antimicrobial therapy. When there is a choice, permissive swab specimens are never as good as nonpermissive aspirate specimens. Swab specimens should be cultured semiquantitatively on agar media only in an attempt to distinguish normal flora contaminants from the infecting pathogen. Needle aspirate specimens can be obtained at most infectious sites invoking Sutton's law ("Go where the money is.") to identify the point of maximal involvement. Office laboratory identification in general should be limited to the identification of yeast forms on Gram stain and the initial separation of Group A streptococci from staphylococci. Other organisms should be sent to a referral laboratory for further identification and susceptibility testing.

Biopsy, Needle↗

PubMed1996

Lyme disease: laboratory diagnosis of infected and vaccinated symptomatic dogs.

Serological assays for detection of canine antibodies to the Lyme agent generally have been difficult to validate because an acceptable standard of comparison such as unequivocal proof of infection status has not been available. For practical and logistical reasons, it has not been possible to use culture of organism from infected animals, seroconversion in a large number of field dogs, or clinical criteria as the standard of comparison for validation of assays. Therefore, estimates of diagnostic sensitivity and specificity based on an appropriate gold standard have not been available. When it was discovered how to infect laboratory dogs via ticks infected with Borrelia burgdorferi, it was possible to define the kinetics and magnitude of the antibody response that might be expected in nature. ELISA and Western immunoblot data from experimental dogs were then compared and correlated with results of the same tests on dogs from endemic and nonendomic areas. Coupled with studies on cross-reactive antibodies elicited from other infectious agents or autoimmune phenomena, it was possible to account for interfering antibodies and to establish estimates of diagnostic sensitivity and specificity for the ELISA based on objective criteria. Such validated assays can predict, with a relatively high degree of proficiency, the infection and/or vaccinal status of animals. These assays have shown that some dogs, vaccinated with the commercially available whole-cell Lyme bacterins develop typical signs of Lyme disease but have no evidence of an underlying infection; antibody elicited only by the vaccine and not by infection is detectable in these animals. Western immunoblot can also confirm infection in animals of equivocal ELISA status if their bands have been evaluated for specificity of antibodies to B burgdorferi. Serology can be a very useful aid in the diagnosis of Lyme disease, but it requires that the assays used have been subjected to rigorous validation criteria. When that is not performed, an unacceptable level of false-positive and false-negative test results is virtually assured.

Animals↗

PubMed2006

Insights in the laboratory diagnosis of celiac disease.

The present report focuses on the diagnosis of celiac disease and its pathogenesis, which depends on a genetic predisposition (HLA DQ2 or DQ8 haplotypes), gluten ingestion and T cell activation, type II transglutaminase (TG2), the autoantigen recognized by the antiendomysial antibody playing a key role. IgA class antibody anti-environmental (gliadin) and endogenous (TG2) antigens are present in the sera of patients with celiac disease. The anti-TG2 antibody has the best available diagnostic accuracy, especially when measured employing second generation ELISA tests, which use the human TG2 antigen, or immunochemiluminescent assay, which is highly sensitive. A diagnosis of celiac disease must always be confirmed by the histological evaluation of multiple duodenal mucosa specimens, and serology is recommended for follow-up controls.

Antibodies↗