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PubMed2001

Laboratory diagnosis of central nervous system infections.

The laboratory diagnosis of CNS infection is essential for optimal therapy. Acute infection requires rapid turn-around testing with high predictive values, that is, the ability of a test to accurately identify those patients who do or do not have disease caused by a specific etiology. The Gram's stain, fungal stains of direct smears, antigen testing for C. neoformans, and culture of bacteria, fungi, mycobacteria, and some viruses are important tests for the diagnosis of acute infection. The laboratory diagnosis of chronic infection necessitates discussion between the clinician and laboratory technician to allow triaging of testing. Antigen tests for bacteria, fungi, and viruses; antibody tests for multiple microorganisms; and PCR testing for bacteria, M. tuberculosis, and many viruses are all important in limited clinical situations. All testing for acute or chronic disease depends on sufficient specimen that is transported to the laboratory in a manner that will not compromise viability or chemical integrity. Sterile containers that maintain moisture content, exclude oxygen for anaerobic requests, and are stored at proper temperatures (22 degrees C room, 4 degrees C refrigeration, or -20 degrees C freezer depending on pathogen and test) are mandatory. Many laboratory issues addressing the diagnosis of CNS infection are changing or evolving. Most important is the recognition that bacterial antigen testing for the diagnosis of acute bacterial meningitis rarely impacts patient management and is not routinely needed, CSF shunt infections differ from usual meningeal infections and require rapid diagnosis, and TB meningitis remains a difficult disease to diagnosis but may be confirmed first by PCR testing of CSF. In addition, Whipple's disease of the CNS can be confirmed using PCR with CSF; CJD has a marker protein, referred to as 14-3-3 antigen, that can be detected in CSF, and the diagnosis of fungal CNS disease requires careful interpretation of direct smears, antigen and antibody testing, and culture. Most difficult to diagnose among the CNS infections are viral meningitis and encephalitis. The appearance of new etiologies, such as West Nile virus, and the common use of PCR for the herpes viruses and enteroviruses represent important advances. Evolving methods for the laboratory diagnosis of CNS infection represent significant improvements over previous testing; however, the array of tests available demands more attention for appropriate selection, is significantly more expensive, and requires new skills for performance and interpretation. The responsibility for proper use of laboratory testing lies both with the clinician and laboratory technician.

Antigens, Bacterial↗
PubMed2006

Comparability of laboratory diagnosis and antimicrobial susceptibility testing of Neisseria gonorrhoeae from reference laboratories in Western Europe.

OBJECTIVES: The aim of this study was to obtain information on the comparability of methods for the laboratory diagnosis of bacterial sexually transmitted infections (STIs) that contribute to the surveillance data in the European Union (EU) and Norway. Surveillance of bacterial STIs is important across Europe because of the movement of individuals between countries at a time when STI incidence appears to be increasing in many countries. METHODS: Cross-sectional survey using a questionnaire, to provide information on laboratory methods for the diagnosis of gonorrhoea, and a panel of strains of Neisseria gonorrhoeae, to compare susceptibility testing, was circulated to laboratories in the EU and Norway. RESULTS: The questionnaire revealed marked diversity in the methodologies used for the laboratory diagnosis of gonorrhoea across Europe. Fourteen laboratories participated in an exchange of gonococcal strains to assess the methodology in current use for susceptibility testing. The methods included disc diffusion and determination of the minimum inhibitory concentration (MIC) using agar dilution and/or Etest. There was no common method used, each centre varied from another by at least one procedure. Overall agreement using all methods was >70%, being highest for ceftriaxone and lowest for tetracycline. Disc diffusion gave the lowest agreement with the consensus compared with determination of MIC by either agar dilution or Etest. CONCLUSIONS: A variety of methods were used across the EU and Norway for the laboratory diagnosis and susceptibility testing and resulted in poor concordance between laboratories on the definition of resistant N. gonorrhoeae. This suggests that there is a need for greater standardization of methodology that provides surveillance data in the EU and Norway.

Anti-Bacterial Agents↗
PubMed1978

New dimensions in the laboratory diagnosis of pancreatic disease.

The laboratory diagnosis of pancreatic disease has been made more precise by certain modifications in older methods and by the introduction of a variety of new technical procedures. The principal human isoamylases may now be distinguished and their activities in serum and urine measured. A test has been devised which helps indicate the presence of acute pancreatitis by showing relatively increased excretion of amylase in the urine as compared with creatinine. The ratio of amylase to creatinine in the urine appears to be a good index of relative hyperamylasuria. A screening test for pancreatic-type hyperamylasuria has been formulated that allows increased urinary excretion of this isoamylase to be identified. These additions and developments have sharpened the interpretation of hyperamylasemia and hyperamylasuria and have added new dimensions to the laboratory diagnosis of pancreatic disease.

Acute Disease↗
PubMed1980

[A suggestion for the uniform laboratory diagnosis of hemophilia].

The laboratory diagnosis of the haemophilia is performed in a different way in the individual laboratories. Differences in the selection and the performance of the methods used render differences in evidence, comparability and expenditure of time. The following proposition for a unitary laboratory diagnostics of haemophilia is made: 1. performance of a basic programme, 2. localisation of the coagulation defect with the help of the PTT using correction plasmas, 3. quantitative estimation of factors (possibly inhibitors) after one-step method, in which cases usual test sets of instruments with standardized directive for the performance are prerequisite for comparable results and a subdivision in degrees of severity.

Blood Coagulation Disorders↗
PubMed1998

[Laboratory diagnosis to dengue virus infections].

Currently, laboratory diagnosis of Dengue virus infection has a special importance because of its emerging character, showing a great geographic propagation of viral activity through out the American Continent. In general, the laboratory diagnosis of Dengue infections is similar to other human infecting viruses, the difference and difficulty of the process lies in the cross reaction activity with other flavivirus that can co-exist in the same region. The effectiveness of the diagnosis depends on the quality of the samples obtained, so it is absolutely necessary to monitor carefully the timing, conditions as well as the accompanying information during the gathering of the samples. The present article describes some of the serologic technics used in the diagnosis of dengue infection: hemaglutination inhibition, plaque reduction neutralization and IgM and IgG ELISA assays, in the same way it outlines the principles and importance of viral isolation and identification as well as the advantages of a new diagnosis technic like PCR.

Clinical Laboratory Techniques↗
PubMed1991

Laboratory diagnosis of HIV infection.

Laboratory diagnosis of human immunodeficiency virus (HIV) infection is complicated by absence of data on sensitivity, specificity and predictive value of the various tests as they apply to children. The presence of maternal anti-HIV passively transmitted across the placenta also confounds diagnosis. The authors review currently available data on the detection of HIV, HIV genome, and HIV gene products, as well as the diagnostic value of detecting serologic and cellular responses to HIV in infants and children.

AIDS Serodiagnosis↗
PubMed1987

[HIV infections in the Frankfurt area: results of viral serologic laboratory diagnosis].

Basing on routine laboratory diagnosis of serum antibodies to the human immunodeficiency virus (HIV-1) in the years 1985 and 1986, the monthly detection rate of infection amounts to 50 persons on an average in the region of Frankfurt/FRG. The relation of female to male persons changed from 1:7 to 1:3 during one year. This might be influenced by a screening programme performed with female prostitutes who are found seropositive in about 2.5%. In December 1986, the first case of an HIV-2 infection was recorded. The clinical examination of HIV-infected patients admitted to the City Hospital of Offenbach/FRG revealed striking signs in about 35-40%, of AIDS in 6%. The infected persons belong to risk groups. No positive result was seen in pregnant women (n = 1100), medical staff (n = 405) and patients requiring renal transplants (n = 115) who do not belong to the risk groups.

Acquired Immunodeficiency Syndrome↗
PubMed1981

General principles of laboratory diagnosis of mycoplasma infections.

Laboratory diagnosis includes 1) methods for direct microscopic demonstration of mycoplasma cells and antigens in animal and plant tissues or excreta, and cell cultures, 2) methods for isolation and growth of mycoplasmas from the said sources, and 3) techniques for identification and classification of mycoplasma isolates by a) determination of biochemical characteristics, and b) serological tests. A great many techniques are available for each of these purposes. Some of them have been used routinely for several years. Other methods that appeared promising when they were first introduced have never obtained general usage or they have more limited applications. Pertinent techniques will be reviewed and described. For demonstration of mycoplasmas in tissues, particular emphasis will be placed on immunofluorescence and immunoperoxidase tests. Attempts at isolation and cultivation of mycoplasmas should take into consideration the source, collection and transport of materials, elimination of growth-inhibiting factors in animals and plant tissues, special growth requirements of mycoplasmas, and the importance of cloning of cultures as a preliminary to further characterization. Although a number of biochemical tests are available for general characterization of mycoplasma isolates, precise identification of the species can usually be made only by serological techniques. For that purpose, growth inhibition, immunofluorescence, and (in the case of spiroplasmas) the deformation test combine the advantages of being highly specific and relatively easy to perform, and hence have obtained most widespread usage.

Antibodies, Bacterial↗
PubMedDate not supplied

Laboratory diagnosis and seroepidemiology of Lyme borreliosis.

Laboratory diagnosis of Lyme borreliosis is performed by direct detection of Borrelia burgdorferi in body fluids and tissue samples. This can be achieved by cultivation of the organisms, staining techniques, or demonstration of parts of the genome. Although the best aetiologic proof in case of positivity, these methods cannot yet serve as routine techniques: they are too time consuming and expensive. Currently, the usual method for establishing the diagnosis of Lyme borreliosis is serologic testing (indirect detection). Immunofluorescence, hemagglutination, ELISA tests with whole cell antigen should be considered as screening methods. Assays with selected fractions of B. burgdorferi antigens or tests using selected recombinant antigens should be considered as more specific. Immunoblotting (Western blotting) may be considered as a confirmatory test. However, the interpretation of test results requires an experienced investigator. Laboratory diagnosis of B. burgdorferi infections of the central nervous systems (CNS) is the most highly developed method. Demonstration of intrathecally produced specific antibodies, and, moreover, demonstration of specific oligoclonal bands may very well prove the actual infection of the CNS and/or the nerve roots. Seroepidemiological investigations identify neurological manifestations as the most frequent ones among European cases of Lyme borreliosis. The true incidence and prevalence of Lyme borreliosis, however, cannot be determined with current diagnostic methods and must await the development of methods to identify actual infection.

Enzyme-Linked Immunosorbent Assay↗
PubMed2002

Polymerase chain reaction for laboratory diagnosis of orf virus infections.

BACKGROUND: The orf virus of sheep and goats is one of several zoonotic parapoxviruses. In the ovine/caprine host it causes contagious ecthyma (contagious pustular dermatitis, scabby mouth), but in humans it normally causes solitary or clustered orf lesions, typically on hands, arms or face. In addition to disease in the animals, the virus can be quite a nuisance as an occupational hazard in farmers and butchers. Clinical diagnosis is often possible, but laboratory diagnosis is sometimes necessary. For virus isolation, primary ovine or bovine cells, not routinely present, are needed. Serological methods exist, but electron microscopy is the most commonly used method. OBJECTIVES: To develop a reliable method for the laboratory diagnosis of orf zoonoses, without virus culture and without access to an electron microscope. STUDY DESIGN: A suitable primer pair was designed for orf polymerase chain reaction (PCR), using the Oligo software and sequence information from GenBank. Orf positive controls and specimens were kindly provided by several public health centers. Molluscum contagiosum specimens were provided by a dermatologist. HSV-1, HSV-2 and VZV positive swab specimens came from our routine diagnostic service. Asymptomatic skin specimens were obtained from sheep heads from the abattoir, and swab specimens from the heads of asymptomatic sheep. Selected amplified orf PCR positive specimens were sequenced to ensure the authenticity of the PCR products. Orf positive specimens were sent to another laboratory for electron microscopy. RESULTS AND CONCLUSIONS: A robust PCR was developed, with very small inter-run variation. All specificity demands were met, and the sensitivity seems to be good or excellent. All negative specificity controls from cell cultures and non-orf viruses were negative. Twenty-two (95.7%) of 23 scab or swab specimens with suspected orf etiology were orf PCR positive. Five of eight skin specimens from sheep heads from the abattoir were positive, and all 11 swab specimens from asymptomatic sheep were negative. Electron microscopy demonstrated orf-like particles in orf-PCR positive specimens. This PCR seems to be suitable as a diagnostic test for orf in humans, but asymptomatic virus shedding in sheep or goats may complicate veterinary applications of the assay.

Animals↗
PubMed1989

Recent advances in the laboratory diagnosis of filariasis.

The specific laboratory diagnosis of filariasis depends either on the demonstration of circulating microfilaria in the peripheral blood or various stages of the parasite in tissue sections. Various morphological characteristics of the parasite will normally assist in its identification to the genus and specific level. Concentration techniques, especially those using the polycarbonate membrane filtration of a ml or more of heparinised blood, can detect the parasite in those with very low microfilaria counts. Serological techniques using the indirect fluorescent assay with microfilaria and adult worm antigens can assist in confirming a clinical suspicion of filaria infection when the parasite is not demonstrable. The development and use of specific monoclonal antibodies for the detection of circulating antigens in the enzyme-linked immunosorbent assay will probably increase the specificity of the assay. Presently available specific DNA probes for filariasis are probably not as useful for patient diagnosis as they are for epidemiological purposes.

Animals↗
PubMed1995

Recent advances in the laboratory diagnosis of equine parasitic diseases.

This article reviews recent advances in laboratory diagnosis of equine parasitic diseases. Laboratory diagnosis of most equine parasitic diseases continues to rely on standard methods. Only laboratory diagnostic tests for EPM, cryptosporidiosis, and giardiasis were included. The criteria for testing and interpretation of results for each new diagnostic method were explained. Western blot and PCR testing for EPM and immunofluorescent staining with monoclonal antibodies for cryptosporidiosis and giardiasis were reviewed.

Animals↗
PubMed2002

Tuberculosis. Advances in laboratory diagnosis and drug susceptibility testing.

Laboratory diagnosis of mycobacterial infection is complicated by the fastidious growth requirements of the bacillus organism. Delays in diagnosis can impede effective treatment and surveillance of the disease. Control of Mycobacterium tuberculosis has also been aggravated by the emergence of multidrug-resistant tuberculosis, and enhanced methods of antibiotic susceptibility testing are needed. Molecular laboratory techniques and advances in rapid culture methods have led to the development of diagnostic and drug susceptibility tests that are rapid and reliable. This article describes recent innovations in the molecular diagnosis and antibiotic susceptibility testing of M tuberculosis.

Animals↗
PubMed1989

Laboratory diagnosis of pneumonia.

Laboratory techniques for the diagnosis of pneumonia are discussed. Gram's stain and culture of the sputum are still the most useful techniques for the diagnosis of bacterial pneumonia. Antigen detection can provide a rapid diagnosis and contribute to the initial choice of therapy in infections caused by Haemophilus influenzae, Legionella pneumophila, Chlamydia psittaci and Pneumocystis carinii.

Clinical Laboratory Techniques↗