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PubMedDate not supplied

Update on the laboratory diagnosis and monitoring of HIV infection.

In China, the estimated number of HIV infected cases is approaching one million. Although public education has been initiated for awareness and behavioral modification for this devastating infection, better diagnostic methods are needed to identify infected persons and manage infection. Simple and more accurate diagnostic tools have become available, particularly for early detection and to monitor treatment in those who receive anti-retroviral treatment. In this short review, we summarize some of the common and new methodologies that can be used in clinical laboratories, in the field, or in private laboratories. These range from simple antibody tests to more sophistical methods that are used to monitor disease progression and identify drug resistance. These tools can assist physicians, medical practitioners, and laboratory personnel to select suitable diagnostic tools for the diagnosis, blood screening, monitoring of disease progression, and for detection of drug resistance to anti-retroviral therapies.

HIV↗

PubMed2004

Laboratory diagnosis of brucellosis in a rural endemic area in northeastern Spain.

Sera obtained from 62 patients from four mountain counties in Catalonia (Northeastern Spain), in whom brucellosis had been diagnosed on the basis of clinical evidence and/or personal history, were analyzed using the rose Bengal test, standard serum agglutination test (SAT), Coombs' test, ELISA, and complement fixation. The diagnosis was further confirmed through blood cultures. Clinical evidence, epidemiology, and the results from serologic tests were used to assign patients to one of two groups: group 1 (n = 38) patients had primary infections, whereas group 2 (n = 24) patients had been previously exposed to the microorganism, i.e. re-infection of group 2 individuals occurred after long periods of time during which no active infection by Brucella had been detected. Receiving-operating charts (ROC) were used to determine the diagnostic value of the different tests and to establish discriminant values. Blood culture was a valuable diagnostic tool in group 1 (0.92 sensitivity) but was inappropriate in group 2 (0.08). The combination of positive rose Bengal test and agglutination >/=1/160 was valid for diagnosis in group 1. In group 2, agglutination <1/160 (including negative agglutination) did not rule out brucellosis. The combination of positive rose Bengal test and Coombs' test >/=1/320 was the best diagnostic criterion (0.8 specificity; 1 sensitivity). ELISA (for IgG, IgM, or both) did not improve diagnostic accuracy.

Brucellosis↗

PubMed1993

Laboratory diagnosis of phaeochromocytoma: which analytes should we measure?

There is a diversity of advice in the literature as to which biochemical assays are best suited to the investigation of patients with a suspected phaeochromocytoma. The challenge for the clinical laboratory is to select those assays which detect all phaeochromocytomas, whilst having the lowest incidence of false positive diagnoses. We compared the sensitivity and specificity of a wide range of assays currently used for the biochemical diagnosis of phaeochromocytoma using either specific gas chromatographic-mass spectrometric (GC/MS) or high performance liquid chromatography-electrochemical detection (HPLC/ED) techniques. Noradrenaline (NA), adrenaline (ADR), dopamine (DA), 3,4-dihydroxyphenylglycol (DHPG), hydroxymethoxymandelic acid (HMMA), normetanephrine (NMET) and metanephrine (MET) were measured in 24 h urine specimens from 20 patients with histologically proven phaeochromocytoma and a large group of patients referred for investigation but subsequently found not to have a phaeochromocytoma. Because phaeochromocytomas are a heterogeneous group of hormone secreting tumours, no single analyte could achieve 100% sensitivity; 100% sensitivity was achieved only when the combination of both NA and ADR or NMET and MET was used. DA, DHPG and HMMA all had poor sensitivities. HMMA had a sensitivity of 70% when using the upper 95% confidence level (48 mumol/24 h) of the non-tumour patients as the cut-off. By lowering the cut-off to 35 mumol/24 h the sensitivity could be increased to 100% but at the expense of the specificity which was decreased from 98 to 92%. On the basis of this study we recommend the specific measurement of either NA and ADR or NMET and MET as the most suitable analytes for the detection of phaeochromocytoma, and further that, due to its poor specificity, HMMA be abandoned as a suitable analyte.

Adrenal Gland Neoplasms↗

PubMed1996

Molecular biology in medicine: laboratory diagnosis of tuberculosis.

Clinical mycobacteriology has benefited much from the application of molecular biology techniques. Early detection and identification of Mycobacterium tuberculosis are achieved by the combined use of the BACTEC system and deoxyribonucleic acid (DNA) probes. High-performance liquid chromatography is the other alternative used in some laboratories. Polymerase chain reaction is still a research tool because of its many problems and limitations. Other promising techniques for rapid diagnosis of Mycobacterium tuberculosis, for example, the serological diagnosis by enzyme-linked immunosorbent assay (ELISA), the Gen-Probe Amplified Mycobacterium tuberculosis Direct Test, DNA hybridization, the Mycobacteria Growth Indicator Tubes System and the strand displacement amplification system are currently under evaluation. The discovery of drug resistant genes such as katG and apoB has important implications for the development of new tests for the rapid detection of resistance to anti-tuberculous drugs.

Bacteriological Techniques↗

PubMed1991

Laboratory diagnosis of worms and miscellaneous specimens.

This article outlines the procedures to be followed when a macroscopic object thought to be a worm or other type of parasite is submitted to the clinical laboratory. These are often collected and submitted by the patient, but also may be submitted by the attending physician, the surgeon, or the pathologist. Examples of the various parasites and parasite-like objects that have been submitted to clinical laboratories are listed. Methods for preserving and examining such objects, using materials and reagents available in the clinical laboratory, are presented.

Animals↗

PubMed2005

Laboratory diagnosis of Clostridium difficile-associated diarrhoea: a plea for culture.

A routine protocol for diagnosing Clostridium difficile-associated diarrhoea (CDAD) based on both faecal-cytotoxin detection and toxigenic culture was adopted by the microbiology laboratory of the St Luc-UCL University Hospital in Brussels in 1997. A toxigenic culture is a faecal culture followed, in the case of positivity, by a direct immunoassay on colonies to detect toxin A production. The results obtained over the past 7 years in the hospital are reviewed here. A total of 10,552 diarrhoeal stools from 7042 patients were analysed, of which 9494 were negative for all tests. A total of 1058 samples (10 %) from 794 patients were culture-positive, of which 460 (4.4 %) were positive for a faecal cytotoxin. The remaining 598 cultures were tested for toxin A on colonies; 355 of them were positive, which is 3.4 % of the total, and the remaining 243 (2.3 %) were negative. The positivity of the faecal-cytotoxin assay was statistically linked to the number of colonies observed on the culture plate. In conclusion, over a 7 year period, toxigenic culture allowed the diagnosis of 355 cases of CDAD that would have been missed by a protocol using a faecal-cytotoxin assay alone. In terms of both patient care, prevention of environmental contamination and prevention of risk of a hospital outbreak, it is proposed that these results justify the recommendation to perform both faecal-toxin assay and culture in routine medical practice.

Bacteriological Techniques↗

PubMed1990

[The laboratory diagnosis of deep localized candidiasis].

A survey on the presently used methods for isolation and differentiation of Candida yeasts as well as on serological methods is presented. The difficulties of the pathognomonic evaluation of laboratory parameters are discussed.

Antibodies, Fungal↗

PubMed1989

Laboratory diagnosis of toxoplasmosis.

Acute infection with Toxoplasma gondii is diagnosed by (i) detection of the parasite directly in patients' specimens using histological or immunological methods, (ii) isolation of T. gondii from blood, body fluids or tissue by inoculation in laboratory mice or on tissue culture cells, or (iii) serological methods for determination of a significant, T. gondii-specific, antibody titre rise or of T. gondii specific IgM (or IgA) antibody. Because of their high sensitivity, specificity and relative ease of performance, serological methods are preferentially used for diagnosis of T. gondii infection. The diagnosis of acute, postnatally-acquired, primary toxoplasmosis is usually established by serological methods and will in general present few problems. However, diagnosis of congenital infections and their late sequelae or of reactivation of a latent infection in immunocompromised patients is often more troublesome because of the absence of a significant antibody titre rise or the lack of specific IgM antibody. In these cases a combination of various methods may be required for definitive diagnosis of T. gondii infection.

Animals↗

PubMed2002