Measurement of serum arabinitol by gas-liquid chromatography: limitations for detection of systemic candida infections

Current status of nonculture methods for diagnosis of invasive fungal infections

The incidence of invasive fungal infections has increased dramatically in recent decades, especially among immunocompromised patients. However, the diagnosis of these infections in a timely fashion is often very difficult. Conventional microbiologic and histopathologic approaches generally are neither sensitive nor specific, and they often do not detect invasive fungal infection until late in the course of disease. Since early diagnosis may guide appropriate treatment and prevent mortality, there has been considerable interest in developing nonculture approaches to diagnosing fungal infections. These approaches include detection of specific host immune responses to fungal antigens, detection of specific macromolecular antigens using immunologic reagents, amplification and detection of specific fungal nucleic acid sequences, and detection and quantitation of specific fungal metabolite products. This work reviews the current status and recent developments as well as problems in the design of nonculture diagnostic methods for invasive fungal infections.

Candida: a causative agent of an emerging infection

Incidences of infections due to Candida have increased over the last 15-20 y. This increase in the incidence and the high associated mortality rate despite therapy has focused the attention on this disease and prompted investigators to undertake research aimed at understanding the pathogenesis of this disease as well as methods to treat it. This paper discusses recent developments in the Candida field and the impact they have on patient management.

Guidelines for the investigation of invasive fungal infections in haematological malignancy and solid organ transplantation. British Society for Medical Mycology

Invasive fungal infections are increasing in incidence and now affect as many as 50% of neutropenic/bone marrow transplant patients and 5 to 20% of solid organ transplant recipients. Unfortunately, many of the diagnostic tests available have a low sensitivity. The guidelines presented here have been produced by a working party of the British Society for Medical Mycology in an attempt to optimise the use of these tests. The yield of fungi from blood cultures can be increased by ensuring that at least 20 ml of blood are taken for aerobic culture, by using more than one method of blood culture, and by employing terminal subculture if continuous monitoring systems are used with a five-day incubation protocol. Skin lesions in febrile neutropenic patients should be biopsied and cultured for fungi. The detection of galactomannan in blood or urine is of value in diagnosing invasive aspergillosis only if tests are performed at least twice weekly in high-risk patients. Antigen detection tests for invasive candidiasis are less valuable. Computed tomography scanning is particularly valuable in diagnosing invasive pulmonary fungal infection when the chest radiograph is negative or shows only minimal changes. Bronchoalveolar lavage is most useful in patients with diffuse changes on computed tomography scan. The major advances in the diagnosis of invasive fungal infection in patients with haematological malignancy or solid organ transplantation have been in the use of imaging techniques, rather than in the development of new mycological methods in the routine laboratory.

Gas chromatographic determination of D-arabinitol/L-arabinitol ratios in urine: a potential method for diagnosis of disseminated candidiasis

A gas chromatographic procedure was developed to determine the relative amounts of D- and L-arabinitol in urine. Samples were filtered, diluted, purified through extractions, evaporated, and treated with trifluoroacetic anhydride; the arabinitol derivatives thus obtained were separated on a chiral stationary phase and registered by using an electron-capture detector. Urine samples from a patient with disseminated candidiasis had higher D-arabinitol/L-arabinitol ratios (referred to as D/L-arabinitol ratios)--up to 19.0--than samples from 96 study individuals with no signs of deep Candida infections (range, 1.1 to 4.5). D/L-Arabinitol ratios in urine samples from hospitalized patients without Candida infections were slightly higher than those in samples from healthy individuals; ratios in urine from children were slightly higher than those in adult urine samples. The D/L-arabinitol ratios in several urine samples culture positive for Candida albicans, but from patients without symptoms of disseminated candidiasis, did not differ from those in the urine of healthy individuals. The described gas chromatographic method is straightforward and can be implemented clinically to determine urine D/L-arabinitol ratios as a means of diagnosing disseminated candidiasis.

Diagnosis and monitoring of disseminated candidiasis based on serum/urine D/L-arabinitol ratios

Disseminated candidiasis, a devastating disease with high morbidity and mortality in immunosuppressed patients, is difficult to diagnose because of the protean nature of symptoms and the lack of rapid and reliable laboratory diagnostic procedures. The subject of this review is the status of gas chromatographic-mass spectrometric techniques for the determination of D-arabinitol, a unique metabolite of pathogenic Candida species, in serum and urine. The enantiomers are separated by chiral chromatography followed by specific and sensitive detection using chemical ionization and selected ion monitoring. Using D/L-arabinitol ratios, instead of individual concentrations, eliminates the need for knowing the volume of samples and for calibration curves. A new filter paper technique requires only an unmeasured drop of whole blood (venous or finger/heel puncture) or urine; paper spots are mailable. Parallel determinations of D/L-arabinitol ratios in serum and urine in normal subjects and cancer patients with both normal and increased D/L-arabinitol ratios revealed constant (1.2-1.3 range) ratios of serum D/L-arabinitol/urine D/L-arabinitol for all populations studied. Analyzing two body fluids taken at the same time increases reliability by reducing false positives.