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

Determination of urinary D-/L-arabinitol ratios as a biomarker for invasive candidiasis in children with cardiac diseases

A non-invasive, non-culture-based method of determining urinary D-/L-arabinitol (D-/L-ARA) ratios was investigated as a tool for the diagnosis of invasive candidiasis in nosocomial paediatric infection cases. The study encompassed 138 children aged 4 days to 16 years (mean ± SD=1.6 ± 4.2 years) with congenital heart defects (91.4%) or with rhythm disorders or circulatory failure (8.6%). ARA enantiomers were detected by GC using an electron capture detector. Positive D-/L-ARA ratios were found for 11/11 patients with proven candidiasis and 17/19 patients with clinically suspected invasive candidiasis. Thirty children were undergoing antifungal chemotherapy. D-/L-ARA ratios (mean ± SD) were 2.601 ± 0.544 in hospitalized cardiac patients without fungal infection and 5.120 ± 1.253 in those receiving antifungal therapy (P<0.001). The sensitivity of the method was 100%, the specificity 97.2%, the positive predictive value was 78.6% and the negative predictive value was 100%.

Evaluation of disseminated candidiasis on an experimental animal model: a fourier transform infrared study

Invasive candidiasis, defined as candidemia and disseminated candidiasis, is the most common fungal infection in hospitalized patients. In the current study, we used Fourier transform infrared (FT-IR) spectroscopy as a rapid, non-perturbing technique to investigate the effects of disseminated candidiasis on mouse liver tissues at the molecular level. The results revealed that the infection caused compositional changes in the tissues by decreasing the lipid content and the ratio of the saturated lipids to unsaturated lipids. An increase in the lipid/protein ratio was also observed. In addition, investigation of the olefinic band at 3014 cm(-1) showed that lipid peroxidation took place in the infected samples. These results indicate that FT-IR spectroscopy is a promising technique for the evaluation and diagnosis of disseminated candidiasis.

Nonribosomal cyclic peptides: specific markers of fungal infections

Some cyclic peptides and depsipeptides are synthesized in microorganisms by large multienzymes called nonribosomal peptide synthetases. The structures of peptide products originating in this way are complex and diverse and are microorganism-specific. This work proposes the use of fungal cyclic peptides and depsipeptides as extremely specific markers of fungal infections. Since a reliable molecular tool for diagnosing fungal infections at an early stage is still missing, we present mass spectrometry as a new, modern, broadband (with respect to fungal strain) and specific tool for clinical mycologists. More than 40 different fungal species can be rapidly characterized according to specific families of cyclic peptides, and in some cases, a particular fungal strain can be identified on the basis of its cyclopeptide profile. This paper is also aimed at initiating discussion on the biological role of these secondary metabolites, especially of those synthesized by medically important strains. Proven cytotoxic, anti-inflammatory or immunosuppressive activities of some cyclic peptides indicate that these molecules may contribute to the synergistic array of fungal virulence factors and support microbial invasion during fungal infection. In addition to an overview on recent mass spectrometric protocols for cyclic peptide sequencing, the structures of new peptides from Paecilomyces and Pseudallescheria are presented.

Gas chromatographic determination of D-/L-arabinitol ratio in healthy Polish children

The D-/L-arabinitol enantiomers ratio (a marker of disseminated candidiasis of Candida species) in urine was determined by gas chromatography (GC) in 198 healthy Polish children ranging in age from 0 to 18 years. The urine samples were dry and trifluoroacetic anhydride (TFAA)-treated. Enantiomers derivatives were separated on a chiral column (beta-Dex 120, 60 m x 0.25 mm I.D.). A glass "solid-phase" injector and electron capture detector (ECD) were used. The ECD response was linear with correlation coefficients 0.999. The limit of detection was 0.02 micromol/l. Good results in terms of reproducibility, accuracy (RSD<10%, bias<6%), and linearity were obtained from real urine samples containing up to 400 micromol/l D-arabinitol. TFA-arabinitol derivatives in biological samples were stable from 1 to 5 days (depending on the arabinitol contents), while TFA-arabinitol standard derivatives were stable for 2 weeks. The identity of D- and L-arabinitol were confirmed by GC-MS analysis. The mean D-/L-arabinitol ratios ranged from 2.48 to 1.65 in the examined groups. The D-/L-arabinitol ratio was found to be exponentially regressive with age. A few cases of diagnosis of disseminated candidiasis by the GC method and confirmed by blood culture are described. The described GC method was also used for monitoring antifungal treatment of patients with disseminated candidiasis.

D-arabinitol--a marker for invasive candidiasis

The five-carbon sugar alcohol D-arabinitol (DA) is a metabolite of most pathogenic Candida species, in vitro as well as in vivo, and can be determined by gas chromatography or enzymatic analysis. Endogenous DA and L-arabinitol (LA) are present in human body fluids, and serum DA and LA increase in renal dysfunction. In prospective clinical studies, elevated DA/LA or DA/creatine ratios in serum or urine have been found in immunocompromised, usually neutropenic, patients with invasive candidiasis. In addition, positive DA results have been obtained several days to weeks before positive blood cultures, and the normalization of DA levels has been correlated with therapeutic response in both humans and animals. However, to date, only a few prospective studies have been conducted in which adequate analytical methods were used. Thus, further investigation of various patient groups is needed to establish the applicability of the 'arabinitol method' in the diagnostic battery for invasive Candida infections.

Diagnosis of invasive candidiasis in neutropenic children with cancer by determination of D-arabinitol/L-arabinitol ratios in urine

Determination of D-arabinitol/L-arabinitol ratios (referred to as D/L-arabinitol ratios) in urine as a tool for the diagnosis of invasive candidiasis was investigated in a prospective study comprising 100 children with cancer. The analyses were made by gas chromatography. Positive D/L-arabinitol ratios were found for 10 of 10 children with confirmed invasive candidiasis, 12 of 23 patients undergoing empiric antifungal chemotherapy, and 4 of 67 children not receiving antifungal treatment. D/L-Arabinitol ratios were positive 3 to 31 days (median, 12 days) before the first culture-positive blood sample was drawn or empiric therapy was initiated. The regular monitoring of D/L-arabinitol ratios in urine holds great promise as a sensitive method for diagnosing invasive candidiasis in immunocompromised children with cancer. Moreover, it may be possible to use an early rise in D/L-arabinitol ratios as a basis for the institution of antifungal chemotherapy and as a means of avoiding unnecessary treatment with potentially toxic antifungal agents.