Reproducible assay results with high specificity and high PPV in a multicenter setting demonstrate that use of an assay to detect serum BG derived from fungal cell walls is a useful diagnostic adjunct for IFI.
The Glucatell (1r3)-b-D-glucan (BG) detection assay (Associates of Cape Cod) was studied as a diagnostic adjunct for invasive fungal infections (IFIs). On the basis of findings from a preliminary study of 30 candidemic subjects and 30 healthy adults, a serum BG level of у60 pg/mL was chosen as the cutoff. Testing was performed with serial serum samples obtained from 283 subjects with acute myeloid leukemia or myelodysplastic syndrome who were receiving antifungal prophylaxis. At least 1 serum sample was positive for BG at a median of 10 days before the clinical diagnosis in 100% of subjects with a proven or probable IFI. IFIs included candidiasis, fusariosis, trichosporonosis, and aspergillosis. Absence of a positive BG finding had a 100% negative predictive value, and the specificity of the test was 90% for a single positive test result and у96% for у2 sequential positive results. The Glucatell serum BG detection assay is highly sensitive and specific as a diagnostic adjunct for IFI.The mortality rate for invasive fungal infections in neutropenic subjects is 50% for subjects with Candida infection [1,2] and may approach 100% for those with invasive aspergillosis [3,4], fusariosis [5], or trichosporonosis [6]. Early diagnosis of invasive fungal infection in neutropenic subjects has the potential to increase antifungal therapeutic response, but meaningful diagnostic tests have proven to be elusive. Histopathologic demonstration of organisms in tissue specimens or growth of fungal agents in culture media is still the
We investigated the influence of spontaneous gut leakage upon polymicrobial sepsis in a lupus model with Fc gamma receptor IIb-deficient (FcGRIIb-/-) mice aged 8 and 40 weeks, as representing asymptomatic and symptomatic lupus, respectively. Spontaneous gut leakage, determined by (i) the presence of FITC-dextran, (ii) elevated serum endotoxin, and (iii) elevated serum (1→3)-β-D-glucan (BG), was demonstrated in symptomatic lupus but not in the asymptomatic group. In parallel, spontaneous gut leakage, detected by elevated serum BG without fungal infection, was demonstrated in patients with active lupus nephritis. Gut leakage induced by dextran sulfate solution (DSS) or endotoxin administration together with BG or endotoxin alone, but not BG alone, enhanced the severity of cecal ligation and puncture (CLP) sepsis more prominently in 8-week-old FcGRIIb-/- mice. Additionally, the bone marrow-derived macrophages of FcGRIIb-/- mice produced higher cytokine levels when coexposed to endotoxin and BG, when compared to wild-type mice. In summary, spontaneous gut leakage was demonstrated in symptomatic FcGRIIb-/- mice and the induction of gut permeability worsened sepsis severity. Gut translocation of endotoxin and BG had a minor effect on wild-type mice, but the synergistic effect of BG and endotoxin was prominent in FcGRIIb-/- mice. The data suggest that therapeutic strategies addressing gut leakage may be of interest in sepsis conditions in patients with lupus.
Gastrointestinal (GI) leakage is believed to exacerbate sepsis and new, validated markers of GI barrier performance might benefit clinical decision-making. Serum (1→3)-β-D-glucan (BG) was evaluated as a potential GI leakage marker. Serum BG was tested in several mouse models of GI leakage, including dextran sulfate solution (DSS) administration, endotoxin (LPS) injection, and cecal ligation and puncture sepsis (CLP). Serum BG titer was also evaluated in patients with sepsis and septic shock, for comparison.With 0.75% DSS administration, BG increased only after oral administration of heat-killed C. albicans, but increased spontaneously with 1.5% DSS. In the LPS and CLP models, BG increased as early as 1 h and at 12 h after LPS administration and surgery, respectively. GI leakage was confirmed by orthogonal validation methods including FITC-dextran oral administration in the DSS, LPS, and CLP models and, in the DSS model, with urine sucralose after oral administration and serum endotoxemia. IL-6 increased in parallel with serum BG. Serum BG or IL-6, at 18 h, anticipated sepsis mortality in the CLP model.Analysis of serum BG from patients with febrile neutropenic sepsis (N = 49) and febrile non-neutropenic sepsis (N = 39) demonstrated BG elevation. Patients with bacterial septic shock had serum BG titers similar to levels observed in invasive fungal disease, regardless of febrile neutropenia. Serum BG was lower in less severe cases of bacterial sepsis. Elevated serum IL-6 was associated with GI leakage and elevated serum BG.Serum BG may have potential as a sepsis/septic shock biomarker and further study in this context is warranted.
Candida albicans is the most common fungus in the human intestinal microbiota but not in mice. To make a murine sepsis model more closely resemble human sepsis and to explore the role of intestinal C. albicans, in the absence of candidemia, in bacterial sepsis, live- or heat-killed C. albicans was orally administered to mice at 3h prior to cecal ligation and puncture (CLP). A higher mortality rate of CLP was demonstrated with Candida-administration (live- or heat-killed) prior to CLP. Fecal Candida presented only in experiments with live-Candida administration. Despite the absence of candidemia, serum (1→3)-β-D-glucan (BG) was higher in CLP with Candida-administration than CLP-controls (normal saline administration) at 6h and/or 18h post-CLP. Interestingly, fluconazole attenuated the fecal Candida burden and improved survival in mice with live-Candida administration, but not CLP-control. Microbiota analysis revealed increased Bacteroides spp. and reduced Lactobacillus spp. in feces after Candida administration. Additionally, synergy in the elicitation of cytokine production from bone marrow-derived macrophages, in vitro, was demonstrated by co-exposure to heat-killed E. coli and BG. In conclusion, intestinal abundance of fungi and/or fungal-molecules was associated with increased bacterial sepsis-severity, perhaps through enhanced cytokine elicitation induced by synergistic responses to molecules from gut-derived bacteria and fungi. Conversely, reducing intestinal fungal burdens decreased serum BG and attenuated sepsis in our model.
The performance of the Fungitell assay was investigated in 100 patients with haematological malignancy undergoing chemotherapy who developed antibiotic-unresponsive neutropenic fever (AUNF). Serum beta-D-glucan (BG) concentrations were significantly elevated on the first day of AUNF and all subsequent alternate days to day 10 in 38 patients who developed an invasive fungal infection (IFI) compared to 42 patients remaining free of such infections. The mean and median values of BG were 171.9+/-29.6 and 95.8 pg ml(-1), respectively, for patients with IFI and 64.4+/-17.1 and 32.9 pg ml(-1) for patients with only AUNF (P<0.0001). The differences remained significant over the 10 days despite antifungal therapy. The occurrence of > or =2 sequential concentrations of > or =80 pg ml(-1) ('positive' test) was found to give the best overall option for diagnosis, with an accuracy of 81.3%, sensitivity of 86.8%, positive predictive value of 76.7% and negative predictive value of 86.5%. Of the patients with an IFI, 78% developed a positive test at or before the clinical diagnosis was made -- this occurred at a mean (range) of 1.25 (-14 to +14) days prior to the IFI diagnosis. By starting sampling of blood from the first day of neutropenia rather than from the first day of AUNF, 50% of the patients with subsequent IFI would have been identified 5 days earlier. Increasing sampling to daily from alternate-day frequency did not further improve this earlier timing of an IFI diagnosis. A greater proportion of patients with persistent high levels of BG without overt IFI had severe enterocyte damage or mucositis than those with lower levels of BG without IFI (P=0.002). If the results of the initial BG test had been acted on to change antifungal therapy, discontinuation would have been inappropriate in 30% of patients and would have delayed definitive antifungal therapy. Although the findings for the cohort of patients studied are very useful, there is inter-patient variability in the test's performance. An holistic diagnostic approach is therefore necessary to interpret the test results optimally. Future studies should address this in further detail as well as the impact of empirical antifungal drug use and patient outcome.
Blood (1 → 3)-β-D-glucan is strongly correlated with HIV-related PCP. In some clinical centers, this may be a more sensitive test than the induced sputum examination and could reduce the need for both bronchoscopy and empirical therapy of PCP.
Non-culture-based diagnostic strategies are needed for diagnosing invasive candidiasis (IC). We evaluated serial serum (133)--D-glucan (BG) levels in patients in the surgical trauma intensive care unit (SICU) patients with clinical evidence of IC. Serum samples from patients admitted to the SICU for a minimum of 3 days were collected twice weekly and analyzed for BG by using a Fungitell kit with a positive cutoff of >80 pg/ml. Diagnosis of IC was done using a set of predefined and validated clinical practice-based criteria. A total of 57 patients consented to participate and were enrolled. The median ICU stay was 16 days (range, 3 to 51). A total of 14 of 57 (25%) false positives were observed in the first sample (ICU day 3) and, overall, 73% of the day 3 samples had higher BG levels than subsequent samples. On the date of clinical diagnosis of IC, the sensitivity of a positive BG for identifying invasive candidiasis was 87%, with a 73% specificity. In patients with evidence of IC, the median BG value was significantly higher than those without evidence of IC (171 versus 48 pg/ml, P ؍ 0.02), respectively. In the three patients with proven IC, BG was detected 4 to 8 days prior to diagnosis. BG serum detection may be a useful tool to aid in the early diagnosis of IC in SICU patients, particularly after day 3 and in patients with at least two positive samples drawn several days apart. Elevated BG levels within the first 3 days need to be further characterized.
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