Albicans Germ Tube Research Articles

Candida albicans cDNA library screening reveals novel potential diagnostic targets for invasive candidiasis

The detection of patterns associated with the invasive form of Candida albicans, such as Candida albicans germ tube antibodies (CAGTA), is a useful complement to blood culture for Invasive Candidiasis (IC) diagnosis. As CAGTA are detected by a non-standardisable and non-automatable technique, a Candida albicans cDNA expression library was screened with CAGTA isolated from serum of an animal model of invasive candidiasis, and five protein targets were identified: hyphally regulated cell wall protein 1 (Hyr1), enolase 1 (Eno1), coatomer subunit gamma (Sec21), a metallo-aminopeptidase (Ape2) and cystathionine gamma-lyase (Cys3). Homology with proteins from other organisms rules out Cys3 as a good biomarker while Sec21 results suggest that it is not in the germ tubes surface but secreted to the external environment. Our analysis propose Ape2, Sec21 and a region of Hyr1 different from the one currently being studied for immunoprotection as potential biomarker candidates for the diagnosis of IC.

Anti-Candida Antibodies of Patients with Invasive Candidiasis Inhibit Growth, Alter Cell Wall Structure, and Kill Candida albicans In Vitro

Invasive candidiasis (IC), caused by Candida yeasts, particularly Candida albicans, poses a significant threat with high mortality rates. Diagnosis is challenging due to Candida's common presence in human microbiota. To address this, our research group developed an immunofluorescence assay detecting Candida albicans Germ Tube Antibodies (CAGTA) in IC patients. CAGTA, indicative of invasive processes, is associated with a lower mortality rate in ICU patients. Based on this premise, this study aims to provide results regarding the lack of knowledge about the potential activity of CAGTA against invasive infections in humans caused by the fungus Candida albicans. Therefore, in order to characterize the activity of CAGTA produced by patients with IC, we used sera from 29 patients with IC caused by either C. albicans or non-albicans Candida species. Whole serum IgG antibodies were fractionated into anti-blastospores, CAGTA-enriched, and purified CAGTA and the assessments included XTT colorimetric assays for metabolic activity, CFU counts for viability, and microscopy for growth, viability, and morphological analysis. The CAGTA-enriched IgG fraction significantly reduced the metabolic activity and viability of C. albicans compared to anti-blastospores. Purified CAGTA altered germ tube cell wall surfaces, as revealed by electron microscopy, and exhibited fungicidal properties by DiBAC fluorescent staining. In conclusion, antibodies in response to invasive candidiasis have antifungal activity against Candida albicans, influencing metabolic activity, viability, and cell wall structure, leading to cell death. These findings suggest the potential utility of CAGTA as diagnostic markers and support the possibility of developing immunization protocols against Candida infections.

Germ Tube Induction Test Comparing Total of Six Liquid and Three Solid Media in Candida albicans

Invasive candidiasis (IC) has a high mortality rate of 70%, thus diagnosis should be established without delay. Given its fast result, serological test such as β-d-glucan (BDG) test is one alternative diagnosis modalities. However, it lacks specificity. Candida albicans germ tube antibody (CAGTA) test is an alternative serological test which has a high sensitivity of 76.2% and specificity of 80.3%. Manufacturing CAGTA serological test requires provision of specific germ tube antigen. In this study, various culture media were tested to find the best media for germ tube induction. This study was an experimental in vitro study. The number and length of the germ tube were recorded in two- and three-hour incubation periods. A total of six samples containing one C. albicans ATCC 90028, four C. albicans wild type strains, and one C. krusei wild type strain were used. Nine media were tested to induce germ tube formation: human and sheep serum, fetal bovine serum, mueller hinton agar and broth, tryptic soy agar and broth, brain heart infusion agar and broth. At both incubation periods, the medium with the highest number of germ tube was human serum (p=0.001 and p=0). The longest germ tube was found in sheep serum at two-hour incubation period (p=0.005). Mueller hinton broth (MHB) showed comparable results with human and sheep serum (p>0.05). Human serum is a superior inducer of morphogenesis. However, the use of MHB is recommended in this study, since provision of fresh human and sheep serum on a regular basis is impractical.

How to Identify Invasive Candidemia in ICU-A Narrative Review.

The incidence of invasive fungal infection in ICUs has increased over time, and Candida spp. is the most common cause. Critical care patients are a particular set of patients with a higher risk of invasive fungal infections; this population is characterized by extensive use of medical devices such as central venous lines, arterial lines, bladder catheters, hemodialysis and mechanical intubation. Blood cultures are the gold standard diagnosis; still, they are not an early diagnostic technique. Mannan, anti-mannan antibody, 1,3-β-D-glucan, Candida albicans germ tube antibody, Vitek 2, PNA-FISH, MALDI-TOF, PCR and T2Candida panel are diagnostic promising microbiological assays. Scoring systems are tools to distinguish patients with low and high risk of infection. They can be combined with diagnostic tests to select patients for pre-emptive treatment or antifungal discontinuation. Candidemia is the focus of this narrative review, an approach to contributing factors and diagnosis, with an emphasis on critical care patients.

A Soluble Tetrazolium-Based Reduction Assay to Evaluate the Effect of Antibodies on <em>Candida tropicalis</em> Biofilms

Candida species are the fourth-most common cause of systemic nosocomial infections. Systemic or invasive candidiasis frequently involves biofilm formation on implanted devices or catheters, which is associated with increased virulence and mortality. Biofilms produced by different Candida species exhibit enhanced resistance against various antifungal drugs. Therefore, there is a need to develop effective immunotherapies or adjunctive treatments against Candida biofilms. While the role of cellular immunity is well established in anti-Candida protection, the role of humoral immunity has been studied less. It has been hypothesized that inhibition of biofilm formation and maturation is one of the major functions of protective antibodies, and Candida albicans germ tube antibodies (CAGTA) have been shown to suppress in vitro growth and biofilm formation of C. albicans earlier. This paper outlines a detailed protocol for evaluating the role of antibodies on biofilms formed by C. tropicalis. The methodology for this protocol involves C. tropicalis biofilm formation in 96-well microtiter plates, which were then incubated in the presence or absence of antigen-specific antibodies, followed by a 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-carboxanilide-2H-tetrazolium (XTT) assay for measuring the metabolic activity of fungal cells in the biofilm. The specificity was confirmed by using appropriate serum controls, including Sap2-specific antibody-depleted serum. The results demonstrate that antibodies present in the serum of immunized animals can inhibit Candida biofilm maturation in vitro. In summary, this paper provides important insights regarding the potential of antibodies in developing novel immunotherapies and synergistic or adjunctive treatments against biofilms during invasive candidiasis. This in vitro protocol can be used to check the effect of potential new antifungal compounds on the metabolic activity of Candida species cells in biofilms.

Effects of Natural Borneol on Germ Tube Formation and Preformed Biofilm Activity in Candida albicans

Candida albicans infection mainly occurs in patients with suppressed immune function and is the main pathogen of nosocomial infections. The use of natural products aimed at controlling fungal diseases is considered an interesting alternative to synthetic fungicides due to their lower adverse reactions and the lower cost of plant preparations compared to modern conventional pharmaceuticals. Natural borneol has a long history of treating ulcers and local infections in traditional Chinese medicine. In this study, we present an analysis of the in vitro effects of natural borneol on planktonic cells of C albicans in the liquid and vapor phases. We also investigated the effects of natural borneol on germ tube formation and mature biofilm activity of C albicans. We found that vapor-phase borneol (minimum inhibitory concentration [MIC] 0.4 mg/cm3) inhibited C albicans more effectively than in the liquid phase (MIC 2 mg/mL). The C albicans germ tube decreased by 99% to 60% at sub-MICs of 0.5 to 0.125 mg/mL. The inhibitory effects of 0.25, 0.5, 1, 2, and 4 mg/mL borneol on the biofilm activity were 33.7%, 48.6%, 49.9%, 52.9%, and 58.2%, respectively. Natural borneol may have potential in the treatment and prevention of C albicans infections.

Assessing Als3 Peptide-Binding Cavity and Amyloid-Forming Region Contributions to Candida albicans Invasion of Human Oropharyngeal Epithelial Cells.

Although it is widely recognized that disruption of ALS3 reduces the invasion of Candida albicans germ tubes into mammalian oral epithelial cells, the mechanism of this interaction was unexplored. C. albicans strains with structurally informed mutations to remove adhesive activity of the peptide-binding cavity (PBC) or aggregative activity mediated by the amyloid-forming region (AFR) were assessed for their ability to invade cultured human oropharyngeal epithelial cells. Initial assays utilized untreated fungal and epithelial cells. Subsequent work used epithelial cells treated with cytochalasin D and C. albicans cells treated with thimerosal to investigate invasion mediated by active penetration of germ tubes and epithelial cell induced endocytosis, respectively. Results demonstrated the importance of the PBC for the invasion process: loss of PBC function resulted in the same reduced-invasion phenotype as a C. albicans strain that did not produce Als3 on its surface. Invasion via active penetration was particularly compromised without PBC function. Loss of AFR function produced a wild-type phenotype in the untreated and thimerosal-treated invasion assays but increased invasion in cytochalasin D-treated epithelial cells. In previous work, reduced AFR-mediated Als3 aggregation increased C. albicans adhesion to cultured epithelial cell monolayers, presumably via increased PBC accessibility for ligand binding. Collectively, results presented here demonstrate that Als3 PBC-mediated adhesion is integral to its invasive function. These new data add to the mechanistic understanding of the role of Als3 in C. albicans invasion into mammalian oral epithelial cells.

Diagnosis and Management of Invasive Candida Infections in Critically Ill Patients.

Invasive candidiasis (IC) has become a serious problem in the intensive care unit patients with an attributable mortality rate that can reach up to 51%. Multiple global surveillance studies have shown an increasing incidence of candidemia. Despite their limited sensitivity (21-71%), cultures remain the gold standard for the diagnosis of IC associated with candidemia. Many adjunct laboratory tests exist to support or rule out the diagnosis, each with its indications and limitations, including procalcitonin, 1,3-β-D-glucan, mannan and anti-mannan antibodies, and Candida albicans germ tube antibody. In addition, polymerase chain reaction-based methods could expedite species identification in positive blood cultures, helping in guiding early empirical antifungal therapy. The management of IC in critically ill patients can be classified into prophylactic, preemptive, empiric, and directed/targeted therapy of a documented infection. There is no consensus concerning the benefit of prophylactic therapy in critically ill patients. While early initiation of appropriate therapy in confirmed IC is an important determinant of survival, the selection of candidates and drug of choice for empirical systemic antifungal therapy is more controversial. The choice of antifungal agents is determined by many factors, including the host, the site of infection, the species of the isolated Candida, and its susceptibility profile. Echinocandins are considered initial first-line therapy agents. Due to the conflicting results of the various studies on the benefit of preemptive therapy for critically ill patients and the lack of robust evidence, the Infectious Diseases Society of America (IDSA) omitted this category from its updated guidelines and the European Society of Intensive Care Medicine (ESICM) and the Critically Ill Patients Study Group of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) do not recommend it.

Antifungal and anti-inflammatory potential of the endangered aromatic plant Thymus albicans

Thymus albicans is an endemic species of the Iberian Peninsula with a vulnerable conservation status. In an attempt to contribute to the valorization of this species, the present study brings new insights on the antifungal and anti-inflammatory mechanism of action of T. albicans essential oil. The antifungal activity of the oil and its major compounds was assessed for the first time against standard and clinically isolated strains of yeasts and filamentous fungi. The effect on the two major virulence factors of Candida albicans (germ tube formation and biofilm disruption) was considered in more detail. At 0.08 μL/mL, the oil inhibited C. albicans germ tube formation by more than 40% and decreased biofilm biomass at MIC values, thus pointing out its antivirulent potential. The anti-inflammatory activity of the essential oil was investigated on LPS-stimulated mouse macrophages (RAW 264.7) by evaluating the levels of several pro-inflammatory mediators, namely nitric oxide (NO), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). T. albicans oil reduced the production of nitrites, a NO derived sub-product, at non-cytotoxic concentrations of 0.32 and 0.64 μL/mL, by 27 and 41%, respectively. In addition, the iNOS protein levels of essential oil pre-treated cells were reduced by 14%. Overall, the high essential oil yield of T. albicans as well as its bioactive effects at concentrations without cytotoxicity, encourage further studies on the potential pharmacological applications of this species. Furthermore, these results raise awareness for the need to preserve endangered species that may hold relevant medicinal value.

Effect of seasonal variation on the chemical composition and antioxidant and antifungal activities of Convolvulus althaeoides L. leaf extracts

The composition of polyphenols, chlorophylls and carotenoids of eight extracts of Convolvulus althaeoides L. leaves, harvested in two different seasons, winter and spring, and extracted by hot extraction method using four solvents (dichloromethane, chloroform, ethyl acetate and ethanol) with increasing polarity, were evaluated along with their antioxidant and antifungal activities. Qualitative and quantitative variations were observed in the composition based on two different high performance liquid chromatography systems, liquid chromatography-photodiode array detection coupled to either atmospheric pressure chemical ionization mass spectrometry or to electrospray ionization mass spectrometry, permitting the identification of 22 polyphenols, 11 chlorophyll derivatives and 10 carotenoid compounds. Polyphenolic compounds were predominant in extracts from leaves collected in winter, whereas pigments were predominant in the spring collections. Antioxidant activities of the extracts were determined by DPPH radical scavenging method, revealing a half inhibition concentration (IC50) ranging from 0.1369 ± 0.0272 mg g−1 to 0.432 ± 0.0018 mg g−1, with no correlation to seasonal fluctuation. Concerning antifungal assays, ethyl acetate and ethanol extracts have been shown to be the most active against dermatophytes (T. rubrum, T. menthagrophytes, M. canis), with inhibiting percentages reaching 100% with 50 mg mL−1. Moreover, ethyl acetate and ethanol extracts showed a maximum inhibition potential with minimum inhibitory/fungicidal concentrations ranging from 0.78 to 6.25 mg mL−1 on Candida spp. cultures. The winter collect of these extracts showed an inhibitory effect of 90% on Candida albicans germ tubes formation, at a concentration of 3.1 mg mL−1. In conclusion, seasonality seems to influence the quality and the quantity of natural substances from leaves of C. althaeoides L., which have major importance on the antioxidant and the antifungal effectiveness.

Antifungal activity of essential oil from Mentha spicata L. and Mentha pulegium L. growing wild in Sardinia island (Italy)

This study aims to evaluate the antifungal activity of Mentha spicata L. and Mentha pulegium L. from Sardinia and to assess their efficacy on virulence factors for Candida albicans, particularly on the inhibition of the germ tube formation. The major compounds of the essential oils were carvone (62.9%) for M. spicata and pulegone (86.2%) for M. pulegium. The essential oil from M. spicata showed a more preeminent effect against Cryptococcus neoformans and the dermatophytes Trichophyton rubrum and T. verrucosum (0.32 μL/mL). Both oils were very effective in inhibiting C. albicans germ tube formation, at doses well below their MIC (0.16 μL/mL).

Unveiling the Antifungal Potential of Two Iberian Thyme Essential Oils: Effect on C. albicans Germ Tube and Preformed Biofilms.

Fungal infections remain a burden worldwide, thus underpinning the need for effective new therapeutic approaches. In the present study, the antifungal effect of the essential oils of two thyme species, Thymus camphoratus and Thymus carnosus, used in traditional medicine in Portugal, as well as their major compounds was assessed. A special focus was placed on their effect on Candida albicans virulence factors. Also, the safety profile of the essential oils was assessed on keratinocytes. The essential oils were analyzed by gas chromatography (GC) and gas chromatography/mass spectroscopy (GC/MS). The minimal inhibitory and minimal fungicidal concentrations of the essential oils and their main compounds were assessed on reference and clinical strains. Also, their effect on C. albicans germ tube formation, metabolism, and biofilm disruption were considered. T. camphoratus oil was rich in 1,8-cineole and α-pinene whereas T. carnosus oil showed high amounts of borneol and camphene. Regarding the antifungal effect, both oils were more active against Cryptococcus neoformans and dermatophytes and very effective in inhibiting C. albicans germ tube formation, at doses well below their MIC and in a higher extend than the isolated compounds and fluconazole, an antifungal drug widely used in the clinic. The oils also disrupted preformed C. albicans biofilms. Furthermore, no toxicity was observed at pharmacological relevant concentrations towards keratinocytes. Our study validates the traditional uses ascribed to these Iberian species. Furthermore, it brings new insights on the antifungal potential and mechanism of action of these thyme species, thus paving the way for the development of novel effective antifungal drugs.

Diagnostic surveillance by Candida albicans germ tube antibody in intensive care unit patients.

The diagnosis of Invasive Candidiasis (IC) presents serious problems, mainly associated with the absence of pathognomonic symptoms of the disease and the difficulty of isolating the fungus in blood culture. Candida albicans germ tube antibody (CAGTA) provides a rapid and simple test for diagnosis of IC. The aim of this study was to evaluate the diagnostic role of the CAGTA in the monitoring of critically-ill patients at risk of developing IC. During diagnostic surveillance in the intensive care units (ICU) CAGTA was performed twice a week if predetermined risk factors were present and a positive result was considered when a serum titer ≥1/160 was detected in at least one sample. Seventy critically ill patients were included in the study. Twenty-three patients with proven/probable IC were identified. The sensitivity, specificity, PPV, and NPV of CAGTA for the diagnosis of proven/probable IC in all 70 patients were 91.3%, 68.1%, 58.3%, and 94.1%, respectively. Statistically significant highest titers were found in patients with proven/probable IC as well as increasing titers more than 1/160. Our results suggest that detection of CAGTA could be a useful biomarker for the diagnosis of proven and probable IC in critical patients during prolonged ICU stay. During the monitoring it is opportune to evaluate the titers kinetics since the clinical diagnosis of proven/probable IC coincided with increase titer from negative (<1/160) to more than 1/160.

Anti-Candidaalbicans germ tube antibodies reduce in vitro growth and biofilm formation of C. albicans

BackgroundInvasive candidiasis by Candida albicans is associated with high morbidity and mortality, due in part to the late implementation of an appropriate antifungal therapy hindered by the lack of an early diagnosis. AimsWe aimed to evaluate the in vitro antifungal activity of the antibodies against C. albicans germ tubes (CAGTA) raised in a rabbit model of candidemia. MethodsWe measured the effect of CAGTA activity by colorimetric XTT and crystal violet assays, and colony forming units count, both on C. albicans planktonic cells and during the course of biofilm formation and maturation. Viability and cell morphology were assessed by optical, fluorescent or scanning electron microscopy. ResultsCAGTA ≥50μg/ml caused a strong inhibition of C. albicans blastospores growth, and DiBAC fluorescent staining evidenced a fungicidal activity. Moreover, electron microscopy images revealed that CAGTA induced morphological alterations of the surface of C. albicans germ tubes grown free as well as in biofilm. Interestingly, CAGTA ≥80μg/ml reduced the amount of C. albicans biofilm, and this effect started at the initial adhesion stage of the biofilm formation, during the first 90min. ConclusionsThis is the first report showing that CAGTA reduce C. albicans growth, and impair its metabolic activity and ability to form biofilm in vitro. The antigens recognized by CAGTA could be the basis for the development of immunization protocols that might protect against Candida infections.

Suppression of the pathogenicity of Candida albicans by the quorum-sensing molecules farnesol and tryptophol.

This study examines the ability of the quorum-sensing molecules (QSMs) farnesol and tryptophol to induce programmed cell death of the pathogenic fungus Candida albicans, to alter the expression of apoptosis-related genes, and to reduce the pathogenicity and virulence of C. albicans in Galleria mellonella. Our results showed that both farnesol and tryptophol inhibited C. albicans germ tube formation. In the QSM-treated group, the expression levels of the apoptosis genes increased, whereas the expression level of the anti-apoptosis gene decreased. Further, pretreatment of C. albicans with tryptophol or farnesol prior to G. mellonella larval infection significantly enhanced host survival compared with larvae infected with untreated C. albicans. Thus, farnesol and tryptophol may trigger apoptosis of C. albicans in vitro and reduce the virulence of C. albicans in vivo. Although further study is needed to identify the precise mechanisms underlying the antifungal properties of farnesol and tryptophol, these results suggest that QSMs may be effective agents for controlling fungal infection.

Diagnostic accuracy of Candida albicans germ tube antibody for invasive candidiasis: systematic review and meta-analysis

BackgroundCandida albicans germ tube antibody (CAGTA) may be helpful as a marker for the diagnosis of invasive candidiasis (IC). However, the performance has been variable. We conducted a meta-analysis to assess the diagnostic accuracy of this assay for diagnosing IC. MethodWe searched MEDLINE, EMBASE, Cochrane Collaboration databases, reference lists of retrieved studies, and review articles. The sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and a summary receiver-operating characteristic curve of CAGTA for diagnosing IC were pooled using meta-analysis. ResultsA total of 976 patients (262 with proven or probable IC), included in 7 studies, were analyzed. The pooled sensitivity, specificity, positive and negative likelihood ratios, and diagnostic odds ratios and area under the curve were 66% (95% confidence interval [95% CI], 59% to 73%), 76% (95% CI, 58% to 88%), 2.8 (95% CI, 1.5 to 5.8), 0.44 (95% CI, 0.34 to 0.57), 6 (95% CI, 3 to 5), and 0.68 (95% CI, 0.64 to 0.72), respectively. Heterogeneity of specificity was significant. ConclusionThe diagnostic accuracy of the CAGTA assay is moderate for IC. Since the CAGTA assay is not absolutely sensitive and specific for IC, the CAGTA results should be interpreted in parallel with other biomarkers and clinical findings.

Performance of Candida albicans germ tube antibodies (CAGTA) and its association with (1 → 3)-β-D-glucan (BDG) for diagnosis daof invasive candidiasis (IC)

Invasive candidiasis (IC) plays an important role as severe infection. Elder population, immunocompromised individuals, and intensive care unit (ICU) patients, especially when exposed to major surgery, are the most affected. IC diagnosis and treatment are difficult because of the absence of pathognomonic signs and symptoms. In addition, culture-based examination (gold standard) is known to have low sensitivity and long time to report. All these often lead to unnecessary and costly empirical antifungal therapies, burdened also by the onset of drug resistance and serious side effects for the patient. To partially overcome these problems, in recent years, novel noncultural markers have been investigated with the aim of easily and rapidly achieving an early diagnosis of IC. Such novel markers include the pan-fungal antigen (1 → 3)-β-D-glucan (BDG) and the anti–Candida albicans germ tube antibodies (CAGTAs). We retrospectively analyzed the presence of CAGTA on −80 °C stored serum samples, where the level of BDG had been previously assessed in a prospective study conducted in the Azienda Ospedaliero–Universitaria Policlinic of Modena (Pini et al. Infection 44:223–233, 2016). In particular, we selected 29 samples from proven IC episodes and 28 from non-IC cases. The 29 IC samples had been diagnosed as infections by C. albicans (n = 16), C. glabrata (n = 8), C. parapsilosis (n = 1), C. pelliculosa (n = 1), and C. tropicalis (n = 1), while 2 samples had intrasurgery biopsies positive for yeast (compatible with Candida spp.). The 28 control samples (non-IC) included 9 sera with positive blood cultures [E. faecium (n = 5), S. pneumoniae (n = 2), P. aeruginosa + A. baumannii (n = 2)] and 19 negative blood cultures. The CAGTA immunofluorescence assay was performed using 1:40, 1:80, 1:160, and 1:320 dilutions (reference dilution, as indicated by the manufacturer). According to the protocol, the samples were evaluated by the operator-dependent optical reading based on immunofluorescence positive/negative samples. In parallel, with the aim of standardizing the reading, the fluorescence images were captured, and the data were expressed as arbitrary fluorescence units (AFU). Finally, the results were interpreted as positive or negative using a cutoff provided by receiver operating characteristic (ROC) curves (Youden index). The traditional operator-dependent optical reading and the AFU measuring protocol provided comparable information with respect to the processed samples since IC and non-IC sera were correctly identified by the 2 CAGTA reading strategies in most of the cases. Interestingly, the AFU reading enabled a semiquantitative evaluation of the samples and an objective interpretation of the results. Based on the cutoff value, the AFU-based CAGTA procedure demonstrated a sensitivity of 52% and a specificity of 89%, while BDG showed a sensitivity of 90% and a specificity of 75%; the overall accuracy was 70% and 83% for CAGTA and BDG, respectively. The association of the 2 markers greatly increased both sensitivity and accuracy to 97% and 84%, respectively. As expected, when excluding non–C. albicans episodes, the sensitivity of CAGTA increased from 52% to 86%; moreover, with the exclusion of the non–deep-seated episodes, the sensitivity of CAGTA increased to 67% and reached 100% for C. albicans deep-seated candidiasis. Finally, when evaluating the influence of colonization, BDG demonstrated the most drastic decrease in specificity that dropped from 88% in noncolonized to 58% in colonized patients. With the exception of non–C. albicans episodes, CAGTA is a good marker of IC, particularly in the presence of deep-seated candidiasis. The performance of CAGTA greatly increases when used in combination with BDG.

Diagnosis of invasive fungal disease in hospitalized patients with chronic obstructive pulmonary disease

BackgroundThe role of culture-independent techniques (galactomannan, (1-3)-β-d-glucan) in the early diagnosis of invasive fungal diseases (IFD) is well assessed in hematological patients, but there are no clear conclusions in patients with chronic obstructive pulmonary disease (COPD). AimsTo study the usefulness of nonculture-based techniques in the diagnosis of IFD in COPD-patients at risk for IFD. MethodsA prospective observational study based on monitoring COPD patients at risk for IFD during 2007–2010 was carried out. The presence of galactomannan, (1-3)-β-d-glucan and an indirect immunofluorescence of Candida albicans germ tube specific antibodies (CAGTA) were performed. ResultsAmong 43 COPD patients, 16 (37.2%) were diagnosed with IFD: seven cases were proven IFD (five invasive candidemia – IC, one invasive aspergillosis – IA and a rhinocerebral zygomycosis) and nine probable IFD (seven IA and two IC). In the diagnosis of IC and IA, the negative predictive value (NPV) of (1-3)-β-d-glucan was 100%. Regarding CAGTA in IC, NPV was 96.2%. Finally, NPV of galactomannan in IA was 91.2%. The area under the ROC curve for (1-3)-β-d-glucan in IC and for the rest of the IFD cases was 0.86 (95% CI, 0.79–0.93) and 0.60 (95% CI, 0.43–0.77), for CAGTA in IC was 0.83 (95% CI, 0.74–0.91) and for galactomannan in IA was 0.71 (95% CI, 0.56–0.85). Positive (1-3)-β-d-glucan preceded the growth of Candida (average of 1.7 days) in blood culture. ConclusionsIn COPD patients at risk for IFD the assayed techniques are especially useful to rule out the presence of IFD.

T2Candida MR as a predictor of outcome in patients with suspected invasive candidiasis starting empirical antifungal treatment: a prospective pilot study

We assessed the potential role of T2Candida MR (T2MR) and serological biomarkers [β-d-glucan (BDG) or Candida albicans germ tube antibodies (CAGTA)], alone or in combination with standard cultures, for identifying patients with suspected invasive candidiasis (IC), who may benefit from maintaining antifungal therapy. Prospective observational multicentre study including all adult patients receiving empirical antifungal therapy for suspected IC, from January to June 2017. CAGTA, BDG and T2MR were determined at baseline and at +2 and +4 days after enrolment. Primary endpoint was the diagnostic value of CAGTA, BDG and T2MR, alone or in combination with standard culture, to predict diagnosis of IC and/or mortality in the first 7 days after starting antifungal therapy (poor outcome). Overall, 14/49 patients (28.6%) had a poor outcome (7 died within the first 7 days of antifungal therapy, whereas 7 ended with a diagnosis of IC). CAGTA [3/14 (21.4%) versus 8/35 (22.9%), P = 1] and BDG [8/14 (57.1%) versus 17/35 (48.6%), P = 0.75] results were similar in poor- and good-outcome patients. Conversely, a positive T2MR was associated with a higher risk of poor outcome [5/14 (35.7%) versus 0/35 (0.0%) P = 0.0001]. Specificity and positive predictive value of a positive T2MR for predicting poor outcome were both 100%, with a negative predictive value of 79.6%. After testing the combinations of biomarkers/standard cultures and T2MR/standard cultures, the combination of T2MR/standard cultures showed a high capacity to discriminate patients with poor outcome from those with good clinical evolution. T2MR may be of significant utility to identify patients who may benefit from maintaining antifungal therapy.

Non-Culture Diagnostics for Invasive Candidiasis: Promise and Unintended Consequences.

Blood cultures are positive for Candida species in < 50% and < 20% of hematogenously disseminated and intra-abdominal candidiasis, respectively. Non-culture tests such as mannan, anti-mannan antibody, Candida albicans germ tube antibody (CAGTA), 1,3-β-d-glucan (BDG), the T2Candida nanodiagnostic panel, and polymerase chain reaction (PCR) are available for clinical use, but their roles in patient care are uncertain. Sensitivity/specificity of combined mannan/anti-mannan, BDG, T2Candida and PCR for candidemia are ~80%/80%, ~80%/80%, ~90%/98%, and ~90%/90%, respectively. Limited data for intra-abdominal candidiasis suggest CAGTA, BDG sensitivity/specificity of ~65%/75% and PCR sensitivity of ~85–90%. PCR specificity has varied widely for intra-abdominal candidiasis (33–97%), and T2Candida data are lacking. Tests will be useful if restricted to cases in which positive and negative predictive values (PPVs, NPVs) differ in a clinically meaningful way from the pre-test likelihood of invasive candidiasis. In some patients, PPVs are sufficient to justify antifungal treatment, even if blood cultures are negative. In most patients, NPVs of each test are excellent, which may support decisions to withhold antifungal therapy. If test results are not interpreted judiciously, non-culture diagnostics may have unintended consequences for stewardship and infection prevention programs. In particular, discrepant non-culture test-positive/culture-negative results may promote inappropriate antifungal treatment of patients who are unlikely to have candidiasis, and lead to spurious reporting of hospital-acquired infections. In conclusion, non-culture Candida diagnostics have potential to advance patient care, but this promise will be realized only if users understand tests’ strengths and limitations, and plan proactively for how best to employ them at their hospitals.