Albicans Germ Tube Research Articles

¿Implica el aislamiento de Candida spp. en muestras intraabdominales de pacientes críticos la necesidad de tratamiento antifúngico?

The diagnostic and therapeutic approaches to IFI have changed significantly in recent years, fostered by the introduction of new diagnostic methods and new antifungal products. The diagnosis of invasive candidiasis (IC) involves both clinical and laboratory parameters, but neither of these are specific and the majority of the yeast isolated showed only colonization but not true infection. This situation occurs in critical care setting especially when surgical drainages are used. A substantial number of patients become colonized with Candida spp. after abdominal surgery, but only a minority subsequently develops invasive candidiasis. The clinical and microbiological diagnosis of Candida peritonitis remains problematic. It is still unclear which patients with may benefit from antifungal treatment. Antifungal therapy can be suggested in critically ill patients with peritonitis where Candida is diagnosed based on perioperatively sampled peritoneal fluid. Since fungal infection is also a relatively common complication of severe pancreatitis it seems reasonable that fungal prophylaxis may be an important component of management although actually there is no evidence to support this approach. However, the high mortality associated with IC is partly correlated to the difficulties of making an early diagnosis, thus, to improve earlier diagnosis and survival of IC, new nonculture-based microbiological tools such as Candida albicans germ tube antibodies (CAGTA) and/or polymerase chain reaction (PCR) techniques for the detection of fungal-specific DNA should be used in conjunction with recent published "Candida score" prediction rule. An algorithm based on this approach has been provided to assess early treatment in surgical patients with yeasts isolated from intra-abdominal samples.

A novel DSF-like signal from Burkholderia cenocepacia interferes with Candida albicans morphological transition

In addition to producing lethal antibiotics, microorganisms may also use a new form of antagonistic mechanism in which signal molecules are exported to influence the gene expression and hence the ecological competence of their competitors. We report here the isolation and characterization of a novel signaling molecule, cis-2-dodecenoic acid (BDSF), from Burkholderia cenocepacia. BDSF is structurally similar to the diffusible signal factor (DSF) that is produced by the RpfF enzyme of Xanthomonas campestris. Deletion analysis demonstrated that Bcam0581, which encodes an RpfF homologue, was essential for BDSF production. The gene is highly conserved and widespread in the Burkholderia cepacia complex. Exogenous addition of BDSF restored the biofilm and extracellular polysaccharide production phenotypes of Xanthomonas campestris pv. campestris DSF-deficient mutants, highlighting its potential role in inter-species signaling. Further analyses showed that Candida albicans germ tube formation was strongly inhibited by either coculture with B. cenocepacia or by exogenous addition of physiological relevant levels of BDSF, whereas deletion of Bcam0581 abrogated the inhibitory ability of the bacterial pathogen. As B. cenocepacia and C. albicans are frequently encountered human pathogens, identification of the BDSF signal and its activity thus provides a new insight into the molecular grounds of their antagonistic interactions whose importance to microbial ecology and pathogenesis is now becoming evident.

Identification of protein and mannoprotein antigens of Candida albicans of relevance for the serodiagnosis of invasive candidiasis.

Antigens from Candida albicans blastoconidia and germ tubes were identified by two-dimensional electrophoresis and Western blotting and characterized by microsequencing, reactivity with concanavalin A, and a panel of human sera. Antigens identified included a polydispersed area in the acidic high-molecular-mass regions of blastoconidium and germ-tube extracts, and 16 antigens varying in molecular masses and isoelectric points (pIs). The majority of the detected antigens, especially those in the polydispersed region, showed mannosyl groups, as determined by concanavalin A reactivity. Antibodies present in sera from patients with invasive candidiasis showed high reactivity with a number of antigens not detected with sera from blood donors. Eight of the 16 antigens could be identified by reactivity with monoclonal antibodies or by microsequencing. Five antigens showed homology with five enzymes previously described as antigens in C. albicans: enolase, phosphoglycerate kinase, malate dehydrogenase, and two isoforms of the fructose biphosphate aldolase. However, to our knowledge, this is the first report of the immunogenic activity of a kexin precursor, a mitochondrial complex I chaperone, and a diacylglycerol kinase catalytic domain from C. albicans. Antigens described in this study may be of potential interest for the serodiagnosis of invasive candidiasis.

Diagnosis of invasive candidiasis by enzyme-linked immunosorbent assay using the N-terminal fragment of Candida albicans hyphal wall protein 1

BackgroundThe diagnosis of invasive candidiasis is difficult because there are no specific clinical manifestations of the disease and colonization and infection are difficult to distinguish. In the last decade, much effort has been made to develop reliable tests for rapid diagnosis of invasive candidiasis, but none of them have found widespread clinical use.ResultsAntibodies against a recombinant N-terminal fragment of the Candida albicans germ tube-specific antigen hyphal wall protein 1 (Hwp1) generated in Escherichia coli were detected by both immunoblotting and ELISA tests in a group of 36 hematological or Intensive Care Unit patients with invasive candidiasis and in a group of 45 control patients at high risk for the mycosis who did not have clinical or microbiological data to document invasive candidiasis. Results were compared with an immunofluorescence test to detect antibodies to C. albicans germ tubes (CAGT). The sensitivity, specificity, positive and negative predictive values of a diagnostic test based on the detection of antibodies against the N-terminal fragment of Hwp1 by immunoblotting were 27.8 %, 95.6 %, 83.3 % and 62.3 %, respectively. Detection of antibodies to the N-terminal fragment of Hwp1 by ELISA increased the sensitivity (88.9 %) and the negative predictive value (90.2 %) but slightly decreased the specificity (82.6 %) and positive predictive values (80 %). The kinetics of antibody response to the N-terminal fragment of Hwp1 by ELISA was very similar to that observed by detecting antibodies to CAGT.ConclusionAn ELISA test to detect antibodies against a recombinant N-terminal fragment of the C. albicans germ tube cell wall antigen Hwp1 allows the diagnosis of invasive candidiasis with similar results to those obtained by detecting antibodies to CAGT but without the need of treating the sera to adsorb the antibodies against the cell wall surface of the blastospore.

Utilidad de la detección de (1→3)-ß-D-glucano y anticuerpos anti-micelio de Candida albicans para el diagnóstico y seguimiento terapéutico de la candidiasis invasora en pacientes neutropénicos adultos

The usefulness to diagnose and monitor invasive candidiasis (IC) using beta-glucan (BG) and antibodies against Candida albicans germ tubes (CAGT) was evaluated in a twice-weekly screening of 35 episodes in neutropenic adults at high risk. Three proven IC and three probable IC were assessed. Diagnostic levels of both markers were detected in 100% of proven IC and in 66% of probable IC. Sensitivity, specificity, positive and negative predictive values of BG and anti-CAGT antibodies detection were 83.3%, 89.6%, 62.5% and 96.3%, and 83.3%, 86.2%, 55.5%, 96.1%, respectively. False positive reactions occurred at a rate of 10.3% and 13.8% for the detection of BG and anti-CAGT antibodies, respectively. However, the patients with false positive results were different by each test. Both tests anticipated the clinical and radiological diagnosis, and the initiation of antifungal therapy in most patients. Combination of both tests improved specificity and positive predictive value to 100%.

In vitro synergistic effect of farnesol and human gingival cells against Candida albicans

Farnesol prevents the germination of yeast cells into mycelia, a fact that may be useful in eliminating C. albicans pathogenicity. Given the clinical potential of farnesol, its impact on C. albicans and host cells merited further investigation. We thus studied the effect of farnesol on C. albicans growth and filamentation and on gingival epithelial cells and fibroblasts and the synergistic effect of both gingival cells and farnesol on C. albicans filamentation. Repeated additions of farnesol reduced the growth of C. albicans. Farnesol was also effective at reducing C. albicans germ tube formation. While farnesol inhibited germ tube formation under the conditions tested, it was most effective at inhibiting C. albicans filamentation when added to the culture medium at the same time as the serum. Farnesol also had an effect on gingival cells. In a serum-free medium, farnesol reduced fibroblast adhesion and proliferation, promoted epithelial cell differentiation and reduced proliferation up to 48 h post-treatment. These effects were not seen in the presence of serum. When C. albicans, farnesol and gingival cells were present in the same culture, significantly greater inhibition of the yeast-to-hyphal transition was observed than germ tube inhibition in cultures containing only C. albicans and farnesol, suggesting a synergistic effect between the gingival cells and farnesol in inhibiting the transition. Overall, the data suggest that farnesol is effective against C. albicans and may have an effect on host cells at certain concentrations.

Anticuerpos anti-micelio de Candida albicans en dos pacientes de cuidados intensivos con candidiasis invasora

Two cases of invasive candidiasis in intensive care patients are presented to illustrate the usefulness of detection of antibodies to Candida albicans germ tubes in the diagnosis of invasive candidiasis and in monitoring the efficacy of the antifungal treatment.

Diagnostische Wertigkeit des Nachweises von Antikörpern gegen Candida‐Keimschlauchantigene bei einer Patientin mit hepatolienaler Candidose

ZusammenfassungBei einer 53jährigen Patientin mit akuter myeloischer Leukämie wurde bei Fieber in der späten Aplasie nach Chemotherapie die Diagnose einer invasiven Mykose mit charakteristischen Infiltrationen in der Leber und Milz gestellt. Zur serologischen Erkennung einer Candidose in der Frühphase der Infektion wurden zwei Nachweismethoden von Antikörpern gegen Candida‐Antigene verglichen. Der ELISA‐gestützte Nachweis von IgM und IgG Antikörpern gegen ein Gemisch von Candida‐Antigenen (ESR 117G und 117M, Virion‐Serion, Würzburg, Deutschland) zeigte die invasive Candidose deutlich früher (22 Tage) an als der Nachweis mittels Immunfluoreszenzdetektion von IgG Antikörpern gegen Candida‐Keimschlauchantigene (Vircell, Granada, Spanien). Im Fall der Patientin war die Detektion einer humoralen Immunantwort gegen Candida‐Keimschlauchantigene von geringer diagnostischer Bedeutung.

Expression of Transglutaminase Substrate Activity on Candida albicans Germ Tubes through a Coiled, Disulfide-bonded N-terminal Domain of Hwp1 Requires C-terminal Glycosylphosphatidylinositol Modification

By serving as a microbial substrate for epithelial cell transglutaminase, Hwp1 (Hyphal wall protein 1) of Candida albicans participates in cross-links with proteins on the mammalian mucosa. Biophysical properties of the transglutaminase substrate domain were explored using a recombinant protein representative of the N-terminal domain of Hwp1 and were similar to other transglutaminase substrates, the small proline-rich proteins of cornified envelopes found in stratified squamous epithelia. Recombinant Hwp1 lacks alpha and beta structures by circular dichroism and likely exists as a disulfide-cross-linked coiled-coil. The transglutaminase substrate property prompted a unique approach for investigating the features of surface Hwp1 on germ tubes. A lysine analog, 5-(biotinamido)pentylamine, was cross-linked to germ tubes catalyzed by transglutaminase 2 prior to cell fractionation, immunoprecipitation, and detection with streptavidin conjugates. The majority of the transglutaminase-modifiable Hwp1 was covalently attached to the beta-glucan of hyphae by the C terminus of Hwp1 via a glycosylphosphatidylinositol remnant anchor. A putative precursor of cell wall forms of Hwp1 was identified in the cell extract and in the culture medium. Hwp1 was modified by relatively short N-linked glycans, and the molecular size of the protein was reduced by hypomannosylation when expressed in O-glycosylation mutant strains. Hwp1 combines features of mammalian transglutaminase substrate proteins with characteristics of fungal cell wall proteins to form an unconventional adhesin at the hyphal wall of C. albicans.

Evaluación de una nueva técnica comercializada (Candida albicans IFA IgG) para el diagnóstico de la candidiasis invasiva

Two tests for the detection of antibodies to Candida albicans germ tubes in patients with invasive candidiasis were compared: a new commercially available test (Candida albicans IFA IgG) and the indirect immunofluorescence test generally used for this purpose. With the use of two indirect immunofluorescence tests, retrospective study was done on 172 sera from 51 patients classified into two groups: Group I included 123 serum samples from 32 patients with invasive candidiasis, and Group II, the control, included 49 serum samples from 19 patients with no evidence of Candida infection. In Group I, 84% of patients presented anti-germ tube antibody titers >or= 1:160 by the Candida albicans IFA IgG test and 78.1% of patients were positive by the generally used test. There was a high correlation between the two tests (R2 =0.9512 by patients; R2 = 0.8986 by sera). When a titer value of >or= 1:160 was used as cutoff, the Candida albicans IFA IgG test showed a sensitivity of 84.4% and a specificity of 94.7%, whereas the traditional test showed a sensitivity of 78.1% and a specificity of 100%. The commercially available Candida albicans IFA IgG test is similar to the test generally used for the detection of antibodies to C. albicans germ tubes and provides faster and easier diagnosis of invasive candidiasis in the clinical microbiology laboratory.

Detection of anti-Candida antibodies by the indirect immunofluorescence assay in patients with cancer in the orofacial region.

An indirect immunofluorescence assay was performed to detect antibodies to Candida albicans blastospores and germ tubes. Serum specimens were obtained from 82 patients with neoplastic diseases in the orofacial region and thrush of the oral mucosa. C. albicans was identified in the oral cavity of 63 patients investigated but serum anti-Candida antibodies were detected in only 23 of them. Serological examination showed that titers of antibodies to C. albicans blastospores ranged from 1:20 to 1:1280. High titers from 1:640 to 1:1280 were detected in patients without antibiotic, cytostatic, or radiotherapeutic treatment. The titers of antibodies to C. albicans germ tubes ranged from 1:20 to 1:640. Our results indicate that titers of antibodies to the C. albicans germ tubes were lower and were detected in a smaller number of patients.

Detection of anti-Candida antibodies in neonates from a Neonatal Intensive Care Unit.

Anti-Candida antibodies were determined in a group of preterm neonates from a neonatal intensive care unit with serious diseases including candidemia. Antibodies to C. albicans blastospores, i.e. antibodies to C. albicans surface mannan and to C. albicans germ tubes were detected. Higher titers of antibodies to blastospores (1:320) occurred in all patients examined while antibodies to C. albicans germ tubes (with the highest titer of 1:160) were present in 32 out of 66 neonates examined. The highest titers of both anti-C. albicans blastospore antibodies and anti-C. albicans germ tube antibodies were detected in neonates with candidemia and disorders of saccharide metabolism.

Involvement of αvβ3 integrin-like receptor and glycosaminoglycans in Candida albicans germ tube adhesion to vitronectin and to a human endothelial cell line

The present study was undertaken to investigate the expression of αvβ3 and αvβ5 integrin-like vitronectin receptors (VNRs) on Candida albicans germ tube and their involvement in its adhesion to vitronectin (VN) and human endothelial cells. By immunofluorescence and FACS analysis, several monoclonal antibodies directed against human αv or β3 integrin subunit or αvβ3 and αvβ5 heterodimers, positively stained C. albicans germ tubes. C. albicans germ tubes specifically adhered (45–50%) to VN and this adhesion was markedly inhibited by RGD-, but not RGE-containing peptides. Adhesion of C. albicans germ tubes to VN was strongly inhibited by anti-αv, anti-β3 or anti-αvβ3, but not by αvβ5 monoclonal antibody. C. albicans germ tube adhesion to VN was also inhibited by glycosaminoglycans (GAGs) such as heparin or chondroitin sulphate. Finally, we show thatC. albicans germ tubes adhere to the human EA.hy 926 endothelial cell line. This adhesion is markedly blocked by anti-β3 monoclonal antibody, GRGDSP peptide or heparin, and is completely abolished by their combination. Overall these results indicate that C. albicans germ tube adherence to VN and to a human endothelial cell line is mediated by αvβ3, but not by αvβ5-like integrin, and depends on GAGs which may act by regulating αvβ3 integrin-like/VN adhesive interaction.

Detection of antibodies to Candida albicans germ tubes in heroin addicts with systemic candidiasis

Detection of antibodies to Candida albicans germ tubes in heroin addicts with systemic candidiasis

Influence of Environmental pH on the Reactivity of Candida albicans with Salivary IgA

Salivary secretory IgA reacts with a group of heat-shock mannoproteins preferentially expressed on Candida albicans yeast cells and germ tubes grown at 37 degrees C. Since other environmental factors can also modulate the expression of those antigens, we have investigated the influence of the pH of the culture medium on the expression of the antigens reacting with human salivary IgA by C. albicans. By indirect immunofluorescence, yeast cells grown in Sabouraud glucose broth at 37 degrees C showed a statistically significant increase in reactivity with salivary IgA (p < 0.0001) when compared with cells grown at 25 degrees C at the 4 pH values studied (3.3, 5.9, 7.5, and 9.5), the highest reactivity and the major heat-shock effect being observed at pH 5.9. The decrease in reactivity with salivary IgA observed in C. albicans cells grown at pH values of 3.3 and 9.5 was confirmed by Western blotting. Salivary IgA reacted with polydispersed materials from the cell walls of molecular masses > 55 kDa, which were more expressed at neutral pH than at acidic or alkaline pH values. A similar reactivity was observed when the antigenic extracts were stained with an antiserum directed against oligosaccharides present in antigen 6 of C. albicans serotype A. The differences in reactivity presented by salivary IgA may be related to a decrease in the expression of polysaccharides present on the surfaces of the yeast cells of C. albicans grown at acidic or alkaline pH values. The low reactivity of salivary IgA with C. albicans cells grown at acidic pH values may help to explain the association between acidic saliva and the carriage of Candida in the oral cavity, as well as with oral candidiasis.

Antimycotic Activity and Phagocytosis Effects of Econazole in Combination with Ibuprofen Isobuthanolammonium Against Vaginal Strains

Vaginal infections caused by Candida spp., other yeasts and Trichomonas vaginalis are problematic mainly due to the various factors involved in development of infection and to the failure of common treatments. In this study we investigated the presence of synergistic activity of econazole and ibuprofen isobuthanolammonium against 310 different vaginal isolates, by using the microdilution broth assay to test in vitro antimicrobial activity and the effect of the two drugs on phagocytosis and intramacrophagic cellular killing of mouse peritoneal macrophages. The effect of sub-inhibitory concentrations of econazole / ibuprofen isobuthanolammonium combination on Candida albicans germ tube formation was also evaluated. The in vitro antifungal activity of econazole was notably improved by addition of ibuprofen isobuthanolammonium. Macrophage killing of C. albicans was significantly increased by the two drugs and also germ-tube formation was significantly affected. We conclude that the addition of ibuprofen isobuthanolammonium to econazole provides better in vitro antifungal activity. However, further studies are needed to elucidate the in vivo action of this formulation.

The Role of Candida albicans Germ Tube Formation in Adherence to Cultured Enterocytes

The Role of Candida albicans Germ Tube Formation in Adherence to Cultured Enterocytes

Rapid identification of Candida dubliniensis by indirect immunofluorescence based on differential localization of antigens on C. dubliniensis blastospores and Candida albicans germ tubes.

There is a clear need for the development of a rapid and reliable test for the identification of Candida dubliniensis and for the discrimination of this species from Candida albicans. In the present study we have investigated the potential use of C. dubliniensis-specific antigens as a basis for its identification. We produced an anti-C. dubliniensis serum which, after adsorption with C. albicans blastospores, was found to differentially label C. dubliniensis isolates in an indirect immunofluorescence test. In this test, the antiserum reacted with blastospores and germ tubes of C. dubliniensis and with blastospores of Candida krusei and Rhodotorula rubra but did not react with blastospores of several other Candida species including C. albicans. The antiserum also reacted with C. albicans germ tubes. The anti-C. dubliniensis adsorbed serum reacted with specific components of 25, 28, 37, 40, 52, and 62 kDa in the C. dubliniensis extract and with a variety of antigens from other yeast species. The antigens from non-C. dubliniensis yeasts showing reactivity with the anti-C. dubliniensis adsorbed serum are mostly expressed within the cell walls of these yeast species, and this reactivity does not interfere with the use of the anti-C. dubliniensis adsorbed serum in an indirect immunofluorescence test for the rapid identification of C. dubliniensis.

Detection of antibodies to Candida albicans germ tubes during experimental infections by different Candida species.

Identification and characterization of Candida albicans germ tube-specific antigens may be of relevance for the serodiagnosis of invasive candidiasis since they could be the basis for the development of new diagnostic tests. In this study, we have identified two antigens of 180 and >200 kDa in the cell wall of C. albicans germ tubes which are responsible for the induction of antibodies to C. albicans germ tubes. Antigens of similar molecular masses have been demonstrated in the cell walls of the Candida species C. stellatoidea, C. parapsilosis, C. guilliermondii, C. tropicalis, and C. krusei, but not C. glabrata. The kinetics of the antibody responses to C. albicans germ tubes were studied in rabbits infected with different Candida species. Although these antibodies were detected in rabbits infected with all Candida species except C. glabrata, the kinetics of the antibody responses to C. albicans germ tubes induced by the Candida species studied were different. Both the highest titer and the earliest response of antibodies to C. albicans germ tubes were observed in rabbits infected with either of the two serotypes of C. albicans used. However, the time needed to elicit the antibodies to C. albicans germ tubes can be reduced as the result of an anamnestic antibody response. The results presented in this study show that a test designed to detect antibodies against C. albicans germ tube antigens may be suitable for the diagnosis of infections caused by most of the medically important Candida species.

Detection of antibodies to Candida albicans germ tubes for diagnosis and therapeutic monitoring of invasive candidiasis in patients with hematologic malignancies.

We prospectively investigated the ability of detection of antibodies to Candida albicans germ tubes (CAGT) to diagnose invasive candidiasis in 95 consecutive admissions of 73 patients with hematologic disorders undergoing intensive chemotherapy. The episodes were divided into three groups according to clinical and microbiological diagnosis. Group 1 comprised eight admissions of eight patients with invasive candidiasis. Group 2 comprised 42 admissions of 34 patients without evidence of invasive candidiasis. Group 3 comprised the remaining 45 admissions of 37 patients with febrile episodes which were not diagnosed by microbiological culture. Antibodies to CAGT were detected in 87.5% of group 1 patients. Detection of antibodies to CAGT in patients with Candida fungemia was delayed somewhat relative to the time the blood culture was positive, but antibodies to CAGT were detected earlier than a diagnosis was made in patients with deep-tissue candidiasis. Sera from 2 admissions in group 2 and 12 admissions in group 3 revealed antibodies to CAGT. At a titer of > or = 1:20, detection of antibodies to CAGT had a sensitivity of 87.5%, specificity of 95.2%, positive predictive value of 77.8%, and negative predictive value of 97.6%. Antibodies to CAGT were usually detected before beginning of empiric antifungal therapy. Titers of antibodies to CAGT were maintained in most patients who died but declined and eventually disappeared in the patients who survived. Since antibodies to CAGT were detected in all patients with tissue-proven invasive candidiasis but negative by blood culture, detection of antibodies to CAGT complemented blood cultures for diagnosis and therapeutic monitoring of patients with hematologic malignancies and invasive candidiasis.