Identification and characterization of nine atypical Candida dubliniensis clinical isolates

Candida dubliniensis is a pathogenic yeast of the genus Candida closely related to Candida albicans. The phenotypic similarity of these two species often leads to misidentification of C. dubliniensis isolates in clinical samples. DNA-based methods continue to be the most effective means of discriminating accurately between the two species. Here, we report on the identification of nine unusual Candida isolates that showed ambiguous identification patterns on the basis of their phenotypic and immunological traits. The isolates were categorized into two groups. Group I isolates were unable to produce germ tubes and chlamydospores, and to agglutinate commercial latex particles coated with a mAb highly specific for C. dubliniensis. Group II isolates grew as pink and white colonies on CHROMagar Candida and ChromID Candida, respectively. Carbohydrate assimilation profiles obtained with API/ID32C together with PCR amplification with specific primers and DNA sequencing allowed reliable identification of the nine unusual clinical isolates as C. dubliniensis.

An antibody reactivity-based assay for diagnosis of invasive candidiasis using protein array

The increased incidence of invasive candidiasis and of patients at risk requires early diagnosis and treatment to improve prognosis and survival. The aim of this study was to set up a ten-protein array-based immunoassay to assess the IgG antibody responses against ten well-known immunogenic C. albicans proteins (Bgl2, Eno1, Pgk1, Pdc11, Fba1, Adh1, Als3, Hwp1, Hsp90 and Grp2) in 51 patients with invasive candidiasis (IC) and in 38 culture-negative controls (non-IC). Antibody levels were higher against Bgl2, Eno1, Pgk1, Als3, Hwp1 and Grp2, than against Adh1, Pdc11, Fba1 and Hsp90, irrespectively of the patient group considered. Moreover, the IgG levels against Bgl2, Eno1, Pgk1 and Grp2 were significantly higher in IC than in non-IC patients. Furthermore, the ROC curves generated by the analysis of the antibody responses against Bgl2, Grp2 and Pgk1 displayed AUC values above 0.7, thus discriminating IC and non-IC patients. According to these results, the employment of the microarray immunoassay (a rapid, sensitive and multiparametric system), in parallel with conventional diagnostics, can help to spot IC patients. This ultimately will allow to initiate an early, focused and optimized antifungal therapy.

Anabolic steroids affect human periodontal health and microbiota

OBJECTIVES

This study aims to evaluate periodontal microbiological differences between systemically healthy nonsmoker males taking anabolic androgenic steroids (AASs) and non-AAS users and to find associations between disease severity and AAS use.

METHODS

Ninety-two men practicing bodybuilding were included in the study. They were divided into AAS users and a matched control nonuser group and subgrouped based on their most severe periodontal condition. Pooled subgingival samples from each individual were cultured to evaluate specific periodontopathogen infection.

RESULTS

AAS users had significantly higher prevalence of severe periodontitis. AAS users had greater gingival inflammation and clinical attachment loss of ≥ 3 mm than nonusers (odds ratio (OR) = 2.4; p = 0.09; 95 % confidence interval (CI) 0.8-6.4). AAS users were 4.9 times more likely to be infected with Prevotella intermedia than AAS nonusers (OR = 4.9; p = 0.003; 95 % CI 1.6-14.7). The OR of presenting subgingival Aggregatibacter actinomycetemcomitans was 8.2 times higher in AAS users (OR = 8.2; p = 0.03; 95 % CI 0.9-70.8). AAS users were 5.6 times more likely to present subgingival Candida spp. than nonusers (OR = 5.6; p = 0.02; 95 % CI 1.1-27.1). AAS users were 14.8 times more likely to present subgingival Candida parapsilosis than nonusers (OR = 14.8; p < 0.0001; 95 % CI 3.1-69.2). The likelihood of AAS users presenting subgingival Candida tropicalis was 4.3 times higher than nonusers (OR = 4.3; p = 0.03; 95 % CI 1.1-16.9). A. actinomycetemcomitans was mostly isolated in individuals with severe periodontitis and was associated with subgingival Porphyromonas gingivalis, P. intermedia, and Candida spp.

CONCLUSIONS

AAS use may increase the risk for severe periodontitis and may cause a subgingival selection of certain Candida species. Specific periodontopathogens, such as Candida dubliniensis and Candida albicans, seem to be negatively affected by AAS use. The higher risk for disease progression in AAS users may be explained by the significantly higher proportions of A. actinomycetemcomitans, P. gingivalis, P. intermedia, and Candida species as compared to controls.

CLINICAL SIGNIFICANCE

Data on the influence of AAS on subgingival periodontopathogens and disease progression are scarce. Higher proportions of specific periodontopathogens are plausible in AAS users. AAS users had a higher prevalence of severe periodontitis, gingival inflammation, and clinical attachment loss. Men taking AAS are at greater risk of periodontitis and specific periodontopathogen infection.

Bone microbial decontamination agents in osseous grafting: an in vitro study with fresh human explants

BACKGROUND

Establishing a safe prophylactic antimicrobial protocol in bone grafting may enhance osseous volume outcomes. The purpose of this in vitro study is to assess human osteoblast response and safety after explant antimicrobial exposure.

METHODS

Fresh human bone explants were exposed to three antimicrobials: povidone-iodine (PovI; 0.05%, 1%, and 5%), chlorhexidine (CHX; 0.2% and 1%), and sodium hypochlorite (NaOCl; 2.5%, 4.5%, and 5.25%) at different times (15, 30, 45, and 60 seconds) and concentrations to assess cellular toxicity. Explants were washed three times with saline after exposure. Controls, explants cultured in the absence of antimicrobials, were performed for all experimental situations tested. Trials were conducted in triplicate. Particle size influence on osteoblast growth was determined between bone fragments with a diameter <2 and ≥2 to 5 mm. Test and control groups were monitored by light microscopy to evaluate cellular growth. Osteoblast differentiation and morphology was assessed by alkaline phosphatase activity and scanning electron microscopy (SEM).

RESULTS

Osteoblast growth was similar for particles <2 and ≥2 to 5 mm. Alkaline phosphatase control reference values were not significantly different from test groups (0.35 mU/mL ± 0.004 versus 0.34 mU/mL ± 0.009; P >0.05). Light microscopy showed on average 97% osteoblastic growth for bone particles exposed to PovI 5% and CHX 0.2% for all times and CHX 1% up to 30 seconds. The odds ratio of positive osteoblastic growth after a 30-second 2.5% NaOCl exposure was 2.4 times higher than after 5.25%. On average, one of two replicas yielded positive growth with 2.5% NaOCl and one of three with 5.25%. After 60-second explant exposure, positive osteoblastic growth was 7.7 times more likely to occur with 5% PovI or 0.2% CHX than with 5.25% NaOCl (P <0.05). SEM analysis confirmed light microscopy similar cellular adhesion and osteoblast phenotypic features between test and control groups.

CONCLUSIONS

Best osteoblastic growth occurred after bone PovI exposure and CHX 0.2%. Cellular toxicity seems to be influenced by the type of antimicrobial, concentration, and exposure time. SEM analysis confirmed absence of osteoblast phenotypic alterations after exposure. Decontamination agents can safely be used in bone transplantation using up to 5% PovI and 0.2% CHX for 1 minute and CHX 1% for 30 seconds.

Potential of anti-Candida antibodies in immunoprophylaxis

The need for new options for the treatment of invasive candidiasis has fuelled the use of antibodies in combination with conventional antifungal therapy. After a long period of time in which antibodies were considered irrelevant in the resistance against invasive candidiasis, it was demonstrated that a number of antibodies or their engineered derivatives directed against Candida albicans cell-wall polysaccharides and glycopeptides, as well as against some protein epitopes, confer protection against invasive candidiasis. This has confirmed this approach as a new strategy for the prophylaxis of invasive candidiasis. Of particular interest is Mycograb, a human recombinant monoclonal antibody that inhibits heat shock protein 90, and has been administrated in combination with lipid-associated amphotericin B to patients with invasive candidiasis, and the fungicidal anti-beta-glucan antibodies induced by the glycoconjugate vaccine composed of a beta-glucan polysaccharide conjugated with the diphtheria toxoid CRM 197. However, despite the promising data obtained in vitro and in animal models, at present there is very little clinical experience on the use of antibodies in Candida immunoprophylaxis.

Pectin Lyase Production by a Penicillium italicum Strain

Growth and concomitant production of an extracellular pectin lyase (PL) [poly(methoxylgalactosiduronate) endolyase; EC 4.2.2.10] were investigated in a group of 16 fungi grown in liquid medium containing pectin as a supplementary carbon source. Culture filtrates of both Penicillium italicum (CECT 2294) and P. expansum (CECT 2275) showed the highest PL activity and contained polygalacturonase but not pectinesterase activity. The effect of the inoculum size, the carbon source (sucrose and glucose syrup), and the presence of pectin on the production of PL by P. italicum was studied. The presence of 2.6 mM glycerophosphate in the culture medium enhanced the appearance of PL but was not inhibitory for the in vitro activity. However, glycerol inhibited the enzyme nearly 50% at such a concentration.

Bone microbial contamination influences autogenous grafting in sinus augmentation

BACKGROUND

The oral occurrence of putative microbial pathogens in humans has been documented in health and disease. The presence of periodontopathogens in patients with a history of periodontal disease may have a negative impact on bone regeneration. This investigation was conducted to confirm the presence of periodontal pathogens in bone particles harvested intraorally for maxillary sinus augmentation and to assess the clinical and radiographic outcomes 6 to 12 months after bone augmentation.

METHODS

Culture and polymerase chain reaction (PCR)-based identification were performed by paper-point sampling of intraorally harvested bone particles in a group of 12 maintenance patients undergoing maxillary sinus augmentation. Radiographs were taken to assess and compare bone healing and volume gain at baseline and at 6 to 12 months after augmentation.

RESULTS

The presence of periodontal pathogens (Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans [previously Actinobacillus actinomycetemcomitans], Prevotella intermedia, Tannerella forsythia [previously T. forsythensis], Fusobacterium nucleatum, Parvimonas micra [previously Peptostreptococcus micros or Micromonas micros], Campylobacter rectus, enteric Gram-negative rods, and Dialister pneumosintes) was identified in 10 of 12 patients (83%) by culture, PCR, or both and was associated with greater bone volume loss at 6 months postaugmentation. The PCR-positive triad, P. gingivalis, A. actinomycetemcomitans, and P. intermedia, was associated with pronounced volume loss of the grafted sinus at 6 months.

CONCLUSIONS

To the best of our knowledge, this is the first study to confirm osseous microbial contamination with major periodontopathogens in individuals undergoing maxillary sinus augmentation with a history of periodontitis. The effect on the grafting outcome translated into bone volume loss in the grafted sinus 6 months postaugmentation. Specific microbial contamination may have an impact on osteogenesis in osseous regeneration.

Monoclonal antibody-mediated inhibition of adhesion of Candida albicans and Candida dubliniensis to human epithelial cells

The aim of this study was to assess the role of whole saliva, four saliva-derived preparations, and six monoclonal antibodies (mAbs), directed against components of the cell wall of Candida albicans, on the adhesion of C. albicans and Candida dubliniensis to human epithelial cells (HEC). C. albicans serotype A NCPF 3153 and C. albicans serotype B ATCC 90028 showed higher adhesion to HEC than C. dubliniensis NCPF 3949. Pooled whole saliva was more efficient than salivary secretory immunoglobulin A, partially purified by chromatography, at inhibiting the adhesion of C. albicans serotype A NCPF 3153 to HEC. Monoclonal antibodies C7, 14-8, and 26G7 were the most potent inhibitors of adhesion. Our results show that mAbs can mimic the inhibition of adhesion of C. albicans to HEC that is mediated by human saliva.

Evaluation of CHROM-Pal medium for the isolation and direct identification of Candida dubliniensis in primary cultures from the oral cavity

Candida albicans is the species most frequently isolated from oral specimens, but the recovery of other Candida species such as Candida dubliniensis is increasing. Differentiation of C. dubliniensis from C. albicans requires special tests and both species are misidentified in some studies. CHROM-Pal (CH-P) is a novel chromogenic medium used in our laboratory for differentiation between C. albicans and C. dubliniensis on the basis of colony colour and morphology, and chlamydospore production. The performance of CH-P and CHROMagar Candida (CAC) was compared for primary isolation and presumptive identification of yeasts from oral specimens from human immunodeficiency virus (HIV)-infected and uninfected individuals. The identification of Candida species on both media was compared with two reference identification methods (API ID 32 C and multiplex PCR). A total of 137/205 oral swabs (66.8 %) plated onto CH-P and CAC media were positive by culture and resulted in the growth of 171 isolates of Candida species on CH-P, whilst only 159 isolates grew on CAC. C. albicans was the most frequently isolated species in both groups of patients, followed by Candida parapsilosis in the HIV-negative group, and by C. dubliniensis in the HIV-infected group. The other Candida species isolated were Candida guilliermondii, Candida glabrata, Candida krusei, Candida tropicalis, Candida famata, Candida rugosa, Candida kefyr, Candida pelliculosa and Candida pulcherrima. The sensitivity and specificity for identifying C. albicans, C. krusei, C. tropicalis and C. dubliniensis on CH-P were over 98.5 %, always equal to or higher than those obtained when CAC was used. CH-P is a simple reliable medium for primary isolation and presumptive identification of yeast isolates from oral samples. The ability of CH-P to discriminate between C. dubliniensis and C. albicans was significantly higher (P <0.05) than that of CAC.

[Rapid identification of Candida dubliniensis using the Bichro-Dubli test]

OBJECTIVES

Because of its considerable epidemiological relevance, accurate identification of Candida dubliniensis should be routinely performed in clinical microbiology laboratories. In an attempt to facilitate this task, the usefulness of the Bichro-Dubli test (Fumouze Diagnostics, Levallois-Perret, France) was assessed.

METHODS

Seventy-five collection strains (55 C. dubliniensis and 20 C. albicans) and 135 clinical yeast isolates that grew as green colonies in CHROMagar Candida were studied.

RESULTS

Bichro-Dubli was positive in 54 of 55 C. dubliniensis strains (sensitivity 98.2%) and negative in the 20 C. albicans strains (specificity 100%). The test identified 4 C. dubliniensis isolates among the 135 isolates cultured from clinical specimens.

CONCLUSIONS

The Bichro-Dubli test is easy to perform and allows rapid identification of C. dubliniensis.

Cross-reactivity between Candida albicans and oral squamous cell carcinoma revealed by monoclonal antibody C7

BACKGROUND

Monoclonal antibodies developed against Candida albicans cell wall mannoproteins cross-react with human ovarian cancer. These antibodies reacted with the nuclear pore complex protein Nup88, which is overexpressed in a number of human tumors. The aim of this study was to investigate if Nup88 revealed by monoclonal antibody C7 is overexpressed in early oral squamous cell carcinoma (EOSCC) and if this expression has a prognostic value.

PATIENTS AND METHODS

A monoclonal antibody against a C. albicans cell wall manoprotein was used to investigate the expression of Nup88 in 34 EOSCC (T1/T2 N0M0).

RESULTS

Mab C7 was mostly located in the cytoplasm and extracts from EOSCC showed specific bands of 47-40 and 70 kDa that were not observed in normal oral mucosa. The highest levels of Mab C7 reactivity were observed in 13 (38.2%) tumors. The Kaplan-Meier test showed the median survival time to be shorter in those EOSCC cases with the highest Mab C7 reactivity.

CONCLUSION

The monoclonal antibody C7 raised against a C. albicans cell wall mannoprotein cross-reacts with an antigen from oral squamous cell carcinoma whose expression is associated with poor prognosis. The overexpression of this antigen is associated with a poor prognosis in early squamous cell carcinoma.

Fungicidal monoclonal antibody C7 binds to Candida albicans Als3

Monoclonal antibody (MAb) C7 reacted with a >200-kDa component from the Candida albicans cell wall identified by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry as Als3. It also bound the recombinant N terminus of Als3. Binding of MAb C7 to Als3 may explain the biological activities exerted by the MAb on C. albicans.

Evaluation of a novel enzyme-linked immunosorbent assay to detect immunoglobulin G antibody to enolase for serodiagnosis of invasive candidiasis

The performance of a new test to detect antibodies to Candida albicans recombinant enolase was investigated in 47 immunocompromised and 51 immunocompetent patients. The sensitivity, specificity, and positive and negative predictive values of the test for the diagnosis of invasive candidiasis were 81.0, 83.9, 79.1, and 85.5%, respectively.

In VitroActivities of Voriconazole and Five Licensed Antifungal Agents AgainstCandida dubliniensis:Comparison of CLSI M27-A2, Sensititre YeastOne, Disk Diffusion, and Etest Methods

We compared the in vitro activity of six antifungal agents against 62 isolates of Candida dubliniensis by the Clinical Laboratory Standards Institute (CLSI [formerly National Committee for the Clinical Laboratory Standards]) M27-A2, Sensititre YeastOne, disk diffusion, and Etest methods and we studied the effect of the time of reading. For the azoles, voriconazole was the most potent in vitro followed by fluconazole, ketoconazole, and itraconazole. All the isolates were susceptible to amphotericin B and flucytosine. The highest rate of resistance was obtained against itraconazole with a high number of isolates defined as susceptible dose-dependent. At 24 hr, 100% of the isolates were susceptible to ketoconazole, amphotericin B, and flucytosine, 98% susceptible to voriconazole and fluconazole, and 95% for itraconazole. At 48 hr, 100% of the isolates remained susceptible for flucytosine and amphotericin B, 95% for voriconazole, 93% for fluconazole, 90% for ketoconazole, and 82% for itraconazole. The agreement between the CLSI and the other methods was better at 24 than 48 hr.

Evaluation of the new chromogenic medium Candida ID 2 for isolation and identification of Candida albicans and other medically important Candida species

The usefulness of Candida ID 2 (CAID2) reformulated medium (bioMérieux, France) has been compared with that of the former Candida ID (CAID; bioMérieux), Albicans ID 2 (ALB2; bioMérieux), and CHROMagar Candida (CAC; Chromagar, France) chromogenic media for the isolation and presumptive identification of clinically relevant yeasts. Three hundred forty-five stock strains from culture collections, and 103 fresh isolates from different clinical specimens were evaluated. CAID2 permitted differentiation based on colony color between Candida albicans (cobalt blue; sensitivity, 91.7%; specificity, 97.2%) and Candida dubliniensis (turquoise blue; sensitivity, 97.9%; specificity, 96.6%). Candida tropicalis gave distinguishable pink-bluish colonies in 97.4% of the strains in CAID2 (sensitivity, 97.4%; specificity, 100%); the same proportion was reached in CAC, where colonies were blue-gray (sensitivity, 97.4%; specificity, 98.7%). CAC and CAID2 showed 100% sensitivity values for the identification of Candida krusei. However, with CAID2, experience is required to differentiate the downy aspect of the white colonies of C. krusei from other white-colony-forming species. The new CAID2 medium is a good candidate to replace CAID and ALB2, and it compares well to CAC for culture and presumptive identification of clinically relevant Candida species. CAID2 showed better results than CAC in some aspects, such as quicker growth and color development of colonies from clinical specimens, detection of mixed cultures, and presumptive differentiation between C. albicans and C. dubliniensis.

A fungicidal monoclonal antibody protects against murine invasive candidiasis

Mice infected by Candida albicans and treated with monoclonal antibody C7 survived longer than saline-treated animals. A prozone-like effect was observed. The in vitro candidacidal activity of macrophages was strongly enhanced when C. albicans was opsonized by C7 and complete murine serum was present.

Evaluation of Bichro-Dubli Fumouze to distinguish Candida dubliniensis from Candida albicans

We have evaluated the ability of the Bichro-Dubli Fumouze (Fumouze Diagnostics, Levallois-Perret, France) latex agglutination test to identify colonies of Candida dubliniensis grown on different media. The test was positive for 103 of 106 isolates of C. dubliniensis and negative for Candida albicans and other Candida species studied. The sensitivity and specificity of the test were 97.1% and 100%, respectively. The test is very rapid, simple, and reliable giving the same results independently of whether the colonies are grown previously on Sabouraud dextrose agar, CHROMagar Candida medium, Candida ID2 medium, or CHROMagar-Pal's medium.

Supplementation of CHROMagar Candida medium with Pal's medium for rapid identification of Candida dubliniensis

CHROMagar Candida medium is used for the isolation and identification of Candida species, but it does not differentiate Candida albicans from Candida dubliniensis. This differentiation can be achieved by using Pal's agar, which cannot be used in primary isolation. We have combined both media to obtain a new medium that can be used for the isolation and identification of C. dubliniensis in primary cultures.

Antifungal and Antitumor Activities of a Monoclonal Antibody Directed Against a Stress Mannoprotein of Candida albicans

Immunization of mice with a stress mannoprotein of >200 kDa from the cell wall of Candida albicans led to the production of monoclonal antibody (Mab) C7. The immunogen is a major target of secretory IgA and its expression is regulated by different environmental conditions including temperature, pH, glucose concentration and ammonium sulphate in the culture medium. Mab C7 reacted with a peptide epitope present in the >200 kDa antigen as well as in a number of antigens from the blastoconidium and germ tube cell wall, including enolase. In addition to its reactivity with C. albicans, Mab C7 also reacted with antigens present in C. krusei, C, tropicalis, C. glabrata, C. dubliniensis and C. lusitaniae, as well as in Cryptococcus neoformans, Scedosporium prolificans and Aspergillus fumigatus. Mab C7 exhibited four important biological activities, namely inhibition of adhesion of C. albicans to a variety of surfaces, inhibition of germination of C. albicans, direct candidacidal activity and direct tumoricidal activity. In tumor cells, Mab C7 reacted with nucleoporin Nup88, a reactivity that can be utilized for diagnostic and prognostic purposes.

A monoclonal antibody directed against a Candida albicans cell wall mannoprotein exerts three anti-C. albicans activities

Antibodies are believed to play a role in the protection against Candida albicans infections by a number of mechanisms, including the inhibition of adhesion or germ tube formation, opsonization, neutralization of virulence-related enzymes, and direct candidacidal activity. Although some of these biological activities have been demonstrated individually in monoclonal antibodies (MAbs), it is not clear if all these anti-C. albicans activities can be displayed by a single antibody. In this report, we characterized a monoclonal antibody raised against the main target of salivary secretory immunoglobulin A in the cell wall of C. albicans, which exerts three anti-C. albicans activities: (i) inhibition of adherence to HEp-2 cells, (ii) inhibition of germination, and (iii) direct candidacidal activity. MAb C7 reacted with a proteinic epitope from a mannoprotein with a molecular mass of >200 kDa predominantly expressed on the C. albicans germ tube cell wall surface as well as with a number of antigens from Candida lusitaniae, Cryptococcus neoformans, Aspergillus fumigatus, and Scedosporium prolificans. MAb C7 caused a 31.1% inhibition in the adhesion of C. albicans to HEp-2 monolayers and a 55.3% inhibition in the adhesion of C. albicans to buccal epithelial cells, produced a 38.5% decrease in the filamentation of C. albicans, and exhibited a potent fungicidal effect against C. albicans, C. lusitaniae, Cryptococcus neoformans, A. fumigatus, and S. prolificans, showing reductions in fungal growth ranging from 34.2 to 88.7%. The fungicidal activity showed by MAb C7 seems to be related to that reported by antibodies mimicking the activity of a killer toxin produced by the yeast Pichia anomala, since one of these MAbs also reacted with the C. albicans mannoprotein with a molecular mass of >200 kDa. Results presented in this study support the concept of a family of microbicidal antibodies that could be useful in the treatment of a wide range of microbial infections when used alone or in combination with current antimicrobial agents.

Casein agar: a useful medium for differentiating Candida dubliniensis from Candida albicans

Production of chlamydospores on casein agar at 24 degrees C for 48 h provides a simple means for differentiating Candida dubliniensis from Candida albicans based on chlamydospore production. Of 109 C. dubliniensis isolates tested on this medium, 106 (97.2%) produced abundant chlamydospores and three produced few chlamydospores. In contrast, of the 120 C. albicans isolates tested, 111 (92.5%) failed to produce any chlamydospores, whereas the remaining nine isolates produced few chlamydospores. These findings indicate that abundant chlamydospore production on casein agar is a useful test for discriminating between C. dubliniensis and C. albicans.

Immunoreactivity of the fungal cell wall

The cell wall is the major fungal structure involved in the interaction with the host and most of the immunological effects observed with intact fungal cells have been reproduced with cell-wall components. As a result of the exposure to fungal antigens, most individuals develop both cellular and antibody responses intended to limit the invasiveness or to eradicate the fungus from the infected tissues. However, a number of fungi including Candida albicans, Cryptococcus neoformans, Blastomyces dermatitidis, Coccidioides immitis, Trichophyton spp. and Histoplasma capsulatum can also induce T- and B-suppressive activities. A wide diversity of immunodominant cell-wall antigens for both cell-mediated and humoral responses have been identified in the most important fungal pathogens, although considerable differences exist in the information available at the molecular level among the different mycoses. Cellular responses require macrophage and Th1 activation, whereas humoral responses comprise the activation of the complement system and the induction of antibodies. The ability of fungal cell-wall components to elicit cellular or humoral immune responses has been traditionally used in the serodiagnosis of mycoses, the identification of fungal organisms and the development of vaccines for the prevention of mycoses. In the future, the analysis of such molecules will provide critical information in understanding the nature of host-fungus interactions.

Serological differentiation of experimentally induced Candida dubliniensis and Candida albicans infections

Using a rabbit model of systemic infection, we show that it is possible to differentiate infections caused by Candida dubliniensis and other Candida species by detecting the antibody response mounted by the infected animals. These results confirm our previous observation in a patient with C. dubliniensis candidemia and suggest that detection of C. dubliniensis-specific antibodies is useful in the diagnosis of invasive candidiasis caused by this yeast.

Specific antibody response in a patient with Candida dubliniensis fungemia

We report a case of fungemia caused by Candida dubliniensis in a non-HIV infected patient. Multiple cultures of blood performed over a period of 13 days were positive for this recently described yeast species. The C. dubliniensis isolates recovered were susceptible to fluconazole in vitro and the patient responded to intravenous therapy with this antifungal agent. It was possible to differentiate the fungemia caused by C. dubliniensis in this patient from that caused by C. albicans in other patients on the basis of the analysis of the antibody response since the C. dubliniensis-infected patient exhibited a characteristic and specific antibody response against a cell wall component of 160-170 kDa.

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.

The nuclear pore complex protein Nup88 is overexpressed in tumor cells

It has been previously shown (J. Schneider et al., Br. J. Cancer, 77: 1015-1020, 1998) that an antibody directed against Candida albicans proteins (C6) recognizes specifically a protein in human ovarian tumors. We have now performed an immunoscreening of a human cDNA library using this antibody and identified the antigen as Nup88, a protein localized preferentially at the nuclear membrane and probably implicated in nucleocytoplasmic transport. Our results show that Nup88 is strongly expressed in a series of human tumor cell lines compared with nontransformed cell lines at the RNA and the protein levels. Furthermore, we observed that in 76% of 21 ovarian tumors analyzed, the protein is also overexpressed in malignant tissue when compared with healthy adjacent tissue. Nup88 may, therefore, be considered as a putative marker for tumor growth and is probably related to increased cell cycling.

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.

Reactivity of Candida albicans germ tubes with salivary secretory IgA

Salivary secretory IgA (sIgA) has been shown to react with a group of heat shock mannoproteins preferentially expressed on yeast cells grown at 37 degrees C. Since at this temperature C. albicans can induce germ tubes, we explored the role of germ tube induction on human salivary sIgA reactivity in both germinative and agerminative C. albicans strains, in an attempt to investigate whether the germ tube expressed the heat shock mannoproteins reactive with sIgA. The reactivity with sIgA of the agerminative strain, grown at 25 and 37 degrees C for different times, was measured spectrofluorometrically and was fairly constant with time. Yeast cells grown at 37 degrees C tended to be more reactive than those grown at 25 degrees C. In contrast, when compared with the yeast cells of the germinative strain grown at 25 degrees C, there was a statistically significant decrease in reactivity with sIgA during germ tube formation. Serum IgA and IgG did not show statistically significant changes in reactivity with C. albicans during germination, suggesting differences in reactivity with C. albicans cell wall antigens between mucosal and systemic humoral responses. Cell wall mannoproteins of molecular masses > 60 kDa were characterized by Western blotting as responsible for the decrease in sIgA reactivity observed in the germ tube, and the fall in sIgA reactivity was related to the release of cell wall mannoproteins into the culture medium. The release of these mannoproteins may be a mechanism whereby C. albicans avoids the action of sIgA, and it may play an important role in the post-parasite relationship in oral candidiasis.

Candida albicans stress mannoproteins expression in superficial and systemic candidiasis. Stress mannoproteins in Candida albicans

The presence of heat shock mannoproteins (HSMPs) reactive with sIgA was demonstrated in several C. albicans strains. The subculture of the C. albicans isolated from mucosal surfaces on Sabouraud's dextrose agar at 25 degrees C switched off the HSMP expression. A re-expression of the HSMPs was obtained in the same medium by shifting the temperature of incubation to 37 degrees C. However, expression of HSMPs in two strains isolated from deep infections was maintained during several subcultures on Sabouraud's dextrose agar at 25 degrees C. A glycoprotein of 200 kDa seemed to be the main HSMP reacting with vaginal sIgA. The data presented in this study suggest that factors other than temperature can influence the expression of C. albicans HSMPs and therefore these antigens should be referred as stress mannoproteins.

Variability in expression of antigens responsible for serotype specificity in Candida albicans

The monoclonal antibody (mAb) B9E, which reacts with a cell wall surface determinant of Candida albicans serotype A, and a polyclonal monospecific antiserum against the antigen 6 (IF6) were used to investigate the expression of the antigens responsible for the serotype specificity in C. albicans under different growth conditions. By indirect immunofluorescence, both antibodies reacted with the cell wall surface of serotype A yeast cells and germ tubes grown in vitro but no reactivity was observed with serotype B yeast cells. In some cases, only a weak reactivity restricted to a zone close to the parent yeast cell was observed in serotype B germ tubes stained with mAb B9E. Both antibodies reacted strongly with yeast cells and germ tubes present in kidney abscesses from rabbits infected with both serotypes, but only serotype A yeast cells and germ tubes present in smears from patients with vulvovaginal candidiasis reacted with B9E and IF6 antibodies. The expression of antigens reactive with both antibodies was modulated by the pH of the environment in which the fungus was grown. Both antibodies showed a similar pattern of reactivity when studied with a spectrofluorometer. Serotype A yeast cells showed maximum reactivity when cells were grown on Sabouraud dextrose broth supplemented with yeast extract at pH 4.6. The lowest reactivity was observed in cells grown at pH 2.0. Conversely, the reactivity of serotype B yeast cells increased at alkaline pH values, the highest being in cells grown at pH values of 7.2 and 9.5.(ABSTRACT TRUNCATED AT 250 WORDS)

[Comparative study of 2 technics for the diagnosis of invasive candidiasis]

BACKGROUND

We evaluate test for the detection of antibodies against-Candida albicans by indirect immunofluorescence (Candida Spot-IF, BioMérieux, Lyon, France and a test developed in our laboratory to detect anti-germ tube antibodies) comparatively for the serodiagnosis of invasive candidiasis.

METHODS

A total of 121 sera from 62 patients were studied retrospectively. They were divided into two groups: group I included 71 sera from 28 patients with invasive candidiasis and group II, used as control, included 50 sera from 34 patients with non-invasive candidiasis or without evidence of infection by Candida.

RESULTS

Eighty-two percent of group I samples presented anti-germ tube antibodies and 57% of the patients in this group were positive by the Candida Spot-IF test. Both techniques were negative in 5 patients. Five patients in group II showed false positive results by Candida Spot-IF and two of them presented anti-germ tube antibodies also. Both techniques presented a poor correlation (R2 = 0.159; p < 0.001). Detection of anti-germ tube antibodies showed a sensitivity of 82% and a specificity of 94% and Candida Spot-IF showed a sensitivity of 57% and a specificity of 85%. Detection of anti-germ tube antibodies in immunocompetent patients showed a sensitivity of 90% but it decreased to 62% in immunocompromised patients. With the Candida Spot-IF test the sensitivity was 70 and 25%, respectively.

CONCLUSIONS

The detection of anti-germ tube antibodies was more sensitive and specific than detection of antibodies by the Candida Spot-IF test and it can be used for the serodiagnosis and follow up of patients with invasive candidiasis.

Detection of anti-Candida albicans IgE antibodies in vaginal washes from patients with acute vulvovaginal candidiasis

Vaginal washes from 55 women were investigated by means of an ELISA method for the presence of IgE antibodies against Candida albicans. These antibodies were detected in 87.1% of patients with clinical acute vulvovaginal candidiasis (group I), 100% of patients with suspected vulvovaginal candidiasis but negative by microscopy and culture (group II), 0% of asymptomatic carriers (group III) and 33.3% of uninfected controls (group IV). Statistically significant differences were observed comparing groups I and II vs. groups III and IV. The highest IgE vaginal antibody titers were mostly at the expense of serotype A C. albicans strains, which represented 83.3% of the C. albicans isolates. Non-C. albicans species also showed very low IgE levels. No correlation between serum and vaginal IgE was found. Furthermore, a second determination of vaginal IgE levels was performed in 3 patients. A decrease in IgE levels concomitant to a decline in clinical symptoms was observed in all of them after treatment.

Growth and macromolecular content of the dimorphic fungus Aureobasidium pullulans and the effect of hydroxyurea and other inhibitors

The growth kinetics and the macromolecular content of the yeast and ethanol-induced hyphal forms of Aureobasidium pullulans were studied. During the morphological transition from yeasts to hyphae, both the protein and RNA content decreased significantly, the mycelial form containing only 76% of the amount of protein in the yeasts, and 38% of the RNA. The DNA was the only component tested whose level increased during the transition. Among several compounds inhibiting macromolecular synthesis, only hydroxyurea showed a remarkable effect on the morphology of A. pullulans, inducing the mycelial morphology. The macromolecular composition of hydroxyurea-treated cultures changed with time in a way similar to that of the ethanol-Tween 80-ammonia medium, and to that of carbon-starved cultures, without ethanol or glucose.

[Evolution of several enzyme activities of Aureobasidium pullulans during the transition from yeast to mycelium induced by ethanol]

Some key enzyme activities from the energy metabolism of A. pullulans have been studied during the ethanol-induced yeast-to-mycelium transition. Both the mycelial and yeast-like forms showed greater glucose-6-phosphate dehydrogenase activity than phosphofructokinase. During the morphological transition, the most outstanding variations occurred in large cells (3 days), especially for citrate synthase, malate dehydrogenase and isocitrate lyase activities. However, similar variations were detected in cultures without glucose or ethanol, which showed no morphological transition. Therefore, the observed changes in the enzymatic activities may be attributed to the absence of glucose. As this is not sufficient to induce the morphological transition, we conclude that there is no evidence of a clear-cut relationship between morphology and the activity of the enzymes studied.