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J Pontón

Publications and source records attributed to J Pontón.

At least 55 records · Page 3Linked to original sources
PubMed1996

Evaluation of a commercial medium for identification of Candida species.

CHROMagar Candida (CHROMagar, France) was evaluated as a medium for the presumptive identification and isolation of yeasts using 1,537 isolates of medically important yeasts, including 970 Candida albicans, 165 Candida parapsilosis, 131 Candida glabrata, 62 Candida guilliermondii, 35 Candida krusei, 32 Candida tropicalis, 31 Rhodotorula rubra, 23 Trichosporon spp. (17 Trichosporon beigelii), 17 Candida famata, 16 Candida pelliculosa, 10 Pichia etchelsii, 10 Saccharomyces cerevisiae, 8 Candida lusitaniae, 7 Cryptococcus spp., and 20 isolates of other Candida spp. After 48 h of incubation at 37 degrees C, the sensitivity and specificity were, respectively, 99% and 100% for Candida albicans, 93.8% and 99.1% for Candida tropicalis, and 100% and 100% for Candida krusei. In addition to colony color, other colony characteristics were important for identification of some species, such as rough colonies in Candida krusei isolates or the halo around the colonies of Candida tropicalis. A great variety of colors was observed among species other than Candida albicans, Candida tropicalis, and Candida krusei. For identification purposes, CHROMagar Candida medium has an accuracy similar to that of germ-tube tests and chlamydospore development tests for Candida albicans and to that of the ATB ID32C kit (API, bioMérieux, France) for Candida tropicalis and Candida krusei.

Candida↗
PubMed1996

Effect of monoclonal antibodies directed against Candida albicans cell wall antigens on the adhesion of the fungus to polystyrene.

The adhesion of Candida albicans to polystyrene and the effect of three monoclonal antibodies (mAbs) reactive with C. albicans cell wall surface antigens on this process was assessed in vitro with several C. albicans strains. In the absence of mAbs, adhesion of C. albicans to polystyrene increased in parallel with germ-tube formation. However, the growth of the strains in the yeast phase at 25 degrees C or the use of an agerminative mutant inhibited adhesion to polystyrene. Serotype A and B strains showed similar kinetics of adhesion to polystyrene and no statistically significant differences in germination or adhesion were observed when strains from the two serotypes were compared. The three mAbs had different effects on both germination and adhesion of C. albicans. mAbs 3D9 showed no influence on either germination or adhesion to polystyrene in two C. albicans strains. mAb B9E decreased both adhesion (45.6%) and filamentation (52.6%), and mAb 21E6 decreased filamentation (34.0%) but enhanced adhesion by 23.3%. This enhancement was also observed with the agerminative mutant and it was dose-dependent. It was not related to the binding capacity of the MAb to polystyrene nor to an increase in cell surface hydrophobicity of the antibody-treated cells. In conclusion, both growth phases of C. albicans can adhere to polystyrene, although the conditions for this process seem to be different in each phase. The two types of adhesion of C. albicans to polystyrene might have a role in the colonization of medical implants. The disparate effects shown by mAbs directed against cell wall mannoproteins of C. albicans on the adhesion of the fungus to polystyrene should be taken into consideration when designing strategies to block the adhesion of C. albicans to plastic materials with mAbs.

Animals↗
PubMed1996

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.

Antigens, Fungal↗
PubMed1996

[Utility of Fluoroplate Candida for the rapid identification of Candida albicans].

BACKGROUND: Candida albicans infections are frequent in immunocompromised patients and a prompt diagnosis could favor an early and proper antifungal treatment. The rapid identification of clinical yeast isolates facilitate this diagnosis. METHODS: The utility of Fluoroplate Candida ready-to-use plates for Candida albicans rapid identification was evaluated with 653 clinical isolates from 23 yeast species, including 307 C. albicans plated onto Fluoroplate Candida agar (Merck, Germany). Rapid identification of C. albicans was based on the hydrolysis of 4-methylumbelliferyl-N-acetyl-beta-D-galactosaminide by the galactosaminidase activity of C. albicans producing white fluorescent colonies under ultraviolet light. Identification on Fluoroplate Candida was confirmed by germ tube, chlamydoconidia formation and API-ATB ID 32C assays. RESULTS: Three hundred and five of 306 isolates showing fluorescent colonies were C. albicans and one was Candida glabrata (false positive). The rest of the isolates showed colonies without fluorescence and with the exception of two false negatives, these isolates were identified as non-C. albicans by other methods. CONCLUSIONS: Fluoroplate Candida allows a rapid and excellent identification of C. albicans showing a sensitivity and specificity of 99.3 and 99.7%, respectively.

Candida albicans↗
PubMed1995

Biotype diversity of Candida parapsilosis and its relationship to the clinical source and experimental pathogenicity.

Environmental, vaginal, and blood isolates of Candida parapsilosis were biotyped by karyotype analysis in pulsed-field gel electrophoresis. Morphotype and resistotype were also determined as was aspartyl proteinase secretion and pathogenicity in a systemic mouse infection model. Overall, the karyotype patterns consisted of 6-9 chromosome bands (> 3.0-0.6 Mb) with limited clustering, since most isolates had unique chromosome profiles. Major clusters C. parapsilosis, differing by source of isolation and in experimental pathogenicity, could be discriminated by morphoresistotyping. The morphotypes of isolates from subjects with candidemia ranged from one that caused elevated mortality in the normal mouse to those that were totally avirulent in the neutropenic animal. Among clinical isolates, secretion of aspartyl proteinase was higher in vaginitis than in candidemia isolates and did not correlate with the experimental pathogenicity. These results emphasize the biotype diversity of C. parapsilosis and have potentially important epidemiologic and pathologic implications.

Animals↗
PubMed1995

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)

Animals↗
PubMed1995

[Assessment of the sensitivity to antifungal agents of clinical isolates of Candida albicans serotype A and B by the ATB Fungus method].

BACKGROUND: Candida albicans is the most frequently species isolated in patients with candidiasis. This species may be antigenically divided in serotypes A and B, which have a different pathogenic behavior and antifungal susceptibility pattern. METHODS: The antifungal susceptibility of 443 clinical isolates from both serotypes of C. albicans to 5-fluorocytosine (5FC), amphotericin B, nystatin, econazole, miconazole and ketoconazole has been tested by means of the ATB Fungus method. RESULTS: Both serotypes showed a similar in vitro susceptibility to amphotericin B, nystatin, econazole, miconazole and ketoconazole. All the isolates were susceptible to amphotericin B and nystatin. A small number of in vitro resistant isolates were observed to azole compounds. However, serotype B was significantly more resistant than serotype A (p = 0.0001) to 5FC. CONCLUSIONS: C. albicans serotype B shows a lower susceptibility than serotype A to 5FC, an antifungal product not marketed in Spain. Serotyping of C. albicans does not offer additional information on antifungal susceptibility of clinical isolates from this species.

Antifungal Agents↗
PubMed1995

[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.

Adult↗
PubMed1994

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.

Acute Disease↗
PubMed1993

[Estimation of infection by Aspergillus fumigatus in mice infected experimentally by the respiratory route].

BACKGROUND: To evaluate a new chitin detection technique for the quantification of Aspergillus fumigatus infection in organs from air-borne infected mice. METHODS: Different groups of mice were air-borne infected with A. fumigatus spores. The mortality rate was studied as well as the extension of the infection by means of colony counts (UFC) and quantification of chitin . RESULTS: The inhalation of A. fumigatus spores by non-immunosuppressed mice produces a 34% mortality rate, with an initial invasion of lung tissue followed by the spleen, kidneys, heart and liver thereafter. CONCLUSION: The quantification of chitin in involved organs allowed us to estimate the degree of organ-specific fungal infections and perhaps could be an useful method for studying the pathogenesis of A. fumigatus infections.

Administration, Inhalation↗
PubMed1992

Vulvovaginal candidiasis refractory to treatment with fluconazole.

We present the case of an infertile patient, whose first attempt at IVF had to be postponed for 18 months due to a vulvovaginal yeast infection refractory to treatment. The main causative organism was a Candida glabrata strain resistant to all the imidazolic agents tested. The organism and the host's humoral status were studied in depth, looking for possible causes of the refractoriness to treatment.

Adult↗
PubMed1992

Colony morphotype on Sabouraud-triphenyltetrazolium agar: a simple and inexpensive method for Candida subspecies discrimination.

A new method of Candida subspecies discrimination on Sabouraud-triphenyltetrazolium agar is reported. Five hundred sixty-two strains of Candida and Torulopsis glabrata, previously identified by conventional mycological methods, were studied. Each strain received a three-letter code and a number based on its colonial morphology. Sixteen morphotypes were found for Candida albicans, 6 were found for Candida parapsilosis, 4 were found for both Candida guilliermondii and Candida krusei, and 12 were found for Candida tropicalis. None of the 56 T. glabrata strains studied grew on this agar. A reproducibility of 95% was found for C. albicans. The simplicity and low cost could make this method useful for typing Candida spp.

Agar↗
PubMed1990

Value of detection of antibodies to Candida albicans germ tube in the diagnosis of systemic candidosis.

To test the value of detection of anti-Candida albicans germ tube antibodies by indirect immunofluorescence assay in the diagnosis of systemic candidosis, a retrospective study was done using 126 sera from 27 patients with presumptive systemic candidosis (13 immunocompromised), 165 sera from 45 patients with aspergillosis (29 immunocompromised), 35 sera from eight patients with cryptococcosis (6 immunocompromised), and 101 sera from 101 blood donors. While 21 of 27 patients with systemic candidosis (77.8%) had anti-germ tube antibodies, these antibodies were absent in all patients with cryptococcosis and in all blood donors. They were however detected in 5 of 45 patients with aspergillosis (11.1%). Ten of 13 (76.9%) immunocompromised patients with candidosis had anti-germ tube antibodies; similar results were obtained in immunocompetent patients with candidosis (78.6%). The specificity was 96.8%, indicating a high degree of discrimination was possible between systemic candidosis and other invasive mycoses in the patients studied. Anti-germ tube responses did not appear to be significantly reduced in immunocompromised patients.

Antibodies, Fungal↗
PubMed1990

Different antibody response against Candida albicans cell wall antigens in cervicovaginal secretions of patients with vulvovaginal candidiasis.

Vaginal washings from 118 women were investigated by means of immunofluorescence for the presence of antibodies against Candida albicans. A significantly (p less than 0.02) higher antibody titer was found in the samples from patients with clinically evident vulvovaginal candidiasis. Vaginal secretions from those patients with a positive culture for C. albicans were assayed by means of Western blotting. A distinct band pattern was found in the group of patients with a positive culture and the classical clinical picture of C. albicans vulvovaginitis.

Antibodies, Fungal↗
PubMed1990

[Microbiological study of 30 samples of heroin].

In the present study, 30 samples of heroin from material seized by the police in Vizcaya from 7-1-1987 to 6-30-1988 were investigated. Bacillus spp were isolated in 19 samples (63.3%), coagulase negative staphylococci in 14 (46.6%), Aspergillus in 3 (10%) and S. aureus in one (3.33%). In addition, chemical analysis of the purity of heroin was carried out with gas chromatography. The purity of the samples ranged from 1.1% to 94.3%. No relation was found between the weight of the sample, its purity and its degree of microbiological contamination. In the microbiological study of 4 lemons used to dissolve the drug, Candida krusei was isolated from three samples, Aspergillus in two and Geotrichum in one.

Aspergillus↗