Molecular epidemiology of the global and temporal diversity of Candida albicans

The epidemiology of Candida albicans has changed with the rise in immunocompromised patients and the pressures of antifungal treatment and prophylaxis. We assessed the genotype distribution of recently obtained, globally diverse isolates in comparison with isolates recovered in the United States and United Kingdom before 1985, in order to determine temporal and geographic differences. We used EcoRI digestion of cellular DNA to generate restriction fragment length polymorphisms, dividing the isolates into 4 groups. From 15 diverse geographic areas, 439 isolates obtained over 20 years were divided into 121 genotypes within groups A (289 isolates), B (85), C (56), and D (9). Differences in genotype distribution existed among the localities (P<.0001) and between isolates obtained before 1990 versus those recovered since then (P=.009). Comparison of pre-1985 United States/United Kingdom isolates with post-1994 United States isolates revealed a trend toward a changing genotype distribution (P=.057). Global post-1985 isolates were different in genotype distribution from United States/United Kingdom isolates (P<.0001). The distribution of isolates from Israel was unique (P<.0001). These differences could be due in part to the increasing prevalence of group C strains worldwide.

Antifungal activity of cerebrospinal fluid against Cryptococcus neoformans and Candida species

The effect of human cerebrospinal fluid (CSF) on the growth of Cryptococcus neoformans and Candida species was tested in RPMI-1640. CSF alone was highly fungistatic for both yeasts and inhibited growth in a concentration-dependent manner. Unlike human serum, CSF did not collaborate with fluconazole for killing C. neoformans. Molecular sieve fractionation of CSF on a G-200 Sephadex column yielded a highly antifungal fraction with a molecular weight around 66 kDa. On SDS-PAGE this fraction migrated as a major and a minor band corresponding to the mobility of bovine serum albumin. These novel findings suggest that CSF contains a factor(s) that provides resistance to the growth of C. neoformans or Candida species.

Protracted results of dose-intensive therapy using cyclophosphamide, carmustine, and continuous infusion etoposide with autologous stem cell support in patients with relapse or refractory Hodgkin's disease: a phase II study from the North American Marrow Transplant Group

To determine the long-term results of high-dose chemotherapy and stem cell support in relapsed or primary refractory Hodgkin disease patients. One hundred and thirty-one patients with relapsed or primary refractory Hodgkin's disease were treated with a dose-intensive therapy protocol consisting of etoposide (2400 mg/m2 continuous intravenous infusion) cyclophosphamide (7200 mg/m2 intravenously), and carmustine (300-600 mg/m2 intravenously) CBVi. All patients had previously failed conventional chemoradiotherapy. Severe toxicities were related to infectious, hepatic, and pulmonary complications. Fatal, regimen-related toxicity was 19%; liver and lung dysfunction, as well as infection, were the most frequent problems. Ninety-one (69%) of the patients achieved a complete response (CR) (95% CI = 59% to 75%) after CBVi and autologous stem cell infusion. With a median follow-up of 5.1 years (range 3.0 to 9.5 years), overall and event-free survival are 44% (95% CI = 33% to 47%) and 38% (95% CI = 28% to 46%) respectively. While univariate analysis did not reveal a statistically significant variable to predict a better response, responsiveness to therapy demonstrated a trend. We conclude that CBVi is an effective therapy for relapsed or refractory Hodgkin's disease, producing long-term, durable remissions.

Dose-intensive chemotherapy for breast cancer with brain metastases: a case series

Most clinical trials using dose-intensive chemotherapy exclude patients with brain metastases. This exclusion was based on anecdotal experience reflecting high treatment-related mortality. We analyzed the outcome of 11 patients with metastatic breast cancer who had brain metastases, diagnosed either before or during high-dose chemotherapy. In three patients, the death was attributed to non-central nervous system (CNS) regimen-related toxicity. Five patients died as a results of non-CNS disease progression. One patient died as a result of both CNS and non-CNS disease progression. Two patients are alive without disease progression with follow-up of 13.4 and 7.3 months, respectively. Of the five patients who have survived 1 year, four have hormone receptor expression and continued on antihormone therapy after high-dose therapy. These results are the first to show that breast cancer patients having brain metastases who receive high-dose chemotherapy do not experience more treatment-related complications or treatment failure as a result of the metastatic CNS disease. To this end, exclusion of these patients from high-dose therapy trials, especially those with expression of hormone receptors, needs to be reevaluated.

Isolation of a human serum protein that inhibits the growth of Cryptococcus neoformans

Human serum at 5 to 10% (v/v) in tissue culture medium RPMI-1640, inhibits the growth of Cryptococcus neoformans by 80 to 93%. Serum fractionated on molecular sieve columns (Sephadex G-200) yielded an active protein fraction. This fraction at 100 micrograms protein/ml inhibited the growth of C. neoformans by 54%. When an active G-200 fraction was applied to a dye affinity column (Affi-Gel Blue) the fraction with inhibitory activity was bound by the column and was eluted with 1.4 M NaCl in 0.1 M phosphate buffer (pH 7.4). The bound fraction at 62.5 micrograms protein/ml inhibited C. neoformans growth by 82%. On native polyacrylamide gel electrophoresis (Nu-PAGE) the bound fraction migrated as a major and a minor band. Under the reducing conditions of sodium dodecyl sulfate (SDS)-PAGE the bound fraction yielded 4 prominent bands with MW ranging from 175 kDa to 45 kDa. Purification of the active Sephadex G-200 peak was achieved using an anion exchange column (DEAE-Sephacel). Protein eluted with 0.1 M NaCl had strong anticryptococcal activity (12.5 micrograms/ml, 79% inhibition), which in SDS-PAGE migrated as a single band with an approximate MW of 85 kDA. This protein appears important in natural host resistance to C. neoformans and polymorphisms or deficiencies may have epidemiologic and diagnostic relevance.

Airway coccidioidomycosis--report of cases and review

Infection due to Coccidioides immitis usually begins in the lungs. Despite the initial pulmonary portal of entry, endotracheal and endobronchial coccidioidomycosis has rarely been described. Since the introduction of fiberoptic bronchoscopy and the AIDS epidemic, more C. immitis lesions of the large airways have been noted. We present data on 38 cases of coccidioidomycosis of the airways, including 6 cases detailed from our own experience and 32 from the literature. Direct infection of the airways (28 cases) is a more common mechanism of airways disease than is erosion into the airways from a lymph node (5 cases). Bronchoscopic findings vary and may show mucosal involvement or intrinsic obstruction. Endotracheal and endobronchial disease is not a self-limited disease and requires antifungal therapy. Disseminated disease in these patients is common. Coccidioidomycosis must be considered in the differential diagnosis of airway pathology.

Effects of inhaled beta agonist and corticosteroid treatment on nuclear transcription factors in bronchial mucosa in asthma

BACKGROUND

Inhaled corticosteroids and beta agonists are the most commonly used treatments in asthma and are often used together. Recent evidence suggests that many of the anti-inflammatory actions of corticosteroids are mediated by cross-talk between the activated glucocorticoid receptor (GR) and other transcription factors such as the pro-inflammatory nuclear factor kappa B (NFkappaB). Beta agonists can activate the transcription factor cAMP response element binding protein (CREB). A mutual inhibition between GR and CREB occurs in vitro which raises the possibility of a negative interaction between corticosteroid and beta agonist drugs. A study was undertaken to determine whether these interactions occur during treatment with beta2 agonists and corticosteroids in asthma.

METHODS

Seven subjects who were participating in a randomised, placebo controlled, crossover study of six weeks treatment with inhaled budesonide (400 microg twice daily), terbutaline (1 mg four times daily), and combined treatment were recruited. Biopsy samples of the bronchial mucosa were obtained after each treatment and analysed for the DNA binding activity of GR, CREB, and NFkappaB.

RESULTS

Budesonide increased GR activity (p<0.05) and decreased NFkappaB activity (p<0.05). No treatment combination altered CREB activity and terbutaline had no significant effects on any transcription factor.

CONCLUSIONS

Inhaled corticosteroids have significant effects on GR and NFkappaB activity in bronchial mucosa. A negative interaction between inhaled corticosteroids and beta agonists was not found.

Resistance to Coccidioides immitis in mice after immunization with recombinant protein or a DNA vaccine of a proline-rich antigen

Two inbred strains of mice (BALB/c and C57BL/6) were vaccinated with either recombinant expression protein of a Coccidioides immitis spherule-derived proline-rich antigen (rPRA) in monophosphoryl lipid A-oil emulsion adjuvant or a DNA vaccine based on the same antigen. Four weeks after vaccination, mice were infected intraperitoneally with arthroconidia. By 2 weeks, groups of mice receiving saline or plasmids with no PRA insert exhibited significant weight loss, and quantitative CFUs in the lungs ranged from 5.9 to 6.4 log10. In contrast, groups of mice immunized with either rPRA or DNA vaccine had significantly smaller pulmonary fungal burdens, ranging from 3.0 to 4.5 log10 fewer CFUs. In vitro immunologic markers of lymphocyte proliferation and gamma interferon (IFN-gamma) release after splenocytes were stimulated with rPRA correlated with protection. Also, plasma concentrations of rPRA-specific total immunoglobulin G (IgG), IgG1, and IgG2a showed increases in vaccinated mice. These studies expand earlier work by demonstrating protection in mice which differ in H-2 background, by using an adjuvant that is potentially applicable to human use, and by achieving comparable protections with a DNA-based vaccine. Our in vitro results substantiate a Th1 response as evidenced by IFN-gamma release and increased IgG2a. However, IgG1 was also stimulated, suggesting some Th2 response as well. PRA is a promising vaccine candidate for prevention of coccidioidomycosis and warrants further investigation.

Hormone regulation of chondrocyte differentiation and endochondral bone formation

Endochondral bone formation, the formation of calcified bone on a cartilage scaffold, occurs during skeletal development, post natal growth and during bone remodelling and fracture repair. The epiphyseal growth plates represent classical tissues in which to study the ossification process, which requires two co-ordinated components; progressive chondrocyte differentiation and cartilage neovascularisation. Many gene knockout studies have produced new insights regarding how chondrocyte differentiation and angiogenesis are controlled at the molecular level. Additional genetic studies have produced new information regarding the role of hormones in the regulation of endochondral bone formation. The new challenge for the future is to determine how bone formation and turnover is physiologically regulated and co-ordinated to ensure that skeletal development and growth progresses correctly. This study reviews the emerging data in this quickly growing field which should ultimately provide fundamental insights into the normal control of endochondral ossification.

Distribution of Candida albicans genotypes among family members

Thirty-three families (71 subjects) were screened for the presence of Candida albicans in mouthwash or stool specimens; 12 families (28 subjects) were culture-positive for this yeast. An enrichment procedure provided a twofold increase in the recovery of C. albicans from mouthwash specimens. Nine of the twelve culture-positive families had two positive members each, two families had three positive members each, and one family had four positive members. Genetic profiles were obtained by three methods: pulsed-field gel electrophoresis; restriction endonuclease analysis, and random amplification of polymorphic DNA analysis. DNA fingerprinting of C. albicans isolated from one body site three consecutive times revealed that each of the 12 families carried a distinct genotype. No two families shared the same strain, and two or more members of a family commonly shared the same strain. Intrafamily genotypic identity (i.e., each member within the family harbored the same strain) was demonstrated in six families. Genotypes of isolates from husband and wife differed from one another in five families. All three methods were satisfactory in determining genotypes; however, we concluded that restriction endonuclease analysis provided adequate resolving power.

Bioassays for itraconazole blood levels: an interlaboratory collaborative study

Duplicate bioassays for itraconazole and hydroxy-itraconazole were run with 30 serum samples in five laboratories, each using a different method. Both itraconazole and hydroxy-itraconazole were used as standards. Despite quantitative variations, the results of the bioassays correlated sufficiently to indicate the relative level of antifungal activity in the test samples.

Itraconazole in cyclodextrin solution

Itraconazole, a water-insoluble oral triazole antifungal, has been formulated in cyclodextrin as a solution. Cyclodextrin is a ring of glucose molecules that can accept a lipophilic guest molecule within the ring. This enables solubilization and delivery to the lipid interface of the gut lumen, resulting in absorption of the guest molecule without absorption of the ring. This new system enhances the absorption of itraconazole. Improved blood and tissue levels of itraconazole and topical effect in mucosal disease should result in greater efficacy for a variety of indications, particularly patients with gastroenteropathy in whom absorption of earlier preparations was sometimes problematic.

Collaboration of human phagocytes with LY 303366 for antifungal activity against Aspergillus fumigatus

LY 303366, an inhibitor of 1, 3-beta-D-glucan synthase, was tested alone, or in co-culture with neutrophils or monocytes, for antifungal activity against Aspergillus fumigatus using the XTT metabolism assay. LY 303366 at 0.1 mg/L for 48 h significantly inhibited growth by conidia in a microtest plate XTT assay system. Inhibition was similar if the drug was removed after only 24 h. Microscopically this correlated with less growth and stunted malformed hyphae. LY 303366 (0.1 mg/L) also inhibited the further growth of germlings (43%) in a 24 h assay. Antifungal activity of neutrophils against 24 h control hyphal growth was limited at an effector: target ratio of 400:1. In co-cultures of neutrophils plus drug with hyphal growth from 24 h LY 303366 cultures the antifungal activity was additive. Neutrophils had a similar additive effect even if the drug were not present (i.e. when germinating conidia were pretreated with drug). Under conditions where monocytes did not have significant antifungal activity against hyphae, they collaborated with LY 303366 for significantly increased inhibition from 38% by LY 303366 alone to 67% by co-culture. Thus, LY 303366 has activity against germinating or germinated conidia of Aspergillus, human effector cells act co-operatively with LY 303366, and LY 303366 can sensitize germinating conidia for damage by host cells.

Cytokines and mycoses

Cell-mediated immunity (CMI) has been shown, over many decades of clinical observation and bench research, to be central to the outcome of invasive fungal infections. In recent years, understanding the role of messenger molecules (cytokines), in coordinating and augmenting cellular immunity has been ascendant. These studies have made it possible to consider using cytokines, now available in abundant quantities via recombinant DNA technologies, to treat fungal infections. In this symposium, the most important fungal pathogens that cause infections in humans, particularly in immunocompromised patients, are considered, with emphasis on how recent experimental work may lead to a better understanding of the role of cytokines and their use in therapy.

Dermatophytes and host defence in cutaneous mycoses

Dermatophytosis is the infection of keratinized tissues such as hair, nails and the stratum corneum of the skin by dermatophyte fungi. These fungi are onygenalean anamorphs and anamorphic species belonging to the genera Trichophyton, Microsporum and Epidermophyton. An important characteristic of the dermatophytes as parasites is their restriction to the dead keratinized tissues, except in rare cases where the patient is immunosuppressed. In contrast to many fungi, including normally non-pathogenic species, which can invade systemically in severely immunocompromised (e.g. neutropenic) patients, dermatophytes appear to be unable to cause systemic infection in this population. Thus, these fungi appear to have an unique interaction with the immune system. A better understanding of this interaction will contribute significantly to our knowledge of mammalian host defences.

A survey of percutaneous/mucocutaneous injury reporting in a public teaching hospital

Our objective was to determine if healthcare workers were reporting all percutaneous and/or mucocutaneous injuries and to use such data to formulate appropriate interventions. The Infection Control Department distributed anonymous surveys of healthcare personnel between 1992 and 1995. The elicited information included the number of percutaneous and mucocutaneous injuries experienced and reported in the last five years and the reasons for not reporting every exposure when applicable. Five hundred and forty nine surveys were received, from physicians, dentists, registered nurses, licensed vocational nurses, nurses aides, and operating room technicians. Overall, of the 549 respondents, 45% (245) had no injuries, 30% (163) had been injured and had reported all injuries, and 26% (141) had not reported all injuries. Reasons for not reporting included sterile/clean needlestick (39%), little or no perception of risk to employee (26%), too busy (9%), and dissatisfaction with follow-up procedures (8%). Reasons stated for not reporting injuries indicate a need for continued education in the risk of acquiring blood-borne pathogens from such injuries. The results also illustrate the importance of targeting prevention efforts to specific groups, such as physicians, that would not be identified by routine reporting mechanisms.

Molecular and phenotypic characterization of genotypic Candida albicans subgroups and comparison with Candida dubliniensis and Candida stellatoidea

There have been increased reports of the isolation of unusual genotypic groups of Candida albicans (groups C and D) based on a well-defined genotypic method; this method uses cellular DNA digested with the EcoRI enzyme and the restriction fragment length polymorphisms (RFLPs) generated by agarose gel electrophoresis. The aim of the present study was to use additional molecular tools to characterize these unusual strains and to compare them with authentic strains of C. dubliniensis, a recently delineated species, and type I C. stellatoidea. The RFLPs of PCR products generated from the intergenic transcribed spacer (ITS) region did not differentiate among C. albicans genotypes A, B, and C and type I C. stellatoidea. However, this method did differentiate the C. albicans genotype D strains, which were identical to C. dubliniensis. The RFLPs generated by HaeIII digestion of the PCR products of the V3 region of the 25S rRNA gene (rDNA) could differentiate the same groups as RFLP analysis of the PCR amplicon of the ITS region. C. albicans genotype B isolates have been shown to have a transposable intron in the 25S rDNA, whereas genotype A isolates do not; C. dubliniensis strains also have an intron that is larger than that in genotype B C. albicans strains but that is in the same location. PCR designed to span this region resulted in a single product for C. albicans genotype A (450 bp), B (840 bp), type 1 C. stellatoidea (840 bp), and C. dubliniensis (1,080 bp), whereas the C. albicans genotype C isolates had two major products (450 and 840 bp). All C. albicans genotype D isolates gave a PCR product identical to that given by C. dubliniensis. These results indicate that those strains previously designated C. albicans genotype D are in fact C. dubliniensis, that no differences were found between type 1 C. stellatoidea and C. albicans genotype B strains, and that the C. albicans genotype C strains appear to have the transposable intron incompletely inserted throughout the ribosomal repeats in their genomes. The results of the antifungal susceptibility testing of 105 of these strains showed that, for fluconazole, strains of C. dubliniensis were significantly more susceptible than strains of each of the C. albicans genotypes (genotypes A, B, and C). The flucytosine susceptibility results indicated that strains of C. albicans genotype A were significantly less susceptible than either C. albicans genotype B or C. albicans genotype C strains. These results indicate that there is a correlation between the Candida groups and antifungal susceptibility.

Morphological transition of Paracoccidioides brasiliensis conidia to yeast cells: in vivo inhibition in females

Clinical paracoccidioidomycosis is 13 times more common in men than in women. Estrogen inhibits the transition of mycelia or conidia (the saprophytic form of Paracoccidioides brasiliensis) to yeasts (the parasitic form) in vitro. Here, we show that, in male mice that were infected intranasally (mimicking natural infection) the transition of conidia in bronchoalveolar lavage fluids to intermediate forms and yeasts occurred over 24 to 96 h; CFU and yeasts (shown by histopathology) increased subsequently. In females, transition did not occur and infection cleared. These events in vivo are consistent with epidemiological and in vitro observations, suggesting that female hormones block transition and are responsible for resistance.

Standardized management of patients and employees exposed to pertussis

Waning pertussis immunity and spread of pertussis by asymptomatic adults contributes to increased pertussis exposures of vulnerable children. The Santa Clara Valley Medical Center had 49 pertussis exposures between July 1, 1989, and June 30, 1997, which originated in pediatric units or clinics and had an impact on the Employee Health Service (EHS) and Emergency Department (ED). We have developed a standardized protocol for management of employees and patients exposed to pertussis. The protocol includes a checklist for infection control staff; memoranda to exposed units conveying exposure information, instructions for employees to report to EHS or ED, and disease symptom information; written guidelines for physician management of patient exposures (prophylaxis and isolation) and EHS or ED management of employee exposures; and prophylaxis recommendations. We allow exposed employees to work while wearing a mask (worn until 5 days of prophylaxis are completed or for the entire potential contagious period if prophylaxis was refused). Employees who develop pertussis are restricted from work. Our protocol and standardized forms provide consistent management of pertussis exposures in both patients and employees.

Development of macrophage anticryptococcal activity in vitro is dependent on endogenous M-CSF

We previously showed that nonactivated resident murine peritoneal macrophages (PM) from five strains (e.g., BALB/c) have C'-dependent fungistasis for Cryptococcus neoformans in 24-h coculture, but not CD-1 PM unless culture time was extended or M-CSF treatment was used. We studied effect of a rat IgG1 monoclonal (m) antibody (Ab) to murine M-CSF receptor on this anticryptococal activity. Culture of BALB/c PM with mAb, diluted 1:10, prechallenge reduced fungistasis from 58 to 21% (P < 0.01), whereas further 10-fold dilutions did not. Moreover, M-CSF pretreatment (5000 U/ml) significantly enhanced fungistasis (to 85%), whereas adding mAb 1:10 or 1:100 reduced that (to 58 and 77%, respectively, P < 0.01). In 48-h culture CD-1 PM had 39% fungistasis, reduced to 0% by mAb, M-CSF treatment of CD-1 PM increased fungistasis to 72%, which was reduced to 13 or 58% (P < 0. 001) by 1:10 or 1:100 mAb, respectively. Complete blocking by mAb of CD-1 PM activity was consistent with lack of measurable early endogenous CD-1 M-CSF production. Increasing exogenous M-CSF could overcome the inhibition by mAb (64% fungistasis BALB/c PM reduced to 11% with inhibition by mAb or increased to 94% with 5000 U/ml M-CSF; 37% with both mAb and M-CSF, 51% with mAb and 10,000 U/ml; P < 0.05, 5000 U/ml + mAb vs 10,000 U/ml + mAb). Moreover, rabbit Ab to M-CSF significantly reduced anticryptococcal activity of untreated BALB/c macrophages. In summary, development of PM fugistatic activity is dependent on endogenous M-CSF, since it is blocked by anti-receptor mAb (as is exogenous M-CSF stimulation) or anti-M-CSF Ab, and macrophages of the mouse strain with delayed activity had no measurable early M-CSF production.

A model of coccidioidal meningoencephalitis and cerebrospinal vasculitis in the rabbit

Coccidiodal meningitis is a devastating complication of disseminated coccidioidomycosis. An animal model of this infection could enhance understanding of the pathogenesis of the disease and lead to improvements in therapy. A rabbit model of central nervous system infection simulating human disease was established using a blind cisternal tap technique to inoculate 4 x 10(3)-1 x 10(6) arthroconidia of Coccidioides immitis into the cisterna magna. Systemic, neurologic, and histopathologic findings of meningitis were observed in all rabbits, but an inoculum of 2 x 10(4) arthroconidia produced a chronic illness in which meningeal endarteritis obliterans was consistently observed. Serial sampling of cerebrospinal fluid demonstrated an inflammatory response. Growth of C. immitis was demonstrated by quantitative fungal culture from brains and proximal spinal cords.

Activity of voriconazole combined with neutrophils or monocytes against Aspergillus fumigatus: effects of granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor

Voriconazole (VCZ) was tested for antifungal activity against Aspergillus fumigatus hyphae alone or in combination with neutrophils or monocytes. Antifungal activity was measured as percent inhibition of hyphal growth in assays using the dye MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] or XTT [2, 3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxa nilide ]. With both assays, VCZ inhibited hyphal growth at concentrations of <1 microgram/ml and was almost as active as amphotericin B. VCZ (0.6 microgram/ml) was sporicidal, as was amphotericin B (0.4 microgram/ml). With both the MTT and XTT assays, neutrophils alone inhibited hyphae; when combined with VCZ, there was additive activity. Both granulocyte colony-stimulating factor- and granulocyte-macrophage colony-stimulating factor (GM-CSF)-treated polymorphonuclear neutrophils (PMN) had enhanced inhibition of hyphal growth. Moreover, such treatment of PMN also enhanced the collaboration of PMN with VCZ. Monocytes inhibited hyphal growth. When VCZ was combined with monocytes or monocytes were treated with GM-CSF, inhibition was significantly increased, to similar levels. However, the combination of VCZ with GM-CSF treatment of monocytes did not significantly increase the high-level inhibition by monocytes with either agent alone.

Species identification and virulence attributes of Saccharomyces boulardii (nom. inval.)

Saccharomyces boulardii (nom. inval.) has been used for the treatment of several types of diarrhea. Recent studies have confirmed that S. boulardii is effective in the treatment of diarrhea, in particular chronic or recurrent diarrhea, and furthermore that it is a safe and well-tolerated treatment. The aim of the present study was to identify strains of S. boulardii to the species level and assess their virulence in established murine models. Three strains of S. boulardii were obtained from commercially available products in France and Italy. The three S. boulardii strains did not form spores upon repeated testing. Therefore, classical methods used for the identification of Saccharomyces spp. could not be undertaken. Typing by using the restriction fragment length polymorphisms (RFLPs) of the PCR-amplified intergenic transcribed spacer regions (including the 5. 8S ribosomal DNA) showed that the three isolates of S. boulardii were not separable from authentic isolates of Saccharomyces cerevisiae with any of the 10 restriction endonucleases assessed, whereas 9 of the 10 recognized species of Saccharomyces could be differentiated. RFLP analysis of cellular DNA with EcoRI showed that all three strains of S. boulardii had identical patterns and were similar to other authentic S. cerevisiae isolates tested. Therefore, the commercial strains of S. boulardii available to us cannot be genotypically distinguished from S. cerevisiae. Two S. boulardii strains were tested in CD-1 and DBA/2N mouse models of systemic disease and showed intermediate virulence compared with virulent and avirulent strains of S. cerevisiae. The results of the present study show that these S. boulardii strains are asporogenous strains of the species S. cerevisiae, not representatives of a distinct and separate species, and possess moderate virulence in murine models of systemic infection. Therefore, caution should be advised in the clinical use of these strains in immunocompromised patients until further study is undertaken.

Direct allelic variation scanning of the yeast genome

As more genomes are sequenced, the identification and characterization of the causes of heritable variation within a species will be increasingly important. It is demonstrated that allelic variation in any two isolates of a species can be scanned, mapped, and scored directly and efficiently without allele-specific polymerase chain reaction, without creating new strains or constructs, and without knowing the specific nature of the variation. A total of 3714 biallelic markers, spaced about every 3.5 kilobases, were identified by analyzing the patterns obtained when total genomic DNA from two different strains of yeast was hybridized to high-density oligonucleotide arrays. The markers were then used to simultaneously map a multidrug-resistance locus and four other loci with high resolution (11 to 64 kilobases).

Epidemiology of Candida albicans isolates from heroin addicts analysed by DNA typing

Candida albicans is a ubiquitous commensal organism of humans. Several studies have examined outbreaks of candidiasis in heroin addicts utilizing a variety of methods to assess the epidemiological relatedness of the isolates and suggested the association of certain subtypes with disease in this patient population. The aim of the present study was to assess a separate group of isolates of C. albicans from heroin addicts in Spain using a DNA typing method. Results showed that, of the 34 isolates from heroin addicts, 20 were in subgroup IA, 10 were in subgroup IB and no isolates were of the subtype IA2. In addition, four isolates were in a recently described subgroup IC. Control isolates from the same geographical region (Spain) showed a distribution similar to the Spanish heroin addict isolates (12 subgroup IA, three subgroup IB, two subgroup IC and no isolates of the subtype IA2). In this study isolates from the same locality appeared similar irrespective of the patient population from which they were isolated. These results indicated that there may be differing geographical diversity of C. albicans than has previously been reported and that the newly described genotypic subgroup (IC) of C. albicans may be more widespread than previously shown.