Management of Infections Caused by Candida glabrata

Candida glabrata Has No Enhancing Role in the Pathogenesis of Candida-Associated Denture Stomatitis in a Rat Model

Many denture wearers suffer from Candida-associated denture stomatitis (DS), a fungal infection of the hard palate in contact with dentures. Biofilm formation by Candida albicans on denture/palate surfaces is considered a central process in the infection onset. Although Candida glabrata is frequently coisolated with C. albicans, its role in DS pathogenesis is unknown. We show here, using a contemporary rat model that employed a patented intraoral denture system, that C. glabrata established stable colonization on the denture/palate. However, in contrast to C. albicans inoculated rats, rats inoculated with C. glabrata exhibited minimal changes in weight gain or palatal tissue damage. Likewise, coinoculation with the two Candida species resulted in no exacerbation of C. albicans-induced DS pathology. Together, our findings indicate that C. glabrata has no inducing/enhancing role in DS pathogenesis.

Denture stomatitis (DS) is a condition characterized by inflammation of the oral mucosa in direct contact with dentures and affects a significant number of otherwise healthy denture wearers. Candida-associated DS is predominantly caused by Candida albicans, a dimorphic fungus that readily colonizes and forms biofilms on denture materials. Previous studies showed a requirement for Candida biofilm formation on both palate and dentures in infection and identified fungal morphogenic transcription factors, Efg1 and Bcr1, as key players in DS pathogenesis. While both C. albicans and Candida glabrata are frequently coisolated in mucosal candidiasis, a pathogenic role for C. glabrata in DS remains unknown. Using an established rat model of DS, we sought to determine whether C. glabrata alone or coinoculation with C. albicans establishes colonization and causes palatal tissue damage and inflammation. Rats fitted with custom dentures were inoculated with C. albicans and/or C. glabrata and monitored over a 4-week period for fungal burden (denture/palate), changes in body weight, and tissue damage via lactate dehydrogenase (LDH) release as well as palatal staining by hematoxylin and eosin (H&E) and immunohistochemistry for myeloperoxidase (MPO) as measures of inflammation. C. glabrata colonized the denture/palate similarly to C. albicans. In contrast to C. albicans, colonization by C. glabrata resulted in minimal changes in body weight, palatal LDH release, and MPO expression. Coinoculation with both species had no obvious modulation of C. albicans-mediated pathogenic effects. These data suggest that C. glabrata readily establishes colonization on denture and palate but has no apparent role for inducing/enhancing C. albicans pathogenesis in DS.

IMPORTANCE Many denture wearers suffer from Candida-associated denture stomatitis (DS), a fungal infection of the hard palate in contact with dentures. Biofilm formation by Candida albicans on denture/palate surfaces is considered a central process in the infection onset. Although Candida glabrata is frequently coisolated with C. albicans, its role in DS pathogenesis is unknown. We show here, using a contemporary rat model that employed a patented intraoral denture system, that C. glabrata established stable colonization on the denture/palate. However, in contrast to C. albicans inoculated rats, rats inoculated with C. glabrata exhibited minimal changes in weight gain or palatal tissue damage. Likewise, coinoculation with the two Candida species resulted in no exacerbation of C. albicans-induced DS pathology. Together, our findings indicate that C. glabrata has no inducing/enhancing role in DS pathogenesis.

Genotypic, phenotypic, and proteomic characterization of Candida glabrata during sequential fluconazole exposure

AIM

Candida glabrata is a major pathogen in humans known to be intrinsically resistant to fluconazole. However, genotypic, phenotypic, and proteomic changes associated with reduced susceptibility to fluconazole are not properly understood. The aim of this study was to observe specific phenotypic, chromosomal, and proteomic alterations in a Candida glabrata strain sequentially exposed to fluconazole.

METHODS

Candida glabrata was exposed to increased concentrations of fluconazole in RPMI for 55 days. Phenotypic changes were evaluated using standard assays. Molecular/proteomic changes in C. glabrata were analyzed by contour-clamped homogeneous electric field electrophoresis, reverse transcription-polymerase chain reaction, and mass spectrometry.

RESULTS

  Candida glabrata demonstrated increased fluconazole resistance (>256 μg/mL), with extensive cross-resistance to ketoconazole (0.38-3.0 μg), itraconazole (8 to >32 μg), and voriconazole (0.125-1.5 μg). Morphologically dissimilar colonies on RPMI/fluconazole agar demonstrated variable chromosomal profiles compared with the control isolate. Stable chromosomal changes were associated with a significantly higher (P<0.05) mRNA level of the hemolysin gene compared with the control. Phenotypic switching on CuSO4 agar was associated with variable metallothionein mRNA transcription levels. The proteome analysis of a fluconazole-resistant offshoot demonstrated a total of 98 protein spots, 25 showing a twofold upregulation.

CONCLUSION

Fluconazole exposure initiates the chance evolution of a new colonizing population with specific virulence traits.

Emergence of resistance to amphotericin B and triazoles in Candida glabrata vaginal isolates in a case of recurrent vaginitis

Emergence of resistance to triazoles and amphotericin B in Candida glabrata vaginal isolates is documented by Etest. During the 18-month follow-up of a case of vaginitis, 14 consecutive isolates of C. glabrata were examined. The isolates exhibited development of in vitro resistance beginning with itraconazole (>32 microg/ml), followed by fluconazole (>256 microg/ml), amphotericin B (>32 microg/ml), and voriconazole (>32 microg/ml). The DNA sequence analyses and finger printing of the isolates strongly suggest that our patient remained colonized with a single strain. The report underscores the propensity of C. glabrata to acquire resistance during antifungal therapy and the importance of susceptibility testing in the management of infections caused by this species.

Épidémiologie des fongémies dans les hôpitaux français non universitaires en 2004 : enquête multicentrique ColBVH

INTRODUCTION

The aim of our study was to determinate the frequency of candidemia, the species encountered and their susceptibility to antifungal agents in French hospitals in 2004.

METHODS

A prospective survey of septicaemia, including candidaemia was conducted among 193 non teaching French hospitals during October 2004. All bloodstream infections were reported and the bloodstream isolates sent to two coordinating centers. Species identification and susceptibility were performed by biologists as usual, and further confirmed by use of alternative methods, including Minimal Inhibitory Concentration (MIC) determination.

RESULTS

The survey was effective in 93 hospitals, where 2013 bloodstream infections were noticed, including 46 candidaemia (2.3%). Candida sp. Is the 7th pathogen responsible for bloodstream infection, without concern of the origin of the infection. Candidaemia was hospital acquired in 80.4% of cases (N=37/46). Candidaemia represents 0.7% (N=9/1211) of community-acquired bloodstream infections but 4.5% (N=37/802) of nosocomial cases, placing Candida sp. at the 5th row of frequency in this last group. No mistakes were noticed during identification, but two strains were not named. After confirmation of identification, species are distributed as follows: 23 C.albicans (50%), 13 C.glabrata (28.3%), 5 C.tropicalis (10.9%), 3 C.parapsilosis (6.5%), 1 C.krusei (2.2%), and 1 C.kefyr (2.2%). The overall susceptibility is 97.7% for amphotericin B, 93.2% for 5-fluorocytosin, 88.6% for fluconazole, 70.5% for itraconazole, 95.5% for voriconzole and 100% of strains had very low MIC for caspofungin. Concerning the two main species isolated, 95.5% of C.albicans strains remain susceptible to fluconazole, but only 69% of C.glabrata strains. Two strains, 1 C.albicans and 1 C.glabrata exhibit cross resistance to azoles. The majority of amphotericin, fluconazole, and itraconazole decreased susceptibility strains are found into C.glabrata strains, but susceptibility to 5-fluorocytosin and very low MCI to caspofungin remained in this species.

CONCLUSION

Our survey allowed us to get data from French non-teaching hospitals in 2004 about frequency of candidaemia among septicaemia. Candida species distribution and in vitro susceptibility patterns of the strains isolated. Candidaemia is not a rare event, specially when septicaemia is nosocomially acquired. C.albicans is the main species isolated and remains highly in vitro susceptible to antifungals. One important feature is the frequency of C.glabrata in our survey. Considering its decreased susceptibility to azoles, this finding confirms the need for rapid identification of yeast isolated from bloodstream samples, and antifungal susceptibility testing each time it is available.

Influence of antifungal polyenes on the adhesion of Candida albicans and Candida glabrata to human epithelial cells in vitro

Candidal adherence to mucosal surfaces is considered as the first step in the pathogenesis of oral candidiasis. We examined the effect of antifungal polyenes, amphotericin B, nystatin and natamycin, at sublethal and minimum inhibitory concentrations (MICs) on the adherence of Candida albicans and Candida glabrata to HeLa cervical carcinoma and HSC-3 oral squamous cell carcinoma cells. A total of six oral Candida isolates were used throughout the study. Two Candida strains, C. albicans (44990) and C. glabrata (MYA-275) were obtained from ATCC. Four Candida strains, C. albicans 19 and 24 and C. glabrata 15 and 21, were isolated from patients with documented Candida-associated denture stomatitis. Cells were either incubated with Candida in the presence of the drug, or pre-incubated with yeasts and exposed subsequently to the drug. In the drug-free controls, the mean number of C. albicans yeasts associated with HeLa cells obtained from all experiments (130.1+/-10.1 yeasts/mm(2)) was significantly greater than that for HSC-3 cells (114.7+/-10.1 yeasts/mm(2); P<0.025). For C. glabrata, the mean adherence to HeLa and HSC-3 cells was 84.4+/-5.5 and 84.4+/-3.3 yeasts/mm(2), respectively, and these values were not statistically different (P>0.4). Candidal adherence was significantly reduced when the tested polyenes were present during the "adherence phase". The obtained values were significantly different from the controls, except for the effect of nystatin at the MIC on the adherence of C. glabrata strain MYA-275 to HeLa cells (P<0.375). Amphotericin B had the highest effect against both Candida species, reducing adherence by approximately 50 and approximately 60%, at the MIC and sublethal concentrations, respectively. The susceptibility of cell-associated Candida to polyenes was decreased markedly and the treatment did not result in significant detachment of adherent yeasts. The reduction in adherence was between 2 and 10%, when compared to the drug-free controls. These findings suggest that sub-therapeutic levels of polyenes that are likely to persist in the oral cavity following topical treatment may modulate candidal colonization when present during the "adherence phase".

Prospective, multicenter surveillance study of Candida glabrata: fluconazole and itraconazole susceptibility profiles in bloodstream, invasive, and colonizing strains and differences between isolates from three urban teaching hospitals in New York City (Candida Susceptibility Trends Study, 1998 to 1999)

Since the 1990s, the substantial increase in the rate of Candida glabrata infections has become a serious problem. As most C. glabrata infections arise from the host's endogenous microflora, the present prospective, multicenter analysis included all clinical isolates associated with colonization and with systemic and hematogenous candidiasis. Among 347 C. glabrata isolates, the overall rates of resistance to fluconazole (MIC > or = 64 micro g/ml) and itraconazole (MIC > or = 1 micro g/ml) were 10.7 and 15.2%, respectively, although for half (n = 148) of the itraconazole-susceptible isolates the MICs (0.25 to 0.5 micro g/ml) were in the susceptible-dependent upon dose range. Fluconazole resistance was more common among C. glabrata isolates obtained from centers caring for patients with cancer (MICs at which 90% of isolates are inhibited [MIC(90)s] = 32 micro g/ml) or AIDS (MIC(90)s > 64 micro g/ml) than among C. glabrata isolates from a community-based university medical center (MIC(90)s = 16 micro g/ml) (P = 0.001). Thirty-three bloodstream isolates and those obtained from other body sites had similar in vitro susceptibility profiles. The fluconazole MIC(90)s (< or =16 micro g/ml) for C. glabrata yeast isolates from the gastrointestinal tract were lower than those (> or =64 micro g/ml) for C. glabrata isolates from respiratory and urinary tract samples (P = 0.01). A similar discrepancy for itraconazole was not significant (P > 0.5). We did not observe differences in fluconazole or itraconazole susceptibility profiles among C. glabrata isolates associated with either hematogenous dissemination or colonization. The significant discrepancy in antifungal susceptibility among C. glabrata organisms isolated from hospitals in the same geographic region emphasizes the significance of periodic susceptibility surveillance programs for individual institutions, especially those providing care to patients at risk.

The epidemiology of Candida glabrata and Candida albicans fungemia in immunocompromised patients with cancer

PURPOSE

Candida glabrata is an increasing cause of candidemia, especially at cancer and bone marrow transplant centers where fluconazole is used for antifungal prophylaxis. This yeast is less susceptible to fluconazole in vitro than is Candida albicans. We compared the characteristics of patients who had C. glabrata and C. albicans candidemia at a large cancer center.

SUBJECTS AND METHODS

We searched the microbiological laboratory reports and identified 116 cases of C. glabrata candidemia between 1993 and 1999. The 116 cases of C. albicans candidemia that occurred most closely in time (before or after each case of C. glabrata candidemia) served as the control group. Data were collected from patients' medical records.

RESULTS

When compared with patients who had C. albicans infection, patients with C. glabrata candidemia more often had an underlying hematologic malignancy (68 [59%] vs. 26 [22%], P = 0.0001), had an Acute Physiology and Chronic Health Evaluation (APACHE) II score > or =16 (55 [48%] vs. 28 [25%], P = 0.0002), and received fluconazole prophylaxis (57 [49%] vs. 8 [7%], P = 0.0001). Patients with C. albicans candidemia more often had concomitant infections (101 [87%] vs. 78 [67%], P = 0.0003) and septic thrombophlebitis (11 [10%] vs. 2 [2%], P = 0.01). Among patients treated with antifungal therapy, those with C. albicans candidemia had a significantly greater overall response to therapy (83/104 [80%] vs. 60/97 [62%], P = 0.005) and to primary therapy (74/104 [71%] vs. 45/97 [46%], P = 0.0003). Amphotericin B preparations were not more effective than fluconazole (19/45 [42%] vs. 20/38 [53%], P = 0.5) in patients with C. glabrata candidemia. Fluconazole was less effective against C. glabrata than against C. albicans (20/38 [53%] vs. 57/74 [77%], P = 0.008).

CONCLUSION

C. glabrata has emerged as an important cause of candidemia, especially among neutropenic patients who receive fluconazole prophylaxis.

A clinical perspective for the management of invasive fungal infections: focus on IDSA guidelines. Infectious Diseases Society of America

Invasive fungal infections, especially candidiasis and aspergillosis, are a major cause of morbidity and mortality. Many controversies surround the management of these infections. A critical overview of the recent Infectious Diseases Society of America practice guidelines is provided, as are comments on both the conundrums and future perspectives in medical mycology.