Selection of Candida glabrata in pediatric bone marrow transplant recipients receiving fluconazole

Candida colonization in intensive care unit patients' urine

The objective of this study was to identify possible predisposing factors for candiduria in intensive care unit (ICU) patients from Hospital das Clínicas, Universidade Federal de Goiás, Goiânia, Brazil, during one year. Urine samples from 153 ICU patients were obtained by catheterization on admission day and every seven days. Data such as sex, age, antifungal therapy, and variables as antibiotics, underlying diseases or comorbid conditions and stay in the hospital, were collected from patients who had at least one urine culture that yielded > 10(3) yeast colonies/ml. Candiduria was recovered in 68 patients and the commonest predisposing factors were antibiotic therapy (100%) and indwelling urinary catheter (92.6%). The percentage of Candida spp. isolation increased during the extended periods in which patients remained in the ICU. C. albicans was isolated in 69.1%, and the other species non-albicans as C. glabrata, C. kefyr, C. parapsilosis, C. famata, C. guilliermondii, C. krusei, and C. tropicalis were isolated in lower percentage. The high frequency of candiduria and the possible predisposing factors found in ICU patients show that candiduria surveillance should be performed to help reducing nosocomial infections.

Using action research in paediatric oncology to develop an oral care algorithm

The concurrent use of an oral assessment guide and oral care algorithm proved valuable in providing a more consistent approach to the oral care of children on a particular paediatric oncology ward (Gibson et al. 1997). However, as action research was chosen to develop practice, the diagnosis of new problems was anticipated. The identification of problem areas arose from two sources-informal feedback from the practice setting and via a formal audit using a tripartite approach consisting of a structured interview, vignettes and an analysis of existing documentation. The findings firstly demonstrated that practitioners experienced problems associated with the interpretation of the information contained within the existing algorithm. Secondly, there was also strong evidence to show that the production of a second 'therapeutic' algorithm would be beneficial to patient care. Finally, to ensure clarity, minor changes were required to the oral assessment guide. By using a collaborative approach between researchers and practitioners a positive resolution to a commonly identified clinical problem was expedited.

Current management of fungal infections

The management of superficial fungal infections differs significantly from the management of systemic fungal infections. Most superficial infections are treated with topical antifungal agents, the choice of agent being determined by the site and extent of the infection and by the causative organism, which is usually readily identifiable. One exception is onychomycosis, which usually requires treatment with systemically available antifungals; the accumulation of terbinafine and itraconazole in keratinous tissues makes them ideal agents for the treatment of onychomycosis. Oral candidiasis in immunocompromised patients also requires systemic treatment; oral fluconazole and itraconazole oral solution are highly effective in this setting. Systemic fungal infections are difficult to diagnose and are usually managed with prophylaxis or empirical therapy. Fluconazole and itraconazole are widely used in chemoprophylaxis because of their favourable oral bioavailability and safety profiles. In empirical therapy, lipid-associated formulations of amphotericin-B and intravenous itraconazole are safer than, and at least as effective as, conventional amphotericin-B (the former gold standard). The high acquisition costs of the lipid-associated formulations of amphotericin-B have limited their use.

Assessing risk factors for systemic fungal infections

The incidence of invasive fungal infection has increased in recent years. Most infections are caused by Candida albicans and Aspergillus spp. but the emergence of other fungal infections is changing the spectrum of disease. Immunosuppression and breakdown of anatomical barriers such as the skin are the major risk factors for fungal infections. Health care workers encounter at-risk patients in various settings, including AIDS clinics and intensive care, transplantation and oncology units. Patients with prolonged and deep neutropenia (haematological malignancy patients) are most at risk and are therefore most likely to receive prophylactic therapy. Practical measures can be taken to avoid exposing the patient to fungi (air filtration, regular hand washing, avoiding plants and flowers) and antifungal agents can be administered to prevent systemic fungal infection. Most fungal infections have non-specific symptoms; this makes recognition of the signs and symptoms of the disease important but also makes diagnosis difficult and empirical treatment necessary. Some antifungal agents have limitations but new formulations will improve therapy and play a key role in future antifungal strategies.

The combination of oral amphotericin B with azoles prevents the emergence of resistant Candida species in neutropenic patients

The role of antifungal prophylaxis remains controversial and concerns exist that the use of azoles may potentiate the emergence of resistant Candida species. We used a strategy of combining the latest azole/triazole with oral amphotericin B to reduce this risk. We analysed data on Candida colonization and candidaemia in neutropenic patients from four prophylaxis periods (1985/6: ketoconazole and amphotericin B suspension; 1991/2 & 1997: fluconazole and amphotericin B suspension; 1998/9: itraconazole) to look for evidence of the emergence of potentially resistant species. Overall, the percentage of patients colonized with Candida fell significantly (69.3%, 57.5%, 43.2% and 46%, respectively, P < 0.001) due to a decrease in colonization with C. albicans (49%, 23.1%, 22.2% and 25.2%, respectively, P < 0.001). However, in 1998/9, increased colonization, particularly with C. glabrata in the lower gastrointestinal tract, was noted to coincide with the omission of oral amphotericin B. Despite an increasing population of 'high risk' patients, the incidence of candidaemia has not changed significantly (2%, 1.4%, 1.2% and 2% respectively). However, species causing candidaemia have changed, with resistant organisms now predominating. Our findings support the use of azole prophylaxis although, in view of the trends noted when itraconazole was used alone, we would recommend the additional use of oral amphotericin B.

In vitro susceptibility of yeasts for fluconazole and itraconazole. Evaluation of a microdilution test

In vitro susceptibilities were determined for a total of 159 clinical isolates and 12 reference strains of yeasts belonging to different Candida species including 94 Candida albicans strains, and further genera such as Cryptococcus, Trichosporon, Geotrichum and Saccharomyces. Minimum inhibitory concentration (MIC) values for fluconazole and itraconazole were assessed using a microdilution technique with the semisynthetic high resolution (HR) medium supplemented with glucose and asparagine but without sodium hydrogen carbonate (pH 7.0), according to a proposal of the working group 'Clinical Mycology' of the German Speaking Mycological Society. Fluconazole MIC values for C. albicans were between 0.125 and > or = 128 micrograms ml-1. Thus, the median of 1 microgram ml-1 showed that the overall fluconazole susceptibility was good. As expected, Candida krusei (seven strains) exhibited diminished in vitro susceptibility with MIC values for fluconazole of 8 to 128 micrograms ml-1 with a median of 64 micrograms ml-1. Some Candida kefyr strains seemed to be less susceptible against fluconazole which was indicated by a MIC90 of 64 micrograms ml-1. Surprisingly, no Candida glabrata isolate exhibited a MIC value greater than 16 micrograms ml-1. Other Candida species, Trichosporon cutaneum, Geotrichum candidum and Saccharomyces cerevisiae showed low MICs to fluconazole. In vitro susceptibility testing of itraconazole revealed that all Candida species except C. albicans, but also Trichosporon cutaneum, Geotrichum candidum, and Saccharomyces cerevisiae exhibited acceptable low MIC values against itraconazole (0.03-2 micrograms ml-1). Their MIC90 values for itraconazole were in the close range between 0.125 and 2 micrograms ml-1. MIC values between 0.125 and 2 micrograms ml-1 were obtained, even for C. krusei strains. On the other hand, the range of C. albicans MICs was between 0.0125 and > or = 16 micrograms ml-1 with MIC50 and MIC90 values of 0.125 and > or = 16 micrograms ml-1, respectively, indicating that a considerable number of yeast strains have high MICs. The comparative evaluation of different experimental conditions revealed that there exists a marked influence both of inoculum size and incubation time on the results of susceptibility testing. Therefore, for routine usage 10(2) CFU ml-1 and 18-24 h incubation time for this microdilution method with HR medium are recommended.

Infections in recipients of blood and marrow transplantation

The approach to infections in blood and marrow transplant (BMT) recipients involves an understanding of clinical infection syndromes and the natural history of individual infections, taken in the context of patterns of immunosuppression after transplantation and mechanisms underlying immune system reconstitution over time. The conditioning regimen used to prepare the host is a major determinant of host tissue injury and may lead to mucositis or diarrhea, facilitating transmucosal origin of bloodstream infections. Infectious risk also differs between autologous and allogeneic grafts as a consequence of ongoing immunosuppression from graft-versus-host disease and its therapy. Post-transplant complications may mimic infectious processes, and multiple infections may occur in one patient at the same time. Thus, the BMT patient with suspected infection should be evaluated in the context of pretransplant exposure history (infectious disease serologies), conditioning regimen, available culture data from nonsterile mucosal surfaces, previous and recent infections, contemporary transplant complications, and the current degree and duration of neutropenia, cellular immunodeficiency, and hypogammaglobulinemia.

In vitro activity of rilopirox against fluconazole-susceptible and fluconazole-resistant Candida isolates from patients with HIV infection

The in vitro antifungal activity of the new hydroxypyridone antimycotic rilopirox has been evaluated against 38 fluconazole-susceptible and -resistant clinical isolates of Candida albicans together with other Candida species isolated from patients with human immunodeficiency virus (HIV) infection and oropharyngeal candidosis. Minimum inhibitory concentrations (MICs) of both rilopirox and fluconazole were measured by a microdilution method using high-resolution medium supplemented with asparagine and glucose at pH 7.0. In comparison, an agar dilution technique was carried out for susceptibility testing of the antifungal agents. Rilopirox was found to be able to inhibit growth of all clinical yeast isolates. The rilopirox MICs at which 50% and 90% of strains were inhibited (MIC50 and MIC90 respectively), as determined by the microdilution method, were 4 and 8 micrograms ml-1 respectively. The highest MIC values for rilopirox using microdilution and the agar dilution method were 32 or 25 micrograms ml-1 respectively. On the other hand, for fluconazole, the MIC50 and MIC90 achieved were 0.5 and 128 micrograms ml-1, respectively, which means that the MIC90 value of fluconazole was 16-fold higher than that of rilopirox. Using the agar dilution technique, the MIC values of rilopirox were in the range 0.006-25 micrograms ml-1 with a median of 3.12 micrograms ml-1. For fluconazole, the MIC90 value was four-fold higher than that for rilopirox, indicating a considerable proportion of yeast strains with high MICs of 100 micrograms ml-1, suggesting in vitro resistance to this azole antifungal. All strains with diminished fluconazole susceptibility were susceptible to rilopirox. Even Candida krusei and Candida glabrata exhibited good in vitro susceptibility to rilopirox. Therefore, this new antifungal agent may be used as an alternative not only in the treatment of vaginal candidosis, but also in oropharyngeal Candida infections, e.g. in AIDS patients.

The effect of prophylactic fluconazole on the clinical spectrum of fungal diseases in bone marrow transplant recipients with special attention to hepatic candidiasis. An autopsy study of 355 patients

We reviewed 355 autopsies performed between 1990 and 1994 at a major marrow transplant center to determine whether fluconazole prophylaxis prevented visceral fungal infection. Fluconazole prophylaxis was defined by a minimum of 5 prophylactic doses. Fungal infection (any site) was found in 40% of patients transplanted and autopsied at the center. Overall, the proportion of autopsies with any fungal infection was not different for those patients receiving no fluconazole prophylaxis versus those with prophylactic fluconazole. With fluconazole prophylaxis, candidal infections were less frequent, decreasing from 27% to 8%, while Aspergillus infections were more frequent, increasing from 18% to 29%. No increase in deaths related to non-albicans Candida infections was seen. Of the 329 patients with livers examined, hepatic infection caused by Candida species was significantly less common in patients who had received fluconazole. Fungal liver infection was found in 31 patients (9%), 16% of those who were not treated with fluconazole and 3% of those who were treated with fluconazole. Since patients with candidal infections died earlier after marrow transplant than patients with mold infections, we speculate that a longer length of survival may dispose toward acquisition of mold infections. Fluconazole prophylaxis in this cohort of marrow transplant patients undergoing autopsy resulted in a significant reduction in infection caused by Candida species and an increase in mold infections.

Antifungal resistance trends towards the year 2000. Implications for therapy and new approaches

Medical advances have led to increased numbers of immunocompromised patients living longer. Coinciding with this increase in the immunocompromised patient population is an increase in the number of clinically significant fungal infections. Unfortunately, widespread use of the limited numbers of antifungal agents to treat these infections has led to the development of drug resistance. Thus, in an attempt to sort out the mechanisms of resistance for each of the systemically useful antifungal agents, a comprehensive review of the literature has been carried out. The most common mechanisms for the development of resistance involve changes in the enzymatic pathways which serve as the drug targets. For instance, changes in enzymes responsible for the biosynthesis of ergosterol, the target of azole activity, lead to azole resistance. Another common mechanism used by fungi to avoid drug toxicity includes reduced intracellular accumulation of the drug through both decreased permeability and energy-dependent efflux pumps. Using our current understanding of the mechanisms of drug resistance as a template, several strategies to overcome resistance have been identified. These include improvement of host immune function, the use of adjuvant surgery, the development of new drug delivery systems for currently available drugs and the development of new classes of antifungal agents. Also, clinical trials to establish appropriate drug doses and duration of therapy are needed, as well as the benefits of antifungal prophylaxis explored and the use of combination therapies entertained. The war against drug resistant fungi has been identified as we approach the year 2000. With careful and cogent investigations, we do have the tools to fight back against these opportunists. Of all the strategies reviewed, however, in our opinion, the development of new antifungal drugs is likely to have the most significant future impact on our management of drug resistance in fungal infections.

Antifungal prophylaxis during neutropenia and immunodeficiency

Fungal infections represent a major source of morbidity and mortality in patients with almost all types of immunodeficiencies. These infections may be nosocomial (aspergillosis) or community acquired (cryptococcosis), or both (candidiasis). Endemic mycoses such as histoplasmosis, coccidioidomycosis, and penicilliosis may infect many immunocompromised hosts in some geographic areas and thereby create major public health problems. With the wide availability of oral azoles, antifungal prophylactic strategies have been extensively developed. However, only a few well-designed studies involving strict criteria have been performed, mostly in patients with hematological malignancies or AIDS. In these situations, the best dose and duration of administration of the antifungal drug often remain to be determined. In high-risk neutropenic or bone marrow transplant patients, fluconazole is effective for the prevention of superficial and/or systemic candidal infections but is not always able to prolong overall survival and potentially selects less susceptible or resistant Candida spp. Primary prophylaxis against aspergillosis remains investigative. At present, no standard general recommendation for primary antifungal prophylaxis can be proposed for AIDS patients or transplant recipients. However, for persistently immunocompromised patients who previously experienced a noncandidal systemic fungal infection, prolonged suppressive antifungal therapy is often indicated to prevent a relapse. Better strategies for controlling immune deficiencies should also help to avoid some potentially life-threatening deep mycoses. When prescribing antifungal prophylaxis, physicians should be aware of the potential emergence of resistant strains, drug-drug interactions, and the cost. Well-designed, randomized, multicenter clinical trials in high-risk immunocompromised hosts are urgently needed to better define how to prevent severe invasive mycoses.

Retrospective analysis of yeast colonization and infections in paediatric bone marrow transplant recipients

Sixty-four paediatric patients who underwent allogeneic (n = 35), autologous (n = 28) or syngeneic (n = 1) bone marrow transplantation (BMT) between 1992 and 1994 were evaluated retrospectively. As antifungal prophylaxis, all patients received amphotericin B tablets and 62 of 64 (96.9%) received oral fluconazole. Weekly surveillance cultures revealed fungal colonization in 35 patients (54.7%). Six patients (9.4%) were colonized before BMT only, 17 (26.6%) after BMT only and 12 (18.8%) both before and after BMT. Candida albicans was the most frequently isolated fungus [21 of 46 fungal isolates (45.7%)], followed by C. glabrata [14 isolates (30.4%)]. Non-albicans species of Candida were most frequently isolated after BMT from the faeces, often in high numbers. Autologous marrow recipients had a higher fungal colonization rate both before and after BMT than allogeneic marrow recipients. One patient suffered from invasive pulmonary aspergillosis after BMT. No fungaemias or deep-seated yeast infections were observed. Six of the seven patients who had to be treated with intravenous amphotericin B because of antibiotic-refractory fever had undergone autologous BMT. Multivariate analysis of various parameters showed only pre-BMT yeast colonization to be independently associated with post-BMT colonization. Thus, systemic mycoses occurred only rarely in this study population; however yeast colonization after BMT (especially with non-albicans species) was a frequent event in spite of double prophylaxis with oral amphotericin B and fluconazole.

Orointestinal yeast colonization of paediatric bone marrow transplant recipients: surveillance by quantitative culture and serology

We quantitatively studied the orointestinal yeast colonization of 15 consecutive paediatric patients who underwent 16 bone marrow transplantations (BMT). Cultures were performed initially, longitudinally weekly during the period of aplasia (in-patient treatment) and, if possible, also during out-patient follow-up. With one exception, all patients received fluconazole as antifungal prophylaxis. Patients remained free of yeasts during the complete observation period only in six out of 16 cases (38%). Non-albicans species of Candida were isolated in six out of 16 cases (38%), mainly C. glabrata (five out of 16; 31%). All of these patients had undergone allogeneic BMT. In one case, there was indirect evidence of systemic invasion by C. glabrata. Even combined prophylaxis with fluconazole and and amphotericin B suspension could not reliably prevent yeast colonization but this combination at present appears to be the optimal regime. Regular concomitant Candida serology (determination of specific antibodies by three methods) proved to be a valuable additional surveillance method.