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

Synergistic Interaction of Fluconazole/Amphotericin B on Inhibition of Enzymes Contributes to the Pathogenesis of Candida Tropicalis

Background: Candidiasis has gained much attention in recent decades due to its increasing prevalence in immunocompromised patients. Usually, antifungals such as fluconazole and amphotricin B are used for treatment of candidiasis, but one of the major clinical problems is the emergence of antifungal resistance. Combination antifungal therapy is one of the most commonly used methods to alleviate the problem of antifungal resistance. Methods: The effect of fluconazole alone and in combination with amphotericin B on C. tropicalis isolates were performed using the Clinical and Laboratory Standards Institute (CLSI) reference method. Eventually hypha formation, time kill study, proteinase and phospholipase activity and expression of PLB and SAP2 genes were carried out to investigate the enzymes inhibitory properties of antifungal tested against C. tropicalis. Results: Results showed the significant synergic effect of fluconazole in combination with amphotericin B in inhibiting the growth of C. tropicalis isolates, with fractional inhibitory concentration indices ranging from 0.06 to 0.5. The combination of fluconazole with amphotericin B reduced the number of yeast form and inhibited the yeast to hyphae transition in C. tropicalis. The antifungals tested were able to show the effect of down regulating expression of the selected genes significantly in fluconazole/amphotericin B ranging from 1.42- to 2.27-fold. Conclusion: Our results demonstrated that the synergistic interaction of fluconazole/amphotericin B would be worth exploring for the management of candidiasis. In addition, PLB and SAP2 genes could be probable molecular targets in the synergistic interaction of fluconazole/amphotericin B in C. tropicalis.

Combination liposomal amphotericin B, posaconazole and oral amphotericin B for treatment of gastrointestinal Mucorales in an immunocompromised patient

Mucormycosis is a life threatening infection caused by fungi in the order Mucorales. Mucormycosis can affect any organ system with rhino-orbital-cerebral and pulmonary infections being the most predominant infection types. Gastrointestinal mucormycosis is rare and accounts for only 4-7% of all cases. Here, we present a case of invasive gastrointestinal mucormycosis in an immunocompromised host treated with systemic and topical anti-mold therapy.

Active immunizations with peptide-DC vaccines and passive transfer with antibodies protect neutropenic mice against disseminated candidiasis

We previously report that peptide-pulsed dendritic cell (DC) vaccination, which targeting two peptides (Fba and Met6) expressed on the cell surface of Candida albicans, can induce high degree of protection against disseminated candidiasis in immunocompetent mice. Passive transfer of immune sera from the peptide immunized mice or peptide-related monoclonal antibodies demonstrated that protection was medicated by peptide-specific antibodies. In this study the efficacy of active and passive immunization against disseminated candidiasis was tested in mice with cyclophosphamide-induced neutropenia. Peptide-DC vaccines were given to mice prior to induction of neutropenia. We show active immunization with either Fba or Met6 peptide-DC vaccine significantly improved the survival and reduced the fungal burden of disseminated candidiasis in those immunocompromised mice. Importantly, we show that administration of two protective monoclonal antibodies also protect neutropenic mice against the disease, implying possibility of developing a successful passive immunotherapy strategy to treat the disease and protect against disseminated candidiasis. The results of this study are crucial as they address the fundamental questions as to whether the synthetic peptide vaccine induced immunity protects the host during a neutropenic episode. We anticipate that this peptide-vaccine study will serve as the foundation of future investigations into new peptide vaccines comprised of cell surface peptides from other medically important Candida species, as well as other fungi.

[Impact of antifungal prophylaxis on the gastrointestinal yeast colonisation in patients with haematological malignancies]

Patients with haematological malignancies are at high risk for developing invasive Candida infections. They are often colonised with Candida spp. in the gastrointestinal (GI) tract. In order to prevent infection, the prophylactic use of antifungal agents has been established. The widespread use of fluconazole may lead to the emergence of resistant Candida isolates. We studied the yeast colonisation of the GI tract in patients with haematological malignancies receiving antifungal prophylaxis (AP) in comparison with healthy controls. The study cohort included 46 neutropenic patients with 52 stool samples under 52 episodes of AP and 110 healthy controls. The patients received amphotericin B orally (n = 8), amphotericin B and fluconazole (n = 7), amphotericin B and itraconazole (n = 5), fluconazole orally (n = 15) and itraconazole orally (n = 17). Yeasts were cultured from the stool samples of 63.5% of the patients and 60% of the controls with a mean yeast load of 1.6 x 10(3) and 0.4 x 10(3) cfu g(-1), respectively (P = 0.045). Patients and controls had a low faecal yeast load of 10(3) to 10(4) cfu g(-1) in 19.3% and 37.3%, respectively (P = 0.021), and yeast overgrowth of >10(5) cfu g(-1) in 28.9% and 10.9%, respectively (P = 0.004). The rate of Candida albicans was 32.6% and 54.1% in the patients and controls, respectively (P = 0.021). The rates of fluconazole-resistant yeast species were higher in the patient group than in the control group: C. glabrata 20.9% vs. 11.7% (P = 0.168), C. krusei 25.6% vs. 4.7% (P = 0.001). Not a single patient under AP suffered from proven or probable invasive candidosis. In conclusion, oral AP in haematological patients resulted in a higher colonisation rate with fluconazole-resistant Candida species but efficiently prevented invasive candidosis.

Fludarabine, cytosine arabinoside, granulocyte-colony stimulating factor with or without idarubicin in the treatment of high risk acute leukaemia or myelodysplastic syndromes

The combination of fludarabine (FDR), high dose cytarabine and granulocyte colony stimulating factor (FLAG) with or without idarubicin (Ida) was used in the treatment of poor risk acute leukaemia or myelodysplastic syndrome (MDS) in a single centre experience. A total of 105 patients were treated over a 4-year period with 59% achieving a complete remission (CR); no statistical difference observed between FLAG and FLAG-Ida. For patients responding to FLAG +/- Ida, the median event-free survival (EFS) was 11 months and 23% at 5 years. Such patients proceeded either to further chemotherapy or a haematopoietic stem cell transplant (HSCT). The median EFS (13 months vs. 8 months) and projected 5-year survival (37% vs. 13%) of patients undergoing HSCT was significantly better than those who did not (P = 0.021). In all, 14 of 72 patients remain alive in continuing CR (median duration 43 months) with 10 of 31 having had a HSCT vs. four of 41 that did not (P = 0.033). Both regimens were well tolerated, with the majority of patients experiencing grade 1 or less non-haematological toxicity (mainly nausea and vomiting). The median time to neutrophil and platelet recovery was 28 and 31 d, respectively. No significant differences were seen with the addition of ida. There was a 17% incidence of treatment-related deaths, of which 39% was caused by invasive aspergillus infection. The results show that FLAG +/- Ida is an effective and well-tolerated remission induction regimen for poor risk leukaemia and MDS.

Prospective evaluation of Candida species colonization in hospitalized cancer patients: impact on short-term survival in recipients of marrow transplantation and patients with hematological malignancies

Most hematogenous candidiasis originates from endogenous host flora. The impact of clinically prominent Candida colonization on short-term mortality (<or=14 weeks) was prospectively studied in 193 hospitalized patients from 1998 to 1999. Clinically prominent colonization included yeasts isolated from all sterile body sites and >50 colonies of Candida from non-sterile sites. Fourteen (7.1%) patients were granulocytopenic (ANC <or=100/microl). Nineteen (9.8%) had undergone marrow transplantation, 26 (13.5%) had a hematologic malignancy and 129 (66.5) had non-hematologic cancer. Candida isolates (216) were collected form 210 specimens. Fifty-three (27.5%) patients died; 25 (19.4%) with solid tumors, compared to 16 (61.5%) with hematological malignancy, and 11 (57.9%) BMT recipients (P < 0.001). No deaths were seen in patients with AIDS, and one (7.7%) in a patient with a benign condition (P < 0.001). Twenty-six (29.2%) patients with respiratory tract, 13 (23.2%) with gastrointestinal tract, and three (14.3%) with genitourinary tract colonization died. In patients with multiple-site colonization, mortality was significantly higher (45.5%) (P < 0.05). Mortality was higher in patients with C. glabrata (52.9%) and C. krusei (75%) colonization than with C. albicans (24.1%) (P < 0.025). This study shows that patients with hematologic cancer and recipients of marrow transplant with Candida colonization of multiple body sites, and colonization with C. glabata or C. krusei have poor survival.

Antifungal drug resistance: does it matter?

The objectives of this review are: to review the modes of action of currently available antifungal drugs; to define drug resistance and discuss the mechanisms by which fungi can develop resistance to antifungal drugs; to consider the epidemiological and host factors that contribute to the outcome of antifungal therapy and whether the available in vitro susceptibility test methods can reliably predict clinical response; and to assess the overall relevance of drug resistance to the outcome of fungal infections. The incidence of antifungal drug resistance among pathogens causing invasive fungal infections appears to be increasing. In the case of Candida spp., this may in part be a consequence of selective pressure brought about by more intensive antifungal use leading to a 'pathogen shift'. Non-albicans Candida spp. are more likely to demonstrate reduced susceptibility to fluconazole compared to C. albicans. Susceptibility breakpoints developed by the National Committee for Clinical Laboratory Standards to test azoles and flucytosine against Candida spp. are helpful in guiding therapy. Antifungal drug resistance in yeasts is of clinical importance. Increasingly reliable methods of in vitro susceptibility testing can help predict clinical response to therapy, but other considerations, including host- and drug-related factors, can also have an important bearing on the ultimate outcome of treatment.