The use of fluconazole prophylaxis in patients with chemotherapy-induced neutropenia

Infections in Patients with Cancer: Overview

Patients with neoplastic disease are often highly susceptible to severe infections. The following factors influence the types, severity, and response to therapy of these infections: (1) Changing epidemiology of infections; (2) cancer- and/or treatment-associated neutropenia; (3) acquired immune deficiency states such as cellular immune defect; (4) recent development of new-generation diagnostic tools including widely available DNA amplification tests; (5) effective intervention for infection prevention; (6) empiric or presumptive therapy during high-risk periods; (7) availability of new classes of highly active antimicrobial drugs; (8) strategies to promote hosts’ immune response; and (9) future measures. This introductory chapter intended for the reader to become familiar with the important historical milestones in the understanding and development in the field of infectious diseases in immunosuppressed patients with an underlying neoplasms and patients undergoing hematopoietic stem cell trans­plantation.

Cytotoxic drugs, radiotherapy and oral candidiasis

The increased incidence of oral candidiasis in patients with malignancies stems partly from the systemic disease itself and, partly from the therapeutic measures such as cytotoxic and other immunosuppressive drugs and radiotherapy they receive during management of such malignancies. In this review we discuss the clinical and laboratory findings on the relationship between cytotoxics, radiotherapy and oral candidiasis, possible mechanisms of pathogenicity following such therapy, as well as precautions that could be taken to minimize such recalcitrant yeast infections.

Candida albicansPLD1 activity is required for full virulence

Phospholipase D1 (PLD1) mutants of Candida albicans are defective in important in vivo and in vitro virulence factors. PLD1 mutants colonize the murine alimentary tract as well as PLD1 sufficient strains. In comparison to PLD1 sufficient strains, the PLD1 mutants: (i) are unable to survive in internal organs after intravenous challenge; (ii) do not decrease the body weights of mice after oral challenge; and (iii) are not lethal for immunodeficient mice after oral challenge. In vitro, the PLD1 mutants show a drastically reduced capacity to penetrate epithelial monolayers and they fail to develop hyphae when grown on solid Spider medium. The morphogenic switch from yeast to hyphae is controlled by multiple parallel signaling pathways that couple specific stimuli to the regulation of several transcription factors. Our data suggest that PLD1 functions in at least one of these pathways regulating morphogenesis in vitro and that while the mutants are able to form hyphae in vivo, the hyphae are defective in their ability to cause oroesophageal and gastric candidiasis and to kill the C. albicans-colonized mice.

A strategy for managing fungal infections in haematopoietic stem cell transplantation

As more indications continue to be found for allogeneic haematopoietic transplantation, more patients are at risk for invasive fungal infectious diseases (IFID), particularly candidiasis and aspergillosis. Risk factors for disease are becoming better defined and diagnostic methods have improved considerably. In addition, there is now international agreement that three elements form the basis for defining IFID (host factors, clinical evidence, and mycological results), that imaging is acceptable for diagnosing disease, and that indirect tests such as antigen detection are also adequate mycological proof of cause. There are also more drugs available and still more to come, offering the potential for selective prophylaxis as well as preemptive and specific therapy, as well as for flexible administration. Hence, all the elements are in place for designing and testing an effective and economically sound strategy for dealing with IFID.

High dose cytosine arabinoside is a major risk factor for the development of hepatosplenic candidiasis in patients with leukemia

A retrospective study of hepatosplenic candidiasis in patients with acute leukemia from a single centre was performed. The significance of age, sex, type of leukemia, dose of cytosine arabinoside (Ara-C), duration of neutropenia, steroid use and period of therapeutic antibiotics in the development of hepatosplenic candidiasis was analyzed, using logistic regression analysis. Nine of 51 patients had hepatosplenic candidiasis. Ara-C use was highly associated with the development of hepatosplenic candidiasis (p = 0.001); with a high association with a higher dose (p < 0.0001). On the basis of these results consideration should be given to further trial of antifungal prophylaxis for patients receiving high dose Ara-C.

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.

Liposomes containing Candida albicans ribosomes as a prophylactic vaccine against disseminated candidiasis in mice

This study describes the development of prophylactic anti-Candida vaccine which combines the advantages of Candida albicans ribosomes as antigen(s) and of liposomes as carrier/adjuvant with minimal side-effects, which could be suitable for human use. The liposomal vaccine was composed of C. albicans ribosomes and the lipids dimyristoyl phosphatidyl choline (DMPC) and dimyristoyl phosphatidyl glycerol (DMPG) (9:1 molar ratio). Some of the vaccines contained Lipid-A (LA) as an additional adjuvant. The vaccine was prepared by two methods: (I) dehydration by lyophylization of small liposomes in the presence of the Candida ribosomes (DRV method); (II) colyophylization of DMPC/DMPG (9:1 mole ratio) in tertiary butanol with aqueous dispersion of Candida ribosomes. In both cases a dry powder was obtained which was rehydrated to form large multilamellar vesicles. The efficacy of the vaccines in mice was tested by their protectivity against a challenge with C. albicans, as assessed by survival rate, induction of cell mediated immunity (measured by delayed type hypersensitivity-DTH) and anti-Candida antibody titer. Unimmunized mice and mice vaccinated by ribosomes supplemented with incomplete Freund's adjuvant (IFA) were used as controls. The results indicated that the liposomal vaccines were effective at least as the IFA-based vaccine. The study indicates the feasibility of developing an efficacious anti-Candida vaccine for human use.