Emerging fungal pathogens, drug resistance and the role of lipid formulations of amphotericin B in the treatment of fungal infections in cancer patients: a review

Prognostic factors for risk stratification of adult cancer patients with chemotherapy-induced febrile neutropenia: a systematic review and meta-analysis

BACKGROUND

Increasing numbers of studies identify new prognostic factors for categorising chemotherapy-induced febrile neutropenia adult cancer patients into high- or low-risk groups for adverse outcomes. These groupings are used to tailor therapy according to level of risk. However many emerging factors with prognostic significance remain controversial, being based on single studies only.

OBJECTIVES

A systematic review was conducted to determine the strength of association of all identified factors associated with the outcomes of chemotherapy-induced febrile neutropenia patients.

INCLUSION CRITERIA

The participants included were adults of 15 years old and above, with a cancer diagnosis and who underwent cancer treatment.The review focused on clinical factors and their association with the outcomes of cancer patients with chemotherapy-induced febrile neutropenia at presentation of fever.All quantitative studies published in English which investigated clinical factors for risk stratification of adult cancer patients with chemotherapy-induced febrile neutropenia were considered.The primary outcome of interest was to identify the clinical factors for risk stratification of adult cancer patients with chemotherapy-induced febrile neutropenia.

SEARCH STRATEGY

Electronic databases searched from their respective inception date up to December 2011 include MEDLINE, EMBASE, CINAHL, Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, Science-Direct, Scopus and Mednar.

METHODOLOGICAL QUALITY

The quality of the included studies was subjected to assessment by two independent reviewers. The standardised critical appraisal tool from the Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI) was used to assess the following criteria: representativeness of study population; clearly defined prognostic factors and outcomes; whether potential confounders were addressed and appropriate statistical analysis was undertaken for the study design.

DATA COLLECTION

Data extraction was performed using a modified version of the standardised extraction tool from the JBI-MAStARI. Prognostic factors and the accompanying odds ratio reported for the significance of these factors that were identified by multivariate regression, were extracted from each included study.

DATA SYNTHESIS

Studies results were pooled in statistical meta-analysis using Review Manager 5.1. Where statistical pooling was not possible, the findings were presented in narrative form.

RESULTS

Seven studies (four prospective cohort and three retrospective cohort) investigating 22 factors in total were included. Fixed effects meta-analysis showed: hypotension [OR=1.66, 95%CI, 1.14-2.41, p=0.008] and thrombocytopenia [OR=3.92, 95%CI, 2.19-7.01, p<0.00001)] were associated with high-risk of adverse outcomes for febrile neutropenia. Other factors that were statistically significant from single studies included: age of patients, clinical presentation at fever onset, presence or absence of co-morbidities, infections, duration and severity of neutropenia state. Five prognostic factors failed to demonstrate an association between the variables and the outcomes measured and they include: presence of pneumonia, total febrile days, median days to fever, recovery from neutropenia and presence of moderate clinical symptoms in association with Gram-negative bacteraemia.

CONCLUSIONS

Despite the overall limitations identified in the included studies, this review has provided a synthesis of the best available evidence for the prognostic factors used in risk stratification of febrile neutropenia patients. However, the dynamic aspects of prognostic model development, validation and utilisation have not been addressed adequately thus far. Given the findings of this review, it is timely to address these issues and improve the utilisation of prognostic models in the management of febrile neutropenia patients.

IMPLICATIONS FOR PRACTICE

The identified factors are similar to the factors in current prognostic models. However, additional factors that were reported to be statistically significant in this review (thrombocytopenia, presence of central venous catheter, and duration and severity of neutropenia) have not previously been included in prognostic models. This review has found these factors may improve the performance of current models by adding or replacing some of the factors.

IMPLICATIONS FOR RESEARCH

The role of risk stratification of chemotherapy-induced febrile neutropenia patients continues to evolve as the practice of risk-based therapy has been demonstrated to be beneficial to patients, clinicians and health care organisations. Further research to identify new factors /markers is needed to develop a new model which is reliable and accurate for these patients, regardless of cancer types. A robust and well-validated prognostic model is the key to enhance patient safety in the risk-based management of cancer patients with chemotherapy-induced febrile neutropenia.

Fungal Infections

The incidence of invasive fungal infections has increased dramatically over the past two decades, mostly due to an increase in the number of immunocompromised patients.1–4 Patients who undergo chemotherapy for a variety of diseases, patients with organ transplants, and patients with the acquired immune deficiency syndrome have contributed most to the increase in fungal infections.5 The actual incidence of invasive fungal infections in transplant patients ranges from 15% to 25% in bone marrow transplant recipients to 5% to 42% in solid organ transplant recipients.6,7 The most frequently encountered are Aspergillus species, followed by Cryptococcus and Candida species. Fungal infections are also associated with a higher mortality than either bacterial or viral infections in these patient populations. This is because of the limited number of available therapies, dose-limiting toxicities of the antifungal drugs, fewer symptoms due to lack of inflammatory response, and the lack of sensitive tests to aid in the diagnosis of invasive fungal infections.1 A study of patients with fungal infections admitted to a university-affiliated hospital indicated that community-acquired infections are becoming a serious problem; 67% of the 140 patients had community-acquired fungal pneumonia.8

Biomedical coatings based on chitin soluble extract for inhibition of fungal adhesion to polymeric surfaces

Indwelling medical devices made of polymeric materials, such as intravenous (IV) catheters, are known risk factors for development of fungal infection, particularly systemic candidiasis, that are a significant cause of morbidity and lethality in compromised patients. Candida can form a biofilm on the polymeric surface, serving as a nidus for systemic, difficult to eradicate infection. The current research focuses on development and study of a chitin soluble extract (CSE) coating on polyurethane (PU), in order to reduce the level of adherence of C. albicans to the PU surface. The immobilization of CSE onto the PU surface was performed using both, chemical binding and physical adsorption. Our results indicate that CSE develops a unique tertiary structure in which basic elements in the range of 100 nm build "fingers" and these "fingers" are arranged in a concentric structure around a center. The CSE coated films showed 75% inhibition of C. albicans adhesion for the chemical binding and 83% for the physical adsorption coating and even after 11 weeks the inhibitory effect on adhesion is still significant. Hence, our new coatings may lead to a new generation of medical devices with surfaces that can prevent fungal adhesion.

Nonribosomal cyclic peptides: specific markers of fungal infections

Some cyclic peptides and depsipeptides are synthesized in microorganisms by large multienzymes called nonribosomal peptide synthetases. The structures of peptide products originating in this way are complex and diverse and are microorganism-specific. This work proposes the use of fungal cyclic peptides and depsipeptides as extremely specific markers of fungal infections. Since a reliable molecular tool for diagnosing fungal infections at an early stage is still missing, we present mass spectrometry as a new, modern, broadband (with respect to fungal strain) and specific tool for clinical mycologists. More than 40 different fungal species can be rapidly characterized according to specific families of cyclic peptides, and in some cases, a particular fungal strain can be identified on the basis of its cyclopeptide profile. This paper is also aimed at initiating discussion on the biological role of these secondary metabolites, especially of those synthesized by medically important strains. Proven cytotoxic, anti-inflammatory or immunosuppressive activities of some cyclic peptides indicate that these molecules may contribute to the synergistic array of fungal virulence factors and support microbial invasion during fungal infection. In addition to an overview on recent mass spectrometric protocols for cyclic peptide sequencing, the structures of new peptides from Paecilomyces and Pseudallescheria are presented.

Invasive candidiasis in cancer patients: observations from a randomized clinical trial

BACKGROUND

Invasive candidiasis is a common and serious complication of cancer and its therapy.

METHODS

We retrospectively identified patients with malignancies enrolled in a double-blind randomized trial of caspofungin (50 mg/day after a 70 mg loading dose) vs. conventional amphotericin B (0.6-1.0 mg/kg/day) as treatment of documented invasive candidiasis. A favorable response required complete resolution of signs and symptoms plus eradication of the Candida pathogen(s). The primary efficacy analysis used a modified intention-to-treat (MITT) approach that included all patients with a confirmed diagnosis of invasive candidiasis who received > or =1 dose of study medication.

RESULTS

74/224 (33%) patients in the MITT population had active malignancies. 25/30 (83%) hematological malignancies were acute or chronic leukaemias. 22/44 (50%) solid tumors were related to the gastrointestinal tract. Patients with hematological malignancies tended to be younger (median [range] age: 49 [19-74] vs. 59 [19-81] years) and have higher baseline acute physiology and chronic health evaluation (APACHE) II scores (mean [range]: 17 [0-28] vs. 15 [5-35]) than patients with solid tumors. Neutropenia [< or =500/microl] was present on entry in 23 (77%) patients with hematological malignancies and in one (3%) patient with a solid tumor. Candidemia was demonstrated in 56 (88%) cancer patients. C. albicans was the single most frequent isolate in cancer patients, although the majority of cases were caused by non-albicans species. Cancer patients in the caspofungin arm had more hematological malignancies (55 vs. 29%), higher baseline APACHE II scores (>20 in 36 vs. 15%), more frequent neutropenia (42 vs. 24%), and less C. albicans infections (27 vs. 49%) than the amphotericin B-treated cancer patients. Favorable response rates were 11/18 (61%) and 6/12 (50%) for patients with hematological malignancies treated with caspofungin or amphotericin B, respectively; the corresponding outcomes in patients with solid tumors were 12/15 (80%) and 17/29 (59%) for the 2 treatment arms. 7/14 (50%) caspofungin- and 4/10 (40%) amphotericin B-treated patients who were neutropenic on entry responded favorably. All-cause mortality rates during the study for caspofungin recipients were 11/18 (61%) with hematological malignancies and 6/15 (40%) with solid tumors, and for amphotericin recipients were 4/12 (33%) with hematological malignancies and 6/29 (21%) with solid tumors.

CONCLUSIONS

Underlying cancers, most commonly leukaemias and gastrointestinal tumors, were present in one-third of patients enrolled in this study of invasive candidiasis. Overall, 70% of caspofungin-treated and 56% of amphotericin B-treated cancer patients responded favorably. Response rates were lower for neutropenic leukaemic patients than for non-neutropenic patients with solid tumors in both treatment groups.

A fraction from Escherichia coli with anti-Aspergillus properties

The products of various strains of Escherichia coli (BL21, DH5alpha, HB101 and XL Blue) were investigated for antimycotic properties using pathogenic isolates of Aspergillus. Co-culture experiments revealed that E. coli strains exhibited variable activity against Aspergillus fumigatus. The lysates prepared from DH5alpha, HB101 and XL Blue strains of E. coli showed inhibitory activity against A. fumigatus in the protein concentration range of 62.50 to 250.00 microg ml(-1). The highest activity was seen in the lysate of BL21, which inhibited the growth of A. fumigatus and Aspergillus flavus completely at a concentration of 31.25 microg protein ml(-1). The MIC of BL21 lysate against Aspergillus niger was found to be 62.50 microg ml(-1). The in vitro toxicity of BL21 lysate was evaluated using a haemolytic assay. A BL21 lysate protein concentration of 1250.00 microg ml(-1) was found to be nontoxic to human erythrocytes. The standard drug amphotericin B lysed 100 % of erythrocytes at a concentration of 37.50 microg ml(-1). SDS-PAGE showed the presence of at least 15 major proteins in the lysate of BL21. Ion-exchange chromatography resolved the BL21 lysate into five fractions and fraction III was found to be endowed with anti-Aspergillus properties. The MIC of this fraction was found to be 3.90 microg ml(-1). Further work on the purification of the active molecule and its characterization is in progress.

Patterns of amphotericin B killing kinetics against seven Candida species

In a previous study tolerance to amphotericin B (AMB) was found among Candida parapsilosis and C. dubliniensis strains by seeding the whole volumes of wells used for MIC determinations, and minimum fungicidal concentrations (MFC) for non-C. albicans Candida strains were demonstrated to be above the levels safely achievable in serum. As an extension of that study, we performed time-kill assays with 26 blood culture isolates (6 C. albicans, 5 C. parapsilosis, 5 C. krusei, 4 C. glabrata, 3 C. lusitaniae, and 3 C. tropicalis isolates), 3 oropharyngeal C. dubliniensis isolates, 3 AMB-susceptible isolates (ATCC 90028, ATCC 22019, ATCC 6254), and 6 AMB-resistant isolates (ATCC 200955, ATCC 200956, ATCC 200950, ATCC 200951, ATCC 200952, ATCC 200953) using RPMI 1640 medium and 0.12 to 32 microg of AMB per ml and determined the numbers of CFU per milliliter at 0, 2, 4, 8, 12, 24, and 48 h. MFCs and time-kill patterns were species specific (MFCs, < or =1 microg/ml for all C. dubliniensis and C. albicans isolates except AMB-resistant strain ATCC 200955; MFCs, 2 to >16 microg/ml for the other isolates). The times required to reach the fungicidal endpoint (99.9% killing) at four times the MIC were 2 h for C. albicans and C. dubliniensis, 16 h for C. glabrata, 24 h for C. parapsilosis and C. lusitaniae, and > or =40 h for C. tropicalis and C. krusei. The killing rate increased as the AMB concentration was increased up to 2 microg/ml. The highest killing rates were achieved for C. albicans, C. dubliniensis, and C. lusitaniae, while viable C. tropicalis, C. krusei, and C. parapsilosis cells were present after 48 h (MICs, < or =2 microg/ml) when AMB was used at 2 microg/ml. Time-kill curves and MFCs can detect viable cells after 48 h when AMB is used at > or =2 microg/ml. The failure of AMB treatment could be due to its poor killing activity against some species at the concentrations reached in patients' serum.

Glycosphingolipids of the model fungus Aspergillus nidulans: characterization of GIPCs with oligo-alpha-mannose-type glycans

Aspergillus nidulans is a well-established nonpathogenic laboratory model for the opportunistic mycopathogen, A. fumigatus. Some recent studies have focused on possible functional roles of glycosphingolipids (GSLs) in these fungi. It has been demonstrated that biosynthesis of glycosylinositol phosphorylceramides (GIPCs) is required for normal cell cycle progression and polarized growth in A. nidulans (Cheng, J., T.-S. Park, A. S. Fischl, and X. S. Ye. 2001. Mol. Cell Biol. 21: 6198-6209); however, the structures of A. nidulans GIPCs were not addressed in that study, nor were the functional significance of individual structural variants and the downstream steps in their biosynthesis. To initiate such studies, acidic GSL components (designated An-2, -3, and -5) were isolated from A. nidulans and subjected to structural characterization by a combination of one-dimensional (1-D) and 2-D NMR spectroscopy, electrospray ionization-mass spectrometry (ESI-MS), ESI-MS/collision-induced decomposition-MS (MS/CID-MS), ESI-pseudo-[CID-MS]2, and gas chromatography-MS methods. All three were determined to be GIPCs, with mannose as the only monosaccharide present in the headgroup glycans; An-2 and An-3 were identified as di- and trimannosyl inositol phosphorylceramides (IPCs) with the structures Man alpha 1-->3Man alpha 1-->2Ins1-P-1Cer and Man alpha 1-->3(Man alpha 1-->6)Man alpha 1-->2Ins1-P-1Cer, respectively (where Ins = myo-inositol, P = phosphodiester, and Cer = ceramide). An-5 was partially characterized, and is proposed to be a pentamannosyl IPC, based on the trimannosyl core structure of An-3.

[Fusarium pleural effusion after a ventricular assist device]

We report the case of a 36-year-old man with a pleural effusion that complicates the postoperative period after the implantation of a ventricular assist device (VAD). The epidemiological, etiologic and therapeutic features of Fusarium infections were reviewed. Complete recovery of the infection was obtained after a treatment by liposomal amphotericine B (AmBisome) and 5 fluorocytosine.

Improving efficacy of antifungal therapy by polymerase chain reaction-based strategy among febrile patients with neutropenia and cancer

Early detection of fungal infections in and corresponding early treatment of febrile patients with neutropenia and cancer have been important issues and continue to be major challenges for clinicians. The use of nested PCR to make therapeutic decisions was studied. Sequential blood samples obtained from 42 patients with neutropenia and cancer were tested by nested PCR and culture. Instead of the empirical antifungal therapy strategy, amphotericin B treatment was initiated only for patients who had 2 consecutive positive results by nested PCR. A reduced mortality rate was observed for febrile patients with neutropenia and cancer who had fungal infections. Thus, this strategy, combined with the nested PCR for early detection of fungal infection in febrile patients with neutropenia, may be used as a guideline for antifungal therapy.

Candida glabrata and Candida krusei fungemia after high-risk allogeneic marrow transplantation: no adverse effect of low-dose fluconazole prophylaxis on incidence and outcome

Candidemia is a serious complication in patients following allogeneic blood, marrow, and organ transplantation. Fourteen patients developed nosocomial fungemia among 204 allogeneic marrow transplants performed during 1997-1999. Incidence of hematogenous candidiasis was 6.8 per 100 allogeneic BMT. All 14 had an indwelling central venous catheter (CVC) and fluconazole (100-200 mg daily) was given prophylactically. In 11 (78.5%) neutropenic patients, duration between agranulocytosis and diagnosis of fungemia was (median, +/- s.d.) 10 +/- 8 days. Candida glabrata (53.3%) was the most common yeast species, followed by C. krusei (33.3%), and C. parapsilosis (13.3%). Candida albicans was conspicuously absent. Ten patients (71.4%) had primary transplant-related complication (>2 days) including hemolytic uremic syndrome/thrombotic thrombocytopenic purpura (HUS/TTP) (n = 5), severe hemorrhagic cystitis (n = 3), and bacteremia (n = 2). Seven (50.0%) patients expired and in three (21.4%) deaths were attributed to fungemia. The impact of a primary transplant-related complication on short-term survival in this setting was not significant (P = 0.07) (HUS/TTP (P > 0.5); neutropenia (P > 0.5); GVHD (P = 0.35)). Removal of CVC did not alter outcome in our group (P > or = 0.5) although in patients with persistent fungemia (>72 h), and those with preceding bacteremia, mortality was significantly higher (P = 0.002). Conventional prognosticators of poor outcome did not adversely effect short-term survival in our transplant recipients with hematogenous candidiasis. The predominance of C. glabrata and C. krusei breakthrough infections was similar to what is seen with high-dose fluconazole (400 mg) prophylaxis, and no adverse effects of low-dose fluconazole in terms of increased incidence of non-susceptible Candida species was seen.

Comparative therapeutic and toxic effects of different povidone iodine (PVP-I) formulations in a model of oral candidosis based on in vitro reconstituted epithelium

In vitro models of oral candidosis based on reconstituted epithelium have been successfully used for virulence studies. In the present study we examined the effects of two povidone iodine (PVP-I) formulations (conventional PVP-I ointment, PVP-I liposome hydrogel) on reconstituted human mucosa and on a model of oral candidosis. The morphological alterations of the reconstituted mucosa caused by infection with C. albicans and by treatment were analyzed with light and electron microscopy. Specific alterations of the epithelium (vacuoles, spongiosis, oedema, detachment of keratinocytes) and invasion of the mucosa by fungal cells were reduced by treatment with the liposomal preparation, but not by the conventional ointment. However, a single application of the liposomal hydrogel to the uninfected mucosa demonstrated some structural irritations in the deeper tissue layers which were not seen with the ointment. Light microscopical studies demonstrated multiple globular structures in all samples treated with the liposomal PVP-I preparation. At the ultrastructural level these globular structures were classified as liposomes. The great majority of liposomal particles filled with dark contrasted active substance could be observed in contact with the cell wall of C. albicans and within the fungal cells. Targeting to the fungal surface resulted in a strong amount of the active ingredient next to the pathogens but not to the host cells. In conclusion the liposomal PVP-I formulation appeared superior to the conventional ointment formulation because of both less toxicity and better therapeutical effects.

Infectious morbidity in critically ill patients with cancer

Infection frequently complicates the course of cancer treatment and often adversely affects the outcome. Patients have a greater tendency for acquiring infections caused by opportunistic microorganisms. Agents with low virulence potential may lead to invasive and often life-threatening infections because of altered host immune function. The immune dysfunction may be caused by the underlying malignancy, by antineoplastic chemotherapy, or by invasive procedures during supportive care.

Itraconazole oral solution and intravenous formulations: a review of pharmacokinetics and pharmacodynamics

Itraconazole is a triazole antifungal agent with a broad spectrum of activity. It is well tolerated and highly efficacious, particularly because its main metabolite, hydroxy-itraconazole, also has considerable antifungal activity. Two new formulations of itraconazole, an oral solution and an intravenous formulation, have recently been developed, which combine lipophilic itraconazole with cyclodextrin. These formulations have improved the solubility of itraconazole, leading to enhanced absorption and bioavailability compared with the original capsule formulation, without having an impact on the tolerability profile of itraconazole. The oral solution and intravenous formulations of itraconazole produce consistent plasma concentrations and are ideal for the treatment of systemic fungal infections in a wide range of patient populations. The additional flexibility offered by the different routes of administration means that itraconazole treatment can be specifically tailored for use in all patients, including children and those requiring intensive care.

Infectious complications of febrile leukopenia

It can be foreseen that in the years to come major improvements in neutropenic host infections will be achieved regarding the exact identification of risk factors, allowing better patient stratification; the application of molecular techniques to recognize pathogens; the development of effective new oral antimicrobials allowing home therapy or abbreviated hospitalization; the development of new antifungals; and the development of new effective immunomodulators and cytokines to ameliorate chemotherapy-induced neutropenia. In the years to come the threat of nosocomial infections unfortunately will not be eliminated, while the development of major new parenteral antibiotics cannot be foreseen. It is therefore the caregiver/physician himself who, by applying rational antibiotic policies and strict handwashing rules, will probably escape, for his neutropenic patient's sake, the imminent threat of multiresistant pathogens.