Recent advances in the epidemiology, prevention and treatment of invasive fungal infections in neutropenic patients

Molecular Pathway, Epidemiological Data and Treatment Strategies of Fungal Infection (Mycoses): A Comprehensive Review

The recent increase in fungal infections is a health crisis. This surge is directly tied to the increase in immunocompromised people caused by changes in medical practice, such as the use of harsh chemotherapy and immunosuppressive medicines. Immunosuppressive disorders such as HIV have exacerbated the situation dramatically. Subcutaneous or superficial fungal infections can harm the skin, keratinous tissues, and mucous membranes. This category includes some of the most common skin disorders that impact millions of people worldwide. Despite the fact that they are seldom fatal, they can have a catastrophic impact on a person's quality of life and, in rare situations, spread to other people or become obtrusive. The majority of fungal infections under the skin and on the surface are simply and quickly cured. An opportunistic organism that preys on a weak host or a natural intruder can both result in systemic fungal infections. Furthermore, it might be exceedingly lethal and dangerous to one's life. Dimorphic fungi may pose a hazard to healthy populations that are not exposed to endemic fungi. Increased surveillance, the availability of quick, noninvasive diagnostic tests, monitoring the emergence of antifungal medication resistance, and research on the pathophysiology, prevention, and management of fungal infections are just a few potential solutions to these new health problems. The goal of this review is to summarize the data available for fungal infections and the different therapies which are involved in their treatment. Additionally, it also summarizes the molecular and scientific data of the plants which contain anti-fungal activity. Data are acquired using Google, PubMed, Scholar, and other online sources.

Clinicopathologic presentations of dermatomycoses in cancer patients

Many of the skin fungal infections in cancer patients may look similar to those infections in non-cancer patients. However, in some cases, they become more extensive and even life threatening. Prolonged and severe neutropenia is the main risk factor for the dramatic issue of fungal infections. The dermatomycoses in cancer patients can be classified in four broad groups: primary superficial dermatophytoses, primary superficial yeast infections, opportunistic mold infections with distinct potential for dissemination and secondary cutaneous manifestations of fungaemia. Occasionally, more than one fungus are found inside a given skin lesion. A special condition is represented by the mycotic colonization of mucosal squamous cell carcinomas. Angio-invasion by fungi accounts for the frequency of disseminated infections prevailing in immunocompromised cancer patients. In case of skin involvement, the dermatologist may assist by recognizing subtle semiological signs and performing biopsies for swift histological examination, molecular biology and/or culture.

Galactomannan does not precede major signs on a pulmonary computerized tomographic scan suggestive of invasive aspergillosis in patients with hematological malignancies

BACKGROUND

Detection of serum galactomannan (GM) antigen and presence of the halo sign on a pulmonary computerized tomographic (CT) scan have a high specificity but a low sensitivity to diagnose invasive aspergillosis (IA) in patients at risk for this disease. To our knowledge, the relationship between the time at which pulmonary infiltrates are detected by CT and the time at which GM antigens are detected by enzyme immunoassay (EIA) has not been studied.

METHODS

In a prospective study, tests for detection of GM were performed twice weekly for patients with hematological malignancies who had undergone hematopoetic stem cell transplantation (HSCT) or had received induction and/or consolidation chemotherapy. A pulmonary CT scan was performed once weekly. Infiltrates were defined as either major or minor signs. IA was classified as proven, probable, or possible, in accordance with the definition stated by the European Organization for Research and Treatment of Cancer-Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group.

RESULTS

We analyzed 161 episodes of infection in 107 patients (65 allogeneic HSCT recipients, 30 autologous HSCT recipients, and 66 induction and/or consolidation chemotherapy recipients). A total of 109 episodes with no IA, 32 episodes with possible IA, and 20 episodes with probable or proven IA were identified. Minor pulmonary signs were detected by CT in 70 episodes (43%), and major pulmonary signs were detected by CT in 11 episodes (7%). Univariate and multivariate analyses revealed no significant association between detection of GM by EIA and detection of abnormal pulmonary signs by CT. A significant association was found between GM levels and receipt of piperacillin-tazobactam. GM test results were not positive before major signs were seen on CT images. Only 7 (10%) of 70 patients with minor pulmonary signs had positive GM test results before detection of the greatest pathologic change by CT.

CONCLUSIONS

We show that detection of GM by EIA does not precede detection of major lesions by pulmonary CT. In the clinical setting, the decision to administer mold-active treatment should based on detection of new pulmonary infiltrates on CT performed early during infection, rather than on results of EIA for detection of GM.

Antifungal chemotherapeutics

This review addresses trends in outcome and risk factors for invasive fungal infections, current antifungal agents and new therapeutic strategies. Current prospects for new therapies rest upon caspofungin, the first of a new class of antifungal molecules, the echinocandins, and new extended-spectrum azoles, voriconazole, posaconazole and ravuconazole. Approval by the Food and Drug Administration of the USA and the European Medicine Agency was given in 2001-2002 to voriconazole and caspofungin. Voriconazole clearly demonstrated a decrease in mortality in invasive aspergillosis and fusariosis fungal infections.

Antifungal therapy--state of the art at the beginning of the 21st century

The most relevant information on the present state of the art of antifungal chemotherapy is reviewed in this chapter. For dermatomycoses a variety of topical antifungals are available, and safe and efficacious systemic treatment, especially with the fungicidal drug terbinafine, is possible. The duration of treatment can be drastically reduced. Substantial progress in the armamentarium of drugs for invasive fungal infections has been made, and a new class of antifungals, echinocandins, is now in clinical use. The following drugs in oral and/or intravenous formulations are available: the broad spectrum polyene amphotericin B with its new "clothes"; the sterol biosynthesis inhibitors fluconazole, itraconazole, and voriconazole; the glucan synthase inhibitor caspofungin; and the combination partner flucytosine. New therapy schedules have been studied; combination therapy has found a significant place in the treatment of severely compromised patients, and the field of prevention and empiric therapy is fast moving. Guidelines exist nowadays for the treatment of various fungal diseases and maintenance therapy. New approaches interfering with host defenses or pathogenicity of fungal cells are being investigated, and molecular biologists are looking for new targets studying the genomics of pathogenic fungi.

In vitro and in vivo antifungal activities of TAK-456, a novel oral triazole with a broad antifungal spectrum

TAK-456 is a novel oral triazole compound with potent and broad-spectrum in vitro antifungal activity and strong in vivo efficacy against Candida albicans and Aspergillus fumigatus. TAK-456 inhibited sterol synthesis of C. albicans and A. fumigatus by 50% at 3 to 11 ng/ml. TAK-456 showed strong in vitro activity against clinical isolates of Candida spp., Aspergillus spp., and Cryptococcus neoformans, except for Candida glabrata. The MICs at which 90% of the isolates tested were inhibited byTAK-456, fluconazole, itraconazole, voriconazole, and amphotericin B were 0.25, 4, 0.5, 0.13, and 0.5 microg/ml, respectively, for clinical isolates of C. albicans and 1, >64, 0.5, 0.5, and 0.5 microg/ml, respectively, for clinical isolates of A. fumigatus. Therapeutic activities of TAK-456 and reference triazoles against systemic lethal infections caused by C. albicans and A. fumigatus in mice were investigated by orally administering drugs once daily for 5 days, and efficacies of the compounds were evaluated by the prolongation of survival. In normal mice, TAK-456 and fluconazole were effective against infection caused by fluconazole-susceptible C. albicans at a dose of 1 mg/kg. In transiently neutropenic mice, therapeutic activity of TAK-456 at 1 mg/kg of body weight against infection with the same strain was stronger than those at 1 mg/kg of fluconazole. TAK-456 was effective against infections with two strains of fluconazole-resistant C. albicans at a dose of 10 mg/kg. TAK-456 also expressed activities similar to or higher than those of itraconazole against the infections caused by two strains of A. fumigatus in neutropenic mice at a dose of 10 mg/kg. These results suggest that TAK-456 is a promising candidate for development for the treatment of candidiasis and aspergillosis in humans.

Follow-up of anti-Aspergillus IgG and IgA antibodies in bone marrow transplanted patients with invasive aspergillosis

A total of 89 patients at risk for, or with invasive aspergillosis (IA) were recruited from bone marrow transplantation (BMT) units in two Lisbon hospitals, and followed for 2(1/2) years to monitor their immune response. Of these patients, six developed probable IA, from which five died. The presence of serum IgG or IgA antibodies against seven Aspergillus recombinant antigens was assessed in patients with IA, using an enzyme-linked immunosorbent assay (ELISA). In parallel, the serum levels of galactomannan (GM) were also monitored, using the Platelia Aspergillus kit (Sanofi Pasteur, Marnes-la-Coquette, France). Superoxide dismutase (Sod) and 94 kDa were the most immunogenic antigens for IgA, while the IgG pattern of recognition changed from patient to patient. From our results we conclude that although follow-up of antibodies against these antigens should not be used as a diagnostic method, patients with IA do produce an immune response that may influence disease outcome.

A randomized, double-blind, double-dummy, multicenter trial of voriconazole and fluconazole in the treatment of esophageal candidiasis in immunocompromised patients

The efficacy, safety, and tolerability of voriconazole and fluconazole were compared in 391 immunocompromised patients with mycology- and biopsy-proven esophageal candidiasis. Primary efficacy analysis (256 patients) of esophageal treatment as assessed by esophagoscopy revealed success rates of 98.3% with voriconazole and 95.1% with fluconazole. The 95% confidence interval for the difference in success rates ranged from -1.0% to 7.5%. The overall safety and tolerability of both antifungals were acceptable. Fewer patients discontinued voriconazole treatment because of insufficient clinical response (4 patients [2.0%] vs. 5 patients [2.6%]). More patients discontinued voriconazole than fluconazole treatment because of laboratory test abnormalities (7 patients [3.5%] vs. 2 patients [1.0%]) or treatment-related adverse events (5 patients [2.5%] vs. 1 patient [0.5%]). The most frequent adverse events (23%) with voriconazole were mild, transient visual disturbances. Voriconazole (200 mg, b.i.d.) was shown to be at least as effective as fluconazole in the treatment of biopsy-proven esophageal candidiasis in immunocompromised patients.

Screening for circulating galactomannan as a noninvasive diagnostic tool for invasive aspergillosis in prolonged neutropenic patients and stem cell transplantation recipients: a prospective validation

The diagnosis of invasive aspergillosis (IA) in patients with hematologic disorders is not straightforward; lack of sensitive and specific noninvasive diagnostic tests remains a major obstacle for establishing a precise diagnosis. In a series of 362 consecutive high-risk treatment episodes that were stratified according to the probability of IA based on recently accepted case definition sets, the potential for diagnosis of serial screening for circulating galactomannan (GM), a major aspergillar cell wall constituent was validated. After incorporating postmortem findings to allow a more accurate final analysis, this approach proved to have a sensitivity of 89.7% and a specificity of 98.1%. The positive and negative predictive values equaled 87.5% and 98.4%, respectively. False-positive reactions occurred at a rate of 14%, although this figure might be overestimated due to diagnostic uncertainty. More or less stringent criteria of estimation could highly influence sensitivity, which ranged from 100% to 42%; the impact on other test statistics was far less dramatic. All proven cases of IA, including 23 cases confirmed after autopsy only, had been detected before death, although serial sampling appeared to be necessary to maximize detection. The excellent sensitivity and negative predictive value makes this approach suitable for clinical decision making. Unfortunately, given the species-specificity of the assay, some emerging non-Aspergillus mycoses were not detected. In conclusion, serial screening for GM, complemented by appropriate imaging techniques, is a sensitive and noninvasive tool for the early diagnosis of IA in high-risk adult hematology patients.

Fungal infections in the immunocompromised host

In recent years many remarkable changes occurred in our way of life, producing opportunities for microbes. All these changes are related to the recent emergence of previously unrecognized diseases, or the resurgence of diseases that, at least in developed countries, were thought to be under control. This concept is reviewed regarding fungal infections and their agents in the immunocompromised host. The changing pattern of these infections, the portals of entry of fungi into the human host, fungal pathogenicity and the main predisposing factors are analyzed. Opportunistic fungal infections in cancer, organ transplant and acquired immunodeficiency syndrome patients are reviewed, specially candidiasis and aspergillosis.

Identification of Candida albicans clinical isolates by PCR amplification of an EFB1 gene fragment containing an intron-interrupted open reading frame

The use of a single pair of primers, deduced from the intron and exon nucleotide sequences of the Candida albicans EFB1 gene, in polymerase chain reaction (PCR) assays performed with whole cells of both laboratory strains and clinical isolates of Candida species, resulted in the species-specific amplification of a 785 bp DNA fragment in C. albicans strains. Clinical C. albicans isolates were tested, and 85 out of 86 generated the expected PCR-amplified product; other Candida species, both laboratory strains and clinical isolates, as well as laboratory strains belonging to other fungal genera, including medically relevant taxa, failed to amplify any DNA fragment. In addition, unusual C. albicans isolates (glucosamine- and N-acetylglucosamine-negative) from Africa also yielded the expected PCR-generated DNA fragment. These results indicate that genes containing intron sequences may be useful to design species-specific primers for the identification of fungal strains by PCR.

Autopsy-controlled prospective evaluation of serial screening for circulating galactomannan by a sandwich enzyme-linked immunosorbent assay for hematological patients at risk for invasive Aspergillosis

Efforts to improve the diagnosis of invasive aspergillosis (IA) have been directed towards the detection of fungal antigens, including galactomannan (GM). However, previous evaluations of GM detection have been hampered by a lack of proven cases of IA and by a nonserial study design. This prospective study assessed the diagnostic value of serial screening for circulating GM by using a recently developed sandwich enzyme-linked immunosorbent assay (ELISA) for prolonged-neutropenic and/or steroid-treated patients with hematological disorders. Serum GM levels were monitored twice weekly for 186 consecutive patients at increased risk for IA. The patients were stratified according to the likelihood of IA (proven, probable, possible, and no evidence of IA) by using stringent criteria. Proven IA was defined by characteristic histopathological findings together with a positive culture for Aspergillus species. Autopsy and culture from autopsy specimens was used to verify both positive and negative test results. A total of 2,172 serum samples were tested from 243 episodes (mean, 9 samples/episode). Based on the analysis of 71 patients with confirmed disease status (culture and histology), the sensitivity and specificity of serial GM monitoring were 92.6 and 95.4%, respectively. The positive predictive value was almost 93%, the negative predictive value was 95%, and the efficacy was 94%. False-positive reactions occurred at a rate of nearly 8%, although this figure might have been overestimated. Less than 1% of all tested sera were considered inconclusive. In more than half of the cases, antigenemia was detected before clinical suspicion of IA (median, 6 days before). Serial determination of serum GM by the sandwich ELISA technique is a sensitive tool for the diagnosis of IA in hematological patients at risk. This approach may substantially influence clinical management with regard to preemptive and empirical antifungal therapy.

Retrospective study of candidemia in patients with hematological malignancies. Clinical features, risk factors and outcome of 76 episodes

A retrospective study of 76 episodes of candidemia in 73 patients with underlying hematological malignancy, from 1988 until 1997, has been conducted to evaluate the clinical characteristics and to ascertain the variables related to the onset and the outcome of candidemia. The most frequent malignancy was acute myeloid leukemia (29 episodes). Candidemia developed mainly during aplasia in patients refractory to chemotherapy (42%). In 65 episodes (86%) the patients were neutropenic (ANC <1 x 10(9)/l) before the candidemia diagnosis for a median time of 13 d, and in 53 episodes (70%) at microbiological diagnosis of candidemia ANC was <1 x 10(9)/l. Candida albicans was the most frequently isolated etiologic agent (31 episodes), but C. non-albicans species sustained the majority of candidemia. Seventeen candidemias developed during azoles prophylaxis. One month after the diagnosis of candidemia, 26 patients died. In 19 cases, death was attributable to candidemia. The case-control study demonstrated, at univariate analysis, that the colonization with Candida. spp. (p=0.004), antimycotic prophylaxis (p=0.01), presence of central venous catheter (p=0.01), neutropenia (p=0.002), and the use of glycopeptide (p=0.0001) increased the risk of candidemia. Using multivariate regression analysis only colonization with Candida spp. and the previous therapy with glycopeptide were associated with a significantly increased risk. Acute mortality, expressed by a cumulative probability of survival at 30 d from diagnosis of candidemia, was 0.67 (95% C.I. 0.55-0.77) and was significantly reduced in patients with neutrophils <1 x 10(9)/l when compared to those with neutrophils >1 x 10(9)/l (p at Mantel-Cox=0.029). Overall cumulative probability of survival at 1 yr was 0.38 (95% C.I. 0.27-0.49) and only the treatment with Amfotericin B significantly reduced the risk of death.

Fungal sinusitis

Until several years ago, no criteria for diagnosis or consensus on the classification of fungal sinusitis existed. Many reports were grouped under the heading of "aspergillus sinusitis," regardless of invasiveness; thus, published information on the diagnosis, natural history, and treatment of fungal sinusitis was of limited value. Diagnostic criteria and clinical descriptions for allergic fungal sinusitis, sinus mycetoma, and invasive fungal sinusitis have now been published. These criteria, a new classification system, and the clinical approach to patients with fungal sinusitis are reviewed in this article. Although fungal sinusitis is not a rare disease, much remains to be learned about its optimal clinical management.

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.

Evaluation of a commercial medium for identification of Candida species

CHROMagar Candida (CHROMagar, France) was evaluated as a medium for the presumptive identification and isolation of yeasts using 1,537 isolates of medically important yeasts, including 970 Candida albicans, 165 Candida parapsilosis, 131 Candida glabrata, 62 Candida guilliermondii, 35 Candida krusei, 32 Candida tropicalis, 31 Rhodotorula rubra, 23 Trichosporon spp. (17 Trichosporon beigelii), 17 Candida famata, 16 Candida pelliculosa, 10 Pichia etchelsii, 10 Saccharomyces cerevisiae, 8 Candida lusitaniae, 7 Cryptococcus spp., and 20 isolates of other Candida spp. After 48 h of incubation at 37 degrees C, the sensitivity and specificity were, respectively, 99% and 100% for Candida albicans, 93.8% and 99.1% for Candida tropicalis, and 100% and 100% for Candida krusei. In addition to colony color, other colony characteristics were important for identification of some species, such as rough colonies in Candida krusei isolates or the halo around the colonies of Candida tropicalis. A great variety of colors was observed among species other than Candida albicans, Candida tropicalis, and Candida krusei. For identification purposes, CHROMagar Candida medium has an accuracy similar to that of germ-tube tests and chlamydospore development tests for Candida albicans and to that of the ATB ID32C kit (API, bioMérieux, France) for Candida tropicalis and Candida krusei.