In vitro interactions between amphotericin B and other antifungal agents and rifampin against Fusarium spp.

Fusarium species are common hyaline soil saprophytes and plant pathogens that are opportunistic fungal pathogens of immunocompromised patients. The treatment for fusariosis remains uncertain with an unfavourable prognosis; new possibilities for treatment, such as various synergistic drug interactions, must be uncovered. In this study, we evaluated the in vitro interactions of amphotericin B with caspofungin, ketoconazole, 5‐flucytosine, itraconazole, miconazole, rifampin, fluconazole, terbinafine and voriconazole against isolates of Fusarium spp. using the chequerboard method with interactions evaluated by fractional inhibitory concentration indices. The highest percentages of synergistic interactions were observed for the combinations of amphotericin B and caspofungin (68.7%), amphotericin B and rifampin (68.7%), amphotericin B plus 5‐flucytosine (59.3%) and amphotericin B with voriconazole (37.5%). The pattern of susceptibility to antifungal agents among Fusarium species and their consequence on the effects of drug combinations are also discussed.     

Kodamaea ohmeri isolate from two immunocompromised patients: first report in Italy

Kodamaea ohmeri is an unusual yeast‐form fungus that has recently been identified as an important aetiological agent of fungaemia, endocarditis, cellulitis, funguria and peritonitis in immunocompromised patients. We present two new isolated of K. ohmeri. The microorganisms were identified by CHROMagar Candida medium, VitekII system and API ID32C. Biochemical identification of the two yeast isolates was confirmed by sequence analysis of the 26S ribosomal DNA. Antifungal susceptibility testing done by Sensititre YeastOne showed that the isolates were susceptible to amphotericin B, voriconazole and itraconazole. This work is the first report of isolation of K. ohmeri in immunocompromised patients in Italy.     

In Vitro Testing of Aspergillus fumigatus Clinical Isolates for Susceptibility to Voriconazole,Amphotericin B and Itraconazole: Comparison of Sensititre versus NCCLS M38-A Using Two Different Inocula

Abstract

Voriconazole, amphotericin B and itraconazole were tested In Vitro against 18 strains of Aspergillus fumigatus isolated from cystic fibrosis patients. Susceptibility was tested with the broth microdilution method (M38-A protocol- NCCLS). Results of this reference method were compared with those of an experimental commercial microdilution broth method (Sensititre). Two different inocula, prepared from 2- and 7-day cultures, were used. Minimum inhibitory concentrations (MICs) of the reference method ranged from 0.25 to 2 μg/ml for voriconazole, 0.06 to 1 μg/ml for amphotericin B, 0.016 to >16 μg/ml for itraconazole. There were no significant differences in the MIC ranges or MIC₉₀ values obtained with the two testing methods or with the two types of inocula. These findings confirm the good In Vitro activity of voriconazole, itraconazole and amphotericin B against A. fumigatus. They also indicate that reliable susceptibility data can be generated more rapidly by commercial systems and use of 2-day cultures for inoculum preparation.     

Combined antifungal therapy against systemic murine infections by rare Cryptococcus species

Cryptococcus albidus and Cryptococcus laurentii are uncommon species of this genus that in recent decades have increasingly caused opportunistic infections in humans, mainly in immunocompromised patients; the best therapy for such infection being unknown. Using a murine model of systemic infection by these fungi, we have evaluated the efficacy of amphotericin B (AMB) at 0.8 mg/kg, administered intravenously, fluconazole (FLC) or voriconazole (VRC), both administered orally, at 25 mg/kg and the combination of AMB plus VRC against three C. albidus and two C. laurentii strains. All the treatments significantly reduced the fungal burden in all the organs studied. The combination showed a synergistic effect in the reduction in fungal load, working better than both monotherapies. The histopathological study confirmed the efficacy of the treatments.     

Antifungal Activity of Amphotericin B and Itraconazole against Filamentous Fungi: Comparison of the Sensititre Yeast OneŴ and NCCLS M38-A Reference Methods

Abstract

The susceptibilities of 81 clinical isolates of Aspergillus spp.Fusarium spp., and Scedosporium spp., to amphotericin B and itraconazole were determined by the colorimetric microdilution method Sensititre® and the reference microdilution method of NCCLS standard M38-A for filamentous fungi. No major discrepancies were found and agreement ranged between 86.4% to 84% and 69.1% to 86.4% for amphotericin B and itraconazole respectively at 48 h and 72 h of incubation by using the recommended endpoints. Within two two-fold dilutions, high levels of agreement were found in general for amphotericin B at 48 or 72 h (86.4 to 87.7%) and itraconazole (91.4 to 93.8%). Relatively better agreement was found for itraconazole at 72 h of incubation and 48 for amphotericin B.     

Antifungal Activity of Voriconazole (UK-109,496), Fluconazole and Amphotericin B Against Hematogenous Candida krusei Infection in Neutropenic Guinea Pig Model

Abstract

Voriconazole (UK-109,496) is a new triazole with in vitro activity against a wide spectrum of fungi including yeasts intrinsically resistant to fluconazole such as Candida krusei. In this study the efficacy of voriconazole was compared to amphotericin B and fluconazole in a neutropenic guinea pig model of hematogenously disseminated C. krusei infection. In guinea pigs, neutropenia was established by using cyclophosphamide (intraperitoneally, i.p., 100 mg/kg on day 1 and 4), and dexamethasone (orally, 2 mg/kg/day, for 8 days). Neutropenic guinea pigs were infected with 0.5 ml of yeast cell suspension (1×10⁸ CFU) intravenously. Challenged animals were treated with antifungals starting 1 h postinfection for 7 days. The animals were divided into five groups: untreated control, amphotericin B (1 mg/kg i.p. on alternate days), fluconazole (20 mg/kg orally twice daily), and voriconazole (two groups: 5 and 10 mg/kg orally twice daily) groups. Guinea pigs were sacrificed 1 day after the last treatment. Brain, liver, and kidneys were removed and weighed, tissues were homogenized and fungal burden determined by serial quantitative counts. Voriconazole at dosages of 5 or 10 mg/kg b.i.d. was shown to be significantly more efficacious than either amphotericin B or fluconazole in eradicating C. krusei from brain, liver and kidney tissue. These data indicate that voriconazole could be efficacious for the treatment of infections caused by fluconazole-resistant Candida, such as C. krusei.     

Treating disseminated fusariosis: amphotericin B,voriconazole or both?

Disseminated Fusarium infection can cause significant morbidity and mortality in immunocompromised patients. We present a case of disseminated fusariosis in a patient with neutropenic fever successfully treated using both liposomal amphotericin B and voriconazole. Combination anti-fungal therapy may be considered for such patients, particularly for those failing single-drug therapy.     

In vitro antifungal activity of amphotericin B and 11 comparators against Aspergillus terreus species complex

Aspergillus terreus infections are difficult to treat because of the intrinsic resistance to amphotericin B, and higher mortality compared to infections caused by other Aspergillus species. The aim of the present study was to determine the in vitro antifungal activity of amphotericin B and 11 comparators against clinical (n = 36) and environmental (n = 45) A. terreus isolates. In vitro antifungal susceptibility was performed using the CLSI M38‐A2 procedure. Amphotericin B exhibited the highest MICs (MIC range, 0.125‐4 μg/mL; MIC₉₀, 2 μg/mL), followed by terbinafine (MIC range, 0.002‐1 μg/mL; MIC₉₀, 1 μg/mL). Only one isolate (1/81) showed amphotericin B MIC above the epidemiologic cut‐off value (ECV; 4 μg/mL). None of the isolates had a MIC of ≥ ECV for voriconazole, itraconazole and posaconazole. The reasons for the difference in amphotericin B susceptibility patterns between studies remain unknown. The genetic and species diversity, clinical, environmental and ecological factors in Terrei section on various amphotericin B susceptibility profiles in different countries should be considered more as the main reasons associated with these differences.     

Fusarium brain abscess: case report and literature review

Severely immunocompromised patients such as those with haematological malignancies and haematopoietic stem cell transplant recipients are at an increased risk of acquiring invasive mould infections. Fusarium, a ubiquitous fungus, can cause potentially fatal infections in such hosts. It usually manifests as skin lesions, fevers and sino‐pulmonary infections. Brain abscesses have been reported, but are relatively uncommon. We report a case of a 50‐year‐old patient with acute lymphocytic leukaemia and failed autologous peripheral stem cell transplant that presented with new onset seizures and was found to have Fusarium solani brain abscess. Nasal route was the presumed mode of entry of the fungus into the cerebrum. Treatment comprised surgical excision of the lesion, and antimycotic therapy with liposomal amphotericin B and voriconazole. Despite aggressive therapy, patient succumbed to the disease. We have provided an overview of infections secondary to Fusarium, along with a review of the central nervous system involvement by this pathogenic mould.     

Emergence of Resistance to Amphotericin B and Triazoles in Candida glabrata Vaginal Isolates in a Case of Recurrent Vaginitis

Abstract

Emergence of resistance to triazoles and amphotericin B in Candida glabrata vaginal isolates is documented by Etest. During the 18-month follow-up of a case of vaginitis, 14 consecutive isolates of C. glabrata were examined. The isolates exhibited development of in vitro resistance beginning with itraconazole (>32 μg/ml), followed by fluconazole (>256 μg/ml), amphotericin B (>32 μg/ml), and voriconazole (>32 μg/ml). The DNA sequence analyses and finger printing of the isolates strongly suggest that our patient remained colonized with a single strain. The report underscores the propensity of C. glabrata to acquire resistance during antifungal therapy and the importance of susceptibility testing in the management of infections caused by this species.     

Oral candidiasis caused by Kodamaea ohmeri in a HIV patient in Chennai,India

Kodamaea ohmeri was isolated from a 38‐year‐old HIV seropositive woman with pseudomembranous oral candidiasis. The isolate was identified by the API 20 C yeast identification system and confirmed by sequence analysis. Antifungal susceptibility testing done by E‐test showed that the isolate was susceptible to voriconazole, amphotericin B and caspofungin.     

CNS-aspergillosis: are there new treatment options?

Invasive aspergillosis is an increasing cause of morbidity and mortality in immunocompromised patients. Extension of invasive aspergillosis to the central nervous system (CNS) is associated with an exceeding high mortality which approaches 100%. One major factor contributing to this devastating outcome is a poor penetration into the CNS of frequently used antifungal drugs, such as amphotericin B or itraconazole. Voriconazole, a new triazole with broad activity against various fungi, including Aspergillus species, shows superior activity in invasive aspergillosis compared to treatment with conventional amphotericin B. Voriconazole readily penetrates the blood-brain barrier yielding fungicidal drug concentrations within the CNS. A growing number of patients with CNS aspergillosis has been successfully treated with voriconazole in recent years. The pharmacological properties, the broad antifungal activity and the promising clinical data suggest that the use of voriconazole in CNS aspergillosis might improve the outcome in this otherwise devastating clinical condition. However, additional clinical data are needed to determine more precisely the role of voriconazole in CNS aspergillosis. In this review, we have compiled the available pharmacological and clinical data on CNS aspergillosis.     

First recovery of Rasamsonia argillacea species complex isolated in adolescent patient with cystic fibrosis in Slovenia – case report and review of literature

We report the isolation of the emerging fungal pathogen Rasamsonia aegroticola, which belongs Rasamsonia argillacea species complex, from a respiratory sample of a patient with cystic fibrosis. This filamentous fungus, resembling members of a Penicillium and Paecilomyces spp., was identified by morphology and confirmed by DNA sequence analysis. Susceptibility pattern showed high minimal inhibitory concentration of voriconazole and amphotericin B but low minimal inhibitory concentration of caspofungin, micafungin and itraconazole.     

Genetic diversity and antifungal susceptibility of Fusarium isolates in onychomycosis

Fusarium species have emerged as an important human pathogen in skin disease, onychomycosis, keratitis and invasive disease. Onychomycosis caused by Fusarium spp. The infection has been increasingly described in the immunocompetent and immunosuppressed hosts. Considering onychomycosis is a difficult to treat infection, and little is known about the genetic variability and susceptibility pattern of Fusarium spp., further studies are necessary to understand the pathogenesis and better to define the appropriate antifungal treatment for this infection. Accordingly, the objective of this study was to describe the in vitro susceptibility to different antifungal agents and the genetic diversity of 35 Fusarium isolated from patients with onychomycosis. Fusarium spp. were isolated predominantly from female Caucasians, and the most frequent anatomical location was the nail of the hallux. Results revealed that 25 (71.4%) of isolates belonged to the Fusarium solani species complex, followed by 10 (28.5%) isolates from the Fusarium oxysporum species complex. Noteworthy, the authors report the first case of Neocosmospora rubicola isolated from a patient with onychomycosis. Amphotericin B was the most effective antifungal agent against the majority of isolates (60%, MIC ≤4 μg/mL), followed by voriconazole (34.2%, MIC ≤4 μg/mL). In general, Fusarium species presented MIC values >64 μg/mL for fluconazole, itraconazole and terbinafine. Accurate pathogen identification, characterisation and susceptibility testing provide a better understanding of pathogenesis of Fusarium in onychomycosis.     

In vitro antifungal susceptibility of clinical isolates of Arthrographis kalrae,a poorly known opportunistic fungus

The in vitro antifungal activity of amphotericin B (AMB), itraconazole, voriconazole, posaconazole, terbinafine (TRB), caspofungin, anidulafungin and micafungin were evaluated by a broth microdilution technique against 22 isolates of Arthrographis kalrae of clinical origin. TRB showed the highest activity, followed by the azoles, particularly posaconazole. AMB exerted low activity whereas the echinocandins showed almost no antifungal activity.     

Primary cutaneous infection with Scedosporium apiospermum successfully treated with voriconazole

We describe a 61‐year‐old male patient with a history of long‐term corticosteroid treatment for chronic obstructive pulmonary disease, who developed subcutaneous nodules on his right forearm. Histopathologic examination showed large epitheloid cell granulomas with multinuclear giant cells that contained hyphae within their cytoplasm. Microbiological testing of biopsies revealed an infection with Scedosporium apiospermum with resistance to common antifungal agents like fluconazole, itraconazole or amphotericin B and sensitivity to voriconazole. After two months of oral therapy with voriconazole the skin lesions have completely cleared according to clinical and sonographic investigations. Adverse effects like nausea and increased photosensitivity immediately disappeared after finishing the 6‐month period of voriconazole treatment.     

Disseminated mucormycosis associated with invasive pulmonary aspergillosis in a patient treated for post-transplant high-grade non-Hodgkin's lymphoma

The incidence of mucormycosis, defined as systemic infection caused by fungi of the class Phycomycetes has been increasing over the past 2 decades, especially in profoundly immunocompromised hosts. We report a new case in a patient presenting with post-transplant high-grade non-Hodgkin's lymphoma who received a prolonged treatment with voriconazole and caspofungin for an invasive pulmonary aspergillosis. Definite diagnosis of mucormycosis was made by liver biopsy of nodules mimicking progressive lymphoma. The patient died 1 week after the diagnosis of mucormycosis despite the administration of liposomal amphotericin B. The role of voriconazole and caspofungin in the emergence of mucormycosis is discussed.     

Susceptibility profile and epidemiological cut‐off values of Cryptococcus neoformans species complex from Argentina

Epidemiological cut‐off values (ECVs) based on minimal inhibitory concentration (MIC) distribution have been recently proposed for some antifungal drug/Cryptococcus neoformans combinations. However, these ECVs vary according to the species studied, being serotypes and the geographical origin of strains, variables to be considered. The aims were to define the wild‐type (WT) population of the C. neoformans species complex (C. neoformans) isolated from patients living in Argentina, and to propose ECVs for six antifungal drugs. A total of 707 unique C. neoformans isolates obtained from HIV patients suffering cryptococcal meningitis were studied. The MIC of amphotericin B, flucytosine, fluconazole, itraconazole, voriconazole and posaconazole was determined according to the EDef 7.2 (EUCAST) reference document. The MIC distribution, MIC₅₀, MIC₉₀ and ECV for each of these drugs were calculated. The highest ECV, which included ≥95% of the WT population modelled, was observed for flucytosine and fluconazole (32 μg ml^?1 each). For amphotericin B, itraconazole, voriconazole and posaconazole, the ECVs were: 0.5, 0.5, 0.5 and 0.06 μg ml^?1 respectively. The ECVs determined in this study may aid in identifying the C. neoformans strains circulating in Argentina with decreased susceptibility to the antifungal drugs tested.     

Diagnosis and therapy of Candida infections: joint recommendations of the German Speaking Mycological Society and the Paul-Ehrlich-Society for Chemotherapy

Invasive Candida infections are important causes of morbidity and mortality in immunocompromised and hospitalised patients. This article provides the joint recommendations of the German‐speaking Mycological Society (Deutschsprachige Mykologische Gesellschaft, DMyKG) and the Paul‐Ehrlich‐Society for Chemotherapy (PEG) for diagnosis and treatment of invasive and superficial Candida infections. The recommendations are based on published results of clinical trials, case‐series and expert opinion using the evidence criteria set forth by the Infectious Diseases Society of America (IDSA). Key recommendations are summarised here: The cornerstone of diagnosis remains the detection of the organism by culture with identification of the isolate at the species level; in vitro susceptibility testing is mandatory for invasive isolates. Options for initial therapy of candidaemia and other invasive Candida infections in non‐granulocytopenic patients include fluconazole or one of the three approved echinocandin compounds; liposomal amphotericin B and voriconazole are secondary alternatives because of their less favourable pharmacological properties. In granulocytopenic patients, an echinocandin or liposomal amphotericin B is recommended as initial therapy based on the fungicidal mode of action. Indwelling central venous catheters serve as a main source of infection independent of the pathogenesis of candidaemia in the individual patients and should be removed whenever feasible. Pre‐existing immunosuppressive treatment, particularly by glucocorticosteroids, ought to be discontinued, if feasible, or reduced. The duration of treatment for uncomplicated candidaemia is 14 days following the first negative blood culture and resolution of all associated symptoms and findings. Ophthalmoscopy is recommended prior to the discontinuation of antifungal chemotherapy to rule out endophthalmitis or chorioretinitis. Beyond these key recommendations, this article provides detailed recommendations for specific disease entities, for antifungal treatment in paediatric patients as well as a comprehensive discussion of epidemiology, clinical presentation and emerging diagnostic options of invasive and superficial Candida infections.     

In vitro susceptibility patterns of clinically important Trichophyton and Epidermophyton species against nine antifungal drugs

Despite the common, worldwide, occurrence of dermatophytes, little information is available regarding susceptibility profiles against currently available and novel antifungal agents. A collection of sixty‐eight clinical Trichophyton species and Epidermophyton floccosum were previously identified and verified to the species level by sequencing the internal transcribed spacer (ITS) regions of rDNA. MICs of amphotericin B, fluconazole, itraconazole, voriconazole, posaconazole, isavuconazole, terbinafine and MECs of caspofungin and anidulafungin were performed based on CLSI M38‐A2. The resulting MIC₉₀s of all strains were, in increasing order, as follows: terbinafine (0.063 mg l^?1); posaconazole (1 mg l^?1); isavuconazole and anidulafungin (2 mg l^?1); itraconazole, voriconazole, amphotericin B, and caspofungin (4 mg l^?1) and fluconazole (>64 mg l^?1). These results confirm that terbinafine is an excellent agent for treatment of dermatophytosis due to T. rubrum, T. mentagrophytes, T. verrucosum, T. schoenleinii and E. floccosum. In addition, the new azoles POS and ISA are potentially useful antifungals to treat dermatophytosis. However, the clinical effectiveness of these novel antifungals remains to be determined.