Molecular analyses of Fusarium isolates recovered from a cluster of invasive mold infections in a Brazilian hospital

Abstract

BackgroundInvasive fusariosis (IF) is a rare but often fatal fungal infection in immunosuppressed patients. In 2007, cases of IF above the expected epidemiologic baseline were detected in the hematology ward of a hospital in Rio de Janeiro, Brazil. Possible sources of infection were investigated by performing environmental sampling and patient isolate collection, followed by molecular typing. Isolates from dermatology patients with superficial fusariosis were included in the study for comparison to molecular types found in the community.MethodsEnvironmental sampling focused on water-related sources in and around the hematology ward. Initially, we characterized 166 clinical and environmental isolates using the Fusarium translation elongation factor 1α (EF-1α) genetic locus. Isolates included 68 collected from water-related sources in the hospital environment, 55 from 18 hematology patients, and 43 from the skin/nails of 40 outpatients seen at the hospital dermatology clinic. Multi-locus sequence typing was performed on Fusarium solani species complex (FSSC) species 1 and 2 isolates to investigate their relatedness further.ResultsMost of the hematology samples were FSSC species 2, with species type FSSC 2-d the most commonly isolated from these patients. Most of the outpatient dermatology samples were also FSSC 2, with type 2-d again predominating. In contrast, environmental isolates from water sources were mostly Fusarium oxysporum species complex (FOSC) and those from air samples mostly Fusarium incarnatum-equiseti species complex (FIESC). A third of the environmental samples were FSSC, with species types FSSC 1-a and FSSC 1-b predominating.ConclusionsFusarium isolate species types from hematology patient infections were highly similar to those recovered from dermatology patients in the community. Four species types (FSSC 1-a, 1-b, 2-d and 2-f) were shared between hematology patients and the environment. Limitations in environmental sampling do not allow for nosocomial sources of infection to be ruled out. Future studies will focus on environmental factors that may have influenced the prevalence of FSSC fusariosis in this hematology ward.

International Evaluation of MIC Distributions and Epidemiological Cutoff Value (ECV) Definitions for Fusarium Species Identified by Molecular Methods for the CLSI Broth Microdilution Method

“…Although case series of Fusarium infections have been reported throughout the years (4,7,9,16,(20)(21)(22), only in a recent report was an indication of a potential correlation between MICs for Fusarium spp. and response to treatment found (22), where CLSI MICs for seven Fusarium isolates identified by molecular methods, antifungal therapy (voriconazole or both voriconazole and amphotericin B), and clinical response were documented for patients with invasive fusariosis.…”

“…However, the perception is that new generic changes may be suggested, such as the establishment of the genus Bisifusarium to include the more commonly known members of the Fusarium dimerum SC and the name Neocosmospora solani to replace Fusarium solani (6). The most frequent causes of fungal infections are members of three complexes, the F. solani species complex (SC), the F. oxysporum SC, and the Fusarium (Gibberella) fujikuroi SC (which includes, among others, F. verticillioides and F. proliferatum), and the next most frequent causes belong to the F. dimerum SC and F. incarnatum-F. equiseti SC; their distribution could be region dependent (4,(7)(8)(9)(10). Common clinical presentations are onychomycosis, keratitis, allergic disease (sinusitis and bronchopulmonary disease) for nonimmunocompromised patients and disseminated disease, as well as other severe invasive infections, in immunocompromised hosts (e.g., patients with prolonged neutropenia and T-cell immunodeficiency) (1,4,(7)(8)(9)(10)(11)(12)(13).…”

“…The most frequent causes of fungal infections are members of three complexes, the F. solani species complex (SC), the F. oxysporum SC, and the Fusarium (Gibberella) fujikuroi SC (which includes, among others, F. verticillioides and F. proliferatum), and the next most frequent causes belong to the F. dimerum SC and F. incarnatum-F. equiseti SC; their distribution could be region dependent (4,(7)(8)(9)(10). Common clinical presentations are onychomycosis, keratitis, allergic disease (sinusitis and bronchopulmonary disease) for nonimmunocompromised patients and disseminated disease, as well as other severe invasive infections, in immunocompromised hosts (e.g., patients with prolonged neutropenia and T-cell immunodeficiency) (1,4,(7)(8)(9)(10)(11)(12)(13). Amphotericin B lipid formulations, voriconazole, posaconazole, and, to a lesser extent, itraconazole have been recommended or used for the treatment and prophylaxis of Fusarium infections, in addition to surgical debridement and reversal of immunosuppression (14)(15)(16)(17)(18)(19).…”

In vitro Antifungal Susceptibility Testing of Clinical and Environmental Fusarium Isolates in Iran

“…Although, the distribution of Fusarium species varies globally, Fusarium solani, F. oxysporum and F. verticillioides are the most frequent causes of fusariosis (16,17). Molecular phylogenetic studies have revealed that this genus comprises species complexes and the majority of Fusarium isolates cannot be identified to the species level using traditional morphological methods (4).…”

Antimold Prophylaxis May Reduce the Risk of Invasive Fusariosis in Hematologic Patients with Superficial Skin Lesions with Positive Culture for Fusarium

“…An environmental investigation was carried out, which found Fusarium species in the hospital water and on the surface of water-related structures. However, molecular typing suggested a communitybased acquisition of infection because, while most clinical isolates were Fusarium solani, environmental isolates were predominantly Fusarium oxysporum (6).…”