By Will Boggs, MD
NEW YORK (Reuters Health) – The establishment of new definitions of opportunistic fungal infections in immunocompromised patients should lead to more meaningful research into their causes and treatments, according to an international group of investigators.
"The definitions are not intended as a guide to therapy in daily practice," Dr. Thomas J. Walsh, from the National Cancer Institute in Bethesda, Maryland, told Reuters Health. "Instead, the definitions offer for the first time a set of standard terms that will permit design of clinical trials and comparison of results, hence fostering international collaboration and uniform data interpretation."
Dr. Walsh and colleagues were part of a consensus effort initiated by the European Organization for Research and Treatment of Cancer (EORTC) to define and classify invasive fungal infections (IFIs) commonly seen and studied in immunocompromised patients with cancer.
Their proposal "includes both diagnostic criteria for proven IFIs and also classification criteria for probable and possible diseases that are intended to promote a more uniform description of the patients when various research endeavors are reported," the authors explain in the January 1st issue of Clinical Infectious Diseases.
The proposed definitions rely on a triad of elements, the report indicates, including host factors, clinical manifestations, and mycological results.
Proven invasive fungal infections are subdivided into deep tissue infections, fungemia, and endemic fungal infections, the researchers note, and require positive blood cultures or histopathological or cytopathological evidence of infection and tissue damage for diagnosis.
The diagnosis of probable or possible invasive fungal infections requires a less stringent combination of host, clinical, and microbiological factors, the investigators say.
According to the report, these proposed definitions differ from earlier definitions published by the National Institute of Allergy and Infectious Diseases (NIAID) by focusing on issues specific to cancer and hematopoietic stem cell transplantation patients.
"This set of definitions offers for the first time standard terminology that will permit design of international collaborative clinical trials as well as uniform interpretation and comparison of results from different countries," Dr. Walsh concluded. "This represents a major achievement in the field of antimicrobial clinical trials for oncology-bone marrow transplant patients, particularly in the design of studies for the prevention and treatment of invasive fungal infections."
Dr. Walsh reiterated, "The definitions are not intended as a guide to therapy in daily practice. Physicians may elect appropriately to treat patients who do not necessarily fit these definitions."
Clin Infect Dis 2002;34:7-14.