Isolation and identification of Fusarium species from the water systems of ICUs and transplant wards of hospitals and determination of the in vitro susceptibilities of isolates to conventional antifungals.

Abstract

Background: The rising prevalence of nosocomial infections, particularly those caused by airborne fungal spores in operating rooms and intensive care units (ICUs), has become a significant public health concern. Fusarium species in water systems pose a severe threat to immunocompromised patients and can disseminate as aerosols through devices such as faucets and showers. This study aimed to isolate and identify Fusarium species from the water systems of the ICUs and transplant units at Imam Khomeini Hospital Complex and Shariati Hospital in Tehran, Iran, as potential sources of future outbreaks. Additionally, the study sought to determine the in vitro susceptibilities of the isolates to conventional antifungal agents.

Methods: Sterile swabs and open plates containing Sabouraud dextrose agar (SDA) with chloramphenicol were used to collect water samples from sink surfaces, shower trays, faucets, and around the drains of sinks, as well as from bathroom areas. Swab samples were cultured, and the open-plate samples were evaluated for the growth of Fusarium species. The validation of all Fusarium sp. isolates was performed using DNA sequencing of the translation elongation factor 1-alpha (TEF-1α) gene. The antifungal susceptibility patterns of each isolate were tested against voriconazole, itraconazole, posaconazole, caspofungin, and amphotericin B using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method for filamentous fungi.

Results: Fusarium species were recovered from six out of 362 water system samples, representing 1.65% of the total. Five isolates were identified as Fusarium oxysporum from the F. oxysporum complex, while one isolate was identified as Fusarium proliferatum from the Fusarium fujikuroi complex. All isolates were obtained from sinks (three isolates) and faucets (three isolates) at Imam Khomeini Hospital. Antifungal susceptibility testing revealed that posaconazole, voriconazole, and amphotericin B were the most effective drugs against all Fusarium isolates, with no instances of resistance to these antifungal agents observed. However, non-wild-type isolates were noted for the other drugs tested.

Discussion: The isolation of pathogenic Fusarium species from water samples collected in the ICU wards of the Imam Khomeini Hospital Complex underscores the urgent need to implement effective control and prevention measures in hospital water systems.