Frequency of occurrence, seasonal variation and antifungal susceptibility of opportunistic Mucorales isolated from hospital soils in Iran.

BACKGROUND: Mucorales are opportunistic pathogens that can cause life-threatening diseases predominantly in immunocompromised patients. OBJECTIVES: This study aimed to investigate the frequency, seasonal variation and antifungal susceptibility of pathogenic Mucorales in the soil collected from seven hospitals in Urmia, Iran, between November 2017 and July 2018 in four different seasons. METHODS: Mucorales isolates obtained from soil were characterised based on conventional and molecular assays. In addition, in vitro antifungal susceptibility was performed using the CLSI M38Ed3 procedure. RESULTS: Out of 196 tested soil samples, 80 (40.8%) samples were positive for mucoralean fungi. Rhizopus arrhizus var. arrhizus (n = 47) was the most frequent species followed by Mucor circinelloides (n = 21) and Cunninghamella echinulata (n = 6). A seasonal variation in the frequency of Mucorales in soil was detected with a maximum of culture-positive soil samples detected in wet autumn (43.2%) followed by winter (23.4%), summer (19.7%) and spring (13.6%). In vitro antifungal susceptibility testing for 80 environmental isolates exhibited MIC of ≤2 µg/ml for amphotericin B indicating the smallest range of MIC variation among the tested Mucorales (range: 0.125-2 µg/ml). Among the azoles, posaconazole was the most effective antifungals (GM MIC, 0.724 µg/ml). CONCLUSIONS: We considered associations of species and seasonal frequencies between soil mucoralean fungi and mucormycosis. The effect of opportunistic Mucorales dominating in the soil and prevalent causative agents of mucormycosis in Iran reported in the literatures but more comprehensive studies are needed to confirm this conclusion.

Outbreaks of Mucorales and the Species Involved.

The order Mucorales is an ancient group of fungi classified in the subphylum Mucoromycotina. Mucorales are mainly fast-growing saprotrophs that belong to the first colonizers of diverse organic materials and represent a permanent part of the human environment. Several species are able to cause human infections (mucormycoses) predominantly in patients with impaired immune system, diabetes, or deep trauma. In this review, we compiled 32 reports on community- and hospital-acquired outbreaks caused by Mucorales. The most common source of mucoralean outbreaks was contaminated medical devices that are responsible for 40.7% of the outbreaks followed by contaminated air (31.3%), traumatic inoculation of soil or foreign bodies (9.4%), and the contact (6.2%) or the ingestion (6.2%) of contaminated plant material. The most prevalent species were Rhizopus arrhizus and R. microsporus causing 57% of the outbreaks. The genus Rhizomucor was dominating in outbreaks related to contaminated air while outbreaks of Lichtheimia species and Mucor circinelloides were transmitted by direct contact. Outbreaks with the involvement of several species are reported. Subtyping of strains revealed clonality in two outbreaks and no close relation in two other outbreaks. Based on the existing data, outbreaks of Mucorales can be caused by heterogeneous sources consisting of different strains or different species. Person-to-person transmission cannot be excluded because Mucorales can sporulate on wounds. For a better understanding and prevention of outbreaks, we need to increase our knowledge on the physiology, ecology, and population structure of outbreak causing species and more subtyping data.

Laboratory diagnosis of mucormycosis: current status and future perspectives.

Fungal infections caused by members of the Mucorales order are rapidly progressing and fatal. The importance of mucormycosis has grown in recent years as the number of patients with predisposing factors has increased dramatically. Clinical symptoms are elusive and conventional techniques are often insensitive and unspecific; in particular, cultures are often negative even though direct microscopy is positive. For early diagnosis of the causative agent of disease and subsequently guiding therapy to improving patients' outcome, molecular assays are promising add-ons. This article provides an overview on current laboratory methods for diagnosing mucormycosis with a special focus on new molecular-based tools. We aim to highlight the pros and cons of various techniques at hand. Given the increase in number and the severity of these infections, molecular approaches for improved diagnosis are highly warranted.

Mucormycosis outbreak associated with hospital linens.

BACKGROUND: Mucormycosis is an invasive fungal infection with a high fatality rate. We investigated an outbreak of mucormycosis in a pediatric hospital to determine routes of pathogen transmission from the environment and prevent additional infections. METHODS: A case was defined as a hospital-onset illness consistent with mucormycosis, confirmed by culture or histopathology. Case-patient medical records were reviewed for clinical course and exposure to items and locations within the hospital. Environmental samples were collected from air and surfaces. Fungal isolates collected from case-patients and the environmental samples were identified using DNA sequencing. RESULTS: Five case-patients had hospital-associated cutaneous mucormycosis over an 11-month period; all subsequently died. Three case-patients had conditions known to be associated with susceptibility to mucormycosis, while 2 had cardiac conditions with persistent acidosis. The cases occurred on several different wards throughout the hospital, and hospital linens were the only exposure identified as common to the case-patients. Rhizopus species were recovered from 26 (42%) of 62 environmental samples from clean linens and associated areas and from 1 (4%) of 25 samples from nonlinen-related items. Case-patients were infected with Rhizopus delemar, which was also isolated from cultures of clean linens and clean linen delivery bins from the off-site laundry facility. CONCLUSIONS: Hospital linens were identified as a vehicle that carried R. delemar into contact with susceptible patients. Fungal species identification using DNA-based methods is useful for corroborating epidemiologic links in hospital outbreak investigations. Hospital linens should be laundered, packaged, shipped and stored in a manner that minimizes exposure to environmental contaminants.

Three cases of cutaneous mucormycosis with Lichtheimia spp. (ex Absidia/Mycocladus) in ICU. Possible cross-transmission in an intensive care unit between 2 cases.

Mucormycoses are rare but emerging diseases with poor prognosis caused by ubiquitous fungi from the environment. In November 2008, our teaching hospital experienced three cutaneous mucormycosis due to Lichtheimia spp. (ex Absidia/Mycocladus) in the intensive care and orthopaedic units. Environmental and epidemiological investigations suggested a possible cross-transmission of L. ramosa between two patients in intensive care. This is the first report of possible person-to-person transmission of mucormycosis species. These cases show the ineffectiveness of hydro-alcoholic solutions against spores and underline the need to respect standard precautions to prevent fungi dissemination.

Healthcare-associated mucormycosis.

Mucormycosis is a severe emerging invasive fungal infection that occurs as a consequence of environmental exposure. We exhaustively reviewed all the cases of mucormycosis (European Organisation for Research and Treatment of Cancer/Mycoses Study Group 2008 criteria) attributed to healthcare procedures that occurred between 1970 and 2008. A total of 169 cases were studied (29% children, 61% male). Major underlying diseases were solid organ transplantation (24%), diabetes mellitus (22%), and severe prematurity (21%). Skin was the most common localization (57%), followed by gastrointestinal tract (15%). Culture results were available in 75% (92% positive), and results of histological examination were positive in 95%. Rhizopus was the most frequent genus (43%). Infection portal of entry included surgery and presence of medical devices such as catheters or adhesive tape. Outbreaks and clusters were related to adhesive bandages (19 cases), wooden tongue depressors (n = 5), ostomy bags (n = 2), water circuitry damage (n = 2), and adjacent building construction (n = 5). Thorough investigations are mandatory to identify healthcare-associated mucormycosis, notably in neonatology, hematological, and transplantation units.

Fatal Apophysomyces elegans infection transmitted by deceased donor renal allografts.

Two patients developed renal mucormycosis following transplantation of kidneys from the same donor, a near-drowning victim in a motor vehicle crash. Genotypically, indistinguishable strains of Apophysomyces elegans were recovered from both recipients. We investigated the source of the infection including review of medical records, environmental sampling at possible locations of contamination and query for additional cases at other centers. Histopathology of the explanted kidneys revealed extensive vascular invasion by aseptate, fungal hyphae with relative sparing of the renal capsules suggesting a vascular route of contamination. Disseminated infection in the donor could not be definitively established. A. elegans was not recovered from the same lots of reagents used for organ recovery or environmental samples and no other organ transplant-related cases were identified. This investigation suggests either isolated contamination of the organs during recovery or undiagnosed disseminated donor infection following a near-drowning event. Although no changes to current organ recovery or transplant procedures are recommended, public health officials and transplant physicians should consider the possibility of mucormycosis transmitted via organs in the future, particularly for near-drowning events. Attention to aseptic technique during organ recovery and processing is re-emphasized.

Correlation of in vitro activity, serum levels, and in vivo efficacy of posaconazole against Rhizopus microsporus in a murine disseminated infection.

A broth microdilution method was used to evaluate the in vitro activities of seven antifungal agents against 15 clinical strains of Rhizopus microsporus. Amphotericin B (AMB) and posaconazole (POS) were the most active drugs. In a model of disseminated R. microsporus infection in immunosuppressed mice, we studied the efficacy of POS administered once or twice daily against four of the strains previously tested in vitro and compared it with that of liposomal AMB (LAMB). LAMB was the most effective treatment for the two strains with intermediate susceptibility to POS. For the two POS-susceptible strains, LAMB and POS at 20 mg/kg of body weight twice a day orally showed similar efficacies. The in vivo efficacy of POS administered twice a day orally correlated with the in vitro susceptibility data and the serum drug concentrations.

Cutaneous zygomycosis (mucormycosis) complicating endotracheal intubation: diagnosis and successful treatment.

Diagnosis and successful therapy for primary cutaneous zygomycosis (mucormycosis) that complicated the securing of an endotracheal tube with cloth tape. Primary cutaneous mucormycosis is a rare fungal infection noted most often in immunosuppressed individuals. Cloth tape, of the type commonly used to secure endotracheal tubes, often is contaminated with fungal spores. In the case reported here, cloth tape securing the endotracheal tube was the probable vector for transmission of zygomycosis to a moderately imunocompromised host. Rapid diagnosis and combined medical and surgical therapy resulted in a favorable outcome.

Nosocomial zygomycotic post-surgical necrotizing fasciitis in a healthy adult caused by Apophysomyces elegans in south India.

Necrotizing fasciitis caused by the zygomycete Apophysomyces elegans of the anterior abdominal wall of a young healthy woman following a lower segment caesarean section is reported. Early clinical diagnosis and laboratory identification followed by appropriate management involving extensive tissue debridement and adequate doses of amphotericin B were eventually successful in controlling the infection and saving her life.

An epizootic of cutaneous zygomycosis in cultured dwarf African clawed frogs (Hymenochirus curtipes) due to Basidiobolus ranarum.

Morbidity and mortality approaching 100% occurred in dwarf African clawed frogs (Hymenochirus curtipes) from a culture facility in central California. Moribund frogs exhibited preference for a terrestrial environment rather than their normal aquatic environment. Affected animals had a slight pallor of the integument but were otherwise grossly unremarkable. Microscopic examination revealed a fungal infection of the integument primarily characterized by the presence of surface and intra-epidermal conidia. Skin cultures of the infected animals yielded an organism identified as Basidiobolus ranarum, based on the formation of conidia in culture with internal cleavage to form sporangiospores. The organism was transmitted to healthy frogs by co-habitation with infected frogs but not by short-term immersion exposure of healthy frogs to homogenized broth cultures of the fungus. Benzalkonium chloride at 2.0 mg l-1 was efficacious in controlling the infection. Although Basidiobolus species are normally found in the intestinal tract of amphibians, the severity of this epizootic indicates that B. ranarum may be an important pathogen of amphibians reared in culture facilities.

Fungal infections of the CNS.

Most CNS fungal infections can be divided into those that occur in normal hosts and those that occur in the immunosuppressed host. Cryptococcal infection, however, is common in both groups. The usual clinical presentation of a CNS fungal infection is chronic headache and mental status change. The CSF shows a lymphocytic meningitis with low sugar and high protein. Amphotericin B remains the drug of choice for most CNS fungal infections.

Nosocomial infection by Rhizomucor pusillus in a clinical haematology unit.

Three patients suffering from acute leukaemia were treated with cytotoxic agents and broad-spectrum antibiotics and received blood transfusion and nasal packing for severe epistaxis. All developed necrosis of nasal and facial tissues, with facial swelling an oedema; two biopsies showed typical phycomycete mycelium, and Rhizomucor pusillus was grown from one biopsy. Air and surfaces in the unit and the air intake and ducting were all heavily colonized by Rh. pusillus and other phycomycetes. It is suggested that Rh. pusillus spores from the air invaded the tissues in the conditions promoted by the nasal packing in these patients with impaired defences.