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.

Pulmonary mucormycosis.

Mucormycosis (formerly zygomycosis) is a life-threatening opportunistic mycosis that infects a broad range of hosts with qualitative or quantitative defects in innate immunity, including patients with severe neutropenia, recipients of corticosteroids or other immunosuppressive medications, poorly controlled diabetes mellitus, and those with iron overload states. Mucormycosis has recently emerged as breakthrough sinopulmonary infection in hematologic patients and recipients of transplantation being on antifungal prophylaxis with Aspergillus-active antifungals that lack activity against Mucorales. Unlike pulmonary aspergillosis, the prognosis and outcome of pulmonary mucormycosis have not improved significantly over the last decade, mainly because of difficulties in early diagnosis and the limited activity of current antifungal agents against Mucorales. Recent evidence suggests a critical role for iron metabolism and fungal-endothelial cell interactions in pathogenesis of mucormycosis, and holds promise for development of novel therapeutic strategies. Currently, prompt initiation of antifungal therapy with a lipid amphotericin B-based regimen, reversal of underlying host factors, and aggressive surgical approach offers the best chances for survival of patients infected with this devastating mycosis.

Antifungal activity of statins and their interaction with amphotericin B against clinically important Zygomycetes.

The in vitro antifungal activity of different statins and the combinations of the two most effective ones (fluvastatin and rosuvastatin) with amphotericin B were investigated in this study on 6 fungal isolates representing 4 clinically important genera, namely Absidia, Rhizomucor, Rhizopus and Syncephalastrum . The antifungal effects of statins revealed substantial differences. The synthetic statins proved to be more effective than the fungal metabolites. All investigated strains proved to be sensitive to fluvastatin. Fluvastatin and rosuvastatin acted synergistically and additively with amphotericin B in inhibiting the fungal growth in clinically available concentration ranges. Results suggest that statins combined with amphotericin B have a therapeutic potential against fungal infections caused by Zygomycetes species.

Systemic zygomycosis in farmed tilapia fish.

Decreased feed intake and persistent low-level mortality in a production tank of hybrid tilapia (Oreochromis niloticus x Oreochromis mossambicus x Oreochromis aureus) prompted the submission of three affected fish for diagnosis. Consistent macrosopical findings included multifocal dermal haemorrhage, excess abdominal fluid and an enlarged friable liver. On microscopical examination, broad non-septate fungal hyphae and chlamydospores were identified within numerous internal organs, often within and adjacent to blood vessels. The fungal hyphae were readily seen by silver staining (GMS) and the chlamydospores were stained deep magenta by the periodic acid-Schiff reaction. In addition to several species of Gram-negative bacteria, moderate growths of woolly white fungal colonies were obtained from the posterior part of the kidney in two of the three tilapia. These colonies were identified as a Rhizomucor sp. on the basis of the morphological characteristics of the sporulating fungi in culture. This represents the first reported episode of zygomycosis in fish.

Serial monitoring of Mucorales DNA load in serum samples of a patient with disseminated mucormycosis after allogeneic bone marrow transplantation.

Mucormycosis is a fatal complication in immunocompromised patients, and is additionally difficult to diagnose due to the lack of useful serum biomarkers. Using a quantitative PCR approach, we retrospectively analyzed Mucorales DNA load in sera collected serially from a 3-year-old patient with chronic granulomatous disease, who died of multi-organ failure probably due to dissemination of Rhizomucor pusillus, which was detected from necropsy specimens. Mucorales DNA load was below the detection limit on days 9, 2, and 4 after unrelated bone marrow transplantation. Rhizomucor DNA was first detected on day 14 (1.6 × 10(3) copies/mL), and subsequently fluctuated between 1.3 × 10(3) and 37.2 × 10(3) copies/mL until day 43. Rhizomucor achieved a peak value of 940.0 × 10(3) copies/mL on day 48 the day before death. The detection or fluctuation of Rhizomucor DNA appeared to be associated with corticosteroid dosages or C-reactive protein levels. This specific, noninvasive, and highly quantitative assay may be useful for the early diagnosis of mucormycosis and prediction of disease progression.