First unusual case of keratitis in Europe due to the rare fungus Metarhizium anisopliae

Insect Fungus Metarhizium robertsii Is a Rare Causative Agent of Keratitis

PURPOSE

This study aimed to describe a case of keratitis secondary to Metarhizium robertsii, a soil-dwelling fungus with typical insect pathogenicity.

METHODS

A Case report.

RESULTS

A 58-year-old man with a ocular history of soft contact lens overwear, poor contact lens hygiene, and ocular exposure to ground well water supplying his house was referred to our university practice for a central corneal ulcer with 40% thinning. Same-day rapid microscopic detection with Giemsa stain identified the presence of many hyphae elements, and he was ultimately diagnosed with M. robertsii keratitis. The patient's course involved severe and progressive corneal thinning that stabilized over a 3-month course of antifungal therapy.

CONCLUSIONS

Metarhizium robertsii seems more aggressive than other forms of fungal keratitis; therefore, this infection may be watched more closely with the risk for quick progressive corneal thinning, even while on antifungal management.

Identification of hypocrealean reptile pathogenic isolates with MALDI-TOF MS

Biotyper analysis of Nannizziopsis guarroi, a fatal fungal pathogen in lizards, was described recently. Hypocrealean fungal infections in captive reptiles appear with an increasing frequency during the last decade. Therefore, the aim of this study was to proof Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) as diagnostic tool for the identification of reptile pathogenic hypocrealean fungi. Ten fungal isolates obtained from nine reptiles with fungal glossitis, disseminated visceral mycosis, pneumomycosis, and fungal keratitis were analyzed. Phylogeny consisted of fragments of the large subunit of nuclear encoded ribosomal DNA (D1/D2, LSU) and the internal transcribed spacer region 1 of nuclear encoded ribosomal DNA (ITS1) as well as the protein coding gene translation elongation factor 1 alpha (TEF). Results revealed unanimously two Metarhizium granulomatis genotypes in a total of three isolates, various M. viride genotypes (n = 3), two different Purpureocillium lilacinum isolates as well as one isolate of each P. lavendulum and Beauveria bassiana. Purpureocillium lilacinum and B. bassiana are likewise frequently employed as a mycoinsecticide and mycoacaricide in agriculture on a worldwide scale and have occasionally been reported in man, causing fungal keratitis, sclerokeratitis, nosocomial infections in immunosuppressed patients, as well as cavitary pulmonary disease and cutaneous hyalohyphomycosis in immunocompetent patients. According to the results establishment of Biotyper analysis for faster differentiation of reptile-associated fungal pathogens is entirely justified.

Multi-locus sequence typing provides epidemiological insights for diseased sharks infected with fungi belonging to the Fusarium solani species complex

Fusarium spp. are saprobic moulds that are responsible for severe opportunistic infections in humans and animals. However, we need epidemiological tools to reliably trace the circulation of such fungal strains within medical or veterinary facilities, to recognize environmental contaminations that might lead to infection and to improve our understanding of factors responsible for the onset of outbreaks. In this study, we used molecular genotyping to investigate clustered cases of Fusarium solani species complex (FSSC) infection that occurred in eight Sphyrnidae sharks under managed care at a public aquarium. Genetic relationships between fungal strains were determined by multi-locus sequence typing (MLST) analysis based on DNA sequencing at five loci, followed by comparison with sequences of 50 epidemiologically unrelated FSSC strains. Our genotyping approach revealed that F. keratoplasticum and F. solani haplotype 9x were most commonly isolated. In one case, the infection proved to be with another Hypocrealian rare opportunistic pathogen Metarhizium robertsii. Twice, sharks proved to be infected with FSSC strains with the same MLST sequence type, supporting the hypothesis the hypothesis that common environmental populations of fungi existed for these sharks and would suggest the longtime persistence of the two clonal strains within the environment, perhaps in holding pools and life support systems of the aquarium. This study highlights how molecular tools like MLST can be used to investigate outbreaks of microbiological disease. This work reinforces the need for regular controls of water quality to reduce microbiological contamination due to waterborne microorganisms.

Surgical treatment of Metarhizium anisopliae sclerokeratitis and endophthalmitis

A 55-year-old nurse was referred with a 5-month history of right eye corneal abscess. The initial injury occurred when doing lawn work. The infection worsened despite multiple antibiotic, antiviral, and steroid treatments. Visual acuity was limited to hand motion. On examination, there was keratitis, ocular hypertension, and a secondary cataract. Corneal scrapings grew a filamentous fungus, identified as Metarhizium anisopliae (MA). Despite intensive antifungal treatment with topical, intravitreous, and systemic voriconazole, purulent corneal melting and scleritis with endophthalmitis rapidly appeared. An emergency surgical procedure including sclerocorneal transplantation, cataract surgery, a pars plana vitrectomy using temporary keratoprosthesis, and scleral crosslinking was necessary. One year after the surgery, there was no recurrence of infection. Functional outcome remained very poor. This is the first case of sclerokeratitis and endophthalmitis caused by MA ever reported. The infection was successfully treated with an aggressive combination of medical and surgical treatments.

Species of Metarhizium anisopliae complex implicated in human infections: retrospective sequencing study

OBJECTIVES

Fungi belonging to the Metarhizium anisopliae complex comprise ubiquitous arthropod pathogenic moulds used as mycopesticides. Rare cases of human infections due to M. anisopliae have been reported. We hypothesize misidentifications of fungal strains implicated in these cases or used in mycopesticides.

METHODS

A review of the literature was conducted to identify previously published cases. We collected some of these previous described strains and reported new cases, and a French mycopesticide containing M. anisopliae. All identifications were performed based on elongation factor-1α gene sequencing.

RESULTS

We report eight new cases of Metarhizium infection in humans (three from France and five from Australia). The strains isolated from these cases, and three others from already published cases and reported as M. anisopliae, were molecularly identified based on elongation factor-1α (Ef1-α) gene sequencing as follows: Metarhizium robertsii (six), Metarhizium guizhouense (three), Metarhizium brunneum (one) and Metarhizium pingshaense (one).

CONCLUSIONS

In this study, we report new human cases of Metarhizium infections, and, based on Ef-1α gene sequencing, we demonstrate the misidentification of species in case reports. We also correct the species identification of a strain reported as M. anisopliae used in a commercially available mycopesticide. According to our results, none of the strains from the human infection reports reviewed belongs to the species M. anisopliae.