Identification of chromoblastomycosis agents by PCR based reverse line blot (PCR-RLB) hybridization assay.

Chromoblastomycosis is one of the most prevalent implantation fungal infections caused by melanized fungi, affecting individuals with certain risk factors with high morbidity due to its recalcitrant nature. It is difficult to identify the etiological agents and thus a suitable reproductive molecular identification method applicable in developing countries has been investigated. We report the identification of four different fungal causative agents of chromoblastomycosis by reverse line blotting hybridization (RLB) based on biotin-labeled PCR products and amine labeled probes to hybridize. Sixty five reference strains, including type strains, i.e. Fonsecaea pedrosoi, F. monophora, F. nubica, and Phialophora verrucosa, obtained from the CBS-KNAW were included in this study. Internal transcribed spacer 1 (ITS1) regions of relevant species were aligned and adjusted using BIONUMERICS v. 4.61 in order to design four specific probes to identify informative nucleotide polymorphisms. The final identification of these species by RLB assay was concordant with ITS sequencing and showed 100% specificity with no cross hybridization, able to identify all tested strains. The time and cost were less compare to other routine identification methods such as sequencing. This assay allows sensitive and specific simultaneous detection and identification of a different fungal species.

Correction to: Rapid Identification of Seven Waterborne Exophiala Species by RCA DNA Padlock Probes.

The Editorial Office of Mycopathologia reports that several paragraphs of Najafzadeh et al. were transcribed with only minor edits from previously published material by Najafzadeh M.J.

Rapid Identification of Seven Waterborne Exophiala Species by RCA DNA Padlock Probes.

The black yeast genus Exophiala includes numerous potential opportunistic species that potentially cause systematic and disseminated infections in immunocompetent individuals. Species causing systemic disease have ability to grow at 37-40 °C, while others consistently lack thermotolerance and are involved in diseases of cold-blooded, waterborne vertebrates and occasionally invertebrates. We explain a fast and sensitive assay for recognition and identification of waterborne Exophiala species without sequencing. The ITS rDNA region of seven Exophiala species (E. equina, E. salmonis, E. opportunistica, E. pisciphila, E. aquamarina, E. angulospora and E. castellanii) along with the close relative Veronaea botryosa was sequenced and aligned for the design of specific padlock probes for the detection of characteristic single-nucleotide polymorphisms. The assay demonstrated to successfully amplify DNA of target fungi, allowing detection at the species level. Amplification products were visualized on 1% agarose gels to confirm specificity of probe-template binding. Amounts of reagents were reduced to prevent the generation of false positive results. The simplicity, tenderness, robustness and low expenses provide padlock probe assay (RCA) a definite place as a very practical method among isothermal approaches for DNA diagnostics.

Evaluation of two molecular techniques for rapid detection of the main dermatophytic agents of tinea capitis.

BACKGROUND: Tinea capitis is very common in Western China, with the most widespread aetiological agent being Trichophyton violaceum, while Microsporum canis is prevalent in the remainder of China. Conventional diagnostics and internal transcribed spacer (ITS) sequencing analyses have proven relatively limited due to the close phylogenetic relationship of anthropophilic dermatophytes. Therefore, alternative molecular tools with sufficient specificity, reproducibility and sensitivity are necessary. OBJECTIVES: To evaluate two molecular techniques [multiplex ligation-dependent probe amplification (MLPA) and rolling circle amplification (RCA)] for rapid detection of the aetiological agents of tinea capitis, T. violaceum and M. canis. METHODS: Probes of RCA and MLPA were designed with target sequences in the rDNA ITS gene region. Strains tested consist of 31 T. violaceum, 22 M. canis and 24 reference strains of species that are taxonomically close to the target species. RESULTS: The specificity and reproducibility of RCA and MLPA in detection of T. violaceum and M. canis were both 100% in both species. Sensitivity testing showed that RCA was positive at concentrations down to 1·68 × 10(6) copies of DNA in the TvioRCA probe, and 2·7 × 10(8) copies of DNA in McRCA. MLPA yielded positive results at concentrations of DNA down to 1·68 × 10(1) copies in the TvioMLPA probe and 2·7 × 10(2) in McMLPA. CONCLUSIONS: The two techniques were sufficiently specific and sensitive for discriminating the target DNA of T. violaceum and M. canis from that of closely related dermatophytes. RCA and MLPA are advantageous in their reliability and ease of operation compared with standard polymerase chain reaction and conventional methods.

Rapid screening for human-pathogenic Mucorales using rolling circle amplification.

Mucormycosis has emerged as a relatively common severe mycosis in patients with haematological and allogeneic stem cell transplantation. Source of transmission is from unidentified sources in the environment. Early diagnosis of infection and its source of contamination are paramount for rapid and appropriate therapy. In this study, rolling circle amplification (RCA) is introduced as a sensitive, specific and reproducible isothermal DNA amplification technique for rapid molecular identification of six of the most virulent species (Rhizopus microsporus, R. arrhizus var. arrhizus, R. arrhizus var. delemar, Mucor irregularis, Mucor circinelloides, Lichtheimia ramosa, Lichtheimia corymbifera). DNAs of target species were successfully amplified, with no cross reactivity between species. RCA can be considered as a rapid detection method with high specificity and sensitivity, suitable for large screening.

In vitro antifungal susceptibility of Cladophialophora carrionii, an agent of human chromoblastomycosis.

A global collection of Cladophialophora carrionii strains (n = 81) was tested against nine antifungal drugs. MIC90s of all strains were as follows in increasing order: itraconazole and posaconazole, 0.063 µg/ml; terbinafine, 0.125 µg/ml; isavuconazole and voriconazole, 0.25 µg/ml; caspofungin, 2 µg/ml; micafungin, 4 µg/ml; amphotericin B, 8 µg/ml; and fluconazole, 64 µg/ml.

In vitro activities of eight antifungal drugs against 106 waterborne and cutaneous exophiala species.

The in vitro activities of eight antifungal drugs against 106 clinical and environmental isolates of waterborne and cutaneous Exophiala species were tested. The MICs and minimum effective concentrations for 90% of the strains tested (n = 106) were, in increasing order, as follows: posaconazole, 0.063 µg/ml; itraconazole, 0.25 µg/ml; micafungin, 1 µg/ml; voriconazole, 2 µg/ml; isavuconazole, 4 µg/ml; caspofungin, 8 µg/ml; amphotericin B, 16 µg/ml; fluconazole, 64 µg/ml.

Identification and typing of isolates of Cyphellophora and relatives by use of amplified fragment length polymorphism and rolling circle amplification.

The species diversity and identification of black fungi belonging to Cyphellophora and Phialophora, which colonize and infect human skin and nails, were studied using amplified fragment length polymorphism (AFLP). A total of 76 Cyphellophora and Phialophora isolates were evaluated, and their delimitation was compared to earlier studies using multilocus sequencing. The results of the AFLP analysis and sequencing were in complete agreement with each other. Seven species-specific padlock probes for the most prevalent species were designed on the basis of the ribosomal DNA internal transcribed spacer region, and identification of the respective species could easily be achieved with the aid of rolling circle amplification.

Taxonomy and epidemiology of Mucor irregularis, agent of chronic cutaneous mucormycosis.

Mucormycosis usually presents as a progressive infection with significant angio-invasion. Mucormycosis due to Mucor irregularis (formerly Rhizomucor variabilis var. variabilis), however, is exceptional in causing chronic cutaneous infection in immunocompetent humans, ultimately leading to severe morbidity if left untreated. More than 90 % of the cases known to date were reported from Asia, mainly from China. The nearest neighbour of M. irregularis is the saprobic species M. hiemalis. The aim of this study was to evaluate the taxonomic position, epidemiology, and intra- and inter-species diversity of M. irregularis based on 21 strains (clinical n = 17) by multilocus analysis using ITS, LSU, RPB1 and RPB2 genes, compared to results of cluster analysis with amplified fragment length polymorphism (AFLP) data. By combining MLST and AFLP analyses, M. irregularis was found to be monophyletic with high bootstrap support, and consisted of five subgroups, which were not concordant in all partitions. It was thus confirmed that M. irregularis is a single species at 96.1-100 % ITS similarity and low recombination rates between populations. Some geographic structuring was noted with some localised populations, which may be explained by limited air-dispersal. The natural habitat of the species is likely to be in soil and decomposing plant material.

Identification problems with sterile fungi, illustrated by a keratitis due to a non-sporulating Chaetomium-like species.

A 39-year-old farm worker was injured in her right eye by a piece of wire, which resulted in a corneal ulcer unresponsive to antibiotic treatment. The clinical appearance was that of a corneal infiltrate with feathery borders resembling fungal keratitis. Corneal scrapings were collected and the patient was started on natamycin 5% eye drops, fluconazole 0.3% eye drops, and oral fluconazole. A non-sporulating fungus was isolated from the samples. Based upon macroscopic and microscopic morphologic features, it was provisionally identified as a Papulaspora species due to the fact that members of this genus generally do not form diagnostically useful conidia. However, it was found through the use of ITS sequencing that the isolate clustered within the ascomycete genus Chaetomium. The sequence did not fully match with any sequences of available ex-type strains of Chaetomium, Thielavia and Papulaspora and hence might belong to an undescribed specie. However, without diagnostic morphological features the taxon cannot be introduced as a novel member of the genus Chaetomium. Antifungal susceptibility testing was performed according to published standards. The corneal ulcer was successfully treated with six weeks of antifungal therapy.

Identification of Pseudallescheria and Scedosporium species by three molecular methods.

The major clinically relevant species in Scedosporium (teleomorph Pseudallescheria) are Pseudallescheria boydii, Scedosporium aurantiacum, Scedosporium apiospermum, and Scedosporium prolificans, while Pseudallescheria minutispora, Petriellopsis desertorum, and Scedosporium dehoogii are exceptional agents of disease. Three molecular methods targeting the partial ß-tubulin gene were developed and evaluated to identify six closely related species of the S. apiospermum complex using quantitative real-time PCR (qPCR), PCR-based reverse line blot (PCR-RLB), and loop-mediated isothermal amplification (LAMP). qPCR was not specific enough for the identification of all species but had the highest sensitivity. The PCR-RLB assay was efficient for the identification of five species. LAMP distinguished all six species unambiguously. The analytical sensitivities of qPCR, PCR-RLB, and LAMP combined with MagNAPure, CTAB (cetyltrimethylammonium bromide), and FTA filter (Whatman) extraction were 50, 5 × 10(3), and 5 × 10(2) cells/µl, respectively. When LAMP was combined with a simplified DNA extraction method using an FTA filter, identification to the species level was achieved within 2 h, including DNA extraction. The FTA-LAMP assay is therefore recommended as a cost-effective, simple, and rapid method for the identification of Scedosporium species.

Rapid identification of fungal pathogens by rolling circle amplification using Fonsecaea as a model.

We aimed to describe a rapid and sensitive assay for identification of pathogenic fungi without sequencing. The method of rolling circle amplification (RCA) is presented with species of Fonsecaea, agents of human chromoblastomycosis, as a model. The internal transcribed spacer (ITS) rDNA region of 103 Fonsecaea strains was sequenced and aligned in view of designing three specific padlock probes to be used for the detection of single nucleotide polymorphisms in three Fonsecaea species. The 38 strains included for testing the specificity of RCA comprised 17 isolates of Fonsecaea pedrosoi, 13 of Fonsecaea monophora and eight of Fonsecaea nubica. The assay successfully amplified DNA of the target fungi at the level of species, while no cross reactivity was observed. The amplification product was visualised on a 1% agarose gel to verify the specificity of probe-template binding. Amounts of reagents were minimised to avoid the generation of false-positive results. The simplicity, sensitivity, robustness and low costs provide RCA a distinct position among isothermal techniques for DNA diagnostics as a very practical identification method.

Molecular identification of Penicillium marneffei using rolling circle amplification.

Penicillium marneffei is the aetiological agent of a severe systemic disease in immunocompromised hosts in Southeast Asia. In the present study, we evaluated an identification method based on rolling circle amplification (RCA) enabling rapid and specific detection of single nucleotide differences. Three padlock probes were designed on the basis of the internal transcribed spacers 1 and 2 (ITS) of the rRNA operon. One of these (PmPL1) allowed specific amplification of P. marneffei DNA within one working day using a newly conceived protocol, while no cross-reactivity was observed with other fungi including related biverticillate penicillia. Amplification products can be detected by electrophoresis on agarose gel. The method provides a powerful tool for a rapid specific identification of P. marneffei in the clinical laboratory and has potential for ecological studies.

Melanization of a meristematic mutant of Fonsecaea monophora increases tolerance to stress factors while no effects on antifungal susceptibility.

Melanin is a complex polymer, which is widely distributed in nature, and is known as an important virulence factor in opportunistic and pathogenic fungi. In this study, three melanin mutants of Fonsecaea monophora from a case of chromoblastomycosis were generated from a parent strain that lacked hyphal morphology but was meristematic instead. Two albino mutants, one of which (CBS 125187) produced secreted melanin and another (CBS 125149) lacked melanin, grew faster than a mutant with cell-wall-associated and secreted melanin (CBS 125188) and than the meristematic parent strain (CBS 122845) (P < 0.05). The albino strains were also more sensitive to low pH, high UV radiation, and oxidative stress (P < 0.05). However, susceptibility testing against eight antifungal agents showed no statistical difference (P > 0.05). The discovery of three melanin mutants of a single meristematic mutant provided an alternative way to study the role of cell-wall-associated and secreted melanins in the pathogenesis of black fungi.

Fonsecaea nubica sp. nov, a new agent of human chromoblastomycosis revealed using molecular data.

A new species of Fonsecaea, Fonsecaea nubica, morphologically similar to F. pedrosoi and F. monophora, is described using multilocus molecular data including AFLP profiles, sequences of the ribosomal internal transcribed spacers (ITS), and partial sequences of the cell division cycle (cdc42), beta-tubulin (tub1) and actin (act1) genes. A phylogenetic approach was used to evaluate species delimitation. Topologies of the trees were concordant. Fonsecaea strains could be classified into three major entities, i.e., one representing Fonsecaea pedrosoi isolates, another consisting of strains of F. monophora, and a third, unnamed group comprising isolates mostly recovered from cases of chromoblastomycosis in South America and China. F. nubica is part of this latter group. Based on strains analyzed thus far, we have found that the pathologies of these three Fonsecaea species are somewhat different in that F. pedrosoi and F. nubica are preponderantly associated with chromoblastomycosis, while F. monophora may also act as a systemic opportunist in cases involving brain infections. The latter species is also the most frequently recovered of the three from environmental samples.

Subcutaneous phaeohyphomycotic cyst caused by Pyrenochaeta romeroi.

Pyrenochaeta romeroi is a rare agent of chronic, suppurative subcutaneous infections which ultimately lead to mycetoma. It has only rarely been reported from deep, non-mycetomatous infections. We describe a case of a subcutaneous phaeohyphomycotic cyst in a 45-year-old Indian female who suffered from verrucous plaque and a swelling (30 mm in diameter) on the right forearm that gradually increased in size over a period of 3 months. Direct microscopic examination with 10% KOH and histopathological investigation of exudates revealed septate hyphae without granules, the hallmark of mycetoma. The lesion appeared to be a subcutaneous phaeohyphomycotic cyst caused by P. romeroi. The suspected agent was recovered in culture, identified on the basis of morphologic features and its identification confirmed by sequencing of the internal transcribed spacer regions of rDNA. Treatment consisted of surgical excising of the cyst without any antifungal therapy. There was no relapse during a one-year follow-up and the patient was successfully cured. In vitro antifungal susceptibility tests demonstrated that itraconazole (0.5 microg/ml), isavuconazole (0.125 microg/ml) and posaconazole (0.5 microg/ml) had potent activity against this isolate of P. romeroi. High MICs were found with amphotericin B (4 microg/ml), fluconazole (>64 microg/ ml), voriconazole (4 microg/ml) and caspofungin (8 microg/ml). However, their clinical effectiveness in the treatment of P. romeroi infections remains to be evaluated.

The clinical spectrum of Exophiala jeanselmei, with a case report and in vitro antifungal susceptibility of the species.

Exophiala jeanselmei is clinically redefined as a rare agent of subcutaneous lesions of traumatic origin, eventually causing eumycetoma. Mycetoma is a localized, chronic, suppurative subcutaneous infection of tissue and contiguous bone after a traumatic inoculation of the causative organism. In advanced stages of the infection, one finds tumefaction, abscess formation and draining sinuses. The species has been described as being common in the environment, but molecular methods have only confirmed its occurrence in clinical samples. Current diagnostics of E. jeanselmei is based on sequence data of the Internal Transcribed Spacer (ITS) region of ribosomal DNA (rDNA), which sufficiently reflects the taxonomy of this group. The first purpose of this study was the re-identification of all clinical (n=11) and environmental strains (n=6) maintained under the name E. jeanselmei, and to establish clinical preference of the species in its restricted sense. Given the high incidence of eumycetoma in endemic areas, the second goal of this investigation was the evaluation of in vitro susceptibility of E.jeanselmei to eight conventional and new generations of antifungal drugs to improve antifungal therapy in patients. As an example, we describe a case of black grain mycetoma in a 43-year-old Thai male with several draining sinuses involving the left foot. The disease required extensive surgical excision coupled with intense antifungal chemotherapy to achieve cure. In vitro studies demonstrated that posaconazole and itraconazole had the highest antifungal activity against E. jeanselmei and E. oligosperma for which high MICs were found for caspofungin. However, their clinical effectiveness in the treatment of Exophiala infections remains to be determined.

Successful treatment of chromoblastomycosis of 36 years duration caused by Fonsecaea monophora.

We report a case of chromoblastomycosis in a 67-year-old female farmer, which involved a large (20 x 30 cm) cicatricial erythematous plaque on the inner side of her right thigh. The lesion was initially a small nodule which gradually extended over 36 years. Direct microscopic examination revealed a granulomatous lesion with muriform cells surrounded by giant cells. The mould recovered in cultures was dark olivaceous and identified as Fonsecaea monophora by ribosomal internal transcribe spacer (ITS) sequence data. The lesion was successfully cured after 4 months treatment with itraconazole, but there was a relapse.

Environmental isolation of black yeast-like fungi involved in human infection.

The present study focuses on potential agents of chromoblastomycosis and other endemic diseases in the state of Paraná, Southern Brazil. Using a highly selective protocol for chaetothyrialean black yeasts and relatives, environmental samples from the living area of symptomatic patients were analysed. Additional strains were isolated from creosote-treated wood and hydrocarbon-polluted environments, as such polluted sites have been supposed to enhance black yeast prevalence. Isolates showed morphologies compatible with the traditional etiological agents of chromoblastomycosis, e.g. Fonsecaea pedrosoi and Phialophora verrucosa, and of agents of subcutaneous or systemic infections like Cladophialophora bantiana and Exophiala jeanselmei. Some agents of mild disease were indeed encountered. However, molecular analysis proved that most environmental strains differed from known etiologic agents of pronounced disease syndromes: they belonged to the same order, but mostly were undescribed species. Agents of chromoblastomycosis and systemic disease thus far are prevalent on the human host. The hydrocarbon-polluted environments yielded yet another spectrum of chaetothyrialean fungi. These observations are of great relevance because they allow us to distinguish between categories of opportunists, indicating possible differences in pathogenicity and virulence.

Biodiversity of the genus Cladophialophora.

Cladophialophora is a genus of black yeast-like fungi comprising a number of clinically highly significant species in addition to environmental taxa. The genus has previously been characterized by branched chains of ellipsoidal to fusiform conidia. However, this character was shown to have evolved several times independently in the order Chaetothyriales. On the basis of a multigene phylogeny (nucLSU, nucSSU, RPB1), most of the species of Cladophialophora (including its generic type C. carrionii) belong to a monophyletic group comprising two main clades (carrionii- and bantiana-clades). The genus includes species causing chromoblastomycosis and other skin infections, as well as disseminated and cerebral infections, often in immunocompetent individuals. In the present study, multilocus phylogenetic analyses were combined to a morphological study to characterize phenetically similar Cladophialophora strains. Sequences of the ITS region, partial Translation Elongation Factor 1-alpha and beta-Tubulin genes were analysed for a set of 48 strains. Four novel species were discovered, originating from soft drinks, alkylbenzene-polluted soil, and infected patients. Membership of the both carrionii and bantiana clades might be indicative of potential virulence to humans.