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Colletotrichum Corda is a complex form genus of the form class Coelomycetes, asexual fungi producing conidia within fruit bodies, named conidiomata. These structures are spherical (pycnidia), with conidiogenous cells lining the inner cavity wall, or are cup-shaped (acervuli), in which case, the conidiogenous cells form a palisade on the surface of the conidiomata. This genus comprises several hundred species, mostly plant pathogens, which have been described mainly on the basis of their conidial morphology and the presence or absence of setae. The genus Colletotrichum was monographed by von Arx (16), and only a restricted number of species was accepted. Although only rarely pathogenic to humans, Colletotrichum spp. have been reported as almost exclusively causing keratitis (6-8, 11, 12), usually after an eye injury. In this report, we describe a diabetic man with a history of trauma who developed a subcutaneous infection caused by Colletotrichum gloeosporioides (Penz.) Sacc.

Case report. A 56-year-old male farmer and resident of Maringá in the state of Paraná, Brazil, presented himself to the Serviço de Dermatologia do Hospital Universitario Regional de Maringá in May 1996 because of the presence of nodular lesions on his left forearm and elbow. Past medical history revealed that he was diabetic and hypertensive and that he was receiving prednisone (20 mg/day) by autoprescription. He reported a previous traumatic injury of his left hand by rotten wood that had required local suturing. He told of the appearance, approximately 1 year later, of nonpruritic nodules in the same trauma site. He denied having suffered fever and loss of weight. On examination, he presented tuberose-nodular, erythematous, violaceous, solitary or confluent lesions measuring 1 to 3 cm in diameter and localized on the left forearm and elbow. In addition, several vinaceous, macular lesions of ca 1.5- cm diameter were observed, also on the dorsum of the forearm (Fig. 1). The results of routine laboratory investigations of blood and urine were within normal limits. Radiography of the thorax showed cardiomegaly with left ventricular hypertrophy and ectasia of the aortic arch. Radiography of the left elbow showed only soft-tissue thickening without evidence of bone or joint lesions. A computerized tomography scan showed the presence of an expansive, hypodense, and multilocular lesion in the soft tissue of the left elbow region. Biopsy of the lesions was performed, and the contents of some of the nodules were aspirated for examination. Direct examination of all specimens sampled revealed the presence of septate, acute angled branching, irregular, hyaline hyphae. A histologic section of the biopsy material stained with periodic acid-Schiff and Gomori methenamine silver stains showed a hyperplasic epidermis with a psoriasiform pattern. The dermis showed an extensive granulomatous reaction with central necrosis and multiple foci of microabscesses. Throughout the tissue, numerous irregularly shaped, hyaline, septate, branched hyphae were present (Fig. 2 and 3). All of the tissue samples and the contents of the nodules were cultured on Sabouraud's glucose agar (SGA) and potato dextrose agar (PDA). Fungal colonies grew out in all the cases in both media. Microscopic examination of the cultures demonstrated that all of them presumably belonged to the same species. Routine bacteriological cultures and cultures for mycobacteria were negative. While the diagnostic procedures were being performed, and before establishing treatment, the patient unfortunately died as a result of a car accident. An autopsy was not performed.

View larger version (85K): [in this window] [in a new window]   FIG. 1.   Nodular lesions over the dorsum of the patient's left forearm and elbow.

View larger version (142K): [in this window] [in a new window]   FIG. 2.   Periodic acid-Schiff stain of biopsy specimen from the left elbow showing a segmented branched, hyaline hypha. Magnification, ×440.

View larger version (148K): [in this window] [in a new window]   FIG. 3.   Methenamine silver stain of the skin biopsy specimen showing toruloid, septate hyphal elements with irregular forms. Magnification, ×440.

View larger version (157K): [in this window] [in a new window]   FIG. 4.   C. gloeosporioides colony growing on PDA after 10 days of incubation.

View larger version (94K): [in this window] [in a new window]   FIG. 5.   Conidia of C. gloeosporioides. Stain, lactophenol cotton blue. Magnification, ×440.

View larger version (139K): [in this window] [in a new window]   FIG. 6.   Conidia of C. gloeosporioides. Magnification by Nomarski optics, ×1,440.

View larger version (124K): [in this window] [in a new window]   FIG. 7.   Appressoria of C. gloeosporioides. Stain, lactophenol cotton blue. Magnification, ×440.

Antifungal susceptibility testing. The case isolate and four additional isolates of C. dematium (Pers. ex Fr) Grove, five isolates of C. coccodes (Wallr.) Hughes, and seven isolates of C. gloeosporioides from very diverse sources were tested to determine their susceptibility to antifungal drugs (Table 1). Tests were accomplished by a previously described microdilution method (10) performed mainly according to the National Committee for Clinical Laboratory Standards' guidelines for yeasts, by using RPMI 1640 medium (buffered to pH 7.0 with 0.165 M morpholinepropanesulfonic acid [MOPS]), an inoculum of 4.4 × 10⁴ to 2.8 × 10⁵ CFU/ml, a temperature of incubation of 30°C, a second-day reading (48 h), and an additive drug dilution procedure.

Discussion. Colletotrichum spp. are typical fungi pathogenic for plants and causing anthracnosis, necrosis, leaf spot, and fruit rot. The diseases caused are commonly seed borne. Some species cause latent infections on woody plants, and the infected plants often show poor growth, and their fruits may rot (17). The species are anamorphs of the genus Glomerella Spauld. & H. Schrenk, classically considered as belonging to the order Phyllachorales, although some evidence exists about their relationship with the Sordariales (15), both orders of the Ascomycota. von Arx (16) delimited the most important species of Colletotrichum, considering their most distinctive characteristics to be the shape and size of the conidia and their specific hosts. However, further studies have enlarged the genus (13). The taxonomy of the genus is still unclear, and a comprehensive review of the numerous species described is needed. Sutton (14) pointed out that in vitro studies are required to determine the nature of the most representative morphological features, such as sclerotia, setae, and appressoria, in order to compare them with those shown in the host plant, because some differences have been reported. C. gloeosporioides is one of the commonest plant-pathogenic fungi to occur in the tropics and subtropics and is found worldwide. It constitutes a very heterogeneous taxon. von Arx (16) has given more than 600 synonyms for this species and has recognized nine forms, but probably many more can be differentiated by a combination of cultural characteristics, morphology, host range, and pathogenicity. Several molecular techniques have been used for a better characterization of the plant-pathogenic strains of this fungus (1, 5). Up to now, four species of Colletotrichum were known to have caused infections in humans or other animals (2). They are C. coccodes, C. dematium, C. gloeosporioides and C. graminicola (Ces.) Wilson. These species had been associated exclusively with keratitis (6-8, 11, 12), but recently Midha et al. (9) described a case of disseminated infection in a neutropenic patient probably caused by an unidentified Colletotrichum sp. Hence, the case of infection reported here is the second one concerning an extraocular infection caused by a member of this genus. This change in the spectrum of the infection has also been noted in other fungi, first associated with keratitis, such as Fusarium (3) and Acremonium (4) spp. among others. The species pathogenic for humans were recently described and illustrated, and a key for their identification was also included (2). The other three pathogenic species can be easily differentiated from C. gloeosporioides by their setose conidiomata. In particular, C. dematium and C. graminicola are clearly distinguished by their falcate conidia, similar to those of Fusarium spp., although unicellular. The ascigerous state of C. gloeosporioides, Glomerella cingulata (Stoneman) Spauld. & H. Schrenk has been reported as developing on PDA (8).