Indian Journal of Otology

CASE REPORT
Year
: 2011  |  Volume : 17  |  Issue : 1  |  Page : 33--36

A case of otomycosis caused by Lichtheimia corymbifera (syn. Absidia corymbifera, Mycocladus corymbifer) in a healthy immunocompetent individual


Dhara H Vyas, Parul D Shah 
 Department of Microbiology, Smt. N. H. L. Municipal Medical College, Ellisbridge, Ahmedabad, India

Correspondence Address:
Parul D Shah
Department of Microbiology, Smt. N. H. L. Municipal Medical College, Ahmedabad - 380 006
India

Abstract

A case of otomycosis caused by Lichtheimia corymbifera from an immunocompetent patient with no known predisposing factor is reported. A 55-year-old, otherwise healthy male was presented to us with history of left-sided earache and yellowish-white ear discharge since 10 days. Ear discharge and bits of necrotic tissue were collected from ear through otoscope and processed. Direct wet mount by potassium hydroxide (10% KOH) was performed which showed broad, aseptate and branched hyphae suggestive of zygomycosis. On culture after 48 hours, cottony, wooly and fluffy growth was observed. Culture was subjected to Lactophenol Cotton Blue (LCB) mount which confirmed the presence of L. corymbifera. The patient responded well to suction clearance and debridement followed by drug therapy with amphotericin B.



How to cite this article:
Vyas DH, Shah PD. A case of otomycosis caused by Lichtheimia corymbifera (syn. Absidia corymbifera, Mycocladus corymbifer) in a healthy immunocompetent individual.Indian J Otol 2011;17:33-36


How to cite this URL:
Vyas DH, Shah PD. A case of otomycosis caused by Lichtheimia corymbifera (syn. Absidia corymbifera, Mycocladus corymbifer) in a healthy immunocompetent individual. Indian J Otol [serial online] 2011 [cited 2019 Aug 24 ];17:33-36
Available from: http://www.indianjotol.org/text.asp?2011/17/1/33/85806


Full Text

 Introduction



Otomycosis is a subacute or acute superficial mycotic infection of the outer ear canal that is caused by opportunistic fungi. The infection is usually unilateral and characterized by inflammation, pruritus, scaling and severe discomfort such as suppuration and pain. [1] Otomycosis is caused by some species of saprophytic fungi, which are found in nature and / or form a part of the commensal flora of healthy external auditory canal. Common ones are Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus and Candida spp. especially Candida albicans. Others are Pseudallescheria boydii, Scopulariopsis spp., Penicillium, Rhizopus, Absidia, etc. [2]

Mucormycosis is an opportunistic fungal infection that seldom occurs in individuals with a competent immune system. It is caused by fungi of order Mucorales and class Zygomycetes and most commonly by organisms belonging to genus Rhizopus. [3] The Zygomycetes genus Lichtheimia was first named Mycocladus, typified by Mycocladus verticillatus. [4] However, the type strain of that species turned out to represent a mixed culture of Absidia sensu stricto, and possibly, a Lentamyces species; thus, it was not congeneric with any of the thermotolerant species. Therefore, this group had to be renamed with the oldest available genus name, Lichtheimia, [5] typified by Lichtheimia corymbifera. According to Hoffman et al, [5] the genus Lichtheimia contained four species: Lichtheimia corymbifera (syn. Absidia corymbifera, Mycocladus corymbifer), Lichtheimia ramosa (syn. Absidia ramosa, Mycocladus ramosus), Lichtheimia blakesleeana (syn. Absidia blakesleeana, Mycocladus blakesleeanus) and Lichtheimia hyalospora (syn. Absidia hyalospora, Mycocladus hyalosporus). Of these, only L. corymbifera and L. ramosa have been reported from human infections. Others include Mucor, Apophysomyces and Saksenaea species. [3] These fungi are ubiquitous saprophytes found in soil, manure plants and decayed foods and can be pathogenic in immunocompromised patients. [6]

Absidia spp. are filamentous fungi that are cosmopolitan and like other members of the class Zygomycetes, they are common environment contaminants. A. corymbifera is a relatively rare case of human zygomycosis. [7] Although infection with A. corymbifera usually occurs in immunosuppressed individuals, Absidia infections in immunocompetent hosts have also been described. [8],[9],[10]

 Case Report



A 55-year-old male presented to our ENT OPD with history of left-sided earache and ear discharge since 10 days. There was no history of nasal discharge/bleeding or throat pain. There was no fever, vomiting or any other associated symptoms. Patient was not suffering from diabetes or any other chronic illness. History of chronic infection of ear, use of oil, eardrops, steroids, swimming and other immunocompromised conditions were ruled out. Patient had an agricultural background.

On general examination, he was found to be normal. On ear examination, yellowish-white sticky thick discharge along with bits of necrotic tissue was found in the left ear. Right ear examination was normal. Radiological examination did not reveal any bony involvement. Routine laboratory parameters were normal.

Tissue material was sent for mycological examination. Tissue was minced and subjected to wet mount preparation by potassium hydroxide (10% KOH) examination. Zygomycosis was confirmed by the presence of broad, aseptate fungal elements with ribbon-like appearances at places in direct microscopy.

Multiple ear discharge specimens were collected with sterile swab sticks and were rolled over the surface of two different Sabouraud's dextrose agar (SDA) media with antibiotics to rule out any possibility of contamination. Cultures were incubated at 25°-C and 37°-C aerobically. Cottony, wooly and fluffy growth was observed after 48 hours which rapidly filled the entire Petri dish with abundant aerial mycelium [Figure 1]. Initially the colony was white which later turned to olive-gray dotted appearance at places with no pigment on the reverse. In lactophenol cotton blue (LCB) mount, broad, hyaline, thin-walled aseptate hyphal elements were seen. There was a ribbon-like appearance with irregular diameter and branching at approximately 90°. Long hyaline sporangiophores bearing prominent funnel-shaped apophyses were observed [Figure 2]. Hyaline sporangia were pyriform in shape [Figure 3] and had prominent conical columellae with a pointed projection at the apex. Sporangiospores were hyaline, unicellular, round to oval and greenish in color [Figure 4]. Collarette [Figure 4] and nipple-like projection (Hershey's kiss) were observed among the sporangia after their rupture [Figure 5]. {Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}

The growth macroscopically and microscopically was consistent with Lichtheimia spp.

On aerobic bacterial culture, moderate growth of Staphylococcus epidermidis was found. As S. epidermidis is one of the normal floras of the external auditory canal, isolation of S. epidermidis was considered as nonpathogenic. [11]

 Discussion



Otomycosis is one of the common entities affecting the external auditory meatus and the ear canal. The presenting symptoms include: scaling, pain, pruritus and erythema. Wax formation is also common. [11] According to a clinicomycological study by Ravinder Kaur et al, earache and ear discharge are the major complaints in 65.2% and 50.5% patients, respectively. [12] Symptoms correlated well with our patient. A study done by Hueso Gutierrez et al showed that of the positive samples that came from the ENT clinic (84.3% of the positive samples) 60.56% had not had previous otological pathology. [13] Otomycosis can occur in both temperate and tropical environment. The prevalence of disease is greatest in hot, humid and dusty areas. [1] Otomycosis has a worldwide distribution and it is estimated that approximately 10-20% of total external otitis cases are due to otomycosis. Otomycosis is more frequent in adults and is less common among children. [2]

Zygomycetes is one of the causative agents of otomycosis. Lichtheimia is one among different genera of Zygomycetes. The most commonly isolated species is L. corymbifera. It is of interest to note that the patient was a dairy farmer and we speculate that he became colonized with A. corymbifera following occasional exposure to the fungus. Associations between Absidia infection and farms have been previously described. A study in Finland reported high airborne fungal spore concentration including that of A. corymbifera, which is also found in feeding and bedding material in daily farm barns. [14] There have been two case reports of fungal infection with A. corymbifera associated with farming. [8],[9],[10] Still, over 30 cases of disease with this organism have been recorded in the literature, although Furbinger gets the credit for describing the first case of zygomycosis due to A. corymbifera as a cause of pulmonary zygomycosis in 1876. [15],[16]

A. corymbifera grows readily upon routine mycology media that grow more rapidly at 37°-C than at 25°-C. It is capable of growth at temperatures up to 48°-C-52°-C which distinguishes it from other Absidia spp. [17] A. corymbifera produces wooly, cottony colonies which can fill a Petri dish in 24 hours. Absidia is characterized by differentiation of hyphae into arched stolons bearing more or less verticillate sporangiophores at the raised part of the stolon (internode) and rhizoids formed at the point of contact with substrate (at the node). This feature distinguishes Absidia from Rhizopus spp., where the sporangia arise from the nodes opposite the rhizoids. The sporangia are relatively small, globose, and pyriform or pear shaped and are supported by a characteristic funnel-shaped apophysis. This distinguishes Absidia from the genera Mucor and Rhizomucor which have large and globose sporangia without an apophysis. [18]

The only species of genus Absidia found in animals and man are A. ramosa and A. corymbifera. Although closely related, the two are distinguishable by the regularly ovoid spores of A. ramosa and the irregularly ovoid to globose spores of A. corymbifera. In our case reported here, on morphological basis, we diagnosed it to be Absidia corymbifera.[19]

In conclusion, aggressive and early treatment of mucormycosis is paramount; ideally with a combination of surgical removal of devitalized tissue and intravenous administration of amphotericin B. [20] In a review of patients with pulmonary zygomycosis, it was found that mortality was significantly lower in patients treated surgically rather than medically (11% vs 68%, P = 0.0004). [21] This case illustrates the importance of clinical suspicion, isolation of fungus followed by prompt antifungal treatment with surgical debridement.

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