Indian Journal of Pathology and Microbiology

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Year
: 2017  |  Volume : 60  |  Issue : 4  |  Page : 550--555

Scedosporium apiospermum, an emerging pathogen in India: Case series and review of literature


Dabet Rynga1, Malini R Capoor2, Swati Varshney2, Mayuresh Naik3, V Gupta3,  
1 Departments of Microbiology, VMMC and Safdarjung Hospital, New Delhi; Department of Microbiology and Pathology, NEIAH, Shillong, Meghalaya, India
2 Department of Microbiology, VMMC and Safdarjung Hospital, New Delhi, India
3 Department of Ophthalmology, VMMC and Safdarjung Hospital, New Delhi, India

Correspondence Address:
Dr. Malini R Capoor
Department of Microbiology, VMMC and Safdarjung Hospital, New Delhi - 110 029
India

Abstract

Scedosporium apiospermum is a rare cause of infection but is increasingly being reported among immunocompromised individuals around the world. We report two cases of S. apiospermum, one of keratitis and the other of nasal polyp both from immunocompetent patients. The two cases were successfully treated with voriconazole. It is important to diagnose such infections as their antifungal susceptibility to amphotericin B is variable.



How to cite this article:
Rynga D, Capoor MR, Varshney S, Naik M, Gupta V. Scedosporium apiospermum, an emerging pathogen in India: Case series and review of literature.Indian J Pathol Microbiol 2017;60:550-555


How to cite this URL:
Rynga D, Capoor MR, Varshney S, Naik M, Gupta V. Scedosporium apiospermum, an emerging pathogen in India: Case series and review of literature. Indian J Pathol Microbiol [serial online] 2017 [cited 2019 Nov 13 ];60:550-555
Available from: http://www.ijpmonline.org/text.asp?2017/60/4/550/222989


Full Text



 Introduction



The genus Scedosporium consists of two medically important species: Scedosporium apiospermum (and its teleomorph or sexual state Pseudallescheria boydii) and Scedosporium prolificans (formerly S. inflatum). They are saprophytic filamentous fungi found in soil, manure, and polluted water.[1]

The diseases caused by S. apiospermum are diverse, and they range from transient colonization of the respiratory tract to allergic bronchopulmonary reaction, invasive localized disease, and disseminated disease. These infections include skin and soft-tissue infections – extending to tendons, ligaments, bone – septic arthritis, osteomyelitis, lymphocutaneous syndrome, pneumonia, endocarditis, peritonitis, meningoencephalitis, meningitis, brain abscess, parotitis, thyroid abscess, otomycosis, sinusitis, keratitis, chorioretinitis, and endophthalmitis.[2]

Mycotic keratitis is one such infection having a very protean clinical presentation and constitutes a significant proportion of the microbial keratitis.[3],[4] Filamentous fungi are responsible for a larger fraction of these corneal infections in tropical climates, and their treatment requires prompt and accurate identification of these causative microorganisms.[3] Furthermore, keratitis caused by dematiaceous fungi is increasing worldwide, and they were reported to account for 10%–15% of all fungal keratitis. They are the third most frequently encountered fungi following Aspergillus and Fusarium.[4],[5] There have been many reported keratitis cases worldwide that were caused by the common dematiaceous fungi; however, there have been few reports on keratomycosis caused by S. apiospermum in literature.[1],[2],[3],[6],[7],[8],[9],[10],[11],[12]

In addition, recurrent and chronic sinusitis may lead to poorly draining paranasal sinusitis where fungal balls, due to Scedosporium spp., may grow. In such cases, the clinical picture may be that of an acute sinusitis, with facial pain or headache, depending on the involved sinus, along with dark gray thick nasal discharge. Invasion of respiratory mucosa is uncommon, and surgical debridement is generally curative.[2]

 Case Series



We report two cases, one of S. apiospermum keratitis and the other of nasal polyp. In the first case, a 65-year-old man from Bharatpur district of Rajasthan presented to the ophthalmology outpatient department (OPD) of a tertiary care hospital with complaints of watering of eye, pain, redness, and photophobia in his right eye for 4 days. He had a history of trauma with bird feather while relaxing in his home during the day a few days earlier, following which the presenting symptoms had appeared. The complaints were associated with the discharge, which led to the lids of the affected eye to stick together and then to difficulty in opening the eye. The patient had admitted to the use of honey on the affected eye as a local remedy before presenting to the OPD. He had no history of tuberculosis, diabetes mellitus, hypertension, or any other chronic ailment.

On examining the visual acuity of the right eye, the patient could still perceive light but could count fingers only when they were brought close to his face. On further examination of the affected eye, severe congestion of the conjunctiva was observed along with hypopyon [Figure 1] in the cornea and decreased sensation.{Figure 1}

Corneal scrapings were collected aseptically from the patient which were then inoculated onto a blood agar and chocolate agar plate along with a Sabouraud's dextrose agar (SDA) (Hi-Media, Mumbai, India) tube at his bedside. It was also inoculated onto two sets of SDA plates, and one set each of Potato dextrose agar (PDA) (Hi-Media). They were then incubated at room temperature (25°C) and at 37°C.[5]

Smears were also made from the corneal scraping which were then sent to the Mycology Laboratory in the Department of Microbiology, and they were stained with Gram's and Giemsa stain. On examination of the Giemsa stain, septate hyphae were observed as shown in [Figure 2]a. Potassium hydroxide (KOH) mount of the corneal scrapings showed hyaline fungal hyphae.{Figure 2}

On examining the media after 4–5 days of incubation, fast-growing, grayish-white, suede-like to downy colonies with a grayish-black reverse were observed [Figure 2]b. Growth was also observed in the SDA with cycloheximide.

Microscopically, the lactophenol cotton blue (LPCB) preparation showed septate hyphae with short, slender conidiophores, bearing single conidium. The conidia were oval and unicellular, with the larger end toward the apex, and a cutoff appearance near the base [Figure 2]c. Based on cultural and microscopic morphology on PDA, the final diagnosis of S. apiospermum was made.

We also report a case of nasal polyp in a 35-year-old woman who was diagnosed with chronic sinusitis recently. She had presented to the Dermatology OPD with complaints of nasal congestion, facial pain, and headache. She was a postoperative case of orbital decompression for chronic sinusitis with preseptal cellulitis at the time of surgery. Surgery was performed 6 months back, elsewhere. She was apparently relieved of her complaints after 14 days of broad-spectrum antimicrobials. She had no history of tuberculosis, diabetes mellitus, hypertension, or any other underlying disease. There was no history of bathing in ponds.

Nasal polyp was collected aseptically from the patient, and the tissue was processed as per standard procedures.[5] It was inoculated onto duplicate sets of SDA tube and PDA. They were then incubated at room temperature (25°C) and at 37°C.

KOH mount of the nasal tissue showed hyaline fungal hyphae. On examining the PDA after 8 days of incubation, fast-growing, gray, suede-like to downy colonies with a black reverse were observed. Growth was also observed in the SDA with cycloheximide. The LPCB preparation showed septate hyphae with slender conidiophores, bearing single conidium which was also oval and unicellular with the larger apex. The Graphium stage was also observed [Figure 2]d. Based on culture and microscopic morphology characteristics on PDA, the final diagnosis of S. apiospermum was made.

The two strains of S. apiospermum were reconfirmed by DNA sequencing at National Culture Collection for Pathogenic Fungi at Postgraduate Institute of Medical Research, Chandigarh.

The antifungal susceptibility test was performed by broth microdilution method to fluconazole, amphotericin B, and voriconazole as per Clinical and Laboratory Standards Institute guidelines 2010.[13] The two isolates were observed to be susceptible to voriconazole and resistant to amphotericin B and fluconazole.

The first patient was put on natamycin and voriconazole eyedrops for a month, and on follow-up, the patient's condition had improved. While the second patient was started on voriconazole 250 mg once a day and showed complete improvement in nasal cavity after 2 months of treatment with no adverse effects to the drug.

 Discussion



Keratitis is the most common manifestation of S. apiospermum ocular infection in immunocompetent people, and in most cases, they are usually preceded by a corneal injury due to some trauma, as in this case in which the patient was an apparently immunocompetent 65-year-old farmer, from a village in Rajasthan, which was near the Bharatpur Bird Sanctuary and had a history of trauma by a bird while he was relaxing in his home during the day.[6] This was followed by instillation of honey drops soon after the injury. Posttraumatic entry was the most probable route of fungal infection as this fungus was commonly found in the guano of birds. They are also found in soil, sewage, and polluted water. However, common documented modes of trauma are foreign body such as dust, vegetative material, and infection following laser in situ keratomileusis.[7],[9],[14]S. apiospermum keratitis is rare but may be the most common site of infection in immunocompetent patients,[14] as was seen in this case.

Up to now, 23 cases of S. apiospermum keratitis have been reported globally, and most of the cases have a history of trauma. Most of the patients were immunocompetent except for four patients with diabetes mellitus (two cases),[1],[8] multiple sclerosis (one case),[8] and gastric carcinoma.[12] The prognosis of the patients was irrespective of the immune status of the host. The extent of invasion and prompt diagnosis defined the outcome. They were mostly treated with voriconazole, which might be accompanied by an invasive procedure such as a keratoplasty, a lensectomy, or debridement [Table 1].{Table 1}

Despite the extensive involvement of the eye, this patient was successfully treated with voriconazole and natamycin eyedrops. The treatment of fungal keratitis caused by dematiaceous fungi with either natamycin alone or in combination with topical clotrimazole or miconazole was seen to be effective in 88% of the cases. Topical ketoconazole has also been reported to be efficacious. However, in patients with dematiaceous keratitis associated with a deeper tissue invasion, oral ketoconazole has been recommended to be added to the treatment. In severe cases, systemic therapy with ketoconazole, itraconazole, voriconazole, or posaconazole has been advised.[5]

Rhinosinusitis cases caused by Scedosporium spp. are not very common. So far, six such cases have been reported worldwide [Table 2]. Out of these cases, three were immunocompromised – one had an allogeneic bone marrow transplant, another had AIDS, and the other had some other immunosuppressive disorder – and all died due to complications of their underlying disease.[2] Previous nasal surgery for removal of a foreign body was seen in one of the immunocompetent patients.[15] In this case, the patient was a postoperative case of orbital decompression performed 6 months back, for chronic sinusitis with preseptal cellulitis, and the route of entry of S. apiospermum could be traumatic or inhalation. The patient was successfully treated with voriconazole and surgery. Thus, unlike keratitis, the outcome of patients with rhinosinusitis due to S. apiospermum was dependent on their immunity status, as was seen in this case.{Table 2}

In the past few years, S. apiospermum infections have been increasing among patients with hematological malignancies, AIDS, solid organ transplant, and those with cystic fibrosis.[5] Among healthy individuals, the infection by S. apiospermum can either be due to occupational or recreational exposure or due to penetrating injuries. It can grow within the poorly draining bronchi, lung cavity, or paranasal sinuses without causing invasive disease. Dissemination to central nervous system is secondary to this exposure due to the contiguous spread from sinusitis, penetrating trauma, or following near drowning in polluted water.[5],[14] In the present case, the dissemination to the central nervous system was prevented by timely etiological diagnosis and management of the patient.

There are a large number of reports of serious S. apiospermum in the world from immunocompromised patients.[1],[2],[5],[12],[15] However, the reports from immunocompetent patients are relatively few. Furthermore, S. apiospermum is an emerging cause of infections in India.[1],[6],[8],[9],[16]

Identification of the fungus by culture is crucial because of the variable susceptibility of S. apiospermum to amphotericin B and other antifungal agents, and voriconazole is the preferred therapy.[14]

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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