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 Table of Contents  
CASE REPORT
Year : 2022  |  Volume : 2  |  Issue : 3  |  Page : 667-669

Mycotic keratitis due to rare fungal species Neoscytalidium: A case series


1 Cornea and Refractive Services, Aravind Eye Hospital, Pondicherry, India
2 Cornea and Refractive Services, Aravind Eye Hospital, Chennai, Tamil Nadu, India
3 Former Cornea Fellow, Aravind Eye Hospital, Pondicherry; Consultant Lions Eye Hospital, Nanded, Maharashtra, India
4 Fellow Retina and Vitreous Services, Aravind Eye Hospital, Pondicherry, India
5 Microbiologist, Aravind Eye Hospital, Pondicherry, India

Date of Submission21-Nov-2021
Date of Acceptance01-Mar-2022
Date of Web Publication16-Jul-2022

Correspondence Address:
Dr. Neha Kabra
Siddhivinayak, Near Pokarna House, Naya Mondha, Nanded - 431 602, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_2937_21

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  Abstract 


Neoscytalidium dimidiatum is a plant pathogen that rarely causes human infection. Very few cases of ocular infection have been reported. We report a case series of three patients who presented with keratitis caused by it. The culture showed effuse, white-to-grayish colonies with yellow-to-deep orange colony reverse. Chains of arthroconidia typical of Neoscytalidium were seen on staining with lactophenol cotton blue. Two patients responded to topical antifungal treatment while one needed therapeutic keratoplasty. Hence, early diagnosis and intensive antifungal treatment are essential for successful healing in mycotic keratitis caused by Neoscytalidium species.

Keywords: Arthroconidia, neoscytalidium, plant pathogen


How to cite this article:
Mandlik K, Ramakrishnan S, Kabra N, Bhattacharya D, Gubert J. Mycotic keratitis due to rare fungal species Neoscytalidium: A case series. Indian J Ophthalmol Case Rep 2022;2:667-9

How to cite this URL:
Mandlik K, Ramakrishnan S, Kabra N, Bhattacharya D, Gubert J. Mycotic keratitis due to rare fungal species Neoscytalidium: A case series. Indian J Ophthalmol Case Rep [serial online] 2022 [cited 2022 Aug 14];2:667-9. Available from: https://www.ijoreports.in/text.asp?2022/2/3/667/351160



Neoscytalidium dimidiatum is mainly a plant pathogen, that rarely causes human infection. The fungus mostly affects immunocompromised individuals but few cases have been reported in immunocompetent individuals as well. Very few cases of keratitis have been reported in literature. The purpose of this case series is to highlight the clinical appearance and course and treatment of Neoscytalidium keratitis.


  Case Reports Top


Case 1

A 60-year-old male patient with alleged history of vegetative trauma to oculus sinister (OS) presented with complaint of pain, redness, and watering. The patient was non-diabetic and non-hypertensive. At presentation, best corrected visual acuity (BCVA) was counting fingers (CF) at 3 meters. On slit-lamp examination, OS showed circumcorneal congestion with central 6 × 5 mm infiltrate with feathery margins extending up to mid-stroma [Figure 1]a. Corneal scrapings were sent for microbiological evaluation. Gram's stain and KOH mount showed fungal filaments and the patient was started on hourly dose of natamycin 5% and itraconazole 1% eye drops. The culture report confirmed Neoscytalidium dimidiatum. By one month, the infiltrate resolved completely with scarring. At the last follow up after five months, the BCVA on Snellen's chart was 6/24.
Figure 1: Image depicting (a) Central 6 × 5 mm dry-looking infiltrate with feathery margins extending up to mid stroma; (b) Chains of arthroconidia with brown walls of varying widths on lactophenol cotton blue; (c and d) The culture showed effuse, hairy, white-to-greyish colonies with yellow-to-deep orange colony reverse on potato dextrose agar

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Case 2

An 80-year-old male patient presented with oculus dextrus (OD) pain, redness, and watering for five days. There was no history of trauma but patient was using topical dexamethasone on and off since last seven years. At presentation, BCVA was CF at 1 meter. On slit-lamp examination OD showed circumcorneal congestion with full-thickness patchy infiltrate of 8 × 6 mm with feathery margins and a 3-mm hypopyon. Corneal scraping was done and sent for culture. Based on Gram's stain and KOH report, the patient was started on topical natamycin 5% hourly and topical itraconazole 1% with oral ketoconazole 200 mg twice daily, but showed no improvement after two weeks. The culture report confirmed Neoscytalidium dimidiatum. Intrastromal voriconazole in a dose of 50 micrograms in 0.1 ml was also given but showed no response. Finally, therapeutic penetrating keratoplasty (TPK) was performed. Following TPK, the eye was quiet without signs of residual infection for six months. At the last follow up, around 6 months after TPK, BCVA was CF at 5 meters.

Case 3

A 30-year-old male with alleged history of iron nail injury to OS presented with pain, redness, and watering at presentation, BCVA was 6/36. On examination, a 2 × 2 mm central anterior stromal, dry-looking infiltrate was noted. Corneal scrapings revealed fungal filaments on Gram's stain and KOH mount. The patient was started on an hourly dose of topical natamycin 5% and topical itraconazole 1%. The culture report confirmed Neoscytalidium dimidiatum. By two weeks, the infiltrate resolved completely with scarring. At the final follow-up visit, around two months after scarring, the BCVA was 6/12.

In all cases, the culture showed effuse, hairy, white-to-greyish colonies with yellow-to-deep orange colony reverse [Figure 1]c and [Figure 1]d. Chains of arthroconidia with brown walls of varying widths typical of Neoscytalidium were seen on staining with lactophenol cotton blue [Figure 1]b. There was no evidence of same fungal infection in hands and nails of the patient, neither patient was on any dermatological treatment.


  Discussion Top


Neoscytalidium dimidiatum is a filamentous fungus seen in tropical and subtropical areas. In our case series, the diagnosis of Neoscytalidium dimidiatum keratitis was made on the basis of the morphological features of the fungus on culture.[1] The culture showed white-to-greyish colonies with yellow-to deep-orange colony reverse and chains of arthroconidia with brown walls of varying widths on lactophenol cotton blue. Arthroconidia, which is a characteristic feature of Neoscytalidium dimidiatum, are typically present in chains of one to two cells, are darkly pigmented, and are produced by the holothallic fragmentation of undifferentiated hyphae.[1]

The first eye infection was noted in 1993 in a Yemeni farmer with endophthalmitis following trauma. Despite intraocular amphotericin B, miconazole, natamycin, and extensive surgical debridement, there was no improvement and enucleation had to be performed on the patient.[2] Farjo et al.[3] reported one case of Scytalidium dimidiatum keratitis which responded well to topical amphotericin B and oral fluconazole. Kindo et al.[4] also reported one case of keratitis caused by the synanamorph of Neoscytalidium dimidiatum, namely, Nattrassia mangiferae. In that case report, the patient was started on topical itraconazole, one hourly, and topical atropine, thrice a day. However, the patient was lost to follow up and hence treatment outcome was uncertain. A similar case report of keratitis caused by Neoscytalidium was reported by Tendolkar et al.[5] In that case report, the patient was started on topical fluconazole and oral voriconazole. However, the patient did not return for follow-up.

A synanamorph of Scytalidium dimidiatum, Nattrassia mangiferae, has also been implicated in a case of severe keratitis after laser-assisted in situ keratomileusis (LASIK) that was unresponsive to medical therapy and required penetrating keratoplasty,[6] and a case of endophthalmitis reported by Gumbo et al.[7] that responded well to oral ketoconazole.

Despite the in-vitro sensitivity of the fungus to various antifungals such as amphotericin B, voriconazole, and fluconazole, the clinical response is typically poor.[8] In our case series, one patient did not respond to antifungals and needed TPK. This can be explained by its ability to form biofilm which makes it more virulent and difficult to eradicate, with poor clinical response to antifungals.[9] Biofilm structures encase mycelium within an extracellular matrix, confer antifungal and environmental resistance, and can form in natural environments as well as inside the human host.[10] [Table 1] represents a summary of all the ocular infections caused by Scytalidium along with the final outcome.
Table 1: New caption-Summary and outcome of ocular infections caused by Scytalidium

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  Conclusion Top


Neoscytalidium keratitis has the potential to cause severe corneal infection or even endophthalmitis. Hence, early diagnosis and intensive anti-fungal treatment are essential for successful healing and prevention of end-stage blindness.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Kidd S, Halliday C, Alexiou H, Ellis D. Descriptions of Medical Fungi. 3rd ed. Newstyle Printing: Adelaide, Australia; 2016. p. 141.  Back to cited text no. 1
    
2.
al-Rajhi AA, Awad AH, al-Hedaithy SS, Forster RK, Caldwell KC. Scytalidium dimidiatum fungal endophthalmitis. Br J Ophthalmol 1993;77:388-90.  Back to cited text no. 2
    
3.
Farjo QA, Farjo RS, Farjo AA. Scytalidium keratitis: Case report in a human eye. Cornea 2006;25:1231-3.  Back to cited text no. 3
    
4.
Kindo AJ, Anita S, Kalpana S. Nattrassia mangiferae causing fungal keratitis. Indian J Med Microbiol 2010;28:178-81.  Back to cited text no. 4
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5.
Tendolkar U, Tayal RA, Baveja SM, Shinde C. Mycotic keratitis due to Neoscytalidium dimidiatum: A rare case. Community Acquir Infect 2015:2:142-4.  Back to cited text no. 5
    
6.
Jabbarvand M, Hashemian MR, Abedinifar Z, Amini A. Nattrassia mangiferae keratitis after laser in situ keratomileusis. J Cataract Refract Surg 2004;30:268-72.  Back to cited text no. 6
    
7.
Gumbo T, Mkanganwi N, Robertson VJ, Masvaire P. Case report. Nattrassia mangiferae endophthalmitis. Mycoses 2002;45:118-9.  Back to cited text no. 7
    
8.
Dunn JJ, Wolfe MJ, Trachtenberg J, Kriesel JD, Orlandi RR, Carroll KC. Invasive fungal sinusitis caused by scytalidium dimidiatum in a lung transplant recipient. J Clin Microbiol 2003;41:5817-9.  Back to cited text no. 8
    
9.
Calvillo-Medina RP, Martínez-Neria M, Mena-Portales J, Barba-Escoto L, Raymundo T, Campos-Guillén J, et al. Identification and biofilm development by a new fungal keratitis etiologic agent. Mycoses 2018;62:62-72.  Back to cited text no. 9
    
10.
Williams C, Ramage G. Fungal biofilms in human. In: Donelli G, editor. Biofilm-based Healthcare-Associated Infections Volume II, Advances in Experimental Medicine and Biology. Vol 831. Cham, Switzerland: Springer International Publishing; 2015. p. 11-27.  Back to cited text no. 10
    


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