• Users Online: 159
  • Print this page
  • Email this page


 
 Table of Contents  
CASE REPORT
Year : 2022  |  Volume : 2  |  Issue : 1  |  Page : 41-43

Mucor keratitis versus Pythium keratitis: A clinical and microbiological dilemma


1 Cornea Institute, L V Prasad Eye Institute, Hyderabad, Telangana, India
2 Jhaveri Microbiology Centre, L V Prasad Eye Institute, Hyderabad, Telangana, India

Date of Submission29-Mar-2021
Date of Acceptance12-Jul-2021
Date of Web Publication07-Jan-2022

Correspondence Address:
Dr. Bhupesh Bagga
The Cornea Institute, L V Prasad Eye Institute, L V Prasad Marg, Banjara Hills, Hyderabad, Telangana - 500 034
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_714_21

Rights and Permissions
  Abstract 


In the pre-COVID-19 (coronavirus disease 2019) times, a 68-year-old male presented with complaints of decreased vision and whitish discoloration of the right eye. On slit-lamp examination, there was a whitish infiltrate with fuzzy margins measuring 7 mm × 6.5 mm along with <1 mm hypopyon. On microbiological examination of the corneal scraping, KOH (potassium hydroxide) + CFW (calcofluor white stain) mount revealed aseptate, broad, fungal filaments that were initially interpreted as Pythium species, but the growth on the culture was of Mucor species. The patient was managed with antifungal medications. On further follow-up, a complete resolution of the keratitis was achieved. This case highlights the importance of smear and culture correlation in such cases where the filaments of Mucor species closely mimick that of the Pythium species on microscopic examination of corneal scraping.

Keywords: Mucor keratitis, Pythium keratitis, Aseptate filaments


How to cite this article:
Vishwakarma P, Bagga B, Sharma S. Mucor keratitis versus Pythium keratitis: A clinical and microbiological dilemma. Indian J Ophthalmol Case Rep 2022;2:41-3

How to cite this URL:
Vishwakarma P, Bagga B, Sharma S. Mucor keratitis versus Pythium keratitis: A clinical and microbiological dilemma. Indian J Ophthalmol Case Rep [serial online] 2022 [cited 2022 Aug 14];2:41-3. Available from: https://www.ijoreports.in/text.asp?2022/2/1/41/334972



Keratitis caused by Mucor, a nonseptate filamentous fungus (class – Mucormycetes, order – Mucorales, and family – Mucoraceae), is a rarely reported entity.[1] Microscopically, these can be confused with Pythium.


  Case Report Top


A 68-year-old male presented with complaints of decreased vision (perception of hand movement) and whitish discoloration of the right eye since 2 days. Slit-lamp examination showed a 7 mm × 6.5 mm whitish corneal infiltrate with fuzzy margins and streak hypopyon [Figure 1]a. KOH (potassium hydroxide) + CFW (calcofluor white stain) mount revealed aseptate, broad, hyaline filaments with ribbon-like folds [Figure 2]a similar to the Pythium species [Figure 2]b under fluorescence microscope. Later white cottony colonies grew on blood agar and Sabouraud dextrose agar (SDA), completely filling the SDA bottle, suggestive of Mucorales [Figure 3]a, [Figure 3]b. Over 2 weeks, there were tiny gray dots on the cottony surface. Lactophenol cotton blue mount showed broad, aseptate, hyaline hyphae and sporangiophores bearing bulb-like sporangia filled with oblong spores and columella in the center and collarette at the base, consistent with the Mucor species [Figure 3]c, [Figure 3]d. Natamycin 5% eyedrops hourly and oral ketoconazole 200 mg twice daily were started. There was no COVID-19 (coronavirus disease 2019) association. Because the random blood sugar was raised (446 mg/dL), consultation of the diabetologist was taken. Visual acuity improved to 20/80 within 81 days of medical management and follow-up of 1½ years [Figure 1]b.
Figure 1: Slit-lamp picture of the cornea at the time of presentation to the clinic (a). Picture at the time of complete resolution at 1.5 years follow-up (b)

Click here to view
Figure 2: Image of KOH + CFW mount of Mucor (a) and Pythium (b) and their differences

Click here to view
Figure 3: White cottony colony (a) on blood agar completely filling the Sabouraud dextrose agar (b). Lactophenol cotton blue mount (c, d) shows characteristic broad aseptate hyaline hyphae and sporangiophores bearing bulb-like sporangia filled with oblong spores and columella in the center

Click here to view



  Discussion Top


Both Mucor and Pythium have broad, aseptate to sparsely septate, ribbon-like, hyaline filaments folded on themselves.[1],[2],[3] Predisposing factors for Mucormycosis include uncontrolled diabetes mellitus, several immunosuppressive conditions, iron overload, and chelation with deferoxamine; risk factors for Mucor keratitis are similar to other causes of fungal keratitis.[1] Clinically, Pythium keratitis has tentacles, a typical reticular dot-like pattern of subepithelial and superficial stromal infiltrates.[2],[4] Unlike Pythium, Mucor shows variable staining of hyphae with Grocott's methenamine silver stain.[5] Whereas Pythium shows flat, feathery-edged, partially submerged, glabrous, colorless to light-brown colonies [Figure 4],[2] Mucorales shows white, cottony, raised, lid-lifting colonies.[3] Antibacterials such as linezolid and azithromycin are required for Pythium keratitis, whereas Mucor keratitis needs antifungals such as natamycin and amphotericin B.[1],[4]
Figure 4: Flat, feathery-edged, partially submerged, glabrous, colorless to light-brown colonies of Pythium on chocolate agar

Click here to view



  Conclusion Top


The filaments of Mucor closely mimick that of Pythium sp. on microscopic examination of corneal scraping, therefore it should be confirmed in culture. This highlights the importance of smear and culture correlation in making clinical diagnosis of microbial keratitis.

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.
Khalili MR, Abtahi SM, Atighehchian M, Hosseini S, Shirvani M, Sadeghi E, et al. Invasive fungal keratitis as an uncommon form of mucormycosis leading to endophthalmitis: Report of two cases and literature review. Curr Fungal Infect Rep 2020;14:384-90.  Back to cited text no. 1
    
2.
Sharma S, Balne PK, Motukupally SR, Das S, Garg P, Sahu SK, et al. Pythium insidiosum keratitis: Clinical profile and role of DNA sequencing and zoospore formation in diagnosis. Cornea 2015;34:438-42.  Back to cited text no. 2
    
3.
Lass-Florl C. Zygomycosis: Conventional laboratory diagnosis. Clin Microbiol Infect 2009;15(Suppl 5):60-5.  Back to cited text no. 3
    
4.
Bagga B, Sharma S, Madhuri Guda SJ, Nagpal R, Joseph J, Manjulatha K, et al. Leap forward in the treatment of Pythium insidiosum keratitis. Br J Ophthalmol 2018;102:1629-33.  Back to cited text no. 4
    
5.
Guarner J, Brandt ME. Histopathologic diagnosis of fungal infections in the 21st century. Clin Microbiol Rev 2011;24:247-80.  Back to cited text no. 5
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

Top
 
 
  Search
 
Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
Access Statistics
Email Alert *
Add to My List *
* Registration required (free)

 
  In this article
Abstract
Case Report
Discussion
Conclusion
References
Article Figures

 Article Access Statistics
    Viewed449    
    Printed2    
    Emailed0    
    PDF Downloaded52    
    Comments [Add]    

Recommend this journal


[TAG2]
[TAG3]
[TAG4]