|ORIGINAL RESEARCH ARTICLE
|Ahead of print publication
Clinicomicrobiological profile of mycotic keratitis patients presenting at a tertiary care hospital of rural North India
Jyoti Sangwan1, Kirti Lohan1, Manpreet Kaur2, Yogesh Kumar2, Nishtha Saini2, Pratibha Mane1, Pooja Singla1, Sameena Khan3
1 Department of Microbiology, SHKM GMC, Nuh, Haryana, India
2 Department of Opthalomology, SHKM GMC, Nuh, Haryana, India
3 Department of Microbiology, DY Patil Medical College and Hospital, Pune, Maharashtra, India
|Date of Submission||01-Aug-2022|
|Date of Decision||14-Nov-2022|
|Date of Acceptance||15-Nov-2022|
|Date of Web Publication||02-Mar-2023|
Professor, Department of Microbiology, SHKM GMC, Nalhar, Nuh - 122 107, Haryana
Source of Support: None, Conflict of Interest: None
Background: Mycotic keratitis (MK) or keratomycosis is an infection of corneal stroma caused by a variety of fungal species. It is a condition resulting in blindness if untreated seen, especially in tropical and subtropical countries. The identification of causative fungus is key to starting appropriate treatment. This study aimed to describe clinicomicrobiological profile along with associated demographic factors of MK patients presenting at a tertiary care hospital situated in rural North West India.
Methodology: A cross-sectional study was conducted for 3 years from June 2018 to June 2021 at a tertiary care hospital situated in rural North India after obtaining ethics committee approval. After obtaining informed consent, a detailed history was taken from suspected MK patients. Then, corneal scrapings were taken under the slit lamp and processed in the microbiology laboratory for isolation and identification of causative agents. The results obtained were analyzed.
Results: A total of 114 nonrepetitive samples were collected from patients suspected of keratomycosis during the study period. Eighty-one (71.1%) samples were found to be positive for fungal growth. Males were affected more than females (1.53:1). Individuals belonging to the age group of 21–40 years were involved the most. Farmers (48.1%) were affected most of all. The predominant fungal species isolated was Candida followed by Aspergillus and Fusarium.
Conclusion: The present study highlights the different etiology of MK across different geographical regions. Candida spp. was the most common etiological agent observed in the study followed by Aspergillus and Fusarium spp. Its prevalence, risk factors, and causative agents involved vary with geographic variation, occupation, and local prevailing practices. Timely diagnosis can get an individual the right treatment and can save the vision.
Keywords: Corneal scrapings, corneal ulcer, keratomycosis, KOH
|How to cite this URL:|
Sangwan J, Lohan K, Kaur M, Kumar Y, Saini N, Mane P, Singla P, Khan S. Clinicomicrobiological profile of mycotic keratitis patients presenting at a tertiary care hospital of rural North India. J Curr Res Sci Med [Epub ahead of print] [cited 2023 Mar 31]. Available from: https://www.jcrsmed.org/preprintarticle.asp?id=370925
| Introduction|| |
Infective corneal ulcer (infectious keratitis) is a cause of visual impairment in developing countries. Keratitis is an inflammation of the cornea which is one of the important potential causes of blindness in the world with 1.5 million new infections every year. Mycotic keratitis (MK) also called keratomycosis is an infection of corneal stroma by various fungi. It has the potential to cause blindness if left untreated therefore categorized as an ophthalmic emergency. The incidence of MK is about 11 per 100,000 persons/year in the US, and in India, it is 1130 per million. The worldwide reported incidence varies from 17% to 36% in various studies. MK can be caused by more than 100 different species of fungi. Further, MK can be categorized as MK caused by filamentous fungi (Fusarium, Aspergillus, phaeohyphomycetes, etc.) and MK caused by yeast-like fungi such as Candida. Ocular trauma (generally with plant materials), overuse and abuse of corticosteroids, contact lens use, underlying chronic diseases, vitamin deficiency, and immunodeficiencies are some of the common predisposing risk factors for developing MK. When MK is due to filamentous fungi, trauma is usually the sole predisposing factor, although previous use of corticosteroids and contact lens use are becoming importance risk factors; in MK due to yeast-like fungi, there is usually some underlying disease, immunodeficiency or local defects. As far as environmental conditions responsible are concerned, MK is seen more in tropical and subtropical areas compared to the rest of the world.
The duration from trauma to clinical features varies depending on the type of organism, the size of the inoculum, and the resistance of the host. The frequency and spectrum of fungi involved vary from place to place as several factors such as climate, age, gender, and geographical and socioeconomic conditions play a significant role in modulating the incidence and prevalence of fungal corneal infections.,
Corneal ulcers, when untreated might result in scarring, visual loss, corneal perforation, and endophthalmitis, may require evisceration and hence knowing the microbiological profile is of great importance which helps prevent such complications.
Microbiological investigations, particularly direct microscopic examination and culture of corneal scrape or biopsy material, are the cornerstone of diagnosis. In recent years, polymerase chain reaction has gained prominence as a diagnostic aid for MK. This molecular method permits rapid identification of the etiological agent.,,,
Keratitis due to filamentous fungi continues to be difficult to treat despite the use of topical and systemic antifungal agents and adjuvant surgery, such as corneal transplantation. Antifungals used are topical natamycin, voriconazole (given by various routes) and Amphotericin B. Treatment is usually prolonged as antifungals only inhibit the growth of fungus, but it is only the host defense mechanisms that finally eradicate the organism.
There have been many studies reporting MK from India, most being from South India, some from the lower Himalayan region but no data regarding this is available from the Aravali region. Our tertiary care institute is located in the arid and dry region of Mewat located at the foothills of the Aravali range. The region has a largely agrarian population being largely uneducated, practicing poor environmental hygiene, largely undernourished, and utilizing the services of quacks. All these factors predispose them to many diseases including keratitis. Therefore, the present study was taken up to describe the prevalence of MK in infectious keratitis patients, to report the etiological agents responsible, and finally to understand the clinical presentation of these patients and the risk factors involved.
| Materials and Methods|| |
A prospective cross-sectional study was conducted for 3 years from June 2018 to June 2021 at the department of microbiology and ophthalmology of a tertiary care hospital in rural Southern Haryana. Institutional ethics committee approval was granted via letter no SHKM/IEC/15 dated October 29, 2018. A total of 114 nonrepetitive samples from patients clinically suspected of keratomycosis (fungal corneal ulcer) were collected during the study.
After obtaining written informed consent, detailed history including age, residence (rural/urban), gender, occupation, mode of injury if known, pain, watering, discharge, ocular discomfort, and treatment history was taken. Detailed slit-lamp examination was done by the ophthalmologist to know the anterior chamber reaction, stromal infiltration, hypopyon, location, margins of ulcer, and satellite lesions. The affected eye was then anesthetized using 0.5% proparacaine topical eye drops. The margin of the lesion and base of the ulcer if present was scraped using the 26-gauge needle under the slit lamp. Collected scrapings were immediately smeared on two clean glass slides for Gram staining and KOH preparation and then directly inoculated on culture media including Blood agar, MacConkey agar, and Sabouraud Dextrose Agar (SDA) and taken to the microbiology laboratory for further processing. Gram stain was done on one slide and other the slide was used for 10% KOH wet preparation. The findings were noted. The blood agar and MacConkey agar were incubated at 37°C for 24 h. SDA was incubated at 25°C–30°C for 3–4 weeks before declaring negative. Growth if present was identified using standard microbiological procedures. Fungi were identified by their colony characteristics on SDA and by the morphological appearance of the hyphae and spores in lactophenol cotton blue mount.
Samples positive for bacterial growth were excluded from the study. Similarly, repeat samples were excluded from the study.
The collected data were entered into MS Excel to prepare a spreadsheet for the data analysis. Analysis was carried out using statistical tools such as tabulation, diagrams, measure of central tendencies, and percentages wherever applicable. The data analysis was done using statistical analysis was done using Microsoft excel 2010 and SPSS version 2021 (Armonk, NY: IBM Corp).
| Results|| |
A total of 114 samples suspected of infectious/MK were received in the microbiology laboratory during the study period. Among these, 81 samples (71.1%) were positive for fungal growth on SDA agar and were included in the study. Thirty-three samples were excluded from the study as 26 (22.8%) samples from these were positive for bacterial growth and 7 (6.1%) samples did not show any growth at all. Demographic characteristics of patients positive for fungal growth (MK) are given in [Table 1].
|Table 1: Demographic characteristics of mycotic keratitis patient (n=81)|
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As depicted in [Table 1], the majority of patients with MK belonged to the age group of 21–40 years followed by patients in the age group of 41–60 years. There was a male predominance of 49 (60.5%) with male-to-female ratio being 1.53:1. When enquiring about the place of residence, it was observed that 51 (62.9%) patients resided in the rural area. The occupation profile of MK patients mainly consisted of farmers (48.1%), followed by laborers (23.4%), carpenters (20.9%), and other occupations (7.4%).
Predisposing factors for keratitis are listed in [Table 2]. The most common predisposing factor observed in the patients of MK was a trauma, which was seen in 24 (29.6%) patients. Among the reasons for corneal ulcers, trauma due to vegetable matter (14 patients) was the leading cause, followed by wooden objects (eight patients) and stone injury (two patients). Contact lens infection was not a predisposing factor in our study population, probably due to low socioeconomic status among farmers.
|Table 2: Predisposing factors (risk factors) in patients of mycotic keratitis (n=81)|
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The details of positive microbial etiology are given in [Table 3]. The predominant fungal species was Candida spp., followed by Aspergillus spp. and Fusarium. Curvularia spp. was also isolated.
A comparison between direct microscopy and culture positivity is depicted in [Figure 1]. Assuming the culture method to be standard for fungi, smear sensitivity was 82.7%, while the specificity was 100%. Of the total 67 KOH-positive mounts, 21 (31.3%) showed the presence of yeast-like cells with or without pseudo hyphae and 46 (68.6%) showed the presence of fungal hyphae/elements. Fourteen KOH negative samples, later on, grew Candida on SDA [Figure 2], [Figure 3]a and [Figure 3]b.
|Figure 2: KOH mount showing presence of filamentous fungus (magnification × 400)|
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|Figure 3: (a): Aspergillus spp. grown on Sabouraud dextrose agar. (b): Smooth pasty colonies of Candida species grown on Sabouraud dextrose agar|
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While studying the clinical presentation of fungal corneal ulcer (keratomycosis) patients, it was observed that conjunctival injection and anterior chamber reaction were present in all patients. These were followed by stromal infiltration, hypopyon, and the presence of satellite lesions. [Figure 4]a and [Figure 4]b depict slit-lamp images of early and advanced corneal ulcers; [Figure 5] shows the clinical picture of a case of advanced corneal ulcer.
|Figure 4: Slit-lamp image of early fungal keratitis (a) and fungal keratitis with feathery margins (b)|
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| Discussion|| |
MK is one of the potential causes of corneal blindness prevalent in tropical and subtropical countries. In the present study, MK was seen in all age groups with preponderance among middle-aged adults as they are physically more active and involved in outside jobs. Higher preponderance was seen in males (60.5%) than in females (39.5%) as observed in other studies.,,,,
Trauma was the most common predisposing factor in the present study similar to other studies conducted in South India (92.15%) and Madurai, India (65.4%).,,, Corneal injury with vegetable matter like wheat husk, sticks, and leaves was the most commonly seen in the study followed by wooden injury and stone. Basak et al. found vegetative matter, chiefly paddy, and jute, as the principal traumatic agent for the development of keratitis similar to our study., In contrast to our study, wooden injury and thorn injury were more common in other studies.,
A higher incidence of keratitis was observed in farmers (48.1%), followed by laborers (23.4%) and carpenters (20.9%) in agreement with many studies.,,, Injury with wooden objects and vegetable matter representing farmers was also seen in other studies.,,,, This implies a significant association between occupation and infectious MK.
In the present study, fungal growth was seen in 71.0% of suspected corneal ulcer patients. Studies from West Bengal, South India, and Ghana showed similar percentages of fungal etiology.,,,, When KOH positivity was compared with fungal culture positivity, 82.7% concordance was observed. Hence, KOH when done promptly on the correctly collected samples can give an early clue to the pathogens responsible and help initiate treatment. In the present study, 14 KOH-negative samples ended up growing Candida species on culture, highlighting the importance of observing the culture of microscopy negative samples too carefully.
Candida spp. (43.2%) was the predominant fungal isolate reported in the present study as compared to other studies.,,,, When the risk factors in these individuals were studied, the majority of them had a previous history of corticosteroid use (being remote region, quack practices are very common in the region), ocular surface diseases, and diabetes. Furthermore, poor personal and environmental hygiene, rampant in the region, can further enhance the risk of Candida infection. Since the course of treatment of Candida keratitis is a recurrent one involving the use of topical amphotericin B, natamycin, and miconazole and many of these patients end up with keratoplasty also, awareness about Candida as a potential keratomycotic agent in the region is important.,
Aspergillus was grown in 34.6% of culture-positive samples. It is a well-known pathogen responsible for MK, also reported in previous studies.,, In the present study, Fusarium spp. was isolated from only 12% of MK patients; this is very less compared to other studies done across India which reported a much higher prevalence of Fusarium spp. in their studies.,,,,,, However, a study done in Chandigarh by Punia et al. has also demonstrated Aspergillus being more common than Fusarium as in the present study. This variation can be attributed to geographical differences seen among places.
Dematiaceous fungi such as Curvularia spp. were also isolated from 7.4% of MK patients in the present study. These fungi are also well reported as a cause of MK in the literature, especially in the elderly or otherwise immune-compromised hosts.,, Two dematiaceous fungi were also isolated but could not be identified.
Limitation of the study
As the study was an observational cross-sectional one and did not involve the follow-up of the patients, the final outcome of the patients could not be recorded. However, the clinicians were well informed in time about the final microbiological diagnosis which helped in starting the right treatment on time.
| Conclusion|| |
The present study highlights the changing etiology of MK across different geographical regions. Candia spp. was the most common etiological agent observed in the study, followed by Aspergillus and Fusarium spp. Trauma and misuse of steroids mostly due to prevalent quack practices were the common predisposing factors. Corneal ulceration may result when the corneal integrity is disrupted and defense mechanisms are compromised. Detailed history, clinical examination, and laboratory investigations of scrapings in cases of infective corneal ulcers are essential to know the etiology. MK should be suspected in patients with a corneal lesion and should be ruled out before commencing steroids or antibiotics to save the vision. KOH mount microscopy method is a reliable method if done correctly for early detection and fungal culture is the gold standard for diagnosis early correct detection and prompt treatment is key to saving vision.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3]