作者：Ashok Kumar Narsani, Siddiqa Gul, Syed Asher Dabir, Shafi Muhammad Jatoi, Mahtab Alam Khanzada, Mahesh Kumar 作者单位：巴基斯坦海德拉巴,Liaquat大学眼科医院眼科
【摘要】目的：确定真菌性角膜炎的易感因素、致病真菌，以及提高相应的实验室诊断能力。方法：240例240眼临床疑似微生物感染的角膜溃疡患者进入本研究。通过病史回溯及裂隙灯检查获得病例资料。采用标准技术完成角膜刮片检查。取部分刮片样本加入10%的氢氧化钾液后，以及采用革兰氏和吉姆萨染色，在直接在显微镜下观察是否存在真菌、细菌和棘阿米巴。另一部分刮片样本直接接种在血琼脂、麦康基琼脂、巧克力琼脂和萨布罗琼脂表面。结果：在纳入本研究的240例伴有脓性分泌物的角膜溃疡患者中，84例（35%）被确认为真菌感染。其中48例（57.1%）为男性，其余36例（42.9%）为女性。年龄分布从2280岁。其中60例（71.4%）为农村患者，其余24例（28.6%）为城市居民。18例（21.4%）曾有植物外伤史。病变高发于10月至11月间。在84例确诊为真菌性角膜炎的患眼，致病原因为单纯真菌者74眼（80.10%），其余10眼(11.90%)为真菌合并细菌感染。分离得到的最常见致病微生物为白色念珠菌，在66眼（78.6%）中被发现。结论：在巴基斯坦南部，感染性角膜溃疡中，最常见的是真菌性角膜炎，而白色念珠菌是最常见的致病原。采用加入10%的氢氧化钾液后直接显微镜下观察是此类感染原简单、迅速、价廉及可信的诊断方法。
【关键词】真菌性角膜炎;农业;念珠菌
Fungal keratitis:84 cases report in Southern Pakistan
Ashok Kumar Narsani, Siddiqa Gul, Syed Asher Dabir, Shafi Muhammad Jatoi, Mahtab Alam Khanzada, Mahesh Kumar
Department of Ophthalmology, Liaquat University Eye Hospital, Hyderabad, Pakistan
Correspondence to: Ashok Kumar Narsani. Department of Ophthalmology, Liaquat University Eye Hospital, Hyderabad, Pakistan. [email protected]
AbstractAIM: To identify the predisposing factors, causative fungi and to improve the facilities for the laboratory diagnosis of fungal keratitis.METHODS: Two hundred and forty eyes of 240 patients of clinically suspected microbial corneal ulcer were included in the study. Data was collected through history and slit lamp examination. Using standard techniques, corneal scraping was performed.A portion of each scraping was examined by direct microscopy for the presence of fungi, bacteria and acanthamoeba by using 10% potassium hydroxide and also by Gram and Giemsa stainings. Another portion was inoculated directly on the surface of solid media such as Blood agar, MacConkey agar, chocolate agar and Sabouraud agar in Cshaped streaks for culture.
RESULTS: A total of 240 patients with suppurative corneal ulcer were enrolled in the study, out of which fungi were identified in 84 (35%) patients. Of these, 48 (57.1%) were males and 36 (42.9%) females. The age ranged between 2280 years. Sixty patients (71.4%) belonged to rural population and twenty four (28.6%) to urban population. Trauma with vegetative material was the most frequent cause noted in eighteen (21.4%) patients. Peak incidence was in the months of OctoberNovember. Out of 84 eyes with fungal keratitis, fungi alone were the etiologic agents in 74 (80.10%) cases and bacteria with fungi were identified in 10 (11.90%). The most frequently isolated organism was Candida albicans which was found in 66 (78.6%) patients.CONCLUSION: Fungal keratitis is the leading cause of infective corneal ulcer and Candida albicans being the most commonly isolated pathogen in the patients belonging to Southern Pakistan. The direct microscopic examination with potassium hydroxide 100mL/L method is a simple, rapid, inexpensive and reliable method in the diagnosis of this infection.
KEYWORDS: fungal keratitis; agriculture; candida
INTRODUCTION
Fungal keratitis is one of the most severe eye diseases world wide that may lead to blindness, especially in the agricultural countries with temperate climates[1]. It has been found to account for 6% to 50% of all the cases of ulcerative keratits[26]. Factors that have been correlated with this increasing incidence include the growing number of trauma cases, wide spread abuse of broad spectrum antibiotics and steroids and increasing use of corneal contact lenses[7].
Fungi reside as commensals in flora of the conjunctival sac in 3% to 28% of healthy eyes[810]. Thus in the tropical countries, humid atmosphere and outdoor occupations make the population more vulnerable to fungal infections[11].
Despite the advances in diagnosis and medical treatment of keratomycosis 15% to 27% of patients require surgical intervention such as keratoplasty, enucleation or evisceration because of either failed medical treatment or advanced disease at presentation[12].
This study is a humble effort to analyze the epidemiologic features, predisposing factors and the main causative organisms for fungal keratitis in this part of Asia to provide a useful guide for the practicing ophthalmologists.
MATERIALS AND METHODS
This quasiexperimental study of fungal corneal ulcer was conducted at Liaquat University Eye hospital Hyderabad Sindh Pakistan from April 2006 to March 2008.
Patients above 15 years of age presenting with suspected corneal ulceration and having symptoms of pain, redness, watering, photophobia and decreased vision were registered for the study. Patients written consent was obtained and a standardized profoma was used to record the data.
Detailed history of the patients was taken regarding demographic features, time of onset of symptoms, predisposing factors and any previous medical therapy. All the patients underwent through slit lamp examination to locate the size, depth and the nature of the infiltrate; presence of pigmentation; endothelial exudates and anterior chamber reaction or hypopyon at the time of presentation.
After the instillation of local anesthetic 5g/L proparacaine hydrochloride, corneal scrapping were obtained aseptically with a sterile No. 15 surgical blade from the base and edges of each ulcer. A portion of each scrapping was examined microscopically for the presence of fungi, bacteria or acanthamoeba by using 100mL/L potassium hydroxide, Calcoflour white and Gram and Giemsa staining methods.
Another portion was inoculated on to Sarborauds agar, brain heart infusion broth and chocolate agar respectively, in Cshaped streaks and cultured for the potential growth of fungi, bacteria or acanthamoeba. Sarborauds agar slants were incubated at 28℃ while others at 37℃. All media were cultured for a period of fourteen days and observed daily.
A diagnosis of fungal keratitis was made when atleast one of the following was confirmed 1) Corneal scraping examination revealed fungal presence in smears. 2) The same fungal pathogens grew in ≥two culture media. 3) Fungus grew confluently at the inoculated site on a single solid medium and 4) Histopathologic examination revealed fungal presence.
RESULTS
A total of two hundred and forty eyes of 240 patients with suppurative corneal ulcer were enrolled in the study. Of these fungal keratitis was identified in eighty four (35%) patients. Among these, forty eight (57.1%) patients were males and thirty six (42.9%) were females. The age ranged between 22 and eighty years. The mean age was 44.6 years. Sixty patients (71.4%) belong to rural population while twenty four patients (28.6%) belong to Urban background. Of the eighty four patients with fungal keratitis, forty two (50%) were farmers, eighteen (21.4%) were labourers, six (7.14%) students, six (7.14%) teachers and twelve (14.28%) were jobless aged people.
Trauma with vegetative material was the main predisposing factor noted in eighteen (21.4%) patients. Six (7.1%) patients gave the history of corneal contact lens wear while history of ocular surgery and foreign body was also found in six (7.1%) patients each. Forty eight patients (57.1%) had no significant prior history of ocular disorder.
The duration from the onset of symptoms to the presentation to our department ranged from 6 to 150 days. (mean 62 days). Regarding seasonal variation, the peak incidence occurred in the months of October to December followed by March to June. Before the initial visit to our institution seventy two patients (85.5%) received topical antibiotics, antivirals, antifungals and/or corticosteroids either alone or in combination whereas 14.5% had no history of medication.
All patients with fungal corneal ulcer presented with the history of ocular pain photophobia, watering and decrease vision. On slit lamp examination the diameter of the ulcers ranged from 3.212 (mean 6.32.8)mm. Fifty four (64.28%) eyes had larger ulcers (diameter >6mm). The depth was from 1/3rd to almost full thickness of cornea. Epithelial defect, stromal infiltrates and corneal suppuration were present in all the eighty four eyes (100%). Forty eight eyes (57.1%) had feathery projections while anterior chamber reaction was also found in forty eight (57.1%) eyes. Thirty (35.7%) eyes had hypopyon and twenty four eyes (28.6%) had satellite lesions.
Corneal scrapings obtained from eighty four eyes of fungal corneal ulcer patients were examined by direct microscopy with potassium hydroxide 100mL/L and inoculated for culture. Of these,fungi alone were the etiologic agent in seventy four(80.1%) and bacteria along with fungi were identified in ten (11.9%) cases.
Candida albicans was the most frequent organism which was isolated in sixty six (78.6%) patients. Other isolated fungi included aspergillus flavus in eight (9.5%) patients, fusarium soloni in eight (9.5%) patients and penicillium species two (2.4%) patients.
DISCUSSION
Mycotic keratitis is an important ophthalmic problem in all parts of the world and a major cause of visual loss especially in developing countries where a large number of population belongs to agriculture. Moreover, the climate is mild and humid, and malnutrition is common[7]. All these factors predispose people to the development of fungal corneal ulcer from minor eye trauma. In the various published reports, fungal corneal ulcer has been found to be 6% to 50% of all cases of ulcerative corneal ulcer [26].
Of the two hundred and forty patients with infective keratitis from April 2006 to March 2008 presenting at our department, fungal corneal ulcer was diagnosed in 84 (35%) eyes. Shokohi et al[12] and Parshant Garg et al[11] reported, respectively 37.5% and 30.4% incidence of fungal corneal ulcer which is nearly similar to our study. Javadi et al[13] and Mirshahi et al[14] reported 83% cases of fungal corneal ulcer which are quite higher than our study.
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