Usha Gopinathan

The epidemiological features and laboratory results of fungal keratitis: a 10-year review at a referral eye care center in South India.

Purpose. To report the epidemiological features and laboratory results of 1,352 cases of fungal keratitis diagnosed at the L.V. Prasad Eye Institute (LVPEI) in south India. Methods. The medical and microbiology records of 1,352 culture proven cases (1,354 eyes) of fungal keratitis diagnosed at the LVPEI between January 1991 to December 2000 was retrospectively reviewed for demographic features, risk factors, seasonal variation, and laboratory findings. Results. Males (962) were affected significantly more (p < 0.0001) than females (390). Of 1,352 patients, 853 (64.4%) were in the younger age group (16–49 years). Ocular trauma predisposed to infection in 736 (54.4%) of 1,354 eyes. There was a higher incidence of fungal keratitis during the monsoon and winter than summer. A fungal cause was established by smears of corneal scrapings in 1,277 (95.4%) eyes. The potassium hydroxide preparation (KOH), Calcofluor white (CFW), Gram-, and Giemsa-stained smears revealed fungus in 1,219 (91.0%), 1,224 (91.4%), 1,181 (88.2%), and 1,139 (85.1%) eyes, respectively. Fusarium (506, 37.2%) and Aspergillus species (417, 30.7%) predominated the hyaline fungal spectrum (1,133) and Curvularia species (39, 2.8%) were the highest among the dematiaceous isolates (218). Conclusions. To the best of our knowledge, this review presents the epidemiological features and laboratory results of the largest series of fungal keratitis ever reported in the literature. Keratomycosis is predominant in young adults with trauma as the major predisposing factor. With fungal keratitis being a major ophthalmologic problem in the tropical regions of the world, data available on the epidemiological features of a large series would greatly help medical practitioners at primary and secondary health care centers in the management of the disease. A simple KOH preparation of corneal scraping alone is highly beneficial in confirming the diagnosis.

Microbiologic spectrum and susceptibility of isolates

PURPOSE To present the microbial spectrum and susceptibilities of isolates in postoperative endophthalmitis. METHOD Isolates from 206 eyes of 206 patients who underwent vitrectomy for postoperative endophthalmitis were examined. RESULTS One-hundred twelve (54.4%) of 206 vitreous samples were culture positive and 14 (12.5%) of 112 culture-positive cases were polymicrobial, yielding a total of 126 isolates. Isolates included 59 (46.8%) gram-positive cocci, eight (6.3%) gram-positive bacilli, 33 (26.2%) gram-negative organisms, five (4.0%) Actino-mycetes-related organisms, and 21 (16.7%) fungi. Susceptibilities to amikacin, ceftazidime, chloramphenicol, cefazolin, ciprofloxacin, gentamicin, and vancomycin are reported. CONCLUSIONS This is the largest, single-center, prospective series on microbial susceptibilities in postoperative endophthalmitis. We report a high prevalence of gram-negative species and fungi, suggesting that empiric therapy should include coverage for gram-negative pathogens and for fungal pathogens in appropriate settings.

Review of epidemiological features, microbiological diagnosis and treatment outcome of microbial keratitis: Experience of over a decade

Purpose: To review the epidemiological characteristics, microbiological profile, and treatment outcome of patients with suspected microbial keratitis. Materials and Methods: Retrospective analysis of a non-comparative series from the database was done. All the patients presenting with corneal stromal infiltrate underwent standard microbiologic evaluation of their corneal scrapings, and smear and culture-guided antimicrobial therapy. Results: Out of 5897 suspected cases of microbial keratitis 3563 (60.4%) were culture-proven (bacterial – 1849, 51.9%; fungal – 1360, 38.2%; Acanthamoeba – 86, 2.4%; mixed – 268, 7.5%). Patients with agriculture-based activities were at 1.33 times (CI 1.16–1.51) greater risk of developing microbial keratitis and patients with ocular trauma were 5.33 times (CI 6.41–6.44) more likely to develop microbial keratitis. Potassium hydroxide with calcofluor white was most sensitive for detecting fungi (90.6%) and Acanthamoeba (84.0%) in corneal scrapings, however, Gram stain had a low sensitivity of 56.6% in detection of bacteria. Majority of the bacterial infections were caused by Staphylococcus epidermidis (42.3%) and Fusarium species (36.6%) was the leading cause of fungal infections. A significantly larger number of patients (691/1360, 50.8%) with fungal keratitis required surgical intervention compared to bacterial (799/1849, 43.2%) and Acanthamoeba (15/86, 17.4%) keratitis. Corneal healed scar was achieved in 75.5%, 64.8%, and 90.0% of patients with bacterial, fungal, and Acanthamoeba keratitis respectively. Conclusions: While diagnostic and treatment modalities are well in place the final outcome is suboptimal in fungal keratitis. With more effective treatment available for bacterial and Acanthamoeba keratitis, the treatment of fungal keratitis is truly a challenge.

Microbiologic spectrum and susceptibility of isolates: Part II. Posttraumatic endophthalmitis

PURPOSE To present the microbial spectrum and susceptibilities of isolates in posttraumatic endophthalmitis. METHOD Isolates from 182 eyes of 182 patients who underwent vitrectomy for posttraumatic endophthalmitis were examined. RESULTS One hundred thirteen (62.1%) of 182 vitreous samples were culture-positive, and 23 (20.4%) of 113 culture-positive cases were polymicrobial, including three (2.7%) trimicrobial cases, yielding a total of 139 isolates. Isolates included 63 (45.3%) gram-positive cocci, 24 (17.3%) gram-positive bacilli, 25 (18.0%) gram-negative organisms, seven (5.0%) Actinomycetes-related organisms, and 20 (14.4%) fungi. Susceptibilities to amikacin, ceftazidime, chloramphenicol, cefazolin, ciprofloxacin, gentamicin, and vancomycin are reported. CONCLUSIONS This study represents a large series on microbial spectrum and susceptibilities in posttraumatic endophthalmitis. We report a high prevalence of gram-positive bacilli species and polymicrobial infections containing gram-negative species, underscoring the importance of broad-spectrum, combination antibiotics in the empiric treatment of posttraumatic endophthalmitis.

Keratomycosis : Clinical and microbiologic experience with dematiaceous fungi

OBJECTIVE To assess the significance of dematiaceous fungi in the causation of keratomycosis. DESIGN Retrospective, noncomparative case series. PARTICIPANTS Eighty-eight cases of dematiaceous fungal keratitis seen at the L. V. Prasad Eye Institute, Hyderabad, India from January 1991 through December 1996. INTERVENTION Only culture-proven cases were analyzed. MAIN OUTCOME MEASURES Predisposing factors, clinical characteristics, microbiology, treatment methods, and outcome. RESULTS Of 557 cases of fungal keratitis seen during the study period, dematiaceous fungi were the etiologic agents in 88 (15.7%), after Fusarium in 210 (37.6%) and Aspergillus species in 170 cases (30.4%), respectively. Trauma was the most common predisposing factor (47.7%). Fifty-three eyes (61.3%) had the classical clinical picture of yellow-white, dry raised infiltrate with feathery hyphate edges at initial examination. The characteristic macroscopic pigmentation was seen in only 24 eyes (27.27%). Septate branching fungal filaments were identified in 78 smears (88.63%) on light microscopy, of which 5 (5.7%) also showed the presence of bacteria. Curvularia species dominated the spectrum (22.7%). Treatment was started in 48 eyes with topical antifungal agents, whereas 37 received both oral and topical antifungal agents. Outcome data were available for 68 cases. Forty-nine (72%) responded to medical therapy, whereas 13 eyes required therapeutic penetrating keratoplasty and 6 eyes had to be eviscerated. CONCLUSIONS This is the largest series of keratitis caused by dematiaceous fungi reported to date. It clearly brings out the clinical importance of this group of corneal infections.

Evaluation of agent and host factors in progression of mycotic keratitis ☆: A histologic and microbiologic study of 167 corneal buttons

PURPOSE To evaluate the host and agent factors in the progression of mycotic keratitis through the microbiologic evaluation and histologic study of human corneal buttons obtained at the time of therapeutic keratoplasty. DESIGN Retrospective noncomparative consecutive case series. MATERIALS One hundred sixty-seven corneal buttons from 148 patients of microbiologically diagnosed and treated cases of mycotic keratitis who underwent therapeutic keratoplasty between January 1995 and May 1998. METHODS Therapeutic penetrating keratoplasty, review of microbiologic results, histopathologic and microbiologic evaluation of the corneal buttons of mycotic keratitis MAIN OUTCOME MEASURES Histologic evaluation of the buttons for morphologic changes, degree and distribution of inflammatory cells, presence or absence of fungal filaments, and their degree and distribution within the corneal buttons. RESULTS The diagnosis of fungal infection was made on corneal scrapings in 36 cases; whereas in 131 (78%), the fungus was grown in cultures and identified as Aspergillus in 55 (42%), Fusarium in 42 (32%), unidentified hyaline fungi in 22 (17%), dematiaceous (unidentified) in 4 (3%), and others in 8 (6%). The mean interval between diagnosis and keratoplasty was 19 (+/-40) days. From the keratoplasty specimen, the fungus was identified at histologic examination in 127 of 167 (76%) buttons and grown by culture techniques in 76 of 115 (66%) buttons. The fungal species identified in the corneal button were Fusarium in 30 (39%); Aspergillus in 25 (33%); unidentified hyaline in 19 (25%), and others in 2 (3%). Fungus-positive corneal buttons had early surgery (mean, 15 days) compared with fungus-negative (39 days) corneal buttons (P = 0.0005), with 93% fungus positivity in the buttons removed within 2 weeks and 42% after 2 months. In the fungus-positive buttons, there was an inverse correlation between the degree, distribution of inflammatory cells, and fungal filaments (r = -0.255, P = 0.024; r = -0.199, P = 0.027), respectively. The factors necessitating an early keratoplasty were heavy fungal load, deeper penetration of fungus, and possibly insufficient inflammation to combat infection. A granulomatous reaction was noted in the posterior stroma and around the fragmented Descemets membrane in 23 buttons (13.8%), independent of fungal species. Inflammation was unaffected by elimination of fungus and increasing interval between diagnosis and treatment. CONCLUSIONS Rapid progression of mycotic keratitis in the early phases is by agent factors such as heavy load and deeper penetration of the fungus, insufficient inflammatory response, and possibly relative ineffectiveness of antifungal agents. Progression in the later phase of mycotic keratitis need not necessarily be agent mediated; it could be either host-modulated, species-related, or drug resistance, thereby suggesting that ideal treatment regimens should include sensitivity-based antifungal therapy aided by in vivo monitoring of fungal filaments.

Corneal ulceration in the elderly in Hyderabad, south India

AIMS To report demographic, microbiological, therapeutic, anatomical, and visual results of corneal ulceration in the elderly patients seen at a tertiary eye care centre in south India. METHODS 102 consecutive cases of microbial keratitis in patients 65 years and older were studied. Inclusion criteria were: (i) presence of corneal stromal infiltrate upon slit lamp examination; and (ii) microbiological evaluation of corneal scrapings for suspected microbial keratitis. RESULTS The principal predisposing factors identified in this study were ocular disease (38.2%), previous ocular surgery in the same eye (29.4%), trauma (17.6%), and severe systemic disease (16.7%). Contact lens wear was associated with only two cases (2.0%). 99 organisms were isolated in cultures of corneal scrapings from 74 (72.5%) of the 102 cases.Staphylococcus epidermidis (31.1%), filamentous fungi (25.7%), and Streptococcus pneumoniae (13.5%) were the most common isolates. 12 eyes (11.8%) required surgery, 15 (14.7%) eventually required evisceration, and nine (9.6%) of the 94 followed patients achieved an unaided vision of 20/60 or better at last follow up. CONCLUSIONS This work represents the largest recent single centre study on (non-viral) microbial keratitis in the elderly, its management, and outcomes of therapy. While the predisposing factors differ from those of general population, the spectrum of microbes responsible for keratitis in the elderly appears to reflect the local microbial flora rather than a predilection for elderly patients. Delay in diagnosis and systemic conditions associated with advancing age probably contribute to poorer outcome from therapeutic measures.

Evaluation of corneal scraping smear examination methods in the diagnosis of bacterial and fungal keratitis: a survey of eight years of laboratory experience.

Purpose. To determine the sensitivity, specificity, and predictive values of Gram and potassium hydroxide with calcofluor white (KOH+CFW) stains in the diagnosis of early and advanced microbial keratitis, a retrospective analysis of comparative data from a prospectively collected database was done. Methods. Patients with nonviral microbial keratitis seen at L.V. Prasad Eye Institute between February 1991 and December 1998 were included in the study. The type of bacteria seen on Gram stain was determined from 251 corneal scrapings from patients with early keratitis and 841 corneal scrapings from patients with advanced keratitis. The presence of fungi in corneal scrapings was determined by KOH+CFW stain of 114 and 363 scrapings from patients with early and advanced keratitis, respectively. The smear findings were compared with culture results to analyze specificity, sensitivity, and predictive values of the staining techniques. Results. The sensitivity of Gram stain in the detection of bacteria was 36.0% in early and 40.9% in advanced keratitis cases; however, the specificity was higher in both groups (84.9% and 87.1%, respectively). Comparatively, the sensitivity and specificity of fungal detection were higher using KOH+CFW in early (61.1% and 99.0%, respectively) as well as advanced keratitis (87.7% and 83.7%, respectively). Predictive values were high for KOH+CFW in fungus detection, while they were poor for Gram stain in bacteria detection. In advanced keratitis cases, the false positives were higher in fungal detection (16.3%) than in bacterial detection (10.3%), while the false negatives were significantly higher in bacterial detection compared with fungal detection (59.1% versus 12.3%, p < 0.0001). In early keratitis, on the other hand, both false positives and false negatives for bacterial detection were significantly higher than fungal detection. Conclusions. Decisions can reliably be based on KOH+CFW stain of corneal scrapings for initiation of antifungal therapy in mycotic keratitis. The results of Gram stain, on the other hand, have limited value in therapeutic decisions for bacterial keratitis. Therefore, the search for a better modality for early and efficient diagnosis of bacterial keratitis needs to continue.

Ophthalmic Applications of Preserved Human Amniotic Membrane: A Review of Current Indications

Preserved human amniotic membrane (AM) is currently being used for a wide spectrum of ocular surface disorders. The AM has a basement membrane, which promotes epithelial cell migration and adhesion. The presence of a unique avascular stromal matrix reduces inflammation, neovascularization and fibrosis. The basic tenets of amniotic membrane transplantation (AMT) are to promote re-epithelialization, to reconstruct the ocular surface and to provide symptomatic relief from surface aberrations. AMT is a useful technique for reconstruction of surface defects resulting from removal of surface tumors and symblephara. AMT has effectively restored a stable corneal epithelium in eyes with, persistent epithelial defects and corneal ulcers. In the setting of acute ocular burns and SJS, AMT has satisfactorily reduced scarring and inflammation. AMT alone may be an effective alternative for partial limbal stem cell deficiency. However remarkable improvements in surface stability have resulted from concurrent AMT and limbal stem cell transplantation, wherein the limbal grafts are obtained from the normal fellow eye, living relative or cadaveric eye. In severe or bilateral cases, well being of the donor eye is a major concern. Currently, the most unique application of preserved human AM in ophthalmology is its use as a substrate for ex-vivo expansion of corneal and conjunctival epithelium. In this novel technique of tissue engineering, epithelial stem cells can be safely harvested and expanded on denuded AM. The resultant composite cultured tissue has been successfully transplanted to restore vision, as well as the structure and function of damaged ocular surfaces.

Ocular Nocardia Infections with Special Emphasis on the Cornea

Nocardia are aerobic, gram-positive, nonmotile and branching filamentous bacteria. Corneal infection by Nocardia is rare. Trauma is the most common predisposing factor. Isolated case reports of nocardial infection associated with contact lens wear and laser in situ keratomileusis (LASIK) have been reported. The clinical picture usually consists of superficial patchy infiltrates, which may be arranged in a wreath pattern. Presence of gram-positive, branching, beaded filaments that stain with 1% acid-fast stain (using 1% sulfuric acid, modified Kinyouns method) in smears of corneal scrapings is suggestive of nocardial infection. Nocardia grow on commonly used media as tiny, white, dry colonies. Available knowledge and clinical experience suggest that although sulfacetamide eyedrops can be tried as the initial drug, trimethoprim-sulfamethoxazole and amikacin are effective drugs. Once therapy is initiated, the infiltrate responds promptly and resolves, forming a corneal scar with or without vascularization, and good visual recovery can be expected.