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Prashant Garg

Publications and source records attributed to Prashant Garg.

At least 19 recordsLinked to original sources
PubMed2006

3-day treatment with azithromycin 1.5% eye drops versus 7-day treatment with tobramycin 0.3% for purulent bacterial conjunctivitis: multicentre, randomised and controlled trial in adults and children.

AIM: To compare the efficacy and safety of Azyter, azithromycin 1.5% eye drops, for 3 days with tobramycin 0.3% for 7 days to treat purulent bacterial conjunctivitis. METHODS: This was a multicentre, randomised, investigator-masked study including 1043 children and adults with purulent bacterial conjunctivitis. Patients received either azithromycin 1.5% twice-daily for 3 days or tobramycin 0.3%, 1 drop every two hours for 2 days, then four times daily for 5 days. Clinical signs were evaluated and cultures obtained at D0, D3 and D9 (where D refers to "day"). Primary variable was the clinical cure at the Test-of-Cure (TOC)-visit (D9+/-1), for patients with D0-positive cultures. The cure was defined as: bulbar conjunctival injection and discharge scores of 0. RESULTS: Among 471 patients with D0-positivity in the per protocol set, 87.8% of the azithromycin 1.5% group and 89.4% of the tobramycin group were clinically cured at the TOC-visit. Azithromycin was non-inferior to tobramycin for clinical and bacteriological cure. Clinical cure was significantly higher with azithromycin 1.5% at D3. The safety profile of azithromycin was satisfactory with a good patient and investigator's acceptability. CONCLUSIONS: Azithromycin 1.5% for 3 days was as effective and as safe as tobramycin for 7 days. Furthermore, more azithromycin than tobramycin patients presented an early clinical cure at Day 3. Due to its twice daily dosing regimen for 3 days, azithromycin represents a step forward in the management of purulent bacterial conjunctivitis, especially in children.

Adolescent↗
PubMed2006

Confocal microscopy for Nocardia keratitis.

PURPOSE: To assess the role of confocal microscopy for in vivo detection of Nocardia in patients with microbial keratitis. DESIGN: Retrospective interventional case series. PARTICIPANTS: Three patients with microbiologically proven Nocardia keratitis. INTERVENTION: Confocal microscopy. METHODS: We performed confocal microscopy in microbiologically proven cases of Nocardia asteroides keratitis. A masked observer examined the images. For better understanding of the images, we also performed confocal microscopy on a blood agar culture plate with Nocardia growth. RESULTS: Confocal microscopy of infiltrated cornea revealed highly reflective, short, thin branching filaments with bright inflammatory cells in the background. The filaments were seen clearly at the edge of the infiltrate. In scans with faint images, these filaments became more visible on inversion of bright and dark components. Confocal microscopy of cultured organisms also revealed filamentous beaded structures with a morphology identical to that of those seen in vivo. CONCLUSION: Nocardia, a filamentous bacterium, produces a distinct image on confocal microscopy. This in vivo examination technique may be useful in cases of deep-seated infiltrates where routine microbiology workup does not yield positive results.

Adult↗
PubMed2006

Autosomal recessive corneal endothelial dystrophy (CHED2) is associated with mutations in SLC4A11.

OBJECTIVE: To map and identify the gene for autosomal recessive congenital hereditary endothelial dystrophy (CHED2, OMIM 217700), a disorder characterised by diffuse bilateral corneal clouding that may lead to visual impairment and requiring corneal transplantation. METHODS: Members of 16 families with autosomal recessive CHED were genotyped for 13 microsatellite markers at the CHED2 locus on chromosome 20p13-12. Two-point linkage analysis was carried out using the FASTLINK version of the MLINK program. Mutation screening was carried out by amplification of exons and flanking regions by polymerase chain reaction, followed by direct automated sequencing. RESULTS: Linkage and haplotype analysis placed the disease locus within a 2.2 cM (1.3 Mb) interval flanked by D20S198 and D20S889, including SLC4A11. The maximum LOD score of 11.1 was obtained with D20S117 at theta = 0. Sequencing of SLC4A11 showed homozygotic mutations in affected members from 12 of 16 families. CONCLUSION: These results confirm that mutations in the SLC4A11 gene cause autosomal recessive CHED.

Anion Transport Proteins↗
PubMed2006

Histopathological evaluation of ocular microsporidiosis by different stains.

BACKGROUND: There is limited data on comparing stains in the detection of microsporidia in corneal biopsies. Hence we wanted to evaluate various stains for their ability to detect microsporidia in corneal tissue sections. METHODS: Four cases diagnosed with microsporidiosis on Hematoxylin and Eosin and Periodic Acid Schiff's stained sections of the corneal button between January 2002 and December 2004, were included. Further sections were prospectively stained with calcofluor white, Gram, Giemsa, Masson's trichrome, acridine orange, Gomori's methenamine silver, Gram's chromotrope and modified acid fast stain. The stained sections were analyzed for the spore characteristics in terms of size, shape, color contrast, cell wall morphology, waist band in cytoplasm and ease of detection. RESULTS: All sections showed microsporidial spores as 3-5 microm, oval bodies. 1% acid fast, Gram's chromotrope and GMS stains provided a reliable diagnosis of microsporidia as diagnostic waist band could be identified and good contrast helped distinguish the spores from inflammatory debris. CONCLUSION: Considering the ease of performance, cost effectiveness and rapidity of the technique, 1% acid fast stain and Gram's chromotrope stain are ideal for the detection of microsporidia.

Journal Article↗
PubMed2006

Use of different stains for microscopic evaluation of corneal scrapings for diagnosis of microsporidial keratitis.

Retrospective evaluation of potassium hydroxide plus calcofluor white (KOH+CFW), Gram, Giemsa, and modified Ziehl-Neelsen (1% H(2)SO(4), cold) stains for the detection of microsporidia in corneal scrapings from 30 patients showed KOH+CFW and acid-fast stains to be most efficient (29/30 [96.7%] and 28/30 [93.3%], respectively) in the diagnosis of microsporidial keratitis.

Benzenesulfonates↗
PubMed2006

Microsporidial keratitis in India: 16S rRNA gene-based PCR assay for diagnosis and species identification of microsporidia in clinical samples.

PURPOSE: To evaluate 16S rRNA-based polymerase chain reactions for the detection and species identification of the microsporidia that cause keratitis. METHODS: Of the 5892 cases of microbial keratitis seen between September 2002 and December 2005, 31 (0.5%) microscopically diagnosed cases of microsporidial keratitis were included in the test group; 103 patients with nonmicrosporidial keratitis constituted the control group. A 16S rRNA-based pan-microsporidian PCR was chosen for the detection of microsporidian DNA. Species level identification was made using species-specific primer sets of Encephalitozoon spp (E. cuniculi, E. hellem, and E. intestinalis). Sequencing and BLAST analysis of amplicons obtained with pan-microsporidian primers were performed for validation. RESULTS: The corneal scrapings from 26 of 31 cases in the test group and 2 of 103 cases in the control group showed a 250- to 280-bp amplicon in PCR by pan-microsporidian primers (sensitivity of 83% and specificity of 98%). The amplicons of 13 of 26 test group samples were identified by species-specific PCR: E. cuniculi, n = 7 (549 bp); E. hellem; n = 3 (549 bp); E. intestinalis; n = 1 (520 bp). The two cases in the control group were identified to be E. cuniculi. The remaining 15 cases (test group) were confirmed to be Vittaforma corneae by sequencing and BLAST analysis. All species were confirmed by sequencing and database homology comparison. CONCLUSIONS: This study is the first to validate PCR-based assays for detection of microsporidial DNA in corneal scrapings. Pan microsporidian PCR can be a useful adjunct with smear examination in the diagnosis of microsporidial keratitis.

Adolescent↗
PubMed2006

Acanthamoeba keratitis after LASIK.

PURPOSE: To report a case of Acanthamoeba infection following LASIK. METHODS: A 20-year-old woman developed pain, redness, decreased vision, and corneal infiltrate in the right eye 15 days after bilateral LASIK. She did not use contact lenses postoperatively. Patient examination 3 months after surgery revealed a large, central, full-thickness corneal infiltrate with multiple satellite lesions in the right eye. Corneal scrapings were taken and the flap excised, and submitted for histopathologic examination. RESULTS: Microscopic examination of smears revealed Acanthamoeba cysts and non-nutrient agar showed a significant growth of Acanthamoeba. Histopathology examination of the excised flap demonstrated numerous Acanthamoeba cysts in tissue sections. The infiltrate was treated with a combination of topical polyhexamethylene biguanide, chlorhexidine, atropine sulfate, and oral itraconazole and resolved within 2 months. CONCLUSIONS: Laser in situ keratomileusis can be complicated by Acanthamoeba infection. Microbiologic evaluation is essential for accurate early diagnosis and treatment.

Acanthamoeba↗
PubMed2005

Is microsporidial keratitis an emerging cause of stromal keratitis? A case series study.

BACKGROUND: Microsporidial keratitis is a rare cause of stromal keratitis. We present a series of five cases of microsporidial keratitis from a single centre in southern India with microbiologic and histopathologic features. CASE PRESENTATION: Patient charts of five cases of microsporidial stromal keratitis diagnosed between January 2002 and June 2004 were reviewed retrospectively for clinical data, microbiologic and histopathologic data. The presence of microsporidia was confirmed by special stains on corneal scrapings and/or corneal tissues, and electron microscopy. All patients were immunocompetent with a preceding history of trauma in three. Four patients presented with unilateral, small, persisting deep stromal infiltrates, of uncertain etiology, in the cornea, which were not responding to conventional antimicrobial treatment and required penetrating keratoplasty in three. Fifth case was unsuspected and underwent keratoplasty for post-traumatic scar. Three of five cases were diagnosed on corneal scrapings, prior to keratoplasty, while two were diagnosed only on histology. The microsporidia appeared as oval well defined bodies with dense staining at one pole. None of the patients showed recurrence following keratoplasty. CONCLUSION: Microsporidia, though rare, should be suspected in chronic culture-negative stromal keratitis. Organisms could lie dormant without associated inflammation.

Adult↗
PubMed2005

Outcome of corneal transplant rejection: a 10-year study.

PURPOSE: To study the incidence of graft rejection and the predictive factors for its reversibility. METHODS: It is a retrospective study of 1927 consecutive penetrating keratoplasties performed between January 1990 and January 2000 with more than 6 months follow up. A total of 224 rejection episodes were noted in 183 patients. Of these, 184 first rejection episodes were included in this study. RESULTS: The incidence of first rejection episode was 9.55%. Of patients 87% were symptomatic during the episode with vision loss being the commonest. The average time of onset of rejection was 15.25 +/- 14.4 months (median 11.7 months). In total, 53.3% of rejections occurred within 1 year after surgery. Of the patients who completed minimum 3 months follow up after the rejection episode, the rate of reversibility was 63.3%. Major predictive factors for a poor outcome after rejection were repeated grafting and associated anterior vitrectomy during surgery. The reversibility of the episode did not differ significantly with the modality of treatment used, but treatment with intravenous steroids within 7 days of onset of rejection may have a role in reducing the recurrences of rejection episodes, thus increasing the graft survival. CONCLUSION: Regrafts and associated anterior vitrectomy were significant risk factors for a poor outcome following rejection episode.

Adolescent↗
PubMed2004

Keratocyte loss in corneal infection through apoptosis: a histologic study of 59 cases.

BACKGROUND: Keratocyte loss by apoptosis following epithelial debridement is a well-recognized entity. In a study of corneal buttons obtained from patients of corneal ulcer undergoing therapeutic keratoplasty, we observed loss of keratocytes in the normal appearing corneal stroma, surrounding the zone of inflammation. Based on these observations, we hypothesized that the cell loss in the inflammatory free zone of corneal stroma is by apoptosis that could possibly be a non-specific host response, independent of the nature of infectious agent. METHODS: To test our hypothesis, in this study, we performed Terminal deoxyribonucleotidyl transferase-mediated d-Uridine 5" triphosphate Nick End Labelling (TUNEL) staining on 59 corneal buttons from patients diagnosed as bacterial, fungal, viral and Acanthamoeba keratitis. The corneal sections were reviewed for morphologic changes in the epithelium, stroma, type, degree and depth of inflammation, loss of keratocytes in the surrounding stroma (posterior or peripheral). TUNEL positivity was evaluated in the corneal sections, both in the zone of inflammation as well as the surrounding stroma. A correlation was attempted between the keratocyte loss, histologic, microbiologic and clinical features. RESULTS: The corneal tissues were from 59 patients aged between 16 years and 85 years (mean 46 years) and included fungal (22), viral (15), bacterial (14) and Acanthamoeba (8) keratitis. The morphological changes in corneal tissues noted were: epithelial ulceration (52, 88.1%), destruction of Bowman's layer (58, 99%), mild to moderate (28; 47.5%) to severe inflammation (31; 52.5%). Morphologic evidence of disappearance or reduced number of keratocytic nuclei in the corneal stroma was noted in 49 (83%) cases; while the TUNEL positive brown cells were identified in all cases 53/54 (98%), including cases of fungal (19), bacterial (14), viral (13), and Acanthamoeba keratitis. TUNEL staining was located mostly in the deeper stroma and in few cases the peripheral stroma. TUNEL positivity was also noted with the polymorphonuclear infiltrates and in few epithelial cells (10 of 59, 17%) cases, more with viral infections (6/10; 60%). CONCLUSIONS: We report apoptotic cell death of keratocytes in the corneal stroma in infectious keratitis, a phenomenon independent of type of infectious agent. The inflammatory cells in the zone of inflammation also show evidence of apoptotic cell death. It could be speculated that the infective process possibly triggers keratocyte loss of the surrounding stroma by apoptosis, which could possibly be a protective phenomenon. It also suggests that necrotic cell death and apoptotic cell deaths could occur simultaneously in infective conditions of the cornea.

Adolescent↗
PubMed2004

Pigmented plaque presentation of dematiaceous fungal keratitis: a clinicopathologic correlation.

PURPOSE: To evaluate the clinical, microbiologic, and histopathologic features of dematiaceous fungal keratitis cases presenting with pigmented, raised, plaque-like infiltrate. STUDY DESIGN: Consecutive case series. METHODS: Microbiology-proven cases of fungal keratitis presenting with a pigmented infiltrate were included in the study. A detailed clinical and microbiological evaluation was performed in all cases. The lesion was removed by superficial keratectomy, and the specimen was subjected to histopathologic examination. Patients presenting with a large infiltrate had penetrating keratoplasty, and the corneal button was submitted for histopathology examination. RESULTS: We enrolled 15 cases in the study. There were 11 men and 4 women. The mean age of the patients was 48.5 years (range 27-68 years). The patients presented to us with duration of symptoms ranging from 7 to 60 days (mean 27.6 +/- 15.6, median 30). The visual acuity was better than 20/200 in 9 (60%) cases. The infiltrate size varied from 4.3 to 64 mm2 (mean 26.9 +/- 16.6, median 22.5). Ten (66.7%) cases had a central infiltrate. The infiltrate was dry and raised, with brown to black pigmentation on its surface. Corneal scrapings revealed septate fungal filaments in all cases and the characteristic brown to black pigmentation of the fungal cell wall in 10 (66.7%) cases. Although there was a significant growth of dematiaceous fungi on culture in all cases, species identification could be done in 3 cases only. Examination of tissue sections revealed a carpet of pigmented fungal filaments on the corneal surface (n = 12, 92.3%) associated with mild to moderate inflammation (n = 11, 84.7%) and tissue destruction. Nine out of 11 cases that had keratectomy resolved with medical therapy. CONCLUSIONS: The pigmented plaque-like infiltrate in dematiaceous fungal keratitis consists of surface colonization of pigmented fungal filaments associated with mild to moderate inflammation and tissue destruction of the underlying corneal stroma.

Adult↗
PubMed2004

Clinical resistance of Staphylococcus keratitis to ciprofloxacin monotherapy.

PURPOSE: To review the in vitro susceptibility and the clinical response to 0.3% ciprofloxacin in Staphylococcus aureus keratitis. METHODS: This is a non-comparative case series derived from a prospectively collected database and analysed retrospectively. One hundred and twenty one patients presenting in the cornea service of LV Prasad Eye Institute, Hyderabad, India, between January 1993 and December 2000, and identified to have S. aureus keratitis were included in the study. All patients had received slitlamp evaluation of the cornea and diagnostic microbiologic workup. They were treated with topical antimicrobial therapy based on smear and culture results. All S. aureus isolates were tested for antibiotic susceptibility by disk diffusion and those resistant to ciprofloxacin were confirmed by testing for minimum inhibitory concentration. The patients' clinical response to the antimicrobial therapy was noted. RESULTS: Twenty-five (20.6%) of 121 isolates resistant to ciprofloxacin on in vitro susceptibility testing were further analysed in this study. Fifteen of these 25 (60%) patients were initially treated with topical ciprofloxacin. Twelve of 15 (80%) patients showed no clinical improvement (3-8 days). Based on antibiotic susceptibility results, the antibiotic therapy was modified to fortified cefazolin and gentamicin in seven (58.3%), to vancomycin in one and to chloramphenicol in four cases. The corneal infiltrate resolved in 11 (73.3%) of 15 cases. Two patients required penetrating keratoplasty (PK), one required evisceration, and one patient was lost to follow up. Nine of 25 patients were initially started on fortified cefazolin and gentamicin therapy based on smear positive for gram-positive cocci; this resulted in resolution of infiltrate in 44.4% (4/9) while three required change of antibiotics (vancomycin-2, chloramphenicol-1), one required PK and one patient was lost to follow up. One of 25 patients started and continued on chloramphenicol, showed no response and required PK. CONCLUSIONS: This study shows a significant resistance of S. aureus to many antibiotics including ciprofloxacin and highlights the need for an alternative to ciprofloxacin monotherapy for the treatment of staphylococcal keratitis.

Adolescent↗
PubMed2003

Trends in contact lens-associated microbial keratitis in Southern India.

OBJECTIVE: To review the microbiologic profile, clinical course, treatment, and outcome in patients with contact lens-associated microbial keratitis in the setting of a tertiary eye care center in a developing country in the Tropics. DESIGN: Retrospective noncomparative case series selected from an ongoing prospective series. PARTICIPANTS: Twenty-eight subjects examined in the contact lens clinic of L. V. Prasad Eye Institute, Hyderabad, south India, between February 1991 and September 2000, who presented with corneal stromal infiltrate on slit-lamp examination, were included in the study. INTERVENTION: All patients underwent standard diagnostic microbiologic evaluation and smear and culture-guided topical antimicrobial therapy. Penetrating keratoplasty was performed in some patients. MAIN OUTCOME MEASURES: Culture results and clinical response to antimicrobial therapy. RESULTS: Twenty eight (0.11%) of 23,889 contact lens-wearing patients presented with laboratory-proven infectious keratitis; this constituted 0.56% of 4967 corneal ulcer patients seen during the same period. Most (15/28) of the patients wore soft contact lenses on a daily basis. Rigid gas-permeable lenses were worn by six patients, therapeutic bandage contact lenses by four, and Silsoft lenses by four. Laboratory results showed bacterial infections in 25 patients (89.2%); Pseudomonas was the most common organism (13/25; 52%). Acanthamoeba, herpes simplex virus, and Aspergillus niger were isolated in one case each. Laboratory-based medical therapy led to the healing of ulcers in 24 (85.7%) of 28 patients, whereas 4 patients required penetrating keratoplasty. Most of the organisms were sensitive to antibiotics. CONCLUSIONS: Contact lens-associated microbial keratitis is rare in southern India. Soft contact lens wear is the most common risk factor; Pseudomonas keratitis is the predominant causative agent. Fungal, viral, and Acanthamoeba keratitis are rare. The offending bacteria are usually sensitive to antibiotics, and the treatment outcome with medical therapy is good.

Adolescent↗
PubMed2003

Fungal infection of sutureless self-sealing incision for cataract surgery.

PURPOSE: To report the clinical picture and outcome of fungal infection of self-sealing wounds in cataract surgery. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: Seven postoperative cataract patients. METHODS: Seven consecutive patients who underwent cataract surgery in different locations in India and developed microbiologically proven fungal infection of the surgical wound were included. All were managed at a tertiary eye care center in India between May 2001 and April 2002. MAIN OUTCOME MEASURES: The data reviewed included patient age, gender, onset of symptoms after surgery, examination findings at the time of onset of symptoms and referral, laboratory workup, treatment, and outcome. The cataract surgeons involved were contacted to determine their cataract practice and to determine any possible breach in the sterile technique. RESULTS: The median interval to onset of symptoms after cataract surgery was 5.0 days (mean, 5.8 days; range, 3-9 days). The initial diagnoses at the time of onset of symptoms were keratitis (n = 3), scleritis (n = 1), and excessive anterior chamber reaction (n = 3). The last 4 patients were treated with topical and/or systemic corticosteroid therapy before referral. All cases subsequently developed deep keratitis. Specimens for microbiology workup were obtained by scrapings (n = 6), corneoscleral biopsy (n = 4), and anterior chamber paracentesis (n = 4). Organisms identified were Aspergillus flavus (n = 2), Aspergillus terreus (n = 2), Aspergillus spp. (n = 2), and Candida albicans (n = 1). The infection resolved with medical therapy in 2 cases; the final visual acuity was 20/125 in one case and 20/20 in the other case. The infection progressed to endophthalmitis in 5 eyes, resulting in complete loss of vision. The source of infection could not be identified in any case. CONCLUSIONS: Infection of self-sealing tunnel incision for cataract surgery is a diagnostic and therapeutic challenge.

Aged↗
PubMed2003

Posterior capsule dehiscence during phacoemulsification and manual extracapsular cataract extraction: comparison of outcomes.

PURPOSE: To compare the intraoperative behavior and postoperative outcomes of posterior capsule dehiscence during phacoemulsification and during manual extracapsular cataract extraction (ECCE). SETTING: L.V. Prasad Eye Institute, Hyderabad, India. METHODS: This study was a retrospective chart review of consecutive cases of posterior capsule dehiscence over 2 years in patients having phacoemulsification or manual ECCE. A chi-square test was used for statistical comparison of the results in the 2 groups. RESULTS: In the 127 eyes with posterior capsule dehiscence, the incidence of vitreous prolapse was comparable between the 2 groups (phacoemulsification, 61.6%; ECCE, 62.7%). In the phacoemulsification group, vitreous prolapse occurred more frequently if nuclear fragments were present at the time of posterior capsule dehiscence than if they were present during cortex removal (P =.05). Posterior dislocation of nuclear fragments occurred in 4 eyes in the phacoemulsification group. Increased anterior uveitis in the early postoperative period occurred more frequently in the ECCE group (P =.02). The visual outcomes were similar between the 2 groups. CONCLUSIONS: Even though differences existed between the intraoperative factors influencing the management of posterior capsule dehiscence during phacoemulsification and ECCE, the final anatomic and visual outcomes were comparable.

Capsulorhexis↗
PubMed2003

Clinical experience with N-butyl cyanoacrylate tissue adhesive in fungal keratitis.

PURPOSE: To evaluate the role of tissue adhesive in the management of corneal thinning or perforation associated with active fungal keratitis. DESIGN: Retrospective noncomparative interventional case series. METHODS: Seventy-three eyes of 73 patients with microbiologically proven keratomycosis associated with thinning or perforation participated in the study. N-Butyl cyanoacrylate tissue adhesive (medical grade) and bandage contact lens were applied in addition to topical and systemic antifungal therapy. Our outcome measures included resolution of the infiltrate and preservation of the structural integrity of the globe. RESULTS: Outcome data were available for 66 eyes. The infiltrate resolved with scar formation in 42 (63.6%) eyes. In an additional eight (12.1%) eyes, tissue adhesive maintained the structural integrity of the globe while the patients awaited penetrating keratoplasty. Sixteen (24.2%) eyes showed progressive worsening or persistence of the infiltrate after application of tissue adhesive. Twenty-five (37.8%) eyes required multiple applications of tissue adhesive. The outcome was better in cases where the infiltrate measured less than 30 mm2 at the time of presentation and application of tissue adhesive (P < 0.01). CONCLUSION: In view of the poor outcome of penetrating keratoplasty in active fungal keratitis, N-butyl cyanoacrylate tissue adhesive is a useful modality for the management of progressive thinning or perforation associated with active fungal keratitis. However, close observation is mandatory to assess the progression of disease.

Antifungal Agents↗
PubMed2003

Use of 18S rRNA gene-based PCR assay for diagnosis of acanthamoeba keratitis in non-contact lens wearers in India.

Identification of Acanthamoeba cysts and trophozoites in ocular tissues requires considerable expertise and is often time-consuming. An 18S rRNA gene-based PCR test, highly specific for the genus Acanthamoeba, has recently been reported in the molecular diagnosis of Acanthamoeba keratitis. This PCR assay was compared with conventional microbiological tests for the diagnosis of Acanthamoeba keratitis. In a pilot study, the PCR conditions with modifications were first tested on corneal scrapings from patients with culture-proven non-contact lens-related Acanthamoeba, bacterial, and fungal keratitis. This was followed by testing of corneal scrapings from 53 consecutive cases of microbial keratitis to determine sensitivity, specificity, and predictive values of the assay. All corneal scrapings from patients with proven Acanthamoeba keratitis showed a 463-bp amplicon, while no amplicon was obtained from patients with bacterial or fungal keratitis. Some of these amplified products were sequenced and compared with EMBL database reference sequences to validate these to be of Acanthamoeba origin. Out of 53 consecutive cases of microbial keratitis included for evaluating the PCR, 10 (18.9%) cases were diagnosed as Acanthamoeba keratitis on the basis of combined results of culture, smear, and PCR of corneal scrapings. Based on culture results as the "gold standard," the sensitivity of PCR was the same as that of the smear (87.5%); however, the specificity and the positive and negative predictive values of PCR were marginally higher than the smear examination (97.8 versus 95.6%, 87.5 versus 77.8%, and 97.8 versus 97.7%) although the difference was not significant. This study confirms the efficacy of the PCR assay and is the first study to evaluate a PCR-based assay against conventional methods of diagnosis in a clinical setting.

Acanthamoeba↗