Neha Mohan

Factors influencing polymerase chain reaction outcomes in patients with clinically suspected ocular tuberculosis.

BackgroundPolymerase chain reaction (PCR) assay can be a useful method for definitive diagnosis in paucibacillary infections such as ocular tuberculosis (TB). In this study, we have evaluated factors affecting PCR outcomes in patients with clinically suspected ocular TB. Patients with clinically suspected ocular TB were investigated by PCR of aqueous or vitreous samples. Three control groups were also tested: group 1 included culture-proven non-tuberculous endophthalmitis, group 2 culture-negative non-tuberculous endophthalmitis, and group 3 patients undergoing surgery for uncomplicated cataract. PCR targeted one or more of following targets: IS6110, MPB64, and protein b genes of Mycobacterium tuberculosis complex. Multiple regression analysis (5% level of significance) was done to evaluate the associations between positive PCR outcome and laterality of disease, tuberculin skin test (TST)/interferon-gamma release assay (IGRA), chest radiography, and type of sample (aqueous or vitreous). The main outcome measures were positive PCR by one or more gene targets, and factors influencing positive PCR outcomes.ResultsAll 114 samples were tested for MPB64, 110 for protein b, and 88 for IS6110. MPB64 was positive in 70.2% (n = 80) of tested samples, protein b in 40.0% (n = 44), and IS6110 in only 9.1% (n = 8). DNA sequencing of amplicons from four randomly chosen PCR reactions showed homology for M. tuberculosis complex. Of the 80 PCR-positive patients, 71 completed a full course of antitubercular therapy, of which 65 patients (91.5%) had complete resolution of inflammation at final follow-up. Among controls, 12.5% (3 out of 24) in group 1 and 18.7% (6 out of 32) in group 2 also tested positive by PCR. No PCR-positive outcome was observed in control group 3 (n = 25). Multiple regression analysis revealed significant association of positive PCR outcome with bilateral presentation, but not with a positive TST/IGRA, chest radiography, or type of sample (aqueous/vitreous) used.ConclusionsCareful selection of gene targets can yield high PCR positivity in clinically suspected ocular TB. Bilateral disease presentation but not any evidence of latent systemic TB influences PCR outcomes. False-positive results may be seen in ocular inflammation unrelated to ocular TB.

Changing Profile Of Organisms Causing Scleral Buckle Infections: A Clinico-microbiological Case Series

Purpose: To study the microbiological spectrum and in vitro susceptibility of bacterial isolates from explanted scleral buckles and to correlate clinical presentation to the causative agent. Method: Medical records of patients who underwent buckle explantation from July 2007 to May 2012 were reviewed retrospectively. Clinical features and microbiological profile were noted and correlated. Results: Twenty of 24 buckles (83.33%) from 24 patients grew 21 isolates. Isolates included 6 acid-fast bacilli (28.57%; atypical mycobacteria = 5, Nocardia asteroides = 1), 5 gram-positive bacilli (23.8%; Corynebacterium spp. = 4, Bacillus sp. = 1), 4 gram-positive cocci (19.0%; Staphylococcus spp. = 4), 2 gram-negative bacilli (9.5%; Pseudomonas aeruginosa = 2), and 4 fungi (19.0%; Aspergillus spp. = 3, Paecilomyces sp. = 1). Acid-fast bacilli and gram-negative bacilli were sensitive to amikacin and gram-positive bacilli and gram-positive cocci to vancomycin. Buckle exposure within 2 years of primary surgery tended to be noninfective (P = 0.06). Fungal or mycobacterial infections were more symptomatic than those with Corynebacterium species. Results of microscopic examination of conjunctival swab in 5 of 7 eyes (71.4%) were consistent with culture of conjunctival swab and explanted buckles. Conclusion: Clinical features and microscopic examination of conjunctival swab may give a lead toward the causative organism in suspected buckle infections. Based on these leads, vancomycin and amikacin may be used as the initial empirical therapy.

Polymerase Chain Reaction Evaluation of Infectious Multifocal Serpiginoid Choroiditis

Abstract Purpose: To study infectious agents associated with multifocal serpiginoid choroiditis (MSC) based on polymerase chain reaction (PCR) evaluation and specific anti-microbial therapy. Methods: Retrospective review of medical records. Results: Thirteen patients with MSC were evaluated with PCR for the following organisms: Mycobacterium tuberculosis (MTB), herpes simplex virus 1 (HSV 1), varicella zoster virus (VZV), and cytomegalovirus (CMV). Nine (69.2%) were PCR positive for one or more organisms. Seven (53.8%) were positive for MTB, 3 (23.1%) for CMV (1 positive for both MTB and CMV), and 1 (7.6%) for both HSV 1 and MTB. All 13 patients received anti-TB therapy and corticosteroids. Nine patients completed 6 months follow-up; 6 resolved completely, 2 continued to have active lesions, while 1 CMV PCR-positive patient required additional valgancyclovir therapy. Conclusions: TB is the most important etiology for MSC in endemic countries. The role of herpes viruses in MSC remains unclear and needs further investigation.

Outcomes of Repeat Descemetopexy in Post–Cataract Surgery Descemet Membrane Detachment

PURPOSE To assess the outcomes of repeat descemetopexy in post-cataract surgery Descemet membrane detachment. DESIGN Retrospective interventional case series. METHODS This multicenter, institutional study done between January 2007 and July 2013 included 13 eyes of 13 patients who underwent repeat descemetopexy after a failed initial procedure in post-cataract surgery Descemet membrane detachment. Patients without a minimum follow-up of 1 month were excluded. They underwent repeat descemetopexy with either 100% air or isoexpansile mixture of 14% C3F8. At 1 month, final status of Descemet membrane, final best-corrected visual acuity (BCVA), and incidence of postsurgical complications were noted. RESULTS Mean age was 63.7 ± 6.6 years; male-to-female ratio, 8:5. Descemet membrane detachment involved the visual axis in all cases. Mean interval between 2 interventions was 5.1 ± 3.1 days. Same gas was used in 9 of 13 patients (air, 4; C3F8, 5). Air was used earlier and C3F8 later in 4 patients. At 1 month, 12 of 13 patients had an attached Descemet membrane and improved mean logMAR BCVA (P = .0036). One case developed postoperative pupillary block and 1 case required endothelial transplantation. CONCLUSION Repeat descemetopexy for post-cataract surgery Descemet membrane detachment gives good anatomic and visual results and is definitely a worthwhile attempt before a complex surgical procedure like keratoplasty is offered.

Nylon Allergy after Keratoplasty – Fiery Sun

Purpose: To report a case of allergy to the nylon suture material after keratoplasty and its clinical implications Design: Case Report Observation: Seventy-three year old man underwent penetrating keratoplasty for pseudophakic corneal edema. Post-operatively he had profuse watering, photophobia, lid margin swelling, conjunctival ballooning and corneal edema. Persistent anterior segment and ocular surface inflammation lead to extensive suture track vascularisation giving a ‘fiery sun appearance’. Loose sutures required early suture removal by 2 months. Subsequently, anterior segment and ocular surface inflammation decreased. Systemic/topical corticosteroids were tapered. Retrospective diagnosis of allergy to suture material was made. Results and discussion: At 6 months follow-up, patient has BCVA 6/24, normal ocular surface, no intra-ocular inflammation and normal optic disc. This is first report of presumed nylon allergy after keratoplasty. Specific problems like uncontrolled cylinder power, unstable graft-host junction and wound over-ride due to early suture removal were encountered.

The Diagnostic Utility of Anterior Chamber Paracentesis for Polymerase Chain Reaction in Anterior Uveitis

WE READ WITH INTEREST THE ARTICLE BY ANWAR AND associates on diagnostic utility of polymerase chain reaction (PCR) in anterior uveitis. The study addresses an important diagnostic challenge in the management of infectious anterior uveitis. However, it has significant limitations, some of which have been aptly highlighted by the authors themselves. Two-thirds of the patients in the study had chronic uveitis and one-third had received acyclovir therapy. We therefore differ with the authors’ conclusion that PCR should not be the first-line investigation for anterior uveitis. The majority of anterior uveitis cases in clinical practice are noninfectious (eg, HLA-B27-associated) cases that can generally be identified on the basis of specific clinical signs. In our opinion, once noninfectious causes are excluded, an early decision for anterior chamber paracentesis should be taken, especially if suggestive clinical signs like iris atrophy, pigmented keratic precipitates, endotheliitis, or ocular hypertension are present. Definitive diagnosis of infection by PCR at an early stage can help in prompt initiation of specific antimicrobial therapy. Conversely, a negative PCR outcome late in the course of disease, or after a therapeutic trial of acyclovir, can lead to prolonged treatment with corticosteroids for inherently recurrent infections like herpetic uveitis. We are also concerned about the relatively high incidence of adverse effects following anterior chamber paracentesis in this study. We speculate that this might be related to the practice of doing paracentesis in a sitting position on the slit lamp. The development of permanent central scotoma after paracentesis in 1 patient has also not been explained. Finally, we wish that the authors had mentioned the DNA copy numbers in the samples with positive PCR outcomes for various organisms. A decrease in copy numbers post treatment, compared to pretreatment levels, would have better helped in establishing causality, especially in case of novel organisms like the Epstein-Barr virus. To conclude, early paracentesis for PCR in suspected cases of infectious anterior uveitis can help in prompt initiation of antimicrobial therapy, and thus influence our decision making in such cases.