ABSTRACT
Purpose: Extended‑spectrum beta‑lactamases (ESBLs) mediated resistance is more prevalent worldwide, especially among Gram‑negative bacterial isolates, conferring resistance to the expanded spectrum cephalosporins. As limited data were available on the prevalence of ESBLs in this area, the current study was undertaken to determine the prevalence, antibacterial resistance patterns, and molecular detection and characterization of ESBL encoding resistance genes among ocular Gram‑negative bacterial isolates from ocular infections. Materials and Methods: A prospective study was done on 252 ocular Gram‑negative bacterial isolates recovered from ocular infections during a study period from February 2011 to January 2014. All isolates were subjected to detection of ESBLs by cephalosporin/clavulanate combination disc test and their antibacterial resistance pattern was studied. Molecular detection and characterization of ESBL encoding blaTEM‑, blaSHV, blaOXA‑, and blaCTX‑M (phylogenetic groups 1, 2, 9, and 8/25) resistance genes by multiplex polymerase chain reaction and DNA sequence analysis. Results: Of all Gram‑negative bacteria, Pseudomonas aeruginosa (44%) was the most common strain, followed by Enterobacter agglomerans and Klebsiella pneumoniae each (10%). Among the 252, 42 (17%) were ESBL producers. The major source of ESBL producers were corneal scraping specimens, highest ESBL production was observed in P. aeruginosa 16 (38%) and Escherichia coli 7 (16.6%). Among ESBL‑producing genes, the prevalence of blaTEM‑gene was the highest (83%) followed by blaOXA‑gene (35%), blaSHV‑gene (18.5%), and blaCTX‑M‑1‑gene (18.5%) alone or together. Conclusion: The higher rate of prevalence of ESBLs‑encoding genes among ocular Gram‑negative bacteria is of great concern, as it causes limitation to therapeutic options. This regional knowledge will help in guiding appropriate antibiotic use which is highly warranted.
ABSTRACT
PURPOSE: To study the epidemiological characteristics of bacterial keratitis seen at a tertiary eye care referral centre in south India. METHODS: A retrospective review of medical records of all culture-positive bacterial keratitis which were seen over a 3 years period, from September 1999 through August 2002 was performed. After clinical evaluation corneal scrapings were collected and subjected to culture and microscopy using standard protocols in all patients. RESULTS: Out of 3183 corneal ulcers evaluated, 1043(32.77%) were found to be of bacterial aetiology. A total of 1109 bacterial pathogens were isolated from 1046 eyes with keratitis. The predominant bacterial species isolated was Streptococcus pneumoniae (37.5%). Males were 592(56.76%) and 451(43.24%) were females. There were 564(54.07%) rural residents and 479(45.93%) urban residents; this difference was statistically significant (pp< 0.0001). Co-existing ocular diseases predisposing to corneal ulceration were identified in 703(67.4%) patients, compared to other predisposing risk factors in 340(32.6%) patients. One hundred and seventy seven (16.97%) had corneal injury with soil and/or sand, compared to 115(11.03%) patients who had injury due to other materials and the difference was statistically significant. There was lower incidence of bacterial keratitis from June to September. CONCLUSIONS: The epidemiological characteristics of bacterial keratitis vary geographically. This study describing the features of bacterial keratitis would greatly help the practising ophthalmologist and other medical practitioners in the management of their patients.