High-resolution genotyping of Pseudomonas aeruginosa strains linked to acute post cataract surgery endophthalmitis outbreaks in India

BACKGROUND: Investigation of two independent outbreaks of post cataract surgery endophthalmitis identified the reservoir of epidemic strains of P. aeruginosa. METHODS: Patient isolates cultured from vitreous fluid of all the nine cases and from the peripheral devices of phacoemulsification machine were subjected to high-resolution Fluorescent Amplified Fragment Length Polymorphism (FAFLP) analysis. RESULTS: FAFLP based genotyping of the isolates confirmed nosocomial transmission. Although biochemical characterization and antibiotic susceptibility profiles grouped all the isolates together, FAFLP based genotyping revealed that, all the outbreak isolates were derived from 2 different strains, with independent origins. One group of isolates was traced to phacoprobe and the second one to the internal tubing system of the phacoemulsification machine used in cataract surgery. In silico analysis indicated possible evolution in both the clusters of P. aeruginosa isolates due to genetic polymorphisms. The polymorphisms were mapped to gene products (cell envelope, outer membrane proteins) possibly having significant role in pathogenesis. CONCLUSION: The present study is probably the first one to apply FAFLP typing successfully to investigate outbreaks of postoperative endophthalmitis (POE) in an ophthalmic setting, which was able to identify the source, and helped to make rational decisions on sterilization procedures that halted more cases of infection in these hospitals

The Involvement of Complement Factor B and Complement Component C2 in an Indian Cohort with Age-Related Macular Degeneration

PURPOSE. Genes involved in the complement cascade such as complement factor B (CFB) and complement component C2 have been implicated in age-related macular degeneration (AMD) worldwide. In continuation of the analysis of CFH and LOC387715/HTRA1, this study was conducted to gain understanding of the role of CFB and C2 in an Indian AMD cohort. METHODS. Single nucleotide polymorphisms in CFB and C2 were screened in a cohort of clinically well-characterized patients with AMD (n ϭ 177) and unaffected normal control subjects (n ϭ 175). Screening was accomplished by a combination of customized genotyping followed by validation through resequencing. In addition, genotyping of two CFB variants (rs12614 and rs641153) that were in close proximity had to be resolved by resequencing. Estimates of allele and genotype frequencies, odds ratios, Hardy-Weinberg equilibrium, linkage disequilibrium (LD), and haplotype frequencies were also performed. RESULTS. Three SNPs in C2 (rs547154 [IVS10] ; P ϭ 5.4 ϫ 10 Ϫ11 ) and CFB (rs641153 [R32Q], P ϭ 2.2 ϫ 10 Ϫ7 and rs2072633 [IVS17]; P ϭ 2.0 ϫ 10 Ϫ4 ) were strongly associated with reduced risk of AMD. The rs547154 and rs641153 were in strong LD (DЈ ϭ 0.90, 95% CI ϭ 0.81-0.96) and a protective haplotype T-A was observed (OR ϭ 0.10, 95% CI ϭ 0.05-0.20). LD was moderate (DЈ ϭ 0.77, 95% CI ϭ 0.67-0.85) between the rs547154 and the rs2072633 SNPs, and the haplotype T-T generated with these SNPs was relatively less protective (OR ϭ 0.28, 95% CI ϭ 0.18 -0.44). CONCLUSIONS. The results of the present study provide an independent validation of the association of rs547154 (C2) and rs641153 (CFB) SNPs with reduced risk of AMD in an Indian cohort. (Invest Ophthalmol Vis Sci