Veterinary ocular microbiome: Lessons learned beyond the culture.

Ocular pathogens cause many painful and vision-threatening diseases such as infectious keratitis, uveitis, and endophthalmitis. While virulent pathogens and pathobionts play important roles in disease pathogenesis, the scientific community has long assumed disruption of the ocular surface occurs prior to microbial colonization and subsequent infection. While nonpathogenic bacteria are often detected in corneal and conjunctival cultures from healthy eyes, cultures also frequently fail to yield growth of common ocular pathogens or nonpathogenic bacteria. This prompts the following question: Is the ocular surface populated by a stable microbial population that cannot be detected using standard culture techniques? The study of the microbiome has recently become a widespread focus in physician and veterinary medicine. Research suggests a pivotal symbiotic relationship with these microbes to maintain healthy host tissues, and when altered is associated with various disease states ("dysbiosis"). The microbiota that lives within and on mammalian bodies have long been known to influence health and susceptibility to infection. However, limitations of traditional culture methods have resulted in an incomplete understanding of what many now call the "forgotten organ," that is, the microbiome. With the introduction of high-throughput sequencing, physician ophthalmology has recognized an ocular surface with much more diverse microbial communities than suspected based on traditional culture. This article reviews the salient features of the ocular surface microbiome and highlights important future applications following the advent of molecular techniques for microbial identification, including characterizing ocular surface microbiomes in our veterinary species and their potential role in management of infectious and inflammatory ocular diseases.

Post-Traumatic Endophthalmitis: Clinico-Microbiological Profile, Antimicrobial Susceptibility and Prognostic Factors at a Tertiary Eye Care Centre in Eastern India.

Purpose: To analyse clinico-microbiological profile, antimicrobial susceptibilities, and visual prognostic factors in post-traumatic endophthalmitis (PTE).Methods: Retrospective clinico-microbiological data analysis for five years (2014-18). Prognostic factors for visual outcomes were analysed by multivariate logistic regression analysis.Results: Four hundred and eighteen patients with clinically diagnosed PTE were analysed. Culture positivity was found in 46.7% samples (44.5% vitreous, 83.3% non-vitreous). Pathogens isolated were Gram positive cocci (GPC, 49.3%, good susceptibility to vancomycin/cefazolin), Gram negative bacilli (GNB, 28.1%, <90% susceptibility to all antibiotics and 25.8% multidrug resistance), Gram positive bacilli (13.1%) and fungi (9.5%). Poor visual prognosis was associated with culture positivity, fungal or polymicrobial PTE, poor view of fundus and presence of membranes on ultrasound scans.Conclusion: GPC and GNB are the predominant pathogens in PTE, with GNB most commonly multidrug resistant. Culture positivity, polymicrobial and fungal PTE, poor view of fundus and vitreous membranes are markers of poor visual outcome.

Antibiotic Resistance Rates by Geographic Region Among Ocular Pathogens Collected During the ARMOR Surveillance Study.

INTRODUCTION: The Antibiotic Resistance Monitoring in Ocular micRoorganisms (ARMOR) study is an ongoing nationwide surveillance program that surveys in vitro antibiotic resistance rates and trends among ocular bacterial pathogens. We report resistance rates by geographic region for isolates collected from 2009 through 2016. METHODS: Staphylococcus aureus, coagulase-negative staphylococci (CoNS), Streptococcus pneumoniae, Haemophilus influenzae, and Pseudomonas aeruginosa isolates from ocular infections were collected at clinical centers across the US and categorized by geographic region based on state. Minimum inhibitory concentrations (MICs) for various antibiotics were determined at a central laboratory, and isolates were classified as susceptible or resistant based on established breakpoints. Geographic differences in methicillin resistance among staphylococci were evaluated by χ2 test with multiple comparisons, whereas geographic differences in mean percentage antibiotic resistance were evaluated by one-way analyses of variance and Tukey's test. RESULTS: Overall, 4829 isolates (Midwest, 1886; West, 1167; Northeast, 1143; South, 633) were evaluated. Across all regions, azithromycin resistance was high among S. aureus (49.4-67.8%), CoNS (61.0-62.8%), and S. pneumoniae (22.3-48.7%), whereas fluoroquinolone resistance ranged from 26.1% to 47.8% among S. aureus and CoNS. Across all regions, all staphylococci were susceptible to vancomycin; besifloxacin MICs were similar to those of vancomycin. Geographic differences were observed for overall mean resistance among S. aureus, S. pneumoniae, and P. aeruginosa isolates (p ≤ 0.005); no regional differences were found among CoNS and H. influenzae isolates. Methicillin resistance in particular was higher among S. aureus isolates from the South and CoNS isolates from the Midwest (p ≤ 0.006). CONCLUSION: This analysis of bacterial isolates from the ARMOR study demonstrated geographic variation in resistance rates among ocular isolates, with greater in vitro resistance apparent in the South and Midwest for some organisms. These data may inform clinicians in selecting appropriate treatment options for ocular infections. FUNDING: Bausch & Lomb, Inc.