The conjunctival bacterial pattern of diabetics undergoing cataract surgery

Intraocular lens selection in diabetic patients: How to increase the odds for success

The incidence of cataracts is significantly higher in diabetic individuals, particularly in younger age groups, with rates quadrupled in those under 65 and doubled in those over 65 compared to non-diabetics. Cataract surgery in diabetic patients poses many challenges: Poor epithelial healing, decreased corneal sensitivity, increased central corneal thickness, decreased endothelial cell count, variable topography, poor pupillary dilatation, anterior capsular phimosis, posterior capsular opacification (PCO), chances of progression of diabetic retinopathy (DR), zonular weakness, and vitreous prolapse and diabetic macular edema. Selection of an appropriate intraocular lens (IOL) is crucial for visual rehabilitation and monitoring DR. The choice of IOL in diabetic cataract patients is a challenging scenario. Square-edge IOLs are favored for their capacity to mitigate PCO, whereas hydrophilic counterparts may incur calcification in the setting of proliferative DR. The advisability of premium IOLs for achieving spectacle independence warrants judicious evaluation, particularly in the presence of advanced retinopathy. Optimal IOL placement within the capsular bag is advocated to minimize postoperative complications. Rigorous preoperative assessment and informed patient counseling regarding IOL options are indispensable for optimizing surgical outcomes. This review article covers various aspects regarding the choice of IOLs in different case scenarios and complications in the diabetic population.

Changes in the preoperative ocular surface flora with an increase in patient age: A surveillance analysis of bacterial diversity and resistance to fluoroquinolone

PURPOSE

This study analyzed the relationship between patient age and the prevalence and fluoroquinolone susceptibility of gram-positive cocci from the ocular surface flora before ophthalmic surgery.

METHODS

This surveillance study included scraped samples from the conjunctival sac of 8923 eyes of 5490 patients (70.0 ± 13.7 years) without ocular infection before ophthalmologic surgery between August 2018 and December 2020. A review of microbiological records regarding patient age was used to determine the number of isolates and gram-positive species obtained, as well as their fluoroquinolone susceptibility. Fluoroquinolone susceptibility was determined using the Clinical and Laboratory Standards Institute protocols of broth microdilution. Statistical analysis was performed using a generalized additive model and a log-linear model.

RESULTS

In total, 9,894 bacterial isolates obtained from scraped samples from the patients were analyzed. The detected species were Staphylococcus epidermidis (31.0%), Staphylococcus aureus (6.1%), Staphylococcus lugdunensis (3.9%), Enterococcus faecalis (5.8%), Corynebacterium species (31.7%), and Cutibacterium acnes (7.5%) and others. The number of species isolated from the ocular surface was increased at the rate of 1.018 per 10 years of age (p < 0.0001). S. epidermidis, S. lugdunensis, E. faecalis, and Corynebacterium species were isolated more often with an increase in patient age. The levofloxacin resistance ratio of methicillin-sensitive S. epidermidis and Corynebacterium species increased at the rate of 1.204 and 1.087 respectively with a 10-year increase in age (both p < 0.0001).

CONCLUSION

Gram-positive bacteria in the ocular surface flora (OSF) exhibited gradual changes in diversity and fluoroquinolone resistance with an increase in patient age. It is important to monitor the OSF of the patients before ophthalmologic surgery to prevent refractory ocular postoperative infection.

The management of cataract surgery in diabetic patients

A cataract in the eye is a major cause of vision loss in diabetic patients, which occurs earlier and develops faster than non-diabetic patients, and often requires surgery for treatment. However, diabetic patients undergoing cataract surgery have a higher risk of intraoperative and postoperative complications than non-diabetic patients. For diabetic patients undergoing any surgery, careful perioperative assessment and management are required to reduce postoperative complications and improve surgical outcomes. Better understanding of their needs may guide perioperative practitioners to manage their care appropriately. This article presents recent evidence and guidance associated with the preoperative, intraoperative and postoperative management of diabetic patients undergoing cataract surgery and to inform perioperative practitioners of the challenges and potential complications to provide the best care and improve sight.

Conjunctival sac bacterial culture of patients using levofloxacin eye drops before cataract surgery: a real-world, retrospective study

Background

The use of antibiotics preoperatively is effective to decrease the incidence of ocular bacterial infections but may lead to high resistance rate, especially on patients with multi-risk clinical factors. This study systematically analyzed real-world data (RWD) of patients to reveal the association between clinical factors and conjunctival sac bacterial load and offer prophylaxis suggestions.

Methods

We retrieved RWD of patients using levofloxacin eye drops (5 mL: 24.4 mg, 4 times a day for 3 days) preoperatively. Retrieved data included information on the conjunctival sac bacterial culture, sex, presence of hypertension and diabetes mellitus (DM), and history of hospital-based surgeries. Data was analyzed using SPSS 24.0.

Results

RWD of 15,415 cases (patients) were retrieved. Among these patients, 5,866 (38.1%) were males and 9,549 (61.9%) females. 5,960 (38.7%) patients had a history of hypertension, and 3,493 (22.7%) patients had a history of DM. 7,555 (49.0%) patients had a history of hospital-based operations. There were 274 (1.8%) positive bacterial cultures. Male patients with hypertension and DM may be at increased risk of having positive bacterial cultures (P < 0.05). Staphylococcus epidermidis (n = 56, 20.4%), Kocuria rosea (n = 37, 13.5%), and Micrococcus luteus (n = 32, 11.7%) were the top 3 isolated strains. Most bacterial strains were resistant to various antibiotics except rifampin, and 82.5% (33 of 40 isolates) of Staphylococcus epidermidis isolates had multidrug antibiotic resistance. Numbers of culture-positive Staphylococcus epidermidis isolates in the male group and non-DM group were greater than those in the female and DM groups, respectively. Micrococcus luteus (n = 11, 8.8%) was found less frequently in non-hypertension group than in hypertension group.

Conclusion

Sex (Male) and the presence of hypertension and DM are risk factors for greater conjunctival sac bacterial loads. We offer a prophylactic suggestion based on the combined use of levofloxacin and rifampin. However, this approach may aggravate risk of multidrug resistance.

Bacterial distribution on the ocular surface of patients with primary Sjögren's syndrome

Many studies have shown that gut microbial dysbiosis is a major factor in the etiology of autoimmune diseases but none have suggested that the ocular surface (OS) microbiome is associated with Sjögren’s syndrome (SS). In this prospective study, we analyzed bacterial distribution on the OS in patients with primary SS. Among the 120 subjects included in this study, 48 patients (group A) had primary SS, whereas 72 subjects (group B) had dry eye symptoms that were unrelated to SS. We evaluated clinical dry eye parameters such as the OS disease index, ocular staining score (OSS), Schirmer’s I test, and tear break-up time (TBUT). Conjunctival swabs were used to analyze the microbial communities from the two groups. Bacterial 16S rRNA genes were sequenced using the Illumina MiSeq platform, and the data were analyzed using the QIIME 1.9.1 program. The Shannon index was significantly lower in group A than in group B microbiota (p < 0.05). An analysis of similarity using the Bray–Curtis distance method found no difference in beta-diversity between the two groups (p > 0.05). In group A, Actinobacteria at the phylum level and Corynebacteria at the genus level exhibited low abundance than group B, but the differences were not statistically significant (p > 0.05). SS apparently decreases the diversity of the OS microbial community. These observations may be related to the pathophysiology of SS and should be investigated in future studies.

Cataract Surgery Considerations for Diabetic Patients

PURPOSE OF REVIEW

Given the epidemiology and demographic trends of diabetes mellitus and cataracts, ophthalmologists are likely to encounter patients with both comorbidities at an increasing frequency. Patients with diabetes represent a higher risk population than healthy patients for cataract surgery. In this review, we discuss key risks and risk-mitigation practices when performing cataract surgery on these patients.

RECENT FINDINGS

Patients with diabetes continue to represent a high-risk surgical population: Nagar et al. suggest a dose-dependent relationship may exist between number of intravitreal injections and likelihood of posterior capsular rupture. However, novel treatments are improving outcomes for patients with diabetes. Several studies have reported intracameral phenylephrine/ketorolac may reduce the incidence of post-operative cystoid macular edema while others have discussed the efficacy of pre-treatment and post-treatment with intravitreal bevacizumab on improving cataract surgery outcomes in patients with diabetic retinopathy. Pre-operatively, ophthalmologists should perform an enhanced evaluation, consider timing and lens selection decisions, and complete any appropriate pre-operative treatment. Peri-operatively, surgeons should be aware of pupillary dilation adjustments, combination surgery options, and potential complications. Post-operatively, clinicians should address pseudophakic cystoid macular edema, diabetic macular edema, diabetic retinopathy, and posterior capsular opacification.

Gut microbiota and age-related macular degeneration: A growing partnership

Age-related macular degeneration (AMD) is a leading cause of severe, irreversible vision impairment in developed countries, and its prevalence is rising all over the world, increasing sharply with age. AMD represents an acquired degeneration of the retina that causes significant central visual impairment through a combination of noneovascular and neovascular derangement. The main risk factors for the development of advanced AMD are increasing age, genetic factors, and cigarette smoking; however, the exact pathophysiology of AMD is yet relatively poorly understood. In recent years, the gut microbiota has been intensively studied and linked to several pathologic processes, including ocular diseases. In this sense, the aim of this review is to gather published evidence about the relationship between gut microbiota and AMD.

Microbiota and Ocular Diseases

Recent advances have identified significant associations between the composition and function of the gut microbiota and various disorders in organ systems other than the digestive tract. Utilizing next-generation sequencing and multiomics approaches, the microbial community that possibly impacts ocular disease has been identified. This review provides an overview of the literature on approaches to microbiota analysis and the roles of commensal microbes in ophthalmic diseases, including autoimmune uveitis, age-related macular degeneration, glaucoma, and other ocular disorders. In addition, this review discusses the hypothesis of the "gut-eye axis" and evaluates the therapeutic potential of targeting commensal microbiota to alleviate ocular inflammation.

Distribution and risk factors of postoperative endophthalmitis in people with diabetes

Purpose

To evaluate (i) the distribution of postoperative endophthalmitis (POE) in patients who underwent cataract surgery, (ii) risk factors in diabetic versus nondiabetic patients, and (iii) distribution of POE in those who had undergone rapid reduction of preoperative blood sugar levels versus those with normal blood sugar levels.

Methods

Medical records were reviewed from January 1995 to July 2021. In total, 391 eyes of 391 patients who developed POE after cataract surgery were studied. Patients with POE were divided into Group A, patients with diabetes (n = 128), and Group B, patients without diabetes (n = 263), and the associations of various clinical factors in the two groups were studied. Patients with diabetes with raised random blood sugars (RBS) preoperatively were subjected to a rapid reduction of blood sugar (RBS <200 mg%) to be considered eligible for surgery. Microbiological profile of patients was examined.

Results

The cumulative incidence of POE over 26 years was 0.09%. Those who underwent a rapid reduction in preoperative blood sugar levels had higher rates of POE (53.1%) compared with (46.9%) those with blood sugar levels under control (P = 0.486). Men with diabetes had 1.634 times higher odds of POE (P = 0.048), and those with diabetes and hypertension had 3.961 times greater odds of having POE (P < 0.001) when adjusted for age, alcohol, smoking, and socioeconomic strata and presence of posterior capsule rupture. Positive culture results were observed in 45/128 (35%) patients with diabetes and 71/263 (27%) patients without diabetes. Staphylococcus epidermidis was the most commonly identified organism and was detected in 10/45 (22%) in those with diabetes and 21/71 (29%) in those without diabetes of all the culture-positive cases.

Conclusion

In patients with POE, the odds are greater for men with diabetes, those with a history of hypertension, as well as those who undergo a rapid reduction of preoperative blood sugar.

Subjective outcome and quality of life following external dacryocystorhinostomy

Purpose:

To assess the patient reported outcome and quality of life in post external dacryocystorhinostomy operated patients.

Methods:

A prospective questionnaire based study was carried out on 112 patients diagnosed with chronic dacryocystitis who underwent external dacryocystorhinostomy in the department of Orbit and Oculoplasty at a tertiary eye hospital in South India.

Results:

We included 112 cases in our study. Mean (SD) of the age of patients was 48.03 (12.79) years and ranged from 7 to 72 years of age. 44 (39.3%) patients were males and 68 (60.7%) were females. All cases had subjective symptoms of tearing, pain and swelling at baseline which were relieved by post-operative 3 in all cases. The mean (SD) best corrected visual acuity was 0.28 (0.39) at baseline and 0.25 (0.37) at postoperative 3 (p < 0.001). All four parameters studied in the GBI questionnaire - total mean GBI (32.22 vs 48.86, P < 0.001), general subscale (31.21 vs 44.08, P < 0.001), social health (46.28 vs 61.01, P < 0.001), physical outcome (22.17 vs 55.80, P = 0.0001) scores showed significant improvement from 1 vs 3 months post DCR.

Conclusion:

The GBI questionnaire is an effective tool for assessing patients’ quality of life following DCR. External DCR can not only produce a successful anatomical outcome but also bring about a measurable improvement in subjective symptoms and quality of life among patients with symptomatic NLDO.

Characterization of Ocular Surface Microbial Profiles Revealed Discrepancies between Conjunctival and Corneal Microbiota

The ocular microbiome composition has only been partially characterized. Here, we used RNA-sequencing (RNA-Seq) data to assess microbial diversity in human corneal tissue. Additionally, conjunctival swab samples were examined to characterize ocular surface microbiota. Short RNA-Seq reads, obtained from a previous transcriptome study of 50 corneal tissues, were mapped to the human reference genome GRCh38 to remove sequences of human origin. The unmapped reads were then used for taxonomic classification by comparing them with known bacterial, archaeal, and viral sequences from public databases. The components of microbial communities were identified and characterized using both conventional microbiology and polymerase chain reaction (PCR) techniques in 36 conjunctival swabs. The majority of ocular samples examined by conventional and molecular techniques showed very similar microbial taxonomic profiles, with most of the microorganisms being classified into Proteobacteria, Firmicutes, and Actinobacteria phyla. Only 50% of conjunctival samples exhibited bacterial growth. The PCR detection provided a broader overview of positive results for conjunctival materials. The RNA-Seq assessment revealed significant variability of the corneal microbial communities, including fastidious bacteria and viruses. The use of the combined techniques allowed for a comprehensive characterization of the eye microbiome's elements, especially in aspects of microbiota diversity.

The ocular surface bacterial contamination and its management in the prophylaxis of post cataract surgery endophthalmitis

Objective: To investigate the recent pieces of evidence regarding the bacterial ocular surface contamination and its treatment in the prophylaxis of post-cataract surgery endophthalmitis. Methods: We conducted a literature research on the topic of interest and selected the most relevant data. Results: The studies reported a relatively high rate of positive conjunctival culture and the most frequently isolated organism was Coagulase negative Staphylococcus, which is also the most common etiological agent of the postoperative endophthalmitis. The bacterial ocular surface load is influenced by age, climate, associated diseases, topical and systemic medication. The use of povidone-iodine alone or in association with levofloxacin eyedrops as prophylactic method is effective in reducing the conjunctival bacterial contamination and consequently decreases the incidence of postoperative endophthalmitis. Conclusions: Based on the current pieces of evidence, adequate treatment of the bacterial ocular surface contamination prior to cataract surgery seems to be effective in preventing endophthalmitis after cataract surgery. Abbreviations: EU = European Union, Spp. = Species, HIV = Human Immunodeficiency Virus.

Ocular Microbiota and Intraocular Inflammation

The term ocular microbiota refers to all types of commensal and pathogenic microorganisms present on or in the eye. The ocular surface is continuously exposed to the environment and harbors various commensals. Commensal microbes have been demonstrated to regulate host metabolism, development of immune system, and host defense against pathogen invasion. An unbalanced microbiota could lead to pathogenic microbial overgrowth and cause local or systemic inflammation. The specific antigens that irritate the deleterious immune responses in various inflammatory eye diseases remain obscure, while recent evidence implies a microbial etiology of these illnesses. The purpose of this review is to provide an overview of the literature on ocular microbiota and the role of commensal microbes in several eye diseases. In addition, this review will also discuss the interaction between microbial pathogens and host factors involved in intraocular inflammation, and evaluate therapeutic potential of targeting ocular microbiota to treat intraocular inflammation.

Effect of Topical Antibiotic Prophylaxis on Conjunctival Flora and Antibiotic Resistance Following Intravitreal Injections in Patients with Type 2 Diabetes

Purpose

We sought to determine changes in the conjunctival bacterial flora and antibiotic resistance after topical antibiotic drops for infection prophylaxis were administered following intravitreal injections in patients with type 2 diabetes.

Methods

This prospective and nonrandomized cohort study included 116 eyes of 116 treatment-naive patients with type 2 diabetes who received six serial intravitreal anti-vascular endothelial growth factor injections for macular edema. Three conjunctival cultures were obtained from each eye over the course of the study (Culture 1, baseline; Culture 2, 1 month after the third injection; and Culture 3, 1 month after the sixth injection). The study subjects were given topical moxifloxacin hydrochloride for 4 days after each monthly intravitreal injection. The growth patterns of conjunctival bacterial flora and the antibiotic resistance to several commonly used antibiotics were examined.

Results

The rate of culture positivity increased significantly during the observation period (Culture 1, n = 47, 40.5%; Culture 2, n = 58, 50%; Culture 3, n = 76, 65.5%, p < 0.001). The bacterium with the highest baseline culture positivity was Staphylococcus epidermidis (n = 45, 38.8%), which increased significantly during the observation period (p < 0.001). No significant increase was noted in the culture positivity of the other bacteria with baseline culture positivity (p > 0.05). Regarding antibiotic susceptibility, significant increases in resistance to the fluoroquinolone group of drugs were noted (p < 0.001). No significant changes in sensitivity were detected in the other 11 investigated antibiotics that are commonly used in clinical practice (p > 0.05).

Conclusions

The use of topical moxifloxacin after each intravitreal injection significantly increases the fluoroquinolone resistance of the ocular surface flora and the culture-positivity rate of S. epidermidis in patients with type 2 diabetes.

Assessing the ocular surface microbiome in severe ocular surface diseases

PURPOSE

There is growing evidence for a critical role of the microbiome in ocular health and disease. We performed a prospective, observational study to characterize the ocular surface microbiome (OSM) in four chronic ocular surface diseases (OSDs) and healthy controls.

METHODS

Sterile swabs were used to collect samples from each eye of 39 patients (78 eyes). Sterile technique and multiple controls were used to assess contamination during DNA extraction, amplification and sequencing. Concurrent use of topical antibiotics, steroids, and bandage contact lenses (BCLs) was documented.

RESULTS

Despite the low biomass of the ocular surface, 47/78 (60%) eyes sampled had positive sequencing reads. We observed that half of patients (8/17, 47%) had distinct microbiomes in each eye. Healthy controls had a Lactobacillus/Streptococcus mixture or significant Corynebacterium. Staphylococcus predominated in 4/7 (57%) patients with Stevens-Johnson Syndrome (SJS) in at least one eye, compared to 0/10 healthy controls. Interestingly, 8/11 (73%) eyes with SJS were using BCLs, including 4/5 (80%) eyes dominated by Staphylococcus. Lax eyelid syndrome (LES) and Dry Eye Disease (DED) patients had similar OSMs, with Corynebacterium being the most prevalent bacteria. Alpha diversity was higher in controls and ocular graft-vs-host (oGVHD) patients compared to the other OSDs.

CONCLUSIONS

Only 50% of the 39 patients had similar microbiomes in each eye. A majority of healthy eyes had a Lactobacillus/Streptococcus mix or Corynebacterium microbiome. Staphylococcus predominated in SJS, Lactobacillus in oGVHD, and Corynebacterium in DED and LES. There may be an association between different OSDs and the microbiome.

Eye care providers' emerging roles in early detection of diabetes and management of diabetic changes to the ocular surface: a review

US adults visit eye care providers more often than primary healthcare providers, placing these doctors in a prime position to help identify and manage patients with prediabetes and diabetes. Currently, diabetes is identified in eye clinics in an advanced stage, only after visible signs of diabetic retinopathy. Recent ophthalmic research has identified multiple subclinical and clinical changes that occur in the anterior segment of the eye with metabolic disease. The corneal epithelium exhibits increased defects and poor healing, including an increased risk of neurotrophic keratitis. Increased thickness and stiffness of the cornea artificially alters intraocular pressure. There is damage to the endothelial cells and changes to the bacterial species on the ocular surface, both of which can increase risk of complications with surgery. Decreased corneal sensitivity due to a loss of nerve density predispose patients with metabolic disease to further neurotrophic complications. Patients with diabetes have increased Meibomian gland dysfunction, blepharitis and reduced tear production, resulting in increased rates of dry eye disease and discomfort. Early detection of metabolic disease may allow eye care providers to be more proactive in recommending referral and intervention in order to reduce the risk of blindness and other diabetes-related morbidity. Continued research is needed to better understand the time course of changes to the anterior segment and what can be done to better detect and diagnose patients with prediabetes or undiagnosed diabetes and provide improved care for these patients.

In Vitro Biofilm Formation and Antibiotic Susceptibility Patterns of Bacteria from Suspected External Eye Infected Patients Attending Ophthalmology Clinic, Southwest Ethiopia

Background

Ocular disease with its complications is a major public health problem which has significant impacts on the quality of life particularly in developing countries. An eye infection due to bacterial agents can lead to reduced vision and blindness. This study was aimed to assess the antimicrobial susceptibility pattern and biofilm-forming potential of bacteria isolated from suspected external eye infected patients in Jimma.

Method

A cross-sectional facility-based study was conducted on 319 suspect patients with external eye infections from March to June 2017 at Jimma University Medical Center (JUMC) Ophthalmology Department in Ethiopia. External ocular specimens were collected and standard operating procedures were followed to handle and culture throughout the study period. Antimicrobial susceptibility was determined by the disk diffusion method according to CLSI guidelines. Microtiter (96 wells) plate method was used to screen biofilm formation by ELISA reader at 570 nm.

Results

Out of 319 study participants with an external eye infection, the prevalence of bacterial pathogens was 46.1%. The predominant bacterial isolates were coagulase-negative staphylococcus (CoNS) (27.7%) followed by Staphylococcus aureus (19.7%). Among Gram-negative groups, Pseudomonas aeruginosa (6.8%) was the leading isolate. Increased antimicrobial resistance was observed for tetracycline (64%), erythromycin (66.7%), and penicillin (77.1%). Amoxicillin-clavulanic acid, ciprofloxacin, and gentamicin were the most effective drugs for external eye infections due to susceptibility ranging from 70 to 100% among both Gram-negative and Gram-positive groups. Methicillin-resistant S. aureus (MRSA) accounted for 13.8%. Multidrug resistance (MDR) accounted for 68.7%. The overall biofilm formation rate of bacterial ocular pathogens was 66.1%, where P. aeruginosa (40%), CoNS (34.1%), and S. aureus (31%) formed strong biofilm phenotype.

Conclusion

The prevalence rate of bacterial isolates was high. Almost all bacterial isolates were resistant to at least one or more drugs. MDR pathogens were observed increasingly among biofilm formers or vice versa.

Biofilm forming capacity and antibiotic susceptibility of Staphylococcus spp. with the icaA/icaD/bap genotype isolated from ocular surface of patients with diabetes

Introduction

Bacterial biofilm is an exopolysaccharide matrix that is produced by bacteria while they adhere on abiotic or biotic surfaces. The bacteria living in this matrix are more resistant to antibiotics than planctonic bacteria. The biofilm formation property of the bacteria is determined by genes; and this is related to virulence of the microorganism. In ophthalmology, biofilms form especially on abiotic surfaces such as silicon tubes, contact lenses, intraocular lenses etc.

Aim

Our aim was to investigate genotypic and phenotypic structures of biofilms that are produced by Staphylococcus spp., which was obtained from the eyes of diabetic patients and determine the effect on antibiotic susceptibility.

Methods

The study group was comprised with 83 isolates from diabetic patients and 21 isolates from non-diabetic patients. Presumptive isolates were detected and confirmed by a microbial identification system VITEK II. Automated EcoRI Ribotyping was performed. Biofilm production was detected by Congo Red Agar Plate and Microtiter Plate Assay. Disc diffusion method was used for determination of antibiotic susceptibility of isolates.

Results

Out of the 83 isolates from diabetic patients, 25 were weakly (30%), 20 were moderately (24%), and 25 were strongly (30%) biofilm positive. Seven isolates of S. aureus, 11 isolates of S.epidermidis, 2 isolates of S. warneri, 3 isolates of S.hominis, and 2 isolates of S.lugdunensis were identified as strong biofilm producers. Out of the 83 Staphylococcus isolates, 37 were cefuroxime, 18 ciprofloxacin, 11 vancomycin, 12 gatifloxacin, and 18 moxifloxacin resistant. In total, 37 strains were resistant to three or more antibiotics. There was a statistically significant relation between biofilm formation and multidrug resistance (against three or more antibiotics, p<0.001). In nondiabetic patients, 15(71%) isolates were non adherent or weakly adherent, and 2(10%) were strongly adherent biofilm positive.

Conclusion

In conclusion, bacterial conjunctival flora of patients with diabetes is likely to produce biofilm. Biofilm formation is associated with multidrug rsistance in patients with diabetes.

How Ocular Surface Microbiota Debuts in Type 2 Diabetes Mellitus

High glucose represents a good environment for bacterial growth on the skin, on the ocular surface (OS) and in the tears of type 2 diabetes mellitus (T2DM) patients, affecting the conjunctival bacterial community. This study aimed to investigate the OS bacterial flora of T2DM patients and healthy subjects using 16S rRNA sequencing-based bacterial identification. Among 23 healthy subjects (CON) and 31 T2DM patients, 54 eyes were examined to investigate the OS bacterial community. Factors potentially affecting the microbial growth were controlled. Results showed the OS microbiota presented higher diversity in the T2DM group than in the CON group. Bioinformatic analysis showed a lower abundance of Proteobacteria and a higher abundance of Bacteroidetes at the phyla level as well as a significantly increased abundance of Acinetobacter and Pseudomonas at the genus level in the T2DM group. The difference in OS microbiota at taxonomic level was associated with Ocular Surface Disease Index and course of T2DM. These findings indicate the OS flora in T2DM patients is significantly different from that in healthy subjects, which may be closely associated with OS discomfort and course of T2DM.

Metagenomics in ophthalmology: current findings and future prospectives

Less than 1% of all microorganisms of the available environmental microbiota can be cultured with the currently available techniques. Metagenomics is a new methodology of high-throughput DNA sequencing, able to provide taxonomic and functional profiles of microbial communities without the necessity to culture microbes in the laboratory. Metagenomics opens to a ‘hypothesis-free’ approach, giving important details for future research and treatment of ocular diseases in ophthalmology, such as ocular infection and ocular surface diseases.

Diabetes and Phacoemulsification Cataract Surgery: Difficulties, Risks and Potential Complications

Diabetes mellitus is one of the most prevalent chronic diseases worldwide. Diabetic patients are at risk of developing cataract and present for surgery at an earlier age than non-diabetics. The aim of this study was to review the problems associated with cataract surgery in a diabetic patient. Corneal complications in diabetic patients include delayed wound healing, risk of developing epithelial defects or recurrent erosions due to the impairment of epithelial basement membranes and epithelial-stromal interactions. Diabetic patients present lower endothelial cell density and their endothelium is more susceptible to trauma associated with cataract surgery. A small pupil is common in diabetic patients making cataract surgery technically challenging. Finally diabetic patients have an increased risk for developing postoperative pseudophakic cystoid macular edema, posterior capsule opacification or endophthalmitis. In patients with pre-proliferative or proliferative diabetic retinopathy, diabetic macular edema or iris neovascularization adjunctive therapy such as an intravitreal anti-vascular endothelial growth factor injection, can inhibit exacerbation related to cataract surgery.

Composition and Comparison of the Ocular Surface Microbiome in Infants and Older Children

Purpose

Unlike other microbiomes of the body, the composition of the ocular surface microbiome (OSM) in children has yet to be thoroughly explored. Our goal was to evaluate the OSM in young infants and compare its composition to older children using both culture dependent and independent methodologies to assess for differences with age.

Methods

Prospective, observational, cross-sectional study of children <18 years of age at a university-based institution. The mucosal surfaces of both eyes, nose and throat were swabbed with a forensic-quality swab. Half of the swab was plated for culture and the other half underwent 16S sequencing. Culture results and microbiome diversity were analyzed.

Results

Fifty patients (mean age 37 months, range 1-168 months) were enrolled. Forty-seven eyes of 30 patients had positive cultures; four eyes grew >1 species. Culture positive patients were older (43 vs. 29 months, P = 0.19). Additionally, older children had greater diversity than children under 6 months of age by 16S sequencing (P = 0.05). Staphylococcus species were predominant by culture (35/52 isolates) and by 16S sequencing. The OSM was fairly similar to the nose microbiome, whereas the throat microbiome differed significantly and had a higher abundance of Streptococcaceae (P = 0.001).

Conclusions

The OSM is predominantly composed of Staphylococcus species in children, as demonstrated by both culture dependent and culture independent methods. Older children were more likely to have growth on culture and have more a complex bacterial milieu with 16S sequencing.

Translational Relevance

16S sequencing provides more robust information regarding the composition of the microbiomes than culture dependent methods.

Cataract surgery in diabetes mellitus: A systematic review

India is considered the diabetes capital of the world, and a significant proportion of patients undergoing cataract surgery are diabetic. Considering this, we reviewed the principles and guidelines of managing cataract in patients with diabetes. The preoperative, intraoperative, and postoperative factors are of paramount importance in the management of diabetic cataract patients. Particularly, the early recognition and treatment of diabetic retinopathy or maculopathy before cataract surgery influence the final visual outcome and play a major role in perioperative decision-making. Better understanding of various factors responsible for favorable outcome of cataract surgery in diabetic patients may guide us in better overalll management of these patients and optimizing the results.

Effect of clinical parameters on the ocular surface microbiome in children and adults

Purpose

To perform a pilot study to characterize the effect of clinical parameters on the ocular surface microbiome (OSM) in children and adults using 16s ribosomal RNA sequencing.

Methods

Prospective, cross-sectional study using 16s sequencing to evaluate the OSM. Comparisons were made in bacterial composition by 1) age, 2) gender, 3) sampling location of the ocular and periocular surfaces, and 4) topical drop use. 16s sequencing was performed using Illumina MiSeq 250 and analyzed using Qiime.

Results

Thirty patients (15 children [mean 3.7 years], 15 adults [mean 60.4 years]) were sampled. Both principal coordinate analysis and unifrac distance analysis showed significant differences in the composition between the pediatric and adult OSMs (both p=0.001). The eyelid margin microbiota did not show any distinct clustering compared to conjunctiva within the pediatric samples but tended to show a distinction between anatomic sites in adult samples. No differences in OSM were noted by topical drop use.

Conclusion

16s sequencing is a useful tool in evaluating the OSM in patients of all ages, showing a distinct difference between pediatric and adult microbiomes.

Positive bacterial culture in conjunctival sac before cataract surgery with night stay is related to diabetes mellitus

Background

The aim of this study is to elucidate background clinical factors in patients with positive bacterial culture for the conjunctival sac before cataract surgery in Japan.

Methods

Retrospective review was made on medical records of 576 consecutive patients who underwent conjunctival sac culture before cataract surgery with night stay at a hospital in 2 years from January 2013 to December 2014. In the patients with sequential bilateral surgeries, the data were chosen for bacterial culture in the eye which had earlier surgery. The age at surgery ranged from 33 to 100 years (mean, 76.7 years). Clinical factors, analyzed in relation with positive or negative bacterial culture, included the sex, the age, the presence of hypertension or diabetes mellitus, history of cancer, and history of hospital-based surgery at other specialties.

Results

Bacterial culture of the conjunctival sac was positive in 168 patients while negative in 408 patients. In multiple regression analysis, the positive bacterial culture was related with the older age (P = 0.01), the presence of diabetes mellitus (P = 0.004), and the history of hospital-based surgery at other specialties (P = 0.001).

Conclusions

Elderly patients with diabetes mellitus or previous hospital-based surgeries at other specialties have a higher rate of positive bacterial culture in the conjunctival sac before cataract surgery. This study would provide a hint for identifying patients at risk for carrying bacterial flora in the conjunctival sac.

Efficacy of Topical Ofloxacin 0.3 % Administration on Conjunctival Bacterial Flora in Diabetic Patients Undergoing Intravitreal Injections

PURPOSE

This prospective, randomized case series study aims to evaluate the efficacy of ofloxacin 0.3% eye drops in eradication of conjunctival bacterial flora in diabetic patients undergoing intravitreal injections (IVI).

METHODS

Ninety-two diabetic patients (92 eyes) scheduled to undergo intravitreal injection of ranibizumab due to diabetic macular edema were enrolled in the study. Patients were randomly assigned to three different groups. Group 1 (n=32) received ofloxacin eye drops the day before before IVI (four times); patients in Group 2 (n=29) were administered ofloxacin one hour before IVI (every 15 minutes), while Group 3 (n=31) comprised patients that received combined administration of ofloxacin both one day and one hour before IVI (eight doses). Samples were collected from the injection site before and after antibiotic administration. Culture results from BACTEC broth and positive cultures in blood agar and Sabouraud's dextrose agar plates were measured.

RESULTS

In Group 1, BACTEC broth positive cultures decreased from 84.4% at baseline to 50% after ofloxacin administration (p=0.007), and blood agar positive cultures reduced from 65.63% to 34.38% (p=0.02). In Group 2, positive cultures significantly decreased in BACTEC broth (from 79.3% at baseline to 48.28%; p=0.027) and in blood agar (from 68.97% to 37.13%; p=0.034). In Group 3, positive cultures decreased from 77.42% at baseline to 32.26% (p=0.0008) and from 58.06% at baseline to 22.58% (p=0.009) in BACTEC broth and blood agar, respectively. No microorganisms were isolated from Sabouraud's dextrose agar plates.

CONCLUSIONS

The combined one day/one hour (eight doses) ofloxacin administration in diabetic patients is extremely effective in reducing conjunctival bacterial flora. The application of topical ofloxacin for one day or one hour before IVI is also significantly effective.

Risk factors for aerobic bacterial conjunctival flora in preoperative cataract patients

PurposeTo investigate the relationship between the background of preoperative cataract patients and bacterial conjunctival flora.MethodsA total of 990 cataract patients who had completed preoperative examinations in 2007 and 2008 were included. Patients using topical antibiotics at the preoperative examination or having a history of intraocular surgery were excluded. Conjunctival cultures had been preoperatively obtained. Patient characteristics were investigated via medical records. Risk factors for conjunctival flora of seven typical bacteria were analyzed by univariate and multivariate analyses.ResultsThe detection rate of alpha-hemolytic streptococci and Enterococcus faecalis increased with age (P=0.044 and P=0.002, respectively). The detection rate of Gram-negative bacilli was higher among patients with oral steroid use or lacrimal duct obstruction (P=0.038 and P=0.002, respectively). The detection rate of Corynebacterium species was higher among older patients and men, and lower among patients with glaucoma eye drop use (P<0.001, P=0.012 and P=0.001, respectively). The detection rate of methicillin-susceptible coagulase-negative Staphylococci was higher among men and lower among patients with a surgical history in other departments (P=0.003 and P=0.046, respectively). The detection rate of methicillin-resistant coagulase-negative Staphylococci (MR-CNS) was higher among patients with oral steroid use, a visit history to ophthalmic facilities, or a surgical history in other departments (P=0.002, P=0.037 and P<0.001, respectively).ConclusionsElderly patients, men, patients with lacrimal duct obstruction or immunosuppressed patients are more likely to be colonized by pathogens that cause postoperative endophthalmitis. Moreover, MR-CNS colonization was associated with healthcare-associated infection.

Conjunctival Flora in Diabetic and Nondiabetic Individuals

Objectives:

To evaluate the conjunctival bacterial flora in diabetic patients and nondiabetic subjects.

Materials and Methods:

Fifty-three diabetic patients and 43 nondiabetic healthy individuals were included in the study. A specimen was taken from each participant for the study by rubbing a sterile cotton-tipped swab on the inferior palpebral conjunctiva of the right eye. Samples were incubated in blood agar, chocolate agar, eosin methylene-blue lactose sucrose agar and sabouraud 4% dextrose agar. Isolated microorganisms were identified using routine microbiological methods.

Results:

Rates for bacterial isolations were determined as 38.5% in diabetic patients and 34.9% in nondiabetic controls. Staphylococcus aureus was isolated in 30% of cases in the diabetic patient group, while 20% tested positive for Escherichia coli, 10% for coagulase-negative Staphylococcus, 10% for Klebsiella pneumoniae and 30% for multiple bacteria. In the non-diabetic group, 53.3% of patients were positive for Staphylococcus aureus while coagulase-negative Staphylococcus was isolated in 26.7%, Klebsiella pneumoniae in 6.7% and multiple bacteria in 13.3% of patients. Although there was no statistically significant difference in the number of isolated bacteria between the diabetic and nondiabetic groups, gram-negative bacterial colonization was significantly higher in diabetic patients (χ2=0.129, p=0.719 and χ2=5.60, p=0.018, respectively).

Conclusion:

Gram-negative bacteria are more common in the conjunctival flora of diabetic patients. This should be considered by clinicians when treating ocular infections in diabetic patients.

[Spectrum and susceptibility of preoperative conjunctival bacteria]

PURPOSE

To describe the conjunctival bacterial spectrum of our patients undergoing intraocular surgery and their antibiotic sensitivity during the study period.

METHODS

A retrospective study of preoperative conjunctival culture of patients consecutively scheduled for intraocular surgery from 21 February 2011 to 1 April 2013. Specimens were directly seeded onto blood-agar and MacConkey-agar (aerobiosis incubation, 2 days), and on chocolate-agar (6% CO2 incubation, 7 days). The identified bacteria were divided into 3 groups according to their origin; the bacteria susceptibility tests were performed on those more pathogenic and on some of the less pathogenic when more than 5 colonies were isolated. The sensitivity of the exigent growing bacteria was obtained with disk diffusion technique, and for of the non-exigent bacteria by determining their minimum inhibitory concentration. The Epidat 3.1 program was used for statistical calculations.

RESULTS

A total of 13,203 bacteria were identified in 6,051 cultures, with 88.7% being typical colonizers of conjunctiva (group 1), 8.8% typical of airways (group 2), and the remaining 2.5% of undetermined origin (group 3). 530 cultures (8.8%) were sterile. The sensitivity of group 1 was: 99% vancomycin, 95% rifampicin, 87% chloramphenicol, 76% tetracycline. Levels of co-trimoxazole, aminoglycosides, quinolones, β-lactams and macrolides decreased since 2007. The group 2 was very sensitive to chloramphenicol, cefuroxime, rifampicin, ciprofloxacin and amoxicillin/clavulanate. In group 3, to levofloxacin 93%, ciprofloxacin 89%, tobramycin 76%, but ceftazidime 53% and cefuroxime 29% decreased.

CONCLUSIONS

None of the tested antibiotics could eradicate all possible conjunctival bacteria. Bacteria living permanently on the conjunctiva (group 1) have achieved higher resistance than the eventual colonizers.

Pathogenic conjunctival bacteria associated with systemic co-morbidities of patients undergoing cataract surgery

PURPOSE

To identify the risk of patients undergoing cataract surgery of having pathogenic conjunctival bacteria associated with their systemic co-morbidities.

METHODS

Retrospective study of consecutive patients undergoing their first cataract operation from July 2005 to April 2010. Their preoperative conjunctival bacteria were cultured, identified, and classified in bacterial groups. Their co-morbidities were defined from their clinical data and the answers to systematic questions asked in the anaesthetic evaluation. The Microsoft Access databases of the two data sets were merged for carrying out the statistical analysis. Univariate association of each bacterial group with each co-morbidity was studied by using χ(2)-test for categorical data and Student's t-test for continuous variables. Also, logistic regression models were used adjusting for age and sex. SPSS statistic programme, version 18 was used for all these analyses. Endophthalmitis cases in this surgical series were searched.

RESULTS

In the 8333 selected patients, age was associated with increased conjunctival bacteria in all groups except for Streptococcus pneumoniae and Propionibacteriae. However, male sex was associated with these two groups and also with coagulase-negative Staphylococci, Corynebacterium xerosis, Staphylococcus aureus, and Gram-negative rods. After adjusting for age and sex, S. aureus was associated with diabetes, lung diseases, and renal and heart insufficiency; Gram-negative rods with smoking habit; Enterococci with diabetes; Streptococcus pneumoniae with kyphoscoliosis; and other Streptococci with diabetes and handicapped patients.

CONCLUSION

The more pathogenic conjunctival bacteria were more likely associated with patients' co-morbidities, such as diabetes, lung diseases, renal and heart insufficiency, kyphoscoliosis, and smoking habit, than the less pathogenic ones.

Conjunctival microbial florae in patients with seriously sulfur mustard induced eye injuries

INTRODUCTION

Ocular surface disorders and infections in sulfur mustard (SM) exposed patients are of particular clinical importance. The aim of the present study is to detect the conjunctival bacterial florae in patients with seriously SM induced eye injuries.

MATERIALS AND METHODS

Conjunctival bacterial florae of 143 seriously eye injured subjects as the study group was detected. The results were compared with 26 normal participants. Both groups were matched in age and sex. The samples were taken by sterile swab from interior fornixes of conjunctiva in both groups and were transported to microbiology laboratory by Stuart's Transport Medium. All samples were inoculated onto Blood agar, Mac Conkey agar and Chocolate agar and isolated microorganisms were identified by biochemical tests. The data were analyzed by SPSS and Man Whitney tests.

RESULTS

Nineteen cases (13.39%) and none of the controls (0%) had positive culture results (p = .043). Isolated microorganisms from patients included coagulase-negative staphylococci 10 cases (52.6%), Staphylococcus aureus 5 cases (26.3%), non enterobacteriaceae gram negative bacilli 2 cases (10.5%), Penicillium spp. 2 cases (10.5%), Citrobacter sp. 1 case (5.2%), non-spore forming Gram positive bacillus 1 case (5.2%) and α hemolytic streptococcus 1 case (5.2%). Two patients had mixed microorganisms and other patients had just one microorganism. Most of the S. aureus isolates were sensitive to usual antibiotics.

CONCLUSIONS

The results of this study showed that the prevalence rate of conjunctival bacterial isolates in patients with seriously SM induced ocular injuries are higher and potentially more dangerous than normal controls.

Comparison of different techniques of cataract surgery in bacterial contamination of the anterior chamber in diabetic and non-diabetic population

Aim:

To compare the bacterial contamination of the anterior chamber (AC) between manual small incision cataract surgery (SICS) and phacoemulsification (Phaco). To study the conjunctival flora and bacterial contamination of AC between well-controlled diabetics and non-diabetics.

Materials and Methods:

Three hundred and sixty-eight patients were randomized to manual SICS and Phaco. Sixty-eight patients were excluded for not completing follow-up or for intraoperative complications like posterior capsule rupture. One hundred and fifty patients in each group were finally analyzed. Conjunctival swabs were taken on admission, after one day of topical ofloxacin and 15 min after 5% Povidone Iodine (PI) instillation. AC aspirate at the end of the surgery was also cultured.

Results:

Fifty-six (18.66%) patients had positive conjunctival swab on admission which was reduced to 19 (6.33%) with topical ofloxacin and to five (1.66%) with instillation of 5% PI. AC contamination in both manual SICS and Phaco was 0.66%. The conjunctival flora in diabetics was similar to non-diabetics. None of the diabetics had AC contamination. Statistical analysis was performed by Chi-Square test (with Yates’ correction).

Conclusion:

Statistically significant reduction in conjunctival flora was achieved with topical ofloxacin and 5% PI instillation and AC contamination in both manual SICS and Phaco was minimal (0.66%). Well-controlled diabetics who underwent cataract surgery in this study had similar conjunctival flora and AC contamination as non-diabetics.

Prevention of postcataract endophthalmitis: evidence-based medicine

PURPOSE OF REVIEW

To provide a summary of current peer-reviewed publications on the methods of prophylaxis against postcataract endophthalmitis.

RECENT FINDINGS

Preoperative application of povidone-iodine remains the standard protocol for the prevention of postoperative endophthalmitis. More recent evidence suggests that intracameral cefuroxime administered at the conclusion of surgery significantly reduces the risk of endophthalmitis. However, its clinical use has been limited because of a lack of commercially available antibiotic indicated for intraocular injection. Although topical antibiotic application continues to be a controversial topic with respect to the types of antibiotic prescribed and dosage, most ophthalmologists do prescribe an antibiotic for the perioperative period. Resistance against antibiotics, including the very popular classes of fluoroquinolones, is rising. Most notably, methicillin resistance continues to increase over time.

SUMMARY

Prevention of postcataract endophthalmitis remains a difficult topic to study given the low incidence. In addition to appropriate wound construction, a combination of povidone-iodine and antibiotics provide a reasonable approach in reducing the risk of this rare but serious infection.

Diversity of bacteria at healthy human conjunctiva

PURPOSE

Ocular surface (OS) microbiota contributes to infectious and autoimmune diseases of the eye. Comprehensive analysis of microbial diversity at the OS has been impossible because of the limitations of conventional cultivation techniques. This pilot study aimed to explore true diversity of human OS microbiota using DNA sequencing-based detection and identification of bacteria.

METHODS

Composition of the bacterial community was characterized using deep sequencing of the 16S rRNA gene amplicon libraries generated from total conjunctival swab DNA. The DNA sequences were classified and the diversity parameters measured using bioinformatics software ESPRIT and MOTHUR and tools available through the Ribosomal Database Project-II (RDP-II).

RESULTS

Deep sequencing of conjunctival rDNA from four subjects yielded a total of 115,003 quality DNA reads, corresponding to 221 species-level phylotypes per subject. The combined bacterial community classified into 5 phyla and 59 distinct genera. However, 31% of all DNA reads belonged to unclassified or novel bacteria. The intersubject variability of individual OS microbiomes was very significant. Regardless, 12 genera-Pseudomonas, Propionibacterium, Bradyrhizobium, Corynebacterium, Acinetobacter, Brevundimonas, Staphylococci, Aquabacterium, Sphingomonas, Streptococcus, Streptophyta, and Methylobacterium-were ubiquitous among the analyzed cohort and represented the putative "core" of conjunctival microbiota. The other 47 genera accounted for <4% of the classified portion of this microbiome. Unexpectedly, healthy conjunctiva contained many genera that are commonly identified as ocular surface pathogens.

CONCLUSIONS

The first DNA sequencing-based survey of bacterial population at the conjunctiva have revealed an unexpectedly diverse microbial community. All analyzed samples contained ubiquitous (core) genera that included commensal, environmental, and opportunistic pathogenic bacteria.