Bacteria and Dry Eye: A Narrative Review

Genomics of Staphylococcus aureus and Enterococcus faecalis isolated from the ocular surface of dry eye disease sufferers

Ocular surface inflammatory disorders, such as dry eye, are becoming increasingly prevalent. Developing new treatment strategies targeting harmful bacteria could provide significant therapeutic benefits. The purpose of this study was to characterize the common ocular pathogen Staphylococcus aureus and the rarer endophthalmitis-associated species Enterococcus faecalis isolated from the ocular surface of dry eye disease patients in Norway. Together the 7 isolates (5 S. aureus and 2 E. faecalis) comprise the complete set of members of each species isolated in our previous study of the ocular microbiome of 61 dry eye sufferers. We aimed to investigate the pathogenic potential of these isolates in relation to ocular surface health. To this end, we used whole genome sequencing, multiplex PCR directed at virulence genes and antibiotic susceptibility tests encompassing clinically relevant agents. The E. faecalis isolates showed resistance to only gentamicin. S. aureus isolates displayed susceptibility to most of the tested antibiotics, except for two isolates which showed resistance to trimethoprim/sulfamethoxazole and three isolates which were resistant to ampicillin. Susceptibilities included sensitivity to several first-line antibiotics for treatment of ocular infections by these species. Thus, treatment options would be available if required. However, spontaneous resistance development to gentamicin and rifampicin occurred in some S. aureus which could be a cause for concern. Whole genome sequencing of the isolates showed genome sizes ranging from 2.74 to 2.83 Mbp for S. aureus and 2.86 Mbp for E. faecalis, which is typical for these species. Multilocus sequence typing and phylogenetic comparisons with previously published genomes, did not suggest the presence of eye-specific clusters for either species. Genomic analysis indicated a high probability of pathogenicity among all isolates included in the study. Resistome analysis revealed the presence of the beta-lactamase blaZ gene in all S. aureus isolates and the dfrG gene in two of them; while E. faecalis isolates carried the lsa(A) gene which confers intrinsic resistance to lincosamides and streptogramin A in this species. Screening for virulence factors revealed the presence of various pathogenicity associated genes in both S. aureus and E. faecalis isolates. These included genes coding for toxin production and factors associated with evading the host immune system. Some of the identified genes (tst, hylA & hylB) are suggested to be linked to the pathophysiology of dry eye disease. Lastly, the presence of specific S. aureus virulence genes was confirmed through multiplex PCR analysis.

Relationship Between Fluoroquinolone Resistance and Mutations in the Quinolone Resistance-Determining Region in Corynebacterium macginleyi

Purpose

The purpose of this study was to investigate the bacterial composition in the conjunctiva and to determine the relationship between fluoroquinolone resistance and mutations in the quinolone resistance-determining region (QRDR) in Corynebacterium macginleyi (C. macginleyi).

Methods

Bacteria isolated from conjunctival swabs of patients awaiting ophthalmic surgery or patients with presumed keratoconjunctivitis were included in this study. For C. macginleyi isolates from 49 samples, the minimum inhibitory concentrations (MICs) of second- to fourth-generation fluoroquinolones were determined by broth microdilution. Additionally, we determined the sequence of the QRDR in the gyrA gene of C. macginleyi-positive isolates by direct sequencing and investigated the relationship between the QRDR mutation and the MICs of fluoroquinolones for C. macginleyi.

Results

Among 423 eyes of 296 preoperative patients who underwent conjunctival culture testing, 105 eyes of 89 patients were culture-positive, and among 148 eyes of 147 patients with keratoconjunctivitis, 55 eyes of 54 patients were culture-positive. C. macginleyi accounted for the largest proportion of cultured organisms (34.8%). C. macginleyi-positive isolates were found in 45 eyes of 37 preoperative patients and in 4 eyes of 4 patients with keratoconjunctivitis. Direct sequencing revealed that 91.8% of C. macginleyi-positive isolates had amino acid mutations in the QRDR and 95.5% of mutations were found at Ser-87 and Asp-91. Isolates harboring double mutations at Ser-87 and Asp-91 were resistant to second- to fourth-generation fluoroquinolones. One isolate with double mutations at Ser-87 and Ala-88 but no mutation in Asp-91 showed intermediate susceptibility to moxifloxacin, a fourth-generation fluoroquinolone.

Conclusions

C. macginleyi isolated from conjunctiva harboring QRDR amino acid mutations were resistant to second- to fourth-generation fluoroquinolones.

Bridging the gap in managing dry eye disease: a consensus report by the Taiwan society of cataract and refractive surgeons

BACKGROUND

An impaired ocular surface presents substantial challenges in terms of planning for cataract surgery. As a multifactorial ocular disorder, dry eye disease (DED) is common in the general population and prevalent in patients scheduled for lens replacement surgery. Cataract surgery can exacerbate DED and worsen several ocular parameters. Timely diagnosis and appropriate treatment of DED are vital to ensuring positive ophthalmic surgical outcomes. This consensus report of the Taiwan Society of Cataract and Refractive Surgeons (TSCRS) regarding the management of DED before, during, and after cataract surgery highlights the gaps between clinical guidelines and several aspects of DED, including diagnostic testing, diagnostic criteria, and clinical practice treatment.

METHODS

An expert panel of five specialists in the field of ophthalmology was recruited to develop consensus statements regarding the management of DED in both the general population and in patients undergoing cataract surgery in Taiwan. Two separate meetings of the five specialists, who were endorsed by the TSCRS, were convened for this purpose. A survey questionnaire consisting of binary or multiple-choice questions was developed through a consensus-driven formulation process. A percentage value was calculated for each statement, and a minimum of 60% agreement (equivalent to three out of five members) was required to achieve consensus. The second discussion meeting involved the presentation of the finalized consensus statements and concluded the consensus development process. Lastly, the finalized consensus statements were approved by all the experts, and the formulated recommendations for DED in the general population and prospective cataract surgery patients were accordingly presented.

RESULTS

The optimal algorithm for managing DED in the general population and in patients scheduled for cataract surgery was developed to address the unmet needs of this cohort in Taiwan.

CONCLUSION

This report provides recommendations for managing dry eye disease. It is essential to screen and confirm DED through endorsed questionnaires and tests and then diagnose it. Treatment and management of DED should follow a stepwise approach. Screening and diagnosing DED is also recommended before cataract surgery. After cataract surgery, relatively aggressive treatment strategies are recommended to manage DED effectively.

The topical azithromycin meibomian gland dysfunction survey: The effect of topical azithromycin on signs and symptoms of meibomian gland dysfunction

INTRODUCTION

The aim of this study was to assess the long-term effects of topical azithromycin on signs, symptoms and self-management of meibomian gland dysfunction (MGD).

METHODS

Forty participants were assessed for MGD and its effect on the fluorescein tear break-up time (FTBUT). Participants were treated with topical azithromycin twice daily for 2 weeks and then once daily for a further 2 weeks. One year after treatment, 31 participants completed a survey assessing pre- and post-treatment effect on symptoms, lifestyle and self-treatment methods.

RESULTS

Following treatment, there was a significant reduction in MGD grading from a median of grade 2 to grade 0 (z = 4.40, p < 0.0001) and an increase in FTBUT from a median of 3-8 s (z = 4.75, p < 0.0001). One year afterwards, the survey showed a significant improvement in symptoms (sensitivity to light, grittiness, burning, blurred vision, all p < 0.03) and reduction in required self-treatments (lid wipes, tear substitutes, both p < 0.03). There was also a reduced impact on lifestyle (reading, night driving, computer use and watching television, all p < 0.0001) and in all environmental conditions (all p < 0.0001).

CONCLUSIONS

This study confirms the positive effect of topical azithromycin on MGD and shows it has a long-term impact on symptoms, self-treatment methods and lifestyle. This has implications for both chair time and healthcare costs when managing patients with MGD. Pending further clinical trials in a larger population with different demographics, topical azithromycin should be considered by all eyecare practitioners as a viable pharmacological treatment when managing MGD.

Higher incidence of meibomian gland dysfunction in postmenopausal women with primary acquired nasolacrimal duct obstruction

PURPOSE

This study aimed to investigate the incidence of meibomian gland dysfunction (MGD) in postmenopausal women with primary acquired nasolacrimal duct obstruction (PANDO) and enables ophthalmologists to pay attention to ocular surface damage before surgery.

METHODS

165 postmenopausal women with PANDO and 115 postmenopausal women with a normal lacrimal drainage system were enrolled in this prospective study. Based on the results of lacrimal duct irrigation and age, the participants were further subdivided. The incidence of different severities of MGD in different groups was calculated and analyzed by the chi-squared test.

RESULTS

The incidence of MGD in the PANDO group was 81.21%, and in the control group, it was 46.96%, which was significantly higher in the presence of PANDO (p < 0.001). The incidence of severe MGD in the complete and incomplete PANDO groups was higher than that in the control group (all p < 0.05), and no significant differences were observed between the complete and incomplete PANDO groups. The incidence of moderate MGD was significantly higher in the complete PANDO group than in the control group (p < 0.001). When age was considered an independent variable, the results revealed a significant value for patients aged < 70 years (p < 0.001).

CONCLUSIONS

Our study revealed a prodominantly high incidence of MGD in postmenopausal women with PANDO, especially in a complete PANDO or aged < 70 years. Ophthalmologists need to pay close attention to MGD in postmenopausal women with PANDO.

Infectious and Noninfectious Corneal Ulcers in Ocular Graft-Versus-Host Disease: Epidemiology, Clinical Characteristics, and Outcomes

PURPOSE

To evaluate the incidence, clinical characteristics, microbiological profile, and therapeutic outcomes of corneal ulcers in individuals with chronic ocular graft-vs-host disease (coGVHD).

DESIGN

Retrospective clinical cohort study.

METHODS

Review of individuals diagnosed with coGVHD following hematopoietic stem cell transplantation (HSCT) who were seen at the Bascom Palmer Eye Institute between May 2010 and November 2021. Baseline demographics, clinical characteristics, microbiological profile, risk factors for corneal ulceration, and treatment outcomes were collected. Etiology was deemed infectious in individuals with a positive culture or appropriate clinical scenario (presence of stromal infiltrate or hypopyon); otherwise, ulcers were presumed to be noninfectious. Treatment success was defined as reepithelialization with infiltrate resolution, and treatment failure as progression to corneal perforation or keratoplasty. Kaplan-Meier survival analysis estimated the incidence of ulceration. Cox regression analyses examined demographic and risk factors. Infectious and noninfectious ulcer groups were compared using 2-way independent t tests, 1-way analysis of variances, and χ2 tests, as appropriate.

RESULTS

173 individuals were included (53.7±14.4 years old; 59.0% male). Thirty-three individuals developed an ulcer 74.5±54.3 months after HSCT, with estimated 5- and 10-year incidences of 14% and 30%, respectively. Twenty-two (66.6%) ulcers were deemed infectious (15 microbiologically confirmed, 7 clinically) and 11 (33.3%) were deemed noninfectious. Risk factors for corneal ulceration included Black race (hazards ratio [HR] 2.89, 95% CI 1.30-6.42, P < .01), previous ocular surgery (HR 9.16, 95% CI 3.86-21.72, P < .01), eyelid margin abnormalities (HR 3.44, 95% CI 1.69-6.99, P < .01), and topical steroid use (HR 2.74, 95% CI 1.33-5.62, P < .01). Conversely, contact lens use reduced the risk of corneal ulceration (HR 0.29, 95% CI 0.13-0.66, P < .01). Infectious ulcers had a significantly higher frequency of treatment failure than noninfectious ulcers (57.1% vs 20.0%, P = .04).

CONCLUSION

Corneal ulceration is a potential complication of coGVHD, with several clinical features identified as risk factors. Infectious ulcers had worse outcomes than noninfectious ulcers.