Bacterial contamination of intravitreal needles by the ocular surface microbiome

Topical Antiseptics in Minimizing Ocular Surface Bacterial Load Before Ophthalmic Surgery: A Randomized Controlled Trial

PURPOSE

To investigate the reduction of the ocular surface bacterial load induced by 2 commercially available ophthalmic antiseptic formulations, povidone-iodine (PVI) 0.6% and chlorhexidine (CLX) 0.02%, before ocular surgery.

DESIGN

Randomized controlled trial.

METHODS

Seventy adult patients undergoing intraocular surgery (phacoemulsification) were randomized to receive in the index eye PVI (group A) 4 times a day for 3 days or CLX (group B) 4 times a day for 3 days before surgery. The untreated eye was used as control. A conjunctival swab was taken in both eyes before (T0) and after (T1) therapy. Microbial DNA was quantified with real-time polymerase chain reaction (PCR) analysis. The Mick algorithm was used to compare the abundance of each genus/genera against the distribution of abundances from the reference. At T1, patients filled a questionnaire to evaluate therapy-induced symptoms. Primary outcome was the reduction of bacterial DNA at T1 (microbial load), vs control arm, expressed as mean number of real-time PCR cycle times (CTs). Secondary outcomes were taxonomic composition, differential abundance, and therapy-induced ocular symptoms.

RESULTS

The T0-T1 difference in CT was significant in group B, but not in group A (mean [95% CI], 0.99 [0.33] vs 0.26 [0.15], P < .001, and 0.65 [0.3] vs 0.45 [0.41], P = .09, respectively). The taxonomic composition, alpha, and beta diversity remained consistent at all time points in both groups. The rate of patients reporting therapy-induced ocular symptoms and the mean discomfort grade were greater in group A than in group B (97% vs 26% and 4.97±2.48 vs 0.66±1.53, respectively).

CONCLUSIONS

Compared with PVI 0.6%, CLX 0.02% induced a greater reduction of ocular surface bacterial load, with no significant alterations of the taxonomic composition. Moreover, CLX was better tolerated than PVI.

Ocular microbiome changes in dry eye disease and meibomian gland dysfunction

The most common and chronic ocular problem of aging is dry eye disease (DED) and the associated condition of meibomian gland dysfunction (MGD). The resident ocular surface bacteria may have a role in maintaining homeostasis and perturbation may contribute to disease development. The aim of this study was to compare the microbiomes of the conjunctiva and eyelid margin in humans with mild and moderate DED and controls using 16 S rRNA gene sequencing. The conjunctiva and lid margin of three cohorts (N = 60; MGD, MGD with lacrimal dysfunction [MGD + LD] and controls) were swabbed bilaterally three times over three months. Microbial communities were analysed by extracting DNA and sequencing the V3-V4 region of the 16 S ribosomal RNA gene using the Illumina MiSeq platform. Sequences were quality filtered, clustered into amplicon sequence variants (ASVs) using UNOISE algorithm and taxonomically classified using a Bayesian Last Common Ancestor (BCLA) algorithm against the GTDB 2207 database. The overall microbial communities of the MGD, MGD + LD and control groups were significantly different from each other (P = 0.001). The MGD and MGD + LD dry eye groups showed greater variability between individuals compared to the control (PERMDISP, P < 0.01). There was decreased richness and diversity in females compared to males for the conjunctiva (P < 0.04) and eyelid margin (P < 0.018). The conjunctiva in the MGD + LD group had more abundant Pseudomonas azotoformans, P. oleovorans and Caballeronia zhejiangensis compared to MGD and control (P < 0.05), while the MGD group had more abundant Corynebacterium macginleyi and C. kroppenstedtii compared to control (P < 0.05). The lid margin in MGD was more abundant in C. macginleyi, C. accolens, and C. simulans compared to the MGD + LD and control (P < 0.05). There were differences in the overall microbial community composition and certain taxa, including increased levels of lipophilic bacteria, on the conjunctiva and eyelid margin in mild to moderate DED/MGD compared to controls. DED/MGD was also associated with a reduced bacterial richness and diversity in females.

Delineation of the bacterial composition in exogenous endophthalmitis using 16S rDNA sequencing

PURPOSE

To determine the bacterial spectrum of exogenous endophthalmitis of different origins, namely, posttraumatic, postcataract surgery, filtering bleb-associated, and intravitreal treatment-related endophthalmitis, using the 16S rDNA sequencing method.

METHODS

Aqueous humor or vitreous humor samples were collected from 24 endophthalmitis patients. Traditional cultivation and 16S rDNA sequencing were conducted with these samples. Three senile cataract controls and one intraocular irrigating solution were used as sequencing control.

RESULTS

Eleven of the 24 samples (45.8%) obtained positive bacterial cultivation, and each sample positive for only one species. The 11 culture-positive species could all be identified in their corresponding sequencing results, but only four strains being the top one pathogen in the sequencing. A total of 567 species were isolated using 16S rDNA sequencing, with the top five species being Pseudomonas sp., Staphylococcus epidermidis, Staphylococcus sp., Streptococcus sp., and Enterococcus faecalis. The dominant bacterial strains varied among the different endophthalmitis categories but with no significant difference in the overall bacterial spectrum. Bacterial atlas containing Pseudomonas, Streptococcus, Staphylococcus, Actinomycetales_unclassified, Thermus, and Janibacter was shared by the four categories. Aqueous humor bacterial profile showed a higher overlap with contaminating bacteria from the environment.

CONCLUSIONS

16S rDNA sequencing is more efficient for endophthalmitis pathogen screening than the traditional cultivation method in terms of positive detection rate and the number of bacteria identified. But the risk of environmental contamination exists when using 16S rDNA sequencing method for endophthalmitis diagnosis. Different categories of endophthalmitis displayed diversified bacterial composition.

Kocuria Endophthalmitis: Clinical Spectrum and Long-term Outcomes

PURPOSE

To expand the knowledge regarding the clinical presentation of Kocuria endophthalmitis.

METHODS

We included six cases of Kocuria endophthalmitis between January 2018 and December 2020. From all cases, we collected general demographic data, relevant medical, ophthalmological history, microbiological and antibiotic sensitivity results. All cases had a minimum follow-up of 9 months. All cases were treated with intravitreal moxifloxacin and dexamethasone and pars plana vitrectomy. Undiluted vitreous, corneal, conjunctival, and aqueous samples were cultured and analyzed with the Vitek 2 system.

RESULTS

The prevalence of Kocuria endophthalmitis was 6%. (95%CI: 2.26%-12.73%). The mean age at diagnosis was 60.5 ± 15.5 years. All patients had poor visual acuity, severe pain, and severe conjunctival hyperemia at diagnosis. Only one case had a significant improvement in visual acuity at the end of the follow-up.

CONCLUSION

Kocuria spp are an emerging cause of endophthalmitis and should be considered as part of the differential diagnosis.

Association of Antibiotic Alterations in Gut Microbiota With Decreased Osseointegration of an Intramedullary Nail in Mice With and Without Osteomyelitis

Treatment of osteomyelitis requires prolonged antibiotic therapy which significantly alters the gut microbiota. While the influences on bone mass and microstructure have been extensively studied, it is poorly understood what impact the changes in gut microbiota may have on the host response to osseointegration around an intramedullary nail implanted. Here, we explored the influence of gut microbiota on the bone osseointegration process around an implant under two conditions: implantation of an intramedullary nail in the bone marrow cavity and chronic osteomyelitis (CO) induced by Staphylococcus aureus infection. Body weight, hepatorenal functions, serum levels of proinflammatory cytokines were monitored. The composition of gut microbiota was assessed via 16S rRNA sequencing, and the bone condition was analyzed via micro-computed tomography, hematoxylin and eosin staining, Safranin O-fast green and Goldner's trichrome staining. Osteoblastogenesis and osteoclastogenesis were assessed by detecting tartrate-resistant acid phosphatase and osterix expression. We found that perturbation of gut microbiota (increase in Proteobacteria and decrease in Bacteroidetes) associated with delayed osseointegration and increased levels of proinflammatory cytokines in the serum (p<0.05), lower bone mass (p<0.05), deficient endochondral ossification and bone formation, reduced osteoblastogenesis (p<0.05) and enhanced osteoclastogenesis (p<0.001). Survival rates (p=0.002) and bacterial loads (p=0.0363) in bone differed significantly between the CO and antibiotic-treated CO mice, but cytokines levels, bone mineral density, and bone formation did not differ, likely because of the severely damaged bone structure. In summary, antibiotic treatment perturbed the gut microbiota and significantly interfered with the bone osseointegration around the nail by increasing proinflammatory cytokine levels in circulation, inhibiting osteoblastogenesis, enhancing osteoclastogenesis, and thus leading to higher pathogen colonization as well as higher mortality postinfection. This report of ours is the first to demonstrate antibiotic-induced alterations in the gut microbiota affect bone osseointegration, helping us understand the role of gut microbiota disorders in osteoblastogenesis and osteoclastogenesis following implant insertion with or without infection.