Ocular flora in patients undergoing intravitreal injections: antibiotic resistance patterns and susceptibility to antiseptic picloxydine

Antimicrobials and antiseptics: Lowering effect on ocular surface bacterial flora - A systematic review

Topical antimicrobials and antiseptics are used perioperatively to reduce the ocular surface bacteria flora (OSBF) that are involved in the development of post-operative infectious complications. However, their effectiveness is still a controversial topic. This systematic review, performed according to the PRISMA guidelines and registered in PROSPERO, aims to provide an overview of the efficacy of the agents currently used in peri-cataract surgery and -intravitreal injections (IVI) in lowering the OSBF. Although effective in lowering OSBF, perioperative topical antimicrobials are associated with the risk of resistance development, with no obvious additional benefit compared with topical antisepsis. Conversely, the effectiveness of topical antiseptics before cataract surgery and IVI is strongly supported. Based on the available evidence, perioperative antimicrobials are not recommended, whereas the perioperative use of antiseptics is strongly recommended as prophylactic treatment for lowering the infection due to OSBF. Post-operative antimicrobials may be considered in eyes at higher risk for infection.

Is topical antibiotic use necessary to prevent surgical site infection following oculoplastic surgery?

PURPOSE

To assess whether oculoplastic surgeries can be performed without any topical and systemic antibiotics, in a "100% antibiotic free" fashion.

METHOD

We conducted a multicenter retrospective study between November 2017 and December 2022. Patients who underwent an oculoplastic procedure were screened. Patients who received preoperative or postoperative systemic antibiotics were excluded. Intraoperative IV antibiotics were allowed. Patients were divided into two groups: those who were treated with local antibiotics ointments (LATB group) and those who were treated without local antibiotics ointments (LATB free group) postoperatively. The primary outcome was the incidence of surgical site infections (SSI). The relationship between the use of local antibiotics and the occurrence of SSI was assessed using Fisher's exact test. The alpha risk was set to 5% and two-tailed tests were used.

RESULTS

Among the 947 procedures included, 617 were included in the LATB group and 330 in the LATB free group. 853 and 80 procedures were classified Altemeier class 1 (clean) and class 2 (clean-contaminated) surgeries, respectively. Overall, 310 (32.73%) procedures were performed without any systemic nor topical antibiotics (100% antibiotic free fashion). SSI occured in four (4/617; 0.65%) and five (5/330; 1.52%) procedures in the LATB and LATB free group respectively, without any statistical difference between the groups (p = 0.290). A subgroup analysis was carried out by excluding the procedures performed under prophylactic intraoperative intravenous antibiotics and did not reveal any statistical difference between the two groups (p = 0.144). All SSI patients were treated with systemic antibiotics with favorable outcomes. Postoperative wound dehiscence was the only risk factor associated with postoperative SSI (p = 0.002).

CONCLUSION

This study suggests that performing a "100% antibiotic free" oculoplastic surgery without systemic and topical antibiotics is reasonable in Altemeier class 1 and class 2 procedures.

In praise of povidone-iodine application in ophthalmology

Polyvinyl pyrrolidone or povidone-iodine (PVP-I) is a water-soluble complex formed by the combination of iodine and a water-soluble polymer, polyvinyl pyrrolidone. This complex exerts bactericidal, fungicidal, and virucidal action by gradually releasing free iodine at the site of application to react with pathogens. In ophthalmology, PVP-I is used as a disinfectant and antiseptic agent for preoperative preparation of the skin and mucous membranes and for treating contaminated wounds. PVP-I has been shown to reduce effectively the risk of endophthalmitis in various ocular procedures, including cataract surgery and intravitreal injections; however, it has also been used in the treatment of conjunctivitis, keratitis, and endophthalmitis, with promising results especially in low-resource situations. PVP-I has been associated with complications such as postoperative eye pain, persistent corneal epithelial defects, ocular inflammation, and an attendant risk of keratitis. In cases of poor PVP-I tolerance, applying PVP-I at lower concentrations or using alternative antiseptics such as chlorhexidine should be considered. We provide an update on the efficacy of PVP-I in the prophylaxis and treatment of conjunctivitis, keratitis, and endophthalmitis and a comprehensive analysis of the current literature regarding the use of PVP-I in the management of these ocular conditions. Also, PVP-I-related adverse effects and toxicities and its alternatives are discussed. The goal is to present a thorough evaluation of the available evidence and to offer practical recommendations for clinicians regarding the therapeutic usage of PVP-I in ophthalmology.

Corneal foreign bodies: are antiseptics and antibiotics equally effective?

PURPOSE

To compare the effect of antiseptics and antibiotics on the occurrence of Infectious Keratitis (IK) secondary to Corneal Foreign Body (CFB) removal.

METHODS

Multicenter retrospective study conducted between June 2020 and June 2022 in patients referred for CFBs and treated with Picloxydine (Group 1) or Tobramycin (Group 2) for 7 days. A follow-up visit was scheduled on Day 3 (D3) and a phone call on D30. The primary outcome measure was the occurrence of IK.

RESULTS

307 patients (300 men) with a mean age of 42.8 (14.8) years were included. The mean (SD) time to consultation was 43.1 (45.6) hours. Picloxydine and Tobramycin were given to 155 and 152 patients. Half of patients (n = 154, 50.2%) were building workers and 209 (68.1%) did not wear eye protections. CFBs were mainly metallic (n = 292, 95.1%). Upon referral, rust was found in 220 patients (72.1%). A burr was used in 119 (38.9%) patients. IK occurred in 15 (4.9%) patients, 8 (5.3%) in Group 1 and 7 (4.5%) in Group 2 (p = 0.797). IK was successfully treated in all cases. Persistent rust was found in 113 patients (36.9%) on D3 without difference between burr or needle use (p = 0.278). On D3, corneal healing was delayed in 154 patients (47.2%), mainly in burr-treated patients (p = 0.003). The mean (SD) work stoppage duration was 0.32 (0.98) days.

CONCLUSION

IK rate was 4.9%. The efficacy of antibiotics and antiseptics was similar on CFB removal. Using a burr was associated with a longer healing time. CFBs had a limited social impact.

Prophylaxis of Ocular Infection in the Setting of Intraocular Surgery: Implications for Clinical Practice and Risk Management

In this review we discuss the role of intraocular surgery preoperative prophylaxis. The correct choice of antimicrobial drug is variable in each surgical setting, according to the available strengths of evidence, the anatomical district involved, and the type of procedure. In the ophthalmic surgical field, there has been a progressive shift from antibiotic formulations, which are known to cause antibiotic resistance, to a new class of antiseptic compounds, which proved to be effective not only against bacteria, but also against fungi, protozoa, and viruses. Among these, povidone-iodine (PVI) is a water-soluble polymer that can form a complex with iodine, and the perioperative application of PVI 5-10% eye drop for 3 min is the gold standard for infection prophylaxis. A new formulation of 0.6% PVI eye drop is a new option for infection prophylaxis in the days before surgery. Chlorhexidine is a biguanide compound, which is a valid alternative with a good safety and efficacy profile and is the antiseptic of choice in patients with iodine allergy. New compounds that are currently being studied include polyhexamethylene biguanide (PHMB), picloxydine, ozone, hypochlorous acid (HOCl), and Biosecur. PHMB is a biguanide polymer that was found to be more effective than PVI in in vitro studies for reducing microorganisms and extending the duration of antisepsis, but to date, there are no formulations available on the market for preoperative ocular surgery in which it is present as main ingredient. Ozone is a molecule with oxidizing effect, which showed interesting preliminary results but is not effective against virus, Staphylococcus aureus and Candida albicans. HOCl has a natural bactericidal propriety but its applicability to prophylaxis of ocular infection in the setting of ocular surgery is not established. Biosecur is a non-toxic organic alcohol-free compound that exhibited bactericidal and fungicidal effect versus all common microorganisms and is currently available as an ocular spray.

Povidone-Iodine Adverse Effects and Alternatives for Ocular Procedures

Purpose: Povidone-iodine (PVI), also known as Betadine, is a widely used antiseptic agent used in several fields of medicine. In ophthalmology, it is applied as a preoperative antiseptic to prevent infectious complications that can result from surgical procedures. PVI's safety and efficacy have been extensively studied and represented in the literature; however, the incidence of adverse effects has been reported in conjunction. The aim of this paper is to compile information regarding PVIs use, safety profile, adverse effects, and possible alternatives through a review of the existing literature. Methods: Literature was compiled utilizing the database PubMed and Google Scholar using specified keywords with a total of 86 reviewed articles, after excluding search results that did not meet the inclusion criteria. Results: While the allergic potential to PVI is a highly contested topic, there are several nonallergic adverse effects of PVI that should not be overlooked. These effects include chemical burn, cytotoxic effects, and general patient discomfort. In light of these adverse effects, alternatives to PVI may be considered. However, there has been little research identifying feasible alternatives in preoperative intraocular procedures. Alternatives including chlorhexidine, polyhexamethylene biguanide (polyhexanide), and octenidine were identified as potential substitutes for PVI. Conclusions: Further study is needed to provide robust evidence regarding the efficacy profiles of these alternatives in comparison with PVI and to demonstrate comparable tolerance to PVI in intraocular procedures.

[Antibacterial effect of the antiseptic picloxydine dihydrochloride on conjunctival isolates of gram-negative bacteria]

The preoperative and postoperative use of antiseptics can be an alternative to antibiotics in repeated courses of anti-VEGF therapy for reducing the risk of developing antibiotic resistance in eye microflora. Among gram-negative bacteria, the most frequently isolated pathogen that causes eye infections is Pseudomonas aeruginosa, which is characterized by reduced sensitivity to antibiotics and disinfectants.

PURPOSE

To study the effect of the antiseptic picloxydine dihydrochloride on the gram-negative bacteria Escherichia coli, Pseudomonas luteola and P. aeruginosa isolated from the conjunctiva.

MATERIAL AND METHODS

The identification of bacterial isolates and study of their sensitivity to antibiotics were carried out using the automated bacteriological analyzer BD Phoenix 100. To determine the bactericidal concentration, the method of serial dilutions of the antiseptic in a liquid nutrient medium was used. The binding of cationic molecules of picloxydine dihydrochloride to bacterial cells was detected by neutralizing the bacterial surface with increasing amounts of antiseptic, and measuring the zeta potential on the Zetasizer Nano ZS analyzer. The ultrastructure of bacterial cells was studied using the two-beam scanning ion-electron microscope Quanta 200 3D.

RESULTS

The most resistant was P. aeruginosa. The interaction mechanism of picloxydine dihydrochloride with bacterial cells includes electrostatic binding of positively charged antiseptic molecules to negatively charged cell walls. Picloxydine dihydrochloride has a destructive effect on the bacterial cell wall and plasma membrane, which leads to cell lysis and release of intracellular components.

CONCLUSION

Picloxydine dihydrochloride exhibits bactericidal activity against gram-negative conjunctival isolates and is promising for preventive use during repeated courses of intravitreal injections.

Efficacy of a New Commercial Ocular Spray Containing Oftasecur Citrus Extract for Reducing Microbial Load in the Conjunctiva of Patients Receiving Intravitreal Injections

INTRODUCTION

The control of conjunctival microbial load is crucial for patients receiving intravitreal injections (IVTs) in order to reduce the risk of endophthalmitis. The purpose of this work was to assess the antimicrobial activity of a new commercial ocular spray containing Biosecur citrus extract (Oftasecur^®, Off Health, Florence, Italy).

METHODS

This prospective cross-sectional pilot study included patients receiving IVTs who were instructed to apply Oftasecur spray onto the eye to be injected four times daily starting 4 days before surgery. The contralateral eye was considered the control. A conjunctival swab for microbiological analysis was performed in both eyes before starting study treatment and at the time of the injection. The Brief Ocular Discomfort Inventory (BODI) questionnaire was administered to patients based on an 11-point scale (0 for no discomfort and 10 for maximum discomfort).

RESULTS

Thirty patients (15 male, 15 female; mean age 64.7 ± 11.6 [standard deviation, SD] years) were included. Before starting treatment, 53.3% of the total eyes tested positive during the microbiological analysis. After the treatment period, only 20% of the eyes tested positive at the time of injection, showing a significant reduction in the microbial load (p < 0.01). Moreover, in the treated arm, the positive swabs before and after the prophylactic treatment with Oftasecur ocular spray showed a significant reduction (from 70.4% to 29.6%; p = 0.003, McNemar's test). Oftasecur ocular spray was well tolerated, with an average BODI score of 1.2 (± 0.70 SD).

CONCLUSION

Oftasecur ocular spray showed antimicrobial activity that significantly reduced the microbial load in patients receiving intravitreal injections. Therefore, it may have a role in the prophylaxis of infection in the setting of IVTs.

Novel Needle for Intravitreal Drug Delivery: Comparative Study of Needle Tip Aspirates, Injection Stream and Penetration Forces

Purpose

To study the efficacy of a novel needle for intravitreal injection (IVI) in comparison to the conventional needle under experimental conditions.

Methods

The newly designed 30-gauge (G) needle (NDN) (EP 18158 542.3, patent pending) with occluded outer orifice and a side port for drug delivery was compared to the conventional standard hypodermic 30 G needle for IVI (SHN). An animal study to obtain needle tip aspirates was performed on 10 albino rat eyes. During IVIs, cellular content, which was cut by the needle tip, was aspirated. Cellular material was studied in regard to cell types and their quantity. The injection stream was studied using trypan blue dye in vitro and pig cadaver eyes. The penetration force was tested on polyurethane Testing Foil Strips PU 04 (Melab, Leonberg, Germany) by applying a velocity of 100 mm/min. The results were analyzed using descriptive statistics, correlation matrices and t-test methods with p<0.05 as statistically significant.

Results

Cytological analysis of the needle aspirates showed the presence of cellular content in each case. The amount of conjunctival, ciliary body epithelial cells and granulated basophilic protein sediments (sign of cellular damage) in the case of the NDN tips was significantly lower compared to the SHN. The average penetration force of the NDN was 0.791 N, and in the case of the SHN was 0.566 N. The injection stream study revealed a difference in the initial injection phase between the two needle types, although the diffuse filling of the vitreous area which surrounded the needle tip appeared to be similar.

Discussion

The NDN demonstrated superior performance with regard to a significantly reduced number of cells being captured by the needle tip. Delivery of the injected fluid into the vitreous cavity was comparable. In order to investigate superior properties of the NDN needle design, further studies with improved prototypes would be necessary.