Prospective, Randomized Clinical Trial of Povidone-Iodine 1.25% Solution Versus Topical Antibiotics for Treatment of Bacterial Keratitis

Progressive ulcerative keratitis in dogs in the United Kingdom: Microbial isolates, antimicrobial sensitivity, and resistance patterns

OBJECTIVES

The objective of the study was to identify bacterial pathogens and their antimicrobial sensitivity profile associated with cases of canine progressive ulcerative keratitis.

MATERIALS AND METHODS

Analysis of microbial culture and sensitivity results from dogs with progressive ulcerative keratitis presenting to a UK referral practice between December 2018 and August 2020.

RESULTS

Positive bacterial cultures were obtained from 80/148 (54%) of the canine ulcers sampled with 99 bacterial isolates cultured. Streptococcus canis (n = 29), Pseudomonas aeruginosa (n = 19), and Staphylococcus pseudintermedius (n = 16) were the most common isolates. Pseudomonas aeruginosa was more likely to be isolated whether the ulcer was clinically malacic at the time of sampling (OR = 10.1, p < .001). Ulcers treated prior to culture with fusidic acid were 7.6 times more likely to be positive than those treated with any other antimicrobial(s). Bacterial isolates demonstrated resistance against neomycin (85%), fusidic acid (78%), and tetracycline (68%). Conversely, isolates were most likely to be sensitive to gentamicin (88%), ofloxacin (77%), ciprofloxacin (73%), and chloramphenicol (64%). Antimicrobial combinations of chloramphenicol or gentamicin with a fluoroquinolone (ofloxacin or ciprofloxacin) or chloramphenicol combined with gentamicin were the most effective on in vitro analysis (over 90% susceptibility of all isolates).

CONCLUSION

The most common bacterial species associated with canine progressive ulcerative keratitis in a UK referral population were S. canis, P. aeruginosa, and S. pseudintermedius. Combination antimicrobial therapy is recommended pending culture and sensitivity results given the varied antimicrobial susceptibility profiles and significant bacterial in vitro resistance to antimicrobial monotherapy.

Topical Vancomycin is More Efficient than Povidone-Iodine Treatment in Controlling Bacterial Growth in Methicillin-Resistant Staphylococcus Aureus Keratitis Model in Rabbits

To evaluate the efficacy of topical vancomycin and povidone iodine (PI) application on methicillin-resistant Staphylococcus aureus (MRSA) keratitis model in rabbits.

MRSA keratitis was induced by injecting 0.1 mL MRSA containing 1000 colony-forming units (CFU) into central cornea of right eyes of 24 New Zealand White rabbits. Animals were divided into four groups (n = 6): control (treated with balanced salt solution), 50 mg/mL topical vancomycin, 5% topical PI, and combination; examined before and after treatment, and corneal tissues were harvested for analysis at 9th hour of treatment.

Bacterial load was determined as: 7.63 ± 0.82 log10 CFU/g in control group, 6.95 ± 1.66 log10 CFU/g in PI group, 4.67 ± 0.77 log10 CFU/g in combination group, and 4.33 ± 0.71 log10 CFU/g in vancomycin group (p = 0.001). Median of total clinical score increased significantly from 7 [range: 5-8] to 11.5 [range: 11-15] (p = 0.001) in control group, did not change (6 [range: 5-8] to 7 [range: 5-7]; p = 0.695) in vancomycin group, increased significantly from 7 [range: 5-8] to 12.5 [range: 10-14] (p < 0.001) in PI group, increased significantly from 6.5 [range: 5-7] to 8 [range: 7-9] in combination group (p = 0.002). Post-treatment clinical scores for chemosis, conjunctival injection, iritis, hypopyon, epithelial erosion, and corneal infiltrate were significantly lower in vancomycin-treated groups compared to others (p < 0.05). In PI-treated groups, especially scores for chemosis, conjunctival injection, epithelial erosion and corneal infiltrate were significantly higher than vancomycin (p < 0.05).

Topical vancomycin significantly inhibited bacterial growth in MRSA keratitis. However, PI was ineffective in controlling this growth; additionally, exerted toxic effect on ocular surface. When vancomycin was combined with PI, no additional increase in efficacy of treatment was detected compared to only vancomycin.

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.

A systematic review and meta-analysis on the efficacy of topical povidone iodine in adenoviral conjunctivitis

PURPOSE

To evaluate if topical povidone iodine (alone (PI) or combined with dexamethasone (PI-DXM)) is superior to placebo for treating adenoviral conjunctivitis (AC).

METHODS

A systematic review was performed according to Preferred Reporting Items for the Systematic Review and Meta-Analyses (PRISMA) Statement. An electronic search was made on PubMed, Embase and Cochrane Library. Randomized control studies that compared PI or PI-DXM with placebo were included. At least three researchers were involved in all phases. Primary outcomes were AC duration and the number of clinical resolutions during the first week. Secondary outcomes were conjunctival redness and serous discharge one week after starting treatment and the rate of AC complications.

RESULTS

Only five studies met the inclusion criteria. PI-DXM reduced the duration of the disease by 2.4 days (IC95% 4.09-0.71), however this result was based only in one study. PI and PI-DXM did not modify the probability of clinical resolution during the first week; relative risk (RR) = 1.77 (IC95% 0.63-4.96) and 1.70 (IC95% 0.67-4.36). The impact of PI on the probability of pseudomembranes could not be estimated. PI-DXM did not influence the risk of developing subepithelial infiltrates RR = 0.73 (IC95% 0.02-33.38).

CONCLUSIONS

At this time there is great uncertainty about the usefulness of PI on the course of adenoviral conjunctivitis. PI-DXM may have a small effect on AC duration. To make future reviews possible, it is important to standardize the way in which these results are reported. Futures studies should include etiological confirmation, unit of study (eyes vs patients) and report on those aspects that are more relevant for patient quality of life (duration of the disease, development of complications: pseudomembranes and subepithelial infiltrates).

Topical antibiotics for treating bacterial keratitis: a network meta‐analysis

This is a protocol for a Cochrane Review (prototype). The objectives are as follows:

To compare the effectiveness and safety of topical antibiotics for treating BK and to rank different interventions through a systematic review and NMA.

The clinical treatment of bacterial keratitis: A review of drop instillation regimes

Bacterial keratitis (BK) presentations are often treated using the commercially available second-generation fluoroquinolones ciprofloxacin 0.3% and ofloxacin 0.3% as monotherapy. The guidelines available for instillation regimes are often not supported by data from clinical studies. This review examines the peer-reviewed clinical studies and compared treatment failure rates for ciprofloxacin 0.3% and ofloxacin 0.3% for BK in relation to Day-1 drop-regimes. From the statistical analysis, this review derived evidence-based clinically applicable minimum drop-regimes for the treatment of BK on Day-1. Lower numbers of drops of ciprofloxacin on Day-1 were significantly associated with increased treatment failure rates (p < 0.002). The derived minimum number of drops on Day for ciprofloxacin on Day-1 was 47 drops, and for ofloxacin 24 drops. The mean number of drops used in the clinical studies was significantly lower than the manufacturers' recommended Day-1 regimes for both ciprofloxacin (p = 0.0006) and ofloxacin (p = 0.048). From Day-3 to -6 of treatment the drop rates for ciprofloxacin relative to recommended rates were higher, and for ofloxacin lower (p = 0.014). The findings of this review were then compared with a representative sample of published guidelines and case studies to determine the validity of applying those drop-regimes in clinical practice. Although the manufacturers' suggested minimum drop-regimes on Day-1 were significantly different (120 drops ciprofloxacin, 34 drops ofloxacin, p < 0.0001), many of the published guidelines suggested the same drop-regime for both fluoroquinolones. The suggested drop numbers on Day-1 for ciprofloxacin in these guidelines and case studies were significantly less than those used in the clinical studies (p = 0.043). Increased treatment failure rates for ciprofloxacin are associated with lower drop numbers on Day-1. The Day-1 dosing rates for ciprofloxacin and ofloxacin should be considered separately, and the regimes suggested in published guidelines and case studies may need be re-considered in light of the findings of this review.

Doctor I Have an Iodine Allergy

Ophthalmologists frequently face patients who refuse asepsis protocols involving povidone-iodine (PI) due to claims of an allergy to iodine. Such patients usually base this claim on previous reactions to shellfish consumption or to imaging procedures that used iodine-based contrast agents. Allergy to iodine, however, is biologically impossible, and iodine deficiency causes severe developmental problems, including mental retardation. Furthermore, shellfish allergy is due to tropomyosins in muscle tissue, and reactions to intravascular contrast dyes are due to hyperosmolar solutions; neither “allergy” is due to iodine. PI, which contains 9–12% iodine, is the preferred antiseptic for ophthalmic procedures. Experience shows that PI can be administered safely to patients claiming iodine allergy. True allergy to PI is rare and, if indicated, skin patch testing can be performed prior to surgery. Patients who react adversely to highly concentrated (5–10%) PI usually experience toxicity to the corneal and conjunctival epithelium after topical administration. Dilute (0.1–0.25%) PI kills microbes quicker than higher concentrations but for shorter periods of time because the total dose of iodine is smaller. Repeated administration (every 20–30 s) of dilute PI effectively kills microbes for as long as necessary with little risk of epithelial toxicity.

Antiseptics and the Ocular Surface: In Vitro Antimicrobial Activity and Effects on Conjunctival and Corneal Epithelial Cells of a New Liposomal Ocular Spray Containing Biosecur® Citrus Extract

Introduction

Methods

Results

Conclusion

The Role of Topical Povidone-Iodine in the Management of Infectious Keratitis: A Pilot Study

The aim of this prospective explorative study was to evaluate the safety and the effectiveness of topical polyvinylpyrrolidone-iodine (PVP-I) administered during the time-to-results period for pathogen identification and susceptibility testing in patients with infectious keratitis (IK). A corneal swab (CS) for antimicrobial evaluation was performed at enrollment (T0) and topical 0.66%-PVP-I was administered until the laboratory results were available (T1). Ulcer and infiltrate areas and infiltrate depths were compared between T0 and T1 (i.e., time-to-result period). Patients were then shifted to a specific antimicrobial therapy and followed up until resolution of their infiltrates (Tlast-TL). Twenty-five eyes were enrolled, and none showed clinical worsening leading to protocol withdrawal. At T1, ulcer and infiltrate areas showed significant improvement in Gram-positive IK (n = 13–52%; p = 0.027 and p = 0.019, respectively), remained stable in fungal IK (n = 5–20%; both p = 0.98) and increased in those with Gram-negative bacteria (n = 4–16%; p = 0.58 and p = 0.27). Eyes with negative cultures (n = 3–12%) showed complete resolution at T1 and did not initiate any additional antimicrobial therapy. The administration of 0.66% PVP-I during the time-to-result period seems to be a safe strategy in patients with IK while often sparing broad-spectrum antimicrobial agents. In addition, it showed to be effective in eyes with a Gram-positive bacterial infection.

Bacterial keratitis: identifying the areas of clinical uncertainty

Bacterial keratitis is a common corneal infection that is treated with topical antimicrobials. By the time of presentation there may already be severe visual loss from corneal ulceration and opacity, which may persist despite treatment. There are significant differences in the associated risk factors and the bacterial isolates between high income and low- or middle-income countries, so that general management guidelines may not be appropriate. Although the diagnosis of bacterial keratitis may seem intuitive there are multiple uncertainties about the criteria that are used, which impacts the interpretation of investigations and recruitment to clinical studies. Importantly, the concept that bacterial keratitis can only be confirmed by culture ignores the approximately 50% of cases clinically consistent with bacterial keratitis in which investigations are negative. The aetiology of these culture-negative cases is unknown. Currently, the estimation of bacterial susceptibility to antimicrobials is based on data from systemic administration and achievable serum or tissue concentrations, rather than relevant corneal concentrations and biological activity in the cornea. The provision to the clinician of minimum inhibitory concentrations of the antimicrobials for the isolated bacteria would be an important step forward. An increase in the prevalence of antimicrobial resistance is a concern, but the effect this has on disease outcomes is yet unclear. Virulence factors are not routinely assessed although they may affect the pathogenicity of bacteria within species and affect outcomes. New technologies have been developed to detect and kill bacteria, and their application to bacterial keratitis is discussed. In this review we present the multiple areas of clinical uncertainty that hamper research and the clinical management of bacterial keratitis, and we address some of the assumptions and dogma that have become established in the literature.

Paradox of complex diversity: Challenges in the diagnosis and management of bacterial keratitis

Bacterial keratitis continues to be one of the leading causes of corneal blindness in the developed as well as the developing world, despite swift progress since the dawn of the "anti-biotic era". Although, we are expeditiously developing our understanding about the different causative organisms and associated pathology leading to keratitis, extensive gaps in knowledge continue to dampen the efforts for early and accurate diagnosis, and management in these patients, resulting in poor clinical outcomes. The ability of the causative bacteria to subdue the therapeutic challenge stems from their large genome encoding complex regulatory networks, variety of unique virulence factors, and rapid secretion of tissue damaging proteases and toxins. In this review article, we have provided an overview of the established classical diagnostic techniques and therapeutics for keratitis caused by various bacteria. We have extensively reported our recent in-roads through novel tools for accurate diagnosis of mono- and poly-bacterial corneal infections. Furthermore, we outlined the recent progress by our group and others in understanding the sub-cellular genomic changes that lead to antibiotic resistance in these organisms. Finally, we discussed in detail, the novel therapies and drug delivery systems in development for the efficacious management of bacterial keratitis.

In Vitro Antimicrobial Activity of a New Ophthalmic Solution Containing Hexamidine Diisethionate 0.05% (Keratosept)

PURPOSE

To assess the in vitro antimicrobial activity of a new commercial ophthalmic solution containing hexamidine diisethionate 0.05% (Keratosept).

METHODS

Staphylococcus aureus American Type Culture Collection (ATCC 43300), Pseudomonas aeruginosa ATCC 27853, 3 ocular bacterial isolates (1 Staphylococcus epidermidis, 1 S. aureus, and 1 P. aeruginosa), and 5 Candida species were used. The bacterial and fungal isolates were cultured on Columbia blood agar base and Sabouraud-dextrose agar plates, respectively, and incubated overnight at 37°C. Suspensions were prepared in a sterile saline solution with optical density equal to 0.5 McFarland standard (∼10 CFU/mL). Isolate suspensions were made in Keratosept solution to obtain a concentration of 10 CFU/mL. The suspensions were then distributed in conical tubes with a final volume of 1 mL and incubated at 37°C. After 1, 5, 10, 15, 20, 25, 30 minutes, and 24 hours, 10 μL of each suspension was removed, seeded on Columbia blood agar base and Sabouraud-dextrose agar plates and then incubated for 24 hours at 37°C.

RESULTS

After 1-minute incubation, there was no growth on the plates seeded with S. aureus ATCC 43300, S. aureus clinical isolate, S. epidermidis clinical isolate, and all 5 Candida species tested. Conversely, Keratosept solution failed to kill the Pseudomonas isolates after 30 minutes exposure and needed 24 hours to eradicate the organisms.

CONCLUSIONS

Keratosept ophthalmic solution showed in vitro antimicrobial activity against S. epidermidis, S. aureus, and Candida species. Results suggest that it may be a potential candidate for the treatment of staphylococcal and Candida infections of the ocular surface and have some role in antimicrobial prophylaxis before intravitreal injections.

Effectiveness of 0.66% Povidone-Iodine Eye Drops on Ocular Surface Flora before Cataract Surgery: A Nationwide Microbiological Study

A multicenter, nonrandomized, prospective, controlled study was conducted to evaluate, as perioperative prophylactic treatment, the anti-infective effectiveness of 0.66% povidone-iodine eye drops (IODIM^®) against the bacterial flora of the conjunctival surface of patients who undergo cataract surgery. Eye drops containing 0.66% povidone-iodine were applied to the eye undergoing cataract surgery; the untreated contralateral eye was used as control. One hundred and twenty patients set to receive unilateral cataract surgery were enrolled in 5 Italian Ophthalmology Centers and pretreated for three days with 0.66% povidone-iodine eye drops. The contralateral eye, used as control, was left untreated. Conjunctival swabs of both eyes were collected at the baseline visit and after three days of treatment, just before the cataract surgery. A qualitative and quantitative microbiological analysis of bacterial presence was evaluated by means of bacterial culture, followed by identification. Methicillin resistance determination was also performed on staphylococci isolates. Bacterial load before and after treatment of the eye candidate for cataract surgery was evaluated and compared to the untreated eye. A reduction or no regrowth on the culture media of the bacterial load was observed in 100% of the study subjects. A great heterogenicity of bacterial species was found. The 0.66% povidone-iodine eye drops, used for three days prior to cataract surgery, were effective in reducing the conjunctival bacterial load. The 0.66% povidone-iodine eye drops (IODIM^®) might represent a valid perioperative prophylactic antiseptic adjuvant treatment to protect the ocular surface from microbial contamination in preparation of the surgical procedure.

Low-Concentration (0.66%) Povidone Iodine Treatment of a Corneal Ulcer in a Rheumatoid Arthritis Patient

Patient: Female, 89-year-old

Final Diagnosis: Corneal ulcer

Symptoms: Low vision

Medication:—

Clinical Procedure: —

Specialty: Ophthalmology

A new ophthalmic formulation containing antiseptics and dexpanthenol: In vitro antimicrobial activity and effects on corneal and conjunctival epithelial cells

Antibiotic resistance is increasing even in ocular pathogens, therefore the interest towards antiseptics in Ophthalmology is growing. The aim of this study was to analyze the in vitro antimicrobial efficacy and the in vitro effects of an ophthalmic formulation containing hexamidine diisethionate 0.05%, polyhexamethylene biguanide (PHMB) 0.0001% disodium edetate (EDTA) 0.01%, dexpanthenol 5% and polyvinyl alcohol 1.25% (Keratosept, Bruschettini, Genova, Italy) on cultured human corneal and conjunctival cells. The in vitro antimicrobial activity was tested on Staphylococcus aureus, Methicillin-Resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Streptococcus pneumoniae, Streptococcus pyogenes and Streptococcus mitis. For each microbial strain 10 μL of a 0.5 MacFarland standardized bacterial inoculum were incubated at 25 °C with 100 μL of ophthalmic solution for up to 6 h. After different periods of time, samples were inoculated on blood agar with 5% sheep blood. Moreover, a 0.5 MacFarland bacterial inoculum was seeded in triplicate on Mueller-Hinton Agar or on Mueller-Hinton Fastidious Agar; then a cellulose disc soaked with 50 μL of ophthalmic solution was applied on the surface of agar and plates were incubated for 18 h at 37 °C, in order to evaluate the inhibition of bacterial growth around the disc. Human corneal and conjunctival epithelial cells in vitro were incubated for 5, 10 and 15 min with Keratosept or its components. The cytotoxicity was assessed through the release of cytoplasmic enzyme lactate dehydrogenase (LDH) into the medium immediately after exposure to the drugs; the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to evaluate the metabolic cell activity. Our results show that Keratosept ophthalmic solution gave an average logarithmic (log) reduction of bacterial load of 2.14 ± 0.35 within 6 h of exposure (p-value < 0.05 versus control saline solution). On agar plates, all microbial strains, excluding P. Aeruginosa, showed an inhibition zone of growth around the Keratosept-soaked discs. Keratosept and its components after 5 and 10 min did not show any cytotoxic effect on cultured corneal and conjunctival cells, and only after 15 min a significant reduction of cell viability and an increase of cytotoxicity compared to control (vehicle) was seen; dexpanthenol 5% and polyvinyl alcohol accelerated the wounding of corneal cells in vitro. In conclusion, Keratosept showed good antimicrobial activity on the tested strains; the ophthalmic solution and its components were safe and non-toxic for the corneal and conjunctival epithelial cells for 5 and 10 min at the concentrations analyzed, and dexpanthenol 5% and polyvinyl alcohol promoted the wounding of corneal cells.

In vitro antimicrobial activity of a new ophthalmic solution containing povidone-iodine 0.6% (IODIM® )

PURPOSE

To assess the in vitro antimicrobial activity of a new commercial ophthalmic solution containing povidone-iodine 0.6% (IODIM^® ).

METHODS

Staphylococcus aureus ATCC 43300, Pseudomonas aeruginosa ATCC 27853, three ocular bacterial isolates (1 S. epidermidis, 1 S. aureus, 1 P. aeruginosa) and five Candida species were used. The bacterial and fungal isolates were cultured on Columbia blood agar base plates and Sabouraud-dextrose agar plates, respectively and incubated overnight at 37°C. Bacterial and fungal suspensions in sterile saline solution were prepared to an optical density equal to 0.5 McFarland standard (approximately 10⁸ CFU/ml). Suspensions of the isolates were made in IODIM^® solution to obtain a final concentration of 10⁶ CFU/ml. The suspensions were then distributed in conical tubes in a final volume of 1 ml and incubated at 37°C. At different time-points (1, 5, 10, 15, 20, 25, 30 min and 24 hr), 10 μl of each suspension was removed, seeded on Columbia blood agar base and Sabouraud-dextrose agar plates and then incubated for 24 hr at 37°C. Positive and negative controls were included in all experiments.

RESULTS

After 5-min incubation, there was no bacterial growth on any plate. Conversely, IODIM^® failed to kill the Candida isolates after 30 min' exposure and needed 24 hr to eradicate the organisms.

CONCLUSION

IODIM^® ophthalmic solution showed in vitro antimicrobial activity against S. epidermidis, S. aureus, P. aeruginosa and Candida species. Results suggest that it may be a potential candidate for the treatment of ocular surface infections and antimicrobial prophylaxis before intravitreal injections.

Corneal Ulcer Treated with 0.66% Nanoemulsion Povidone-Iodine: A Case Report

Patient: Male, 61-year-old

Final Diagnosis: Corneal ulcer

Symptoms: Pain • redness • watering • photophobia

Medication: —

Clinical Procedure: IODIM therapy

Specialty: Ophthalmology

Ex vivo anti-microbial efficacy of various formaldehyde releasers against antibiotic resistant and antibiotic sensitive microorganisms involved in infectious keratitis

BACKGROUND

Corneal infections with antibiotic-resistant microorganisms are an increasingly difficult management challenge and chemically or photochemically cross-linking the cornea for therapy presents a unique approach to managing such infections since both direct microbial pathogens killing and matrix stabilization can occur simultaneously. The present study was undertaken in order to compare the anti-microbial efficacy, in vitro, of 5 candidate cross-linking solutions against 5 different microbial pathogens with relevance to infectious keratitis.

METHODS

In vitro bactericidal efficacy studies were carried out using 5 different FARs [diazolidinyl urea (DAU), 1,3-bis(hydroxymethyl)-5,5-dimethylimidazolidine-2,4-dione (DMDM), sodium hydroxymethylglycinate (SMG), 2-(hydroxymethyl)-2-nitro-1,3-propanediol (NT = nitrotriol), 2-nitro-1-propanol (NP)] against 5 different microbial pathogens including two antibiotic-resistant species [methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), Pseudomonas aeruginosa (PA), and Candida albicans (CA)]. Standard in vitro antimicrobial testing methods were used.

RESULTS

The results for MSSA were similar to those for MRSA. DAU, DMDM, and SMG all showed effectiveness with greater effects generally observed with longer incubation times and higher concentrations. Against MRSA, 40 mM SMG at 120 min showed a > 95% kill rate, p < 0.02. Against VRE, 40 mM DAU for 120 min showed a > 94% kill rate, p < 0.001. All FARs showed bactericidal effect against Pseudomonas aeruginosa, making PA the most susceptible of the strains tested. Candida showed relative resistance to these compounds, requiring high concentrations (100 mM) to achieve kill rates greater than 50%.

CONCLUSION

Our results show that each FAR compound has different effects against different cultures. Our antimicrobial armamentarium could potentially be broadened by DAU, DMDM, SMG and other FARs for antibiotic-resistant keratitis. Further testing in live animal models are indicated.

The efficacy of diluted topical povidone-iodine rinses in the management of recalcitrant chronic rhinosinusitis: a prospective cohort study

PURPOSE

Recalcitrant chronic rhinosinusitis is a persistent inflammatory condition of the sinonasal mucosa despite adequate medical therapy and sinus surgery. This study aimed to demonstrate the effectiveness and safety of dilute povidone-iodine (PVP-I) sinonasal rinses as an adjunctive therapy.

METHODS

Prospective cohort study. Twenty-nine recalcitrant CRS patients with endoscopic evidence of ongoing inflammation and purulent discharge were prescribed 0.08% diluted PVP-I rinses. Changes to endoscopic modified Lund-Kennedy (MLK) scores at 7 weeks post-PVP-I rinsing served as the primary outcome measure.

RESULTS

The median MLK-discharge score significantly decreased in all patients by 1.50 points post-PVP-I rinsing (p value < 0.01). The total MLK score significantly decreased in all patients by 1.50 points (p value = 0.01). Up to a 17% reduction in serum inflammatory markers was measured post-PVP-I rinsing. Sinonasal culture revealed a shift from moderate-heavy growth to lighter bacterial growth overall. Subjective SNOT-22 scores significantly improved overall by ≥ 1 minimal clinically important difference (MCID > 12; baseline median = 33; follow-up median = 20; p value < 0.01; n = 22). TSH levels increased non-significantly within normal ranges (baseline median = 1.59 mU/L; follow-up median = 1.92 mU/L; p = 0.10; n = 15). Mucociliary clearance time increased non-significantly within normal ranges (baseline median = 9 min; follow-up median = 10 min; p value = 0.53; n = 17). Olfactory Sniffin'16 scores non-significantly decreased within age-related normal ranges (baseline median = 14; follow-up median = 13; p value = 0.72; n = 18).

CONCLUSION

A dilute 0.08% PVP-I sinonasal rinse as an ancillary therapy in recalcitrant CRS significantly reduces signs of infection alongside notable symptom improvement, without affecting thyroid function, mucociliary clearance or olfaction.

Topical Povidone-Iodine for Treatment of Giant Fornix Syndrome

Over a 2-year period, a 68-year-old woman suffered multiple recurrences of left giant fornix syndrome during the repeated tailing of intensive topical steroids and antibiotics; she had also undergone surgery to reduce the left upper fornix. After a further recurrence during tailing of topical therapy for bilateral disease, treatment with 4 times daily preservative-free povidone-iodine 5% eyedrops was started-with a marked improvement of symptoms and signs within a week. The patient is maintained, symptom-free, on once-daily povidone-iodine drops and dexamethasone 0.1% drops. The dramatic improvement on topical povidone-iodine therapy might suggest that, as an initial therapy, this might be more effective than the previously-recommended regime of hourly potent topical steroids and antibiotics.

Effectiveness of Povidone-Iodine 1% Eye Drop on Streptococcus pneumoniae and Escherichia coli Induced-Keratitis in Mice

Background:

Bacterial keratitis is an ophthalmic infection that may result in irreversible corneal damage. This study aimed to examine the effectiveness of povidone-iodine eye drop 1% in eye infection caused by inoculation of Streptococcus pneumoniae and Escherichia coli of mice.

Materials and Methods:

In this study, 49 adult male CBA/J mice were used that divided into seven equal groups. The corneas of all mice were scratched and infected with a clinical strain of either S. pneumoniae or E. coli topically, except control group. Subgroups received chloramphenicol 0.5% eye drop twice daily in case of S. pneumoniae infection or ciprofloxacin 0.3% eye drop every 4 hours following E. coli infection from or povidone-iodine 1% eye drop in both groups, from post infection (PI) day 3 to7. Slit lamp examinations (SLE) of the corneas and eyes were performed every day to examine detectable or intense corneal opacity and erosion.

Results:

In all infected mice, SLE scores were significantly higher than the control group on PI day 3. Scores increased steadily by time in all infected groups without treatment, reached to maximal value on PI day 7. In infected groups, treatment with either povidone-iodine 1% or chloramphenicol 0.5% or ciprofloxacin 0.3% on day 3, significantly decreased the SLE scores on PI day 7.

Conclusion:

Povidone-Iodine 1% was effective to decrease S. pneumoniae and E. coli induced-keratitis symptoms in mice. Treatment with povidone-iodine 1% was observed time-dependently and was comparable to common eye drop antibiotics.

Povidone-iodine concentration and in vitro killing time of bacterial corneal ulcer isolates

Background

The concentration and dosing of povidone-iodine (PI) solution used in surgical site prophylaxis are variable. Prior in vitro work has demonstrated that dilute PI solutions (<1%) had greater bactericidal activity than stock solutions (10%). Studies using pathologic clinical isolates from the eye have yielded mixed results. The purpose of the current study was to evaluate the efficacy of different concentrations of PI on pathologic ocular surface isolates.

Methods

We conducted an in vitro microbiology study using clinical isolates from corneal ulcers. Bacteria were recovered from trypticase soy agar with 5% sheep erythrocytes, chocolate agar, and thioglycollate broth media. A standardized concentration of each bacterial sample (1 × 10⁸ cfu/ml) was exposed to various dilutions of PI. Quantitative cultures were performed to determine the number of organisms surviving PI exposure.

Results

None of the isolates survived exposure to the PI 0.25% solution for 30 seconds. Micrococcus luteus and Staphylococcus aureus survived both 30-second and 1-minute exposure to PI 5% and 10%. The exposure time required to produce no growth was variable with concentrations of <0.25%. In some isolates, the 10% solution was faster than the more dilute solutions (0.1%, 0.05%).

Conclusions

Our results are consistent with prior in vitro studies of PI, from nonocular sources, and suggest that PI has similar bactericidal action on pathologic bacteria from the ocular surface. In vitro exposure to dilute PI (0.25%) resulted in no growth after 30 seconds, whereas 10% and 5% solutions took longer to kill several of the isolates. Future investigations of PI use in ophthalmology as an antimicrobial agent should include the study of low-concentration PI (0.25%).

Povidone-iodine concentration and dosing in cataract surgery

Iodine has been recognized as an effective bactericide since the 1800s, and povidone-iodine (PI) solution has been applied to the ocular surface and periocular skin since the 1980s to prevent endophthalmitis in cataract surgery. In vitro, PI solution kills bacteria quickly at dilute concentrations (0.05%-1.0%). In many instances, PI kills bacteria more quickly at these dilute concentrations than more conventional (5%-10%) concentrations. This is due to greater availability of diatomic free iodine in dilute solution, the bactericidal component of PI. The toxicity of PI, both in vitro and clinically, has been shown to be related to concentration. Current American Academy of Ophthalmology and the European Society of Cataract and Refractive Surgeons recommendations regarding PI use suggest using 5% PI before surgery. An alternative dosing strategy uses dilute PI repetitively throughout cataract surgery (0.25% every 30 seconds). We review the povidone-iodine literature with attention to basic science and use of dilute PI.

The use of povidone-iodine in ophthalmology

PURPOSE OF REVIEW

Povidone-iodine (PVI) is a disinfectant and antiseptic agent used for preoperative preparation of the skin and mucous membranes, as well as for the treatment of contaminated wounds. Currently regimens for prophylaxis against postsurgical endophthalmitis are being modified, including a total withdrawal of antibiotics in intravitreal injections. The aim of this study was to evaluate the use of PVI in ophthalmology.

RECENT FINDINGS

As a result of its broad spectrum of microbicidal activity, PVI is routinely used in ophthalmic surgery. However, various protocols are applied worldwide and within different procedures. Additional indications include prophylaxis against ophthalmia neonatorum, acute conjunctivitis, adenoviral conjunctivitis, bacterial keratitis or corneal ulcer, endophthalmitis, giant fornix syndrome, and antimicrobial prophylaxis in patients with Boston type I keratoprosthesis.

SUMMARY

Despite the introduction of new antiseptics in surgery, PVI is still the preeminent antiseptic measure in ophthalmology. Its use is economically reasonable. There have been no reports of resistance to PVI or anaphylaxis with topical ophthalmic use. Furthermore, it does not induce resistance or cross-grztance to antibiotics. With these advantages the range of indications for topical use of antibiotics might decrease, with PVI as the sole perioperative antiseptic measure. Additional studies are required to assess the optimal timing, concentration and exposure time within different ophthalmic procedures.

Microbial flora and resistance in ophthalmology: a review

Antibiotic resistance in systemic infection is well-researched and well-publicized. Much less information is available on the resistance of normal ocular microbiome and that of ophthalmic infections. An understanding of the distribution of ocular microorganisms may help us in tailoring our empiric treatment, as well as in choosing effective pre-, peri- and postoperative management, to achieve the best results for patients. This study aims to summarize and review the available literature on the subject of normal ocular flora and its resistance, as well as the broader topic of antibiotic resistance in ophthalmology.