Comparative review of topical ophthalmic antibacterial preparations

Construction of a thermosensitive gel based on hydroxypropyl-β-cyclodextrin/meloxicam inclusion complexes for improving meloxicam solubility and prolonging drug retention time in the cornea

The eyes are easily stimulated by external factors, which can cause inflammation. Anti-inflammatory drugs are usually used to inhibit the production of inflammatory factors. Many nonsteroidal anti-inflammatory drugs have been used for the eye, but due to the poor solubility of meloxicam, there are currently no marketed meloxicam preparations for the treatment of eye diseases. This article uses hydroxypropyl-β-CD (HP-β-CD) to encapsulate meloxicam and combined with thermosensitive gel to prepare an HP-β-CD/meloxicam inclusion complex eye thermosensitive gel, which can improved the water solubility of meloxicam and extend the retention time of the drug in the cornea, and achieve the goal of slow release through continuous dissolution. It not only has the advantages of convenient administration and accurate dosage of eye drops, but also overcomes the disadvantage of easy loss of eye drops, showing the advantages of long retention time and fewer administration times, and provides a basis for the development of other dosage forms of meloxicam.

Recent Trends in Therapeutic Drug Monitoring of Peptide Antibiotics

Antimicrobial peptides take a specific position in the field of antibiotics (ATBs), however, from a large number of available molecules only a few of them were approved and are used in clinics. These therapeutic modalities play a crucial role in the management of diseases caused by multidrug-resistant bacterial pathogens and represent the last-line therapy for bacterial infections. Therefore, there is a demand for a rationale use of such ATBs based on optimization of the dosing strategy to minimize the risk of resistance and ensure the sustainable efficacy of the drug in real clinical practice. Therapeutic drug monitoring, as a measurement of drug concentration in the body fluids or tissues, results in the optimization of the patient´s medication and therapy outcome. This strategy is beneficial and could result in tailored therapy for different types of infection and the prolongation of the use and efficacy of ATBs in hospitals. This review paper provides an actual overview of approved antimicrobial peptides used in clinical practice and covers current trends in their analysis by convenient and advanced methodologies used for their identification and/or quantitation in biological matrices for therapeutic drug monitoring purposes. Special emphasis is given to the methods with perspective clinical outcomes.

Ocular drug-metabolizing enzymes: focus on esterases

This review describes current knowledge on the expression of ocular phase I and II drug-metabolizing enzymes in the main animal species used in ocular drug development and in humans, with a focus on ocular esterases and their prodrug substrates. The eye possesses a unique metabolic profile, exhibiting a lower and restricted expression of major cytochrome P450s (CYPs) and most transferases apart from glutathione S-transferases (GST) when compared to the liver. In contrast, hydrolytic enzymes are abundant in many ocular tissues. These enzymes have attracted interest because of their role in prodrug activation and drug elimination. A literature survey suggests profound variations in tissue expression levels and activities between different species but also points out significant gaps in knowledge. These uncertainties highlight a need for more detailed characterization of enzymes in individual ocular tissues and across species to aid future translational studies in ophthalmic drug research. Thus, an in-depth analysis of ocular drug metabolism and species differences is crucial for ocular drug development.

Design, synthesis fusidic acid derivatives alleviate acute lung injury via inhibiting MAPK/NF-κB/NLRP3 pathway

Acute lung injury (ALI) refers to a series of lung lesions resulting from multiple lung injuries, even leading to morbidity and death, abundant previous reports have showed that anti-inflammatory as a key to treatment of ALI. Fusidic acid (FA) as an antibiotic has significant anti-bacterial activity and anti-inflammatory effects. In this study, we designed and synthesized 34 FA derivatives to identify new anti-inflammatory drugs. The anti-inflammatory activities of the derivatives were screened using lipopolysaccharide (LPS)-induced RAW264.7 cells to evaluate the anti-inflammatory activity of the compounds, we measured nitric oxide (NO) and interleukin-6 (IL-6). Most of compounds showed inhibitory effects on inflammatory NO and IL-6 in LPS-induced RAW264.7 cells. Based on the screening results, compound a1 showed the strongest anti-inflammatory activity. Compared with FA, the inhibition rate NO and IL-6 of compound a1 increased 3.08 and 2.09 times at 10 μM, respectively. We further measured a1 inhibited inflammatory factor NO (IC50 = 3.26 ± 0.42 μM), IL-6 (IC50 = 1.85 ± 0.21 μM) and TNF-α (IC50 = 3.88 ± 0.55 μM). We also demonstrated that a1 markedly inhibits the expression of certain immune-related cytotoxic factors, including cyclooxygenase-2 (COX-2) and inducible nitric-oxide synthase (iNOS). In vivo results indicate that a1 can reduce lung inflammation and NO, IL-6, TNF-α, COX-2 and iNOS in LPS-induced ALI mice. On the one hand, we demonstrated a1 inhibits the mitogen-activated protein kinase (MAPK) signaling pathway by down-regulating the phosphorylation of p38 MAPK, c-Jun N-terminal kinase (c-JNK) and extracellular signal-regulated kinase (ERK). Moreover, a1 also suppressing the phosphorylation of inhibitory NF-κB inhibitor α (IκBα) inhibits the activation of the nuclear factor-κB (NF-κB) signaling pathway. On the other hand, we demonstrated a1 also role in anti-inflammatory by inhibits nucleotide-binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasome and further inhibits Caspase-1 and inflammatory factor interleukin-1β (IL-1β). In conclusion, our study demonstrates that a1 has an anti-inflammatory effect and alleviates ALI by regulating inflammatory mediators and suppressing the MAPK, NF-κB and NLRP3 inflammasome signaling pathways.

Eudragit® L100/Polyvinyl Alcohol Nanoparticles Impregnated Mucoadhesive Films as Ocular Inserts for Controlled Delivery of Erythromycin: Development, Characterization and In Vivo Evaluation

The fast elimination of drugs from the cornea is one of many challenges associated with the topical administration of conventional dosage forms. The present manuscript aimed to prepare modified-release inserts containing erythromycin (ERY) to enhance drug delivery and address the aforementioned limitation. Film formulations were developed using Eudragit^® L100 (EUD) and Polyvinyl Alcohol (PVA) polymers. ERY-loaded EUD-based nanoparticles were developed by the colloidal dispersion method using PVA as the emulsifier. The film-casting method was applied to form the mucoadhesive films using sodium alginate, gelatin, cyclodextrin-α, and β as polymeric film matrices. Different physicochemical properties of the optimized formulations and in vitro release profiles were evaluated. The in vivo evaluation was performed by collecting tear samples of rabbits using a novel, non-invasive method following the administration of inserts in the cul-de-sac. The ERY amount was assayed using a microbiological assay. The developed films showed prolonged in vitro and in vivo release profiles over five to six days; they had suitable physicochemical properties and a tensile strength of 2–3 MPa. All formulations exhibited antibacterial efficacy against E. coli and S. aureus with more than 20 mm diameter of inhibited growth zones. None of the formulations caused irritation to the rabbit’s eye. The inserts showed promising pharmacokinetics with AUC_0–120 of 30,000–36,000 µg·h/mL, a C_max of more than 1800 µg/mL at 4 h, and maintained drug concentration over the threshold of 5 µg/mL during the following 120 h of study. Nanoparticle-containing, mucoadhesive films could be fabricated as ocular inserts and can prolong the topical ocular delivery of ERY.

Antibacterial and Antibiofilm Potency of XF Drugs, Impact of Photodynamic Activation and Synergy With Antibiotics

With increasing incidence of antimicrobial resistance, there is an urgent need for novel and effective antibacterials. Destiny Pharma plc have developed a series of porphyrin-based XF drugs, some with dual mechanisms of antibacterial action. An innate mechanism acts through binding to the outer bacterial membrane and a separate, light-activated, photodynamic (PD) mechanism, acts via the generation of reactive oxygen species. This study aimed to assess the innate and PD associated antibacterial activity of XF drugs against planktonic bacteria, their biofilms and combinational effects with conventional antibiotics. Minimum inhibitory concentrations (MICs) were determined for 3 XF drugs against 114 bacterial isolates. MICs for XF-73 and XF-70 were determined (± PD). DPD-207 was designed to not exhibit PD action due to its structure. XF-drugs (± PD) were further assessed for synergy with conventional antibiotics (using a checkerboard assay) and antibiofilm activity against susceptible strains. XF drugs were innately active against all tested Gram-positive isolates. PD action significantly increased bacterial susceptibility to XF-73 and XF-70 for all Gram-positive isolates. Generally, the XF drugs exhibited higher MICs against Gram-negative isolates, however PD significantly enhanced potency, particularly for XF-70. XF-73 and XF-70 exhibited synergy with ertapenem against a methicillin resistant Staphylococcus aureus (MRSA) strain (± PD) and XF-73 with polymyxin B (± PD) against Pseudomonas aeruginosa. No antagonism was seen between the XF drugs and any of the 5 antibiotics tested. The antibiofilm effect of XF drugs was also observed for all Staphylococcus isolates tested. Generally, PD did not enhance activity for other bacterial isolates tested with the exception of XF-73 against Acinetobacter baumannii biofilms. XF drugs exhibited significant antimicrobial activity against Gram-positive bacteria, with PD enhancement of bacterial susceptibility. Additionally, XF drugs displayed synergy with conventional antibiotics and demonstrated antibiofilm effects.

Review of Loteprednol Etabonate 0.5%/Tobramycin 0.3% in the Treatment of Blepharokeratoconjunctivitis

Use of a combination corticosteroid and antibiotic in a single formulation is common in the treatment of ocular inflammatory conditions for which corticosteroid therapy is indicated and there exists a risk of superficial bacterial infection. Loteprednol etabonate (LE) is a corticosteroid engineered to maintain potent anti-inflammatory activity while minimizing the risk of undesirable class effects of corticosteroids, such as elevated intraocular pressure and cataract. Tobramycin is a broad-spectrum aminoglycoside antibiotic that is considered generally safe and well tolerated. An ophthalmic suspension combining LE 0.5% and tobramycin 0.3% (LE/T) is approved in the US and several other countries. Use of a combination therapy increases convenience, which may promote patient adherence. A systematic literature review was conducted to examine the efficacy and safety of LE/T for ocular inflammatory conditions within the scope of its labeled indications. Results of published studies indicate that LE/T is effective in the treatment of blepharokeratoconjunctivitis in adults, with similar efficacy as dexamethasone 0.1%/tobramycin 0.3%, but is associated with a lower risk of clinically significant increases in intraocular pressure as demonstrated in both efficacy and safety studies and studies with healthy volunteers. Furthermore, studies in children with blepharitis or blepharoconjunctivitis indicate LE/T was well tolerated in this population, although efficacy vs vehicle was not demonstrated, potentially due to improvements in all groups overall and/or limited sample size. Separately, tobramycin demonstrated potent in vitro activity against most bacterial species associated with blepharitis. In conclusion, published data demonstrate the utility of LE/T for the treatment of the various clinical manifestations of blepharokeratoconjunctivitis in adults.

Microbial Keratitis After Corneal Collagen Cross-Linking for Corneal Ectasia

PURPOSE

The aim of this study was to report the clinical profile and microbiological of patients with microbial keratitis post accelerated corneal collagen cross-linking (CXL).

METHODS

A retrospective case series of all patients diagnosed with microbial keratitis post-CXL who attended the Sydney Eye Hospital, Australia from January 1, 2012 to December 31, 2019 were included. Patients were identified from hospital coding and pathology data. Data were extracted from patients' medical records.

RESULTS

Eleven eyes from 10 patients with a mean age of 29 ± 11 years (range 16-48) were included. The median time of infection after CXL surgery was 4 days [interquartile range (IQR) 3-83]. Median initial and final Visual acuity at presentation were 1.3 logMAR (IQR 1-2.0) and 0.8 logMAR (IQR 0.6-1.2), respectively. The culture positivity rate was 92%, identifying 13 isolates, predominately made up of coagulase-negative Staphylococcus (n = 6, 50%) and Staphylococcus aureus (n = 3, 25%). The median epithelial healing time was 30 days (IQR 15-53).

CONCLUSIONS

Post-CXL microbial keratitis was predominately associated with gram-positive bacteria and in some cases delayed epithelialization. Microbial keratitis post-CXL may lead to moderate to poor patient outcomes.

Polymyxins and Bacterial Membranes: A Review of Antibacterial Activity and Mechanisms of Resistance

Following their initial discovery in the 1940s, polymyxin antibiotics fell into disfavor due to their potential clinical toxicity, especially nephrotoxicity. However, the dry antibiotic development pipeline, together with the rising global prevalence of infections caused by multidrug-resistant (MDR) Gram-negative bacteria have both rejuvenated clinical interest in these polypeptide antibiotics. Parallel to the revival of their use, investigations into the mechanisms of action and resistance to polymyxins have intensified. With an initial known effect on biological membranes, research has uncovered the detailed molecular and chemical interactions that polymyxins have with Gram-negative outer membranes and lipopolysaccharide structure. In addition, genetic and epidemiological studies have revealed the basis of resistance to these agents. Nowadays, resistance to polymyxins in MDR Gram-negative pathogens is well elucidated, with chromosomal as well as plasmid-encoded, transferrable pathways. The aims of the current review are to highlight the important chemical, microbiological, and pharmacological properties of polymyxins, to discuss their mechanistic effects on bacterial membranes, and to revise the current knowledge about Gram-negative acquired resistance to these agents. Finally, recent research, directed towards new perspectives for improving these old agents utilized in the 21st century, to combat drug-resistant pathogens, is summarized.

Novel Polyvinyl Pyrrolidone-Loaded Olopatadine HCl-Laden Doughnut Contact Lens to Treat Allergic Conjunctivitis

Olopatadine HCl is an antiallergic drug used for the management of allergic conjunctivitis. Currently, it is delivered via eye drop solution, which is highly inefficient due to low bioavailability. Silicone contact lenses can be used to sustain the release of ophthalmic drugs. However, the presence of drug alters the optical transmittance and physical properties of the contact lens. The objective was to design a novel polyvinyl pyrrolidone (PVP)-coated olopatadine-ethyl cellulose microparticles-laden doughnut contact lens to sustained ocular delivery with limited alteration to the optical and swelling properties of the contact lens. The doughnut was implanted within the periphery of the lens using modified casting technique. Olopatadine HCl was loaded by soaking (SM-OL), direct loading (DL-OL), and doughnut casting method (DNT-OL). PVP (comfort agent) was loaded on the surface of contact lens for all the batches via novel curing technique. The in vitro olopatadine HCl release data of SM-OL (up to 48-72 h) and DL-OL batches (up to 72 h) showed high burst release, whereas DNT-OL batch showed sustained release up to 120 h without significant (p > 0.05) alteration in the optical and swelling properties of contact lens. All the batches showed sustained release of PVP up to 120 h. The in vivo studies in the rabbit tear fluid showed improvement in the olopatadine HCl and PVP retention time in comparison to eye drop solution. The PVP-loaded DNT-OL-500 lens showed tear stabilization (comfort wear) in Schirmer strip test (rabbits) with no protein adherence in comparison to DNT-OL-500 lens without PVP. The study demonstrated the successful delivery of olopatadine HCl and PVP-K30 from the doughnut contact lens for the extended period with limited alteration to the optical and swelling properties of contact lens.

Impact of Topically Administered Steroids, Antibiotics, and Sodium Hyaluronate on Bleb-Related Infection Onset: The Japan Glaucoma Society Survey of Bleb-Related Infection Report 4

Purpose

To investigate the impact of topically administered ophthalmic medications on the onset and severity of bleb-related infections.

Methods

Data obtained from 104 eyes of 104 patients with bleb-related infections were analyzed. We assigned an infection stage to each eye (stage 1-4) and analyzed the onset severity.

Results

Steroids and antibiotics were routinely administered to 13 (12.5%) and 42 (40.4%) eyes, respectively. The median stage of steroid-administered eyes was 3 versus 1 for eyes without steroid administration (P = 0.012). The median duration from surgery to infection for the steroid-administered eyes was 2.0 years versus 5.8 years for eyes without steroid administration (P = 0.030). The median duration from surgery to infection for the antibiotic-administered eyes was 6.4 years versus 3.9 years for eyes without antibiotic administration (P = 0.025). Multiple logistic regression analysis revealed that infections were severe in the steroid-administered eyes (odds ratio: 4.57). No infections developed within 16 weeks postoperatively. No relationship was detected between sodium hyaluronate and the analyzed factors.

Conclusions

Topical steroid administration beyond the immediate postoperative period may affect severe and earlier onset bleb-related infections. Conversely, topical antibiotic administration may be effective in suppressing earlier onset bleb-related infections.

Characteristics of corneal phospholipidosis induced by topical ocular application of chloroquine and amiodarone in rabbits

Several cationic-amphiphilic drugs such as chloroquine and amiodarone are known to induce phospholipidosis in the cornea by systemic administration. However, the characteristics of ophthalmological and pathological changes when phospholipidosis-inducing drugs are topically applied have not been well studied. This study was conducted to investigate the characteristics of corneal changes caused by topical application of chloroquine and amiodarone to Japanese white rabbits. The changes were evaluated by ophthalmological, histopathological, and ultrastructural examinations. An in vivo confocal microscopy was also applied to the chloroquine-treated corneas. In both chloroquine- and amiodarone-treated corneas, diffuse cloudiness was observed by slit-lamp biomicroscopy, and its transparency increased with duration of dosing. Confocal microscopy showed punctate dots in the corneal epithelium. Histopathologically, cytoplasmic vacuolation was found in the corneal epithelium and keratocytes in both chloroquine- and amiodarone-treated eyes. Furthermore, foamy cytoplasm of the corneal endothelium was observed in the chloroquine-treated eyes. Ultrastructural examination showed multi-lamellar inclusion bodies or membrane-like debris in the lysosome-like vacuoles in the cytoplasm of corneal cells, which is a characteristic of the lesions of phospholipidosis. These changes disappeared after a withdrawal period. Continuous dosing of chloroquine resulted in corneal erosion and focal corneal opacity as shown by gross observation and slit-lamp biomicroscopy. Confocal microscopy could detect the corneal changes prior to the appearance of these ophthalmological changes. The present study showed that phospholipidosis caused by ocular administration of chloroquine and amiodarone first induces reversible diffuse corneal cloudiness. Confocal microscopy is a useful method for monitoring induction of corneal phospholipidosis.

Topical treatments for blepharokeratoconjunctivitis in children

BACKGROUND

Blepharokeratoconjunctivitis (BKC) is a type of inflammation of the surface of the eye and eyelids that involves changes of the eyelids, dysfunction of the meibomian glands, and inflammation of the conjunctiva and cornea. Chronic inflammation of the cornea can lead to scarring, vascularisation and opacity. BKC in children can cause significant symptoms including irritation, watering, photophobia and loss of vision from corneal opacity, refractive error or amblyopia.Treatment of BKC is directed towards modification of meibomian gland disease and the bacterial flora of lid margin and conjunctiva, and control of ocular surface inflammation. Although both topical and systemic treatments are used to treat people with BKC, this Cochrane review focuses on topical treatments.

OBJECTIVES

To assess and compare data on the efficacy and safety of topical treatments (including antibiotics, steroids, immunosuppressants and lubricants), alone or in combination, for BKC in children from birth to 16 years.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 6), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE ( January 1946 to 11 July 2016), Embase (January 1980 to 11 July 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 11 July 2016. We searched the reference lists of identified reports and the Science Citation Index to identify any additional reports of studies that met the inclusion criteria.

SELECTION CRITERIA

We searched for randomised controlled trials that involved topical treatments in children up to 16 years of age with a clinical diagnosis of BKC. We planned to include studies that evaluated a single topical medication versus placebo, a combination of treatments versus placebo, and those that compared two or multiple active treatments. We planned to include studies in which participants received additional treatments, such as oral antibiotics, oral anti-inflammatories, warm lid compresses and lid margin cleaning.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the results of the literature search (titles and abstracts) to identify studies that met the inclusion criteria of the review and applied standards as expected for Cochrane reviews. We graded the certainty of the evidence using GRADE.

MAIN RESULTS

We included one study from the USA that met the inclusion criteria. In the study, 137 children aged zero to six years old with blepharoconjunctivitis were randomised to treatment in one of four trial arms (loteprednol etabonate/tobramycin combination, loteprednol etabonate alone, tobramycin alone or placebo) for 15 days, with assessments on days 1, 3, 7 and 15. We judged the study to be at high risk of attrition bias and bias due to selective outcome reporting. The study did not report the number of children with improvement in symptoms nor with total or partial success as measured by changes in clinical symptoms.All children showed a reduction in blepharoconjunctivitis grade score, but there was no evidence of important differences between groups. Visual acuity was not fully reported but the authors stated that there was no change in visual acuity in any of the treatment groups. The study reported ocular and non ocular adverse events but was underpowered to detect differences between the groups. Ocular adverse events were as follows: loteprednol/tobramycin 1/34 (eye pain); loteprednol 4/35 (eye pain, conjunctivitis, eye discharge, eye inflammation); tobramycin 0/34; placebo (vehicle) 0/34. The evidence was limited for all these outcomes and we judged it to be very low certainty.There was no information on clinical signs (aside from grade score), disease progression or quality of life.

AUTHORS' CONCLUSIONS

There is no high-quality evidence of the safety and efficacy of topical treatments for BKC, which resulted in uncertainty about the indications and effectiveness of topical treatment. Clinical trials are required to test efficacy and safety of current and any future treatments. Outcome measures need to be developed which can capture both objective clinical and patient-reported aspects of the condition and treatments.

Impact of kanamycin on melanogenesis and antioxidant enzymes activity in melanocytes--an in vitro study

Aminoglycosides, broad spectrum aminoglycoside antibiotics, are used in various infections therapy due to their good antimicrobial characteristics. However, their adverse effects such as nephrotoxicity and auditory ototoxicity, as well as some toxic effects directed to pigmented tissues, complicate the use of these agents. This study was undertaken to investigate the effect of aminoglycoside antibiotic-kanamycin on viability, melanogenesis and antioxidant enzymes activity in cultured human normal melanocytes (HEMa-LP). It has been demonstrated that kanamycin induces concentration-dependent loss in melanocytes viability. The value of EC50 was found to be ~6.0 mM. Kanamycin suppressed melanin biosynthesis: antibiotic was shown to inhibit cellular tyrosinase activity and to reduce melanin content in normal human melanocytes. Significant changes in the cellular antioxidant enzymes: SOD, CAT and GPx were stated in melanocytes exposed to kanamycin. Moreover, it was observed that kanamycin caused depletion of antioxidant defense sytem. It is concluded that the inhibitory effect of kanamycin on melanogenesis and not sufficient antioxidant defense mechanism in melanocytes in vitro may explain the potential mechanisms of undesirable side effects of this drug directed to pigmented tissues in vivo.

Etiology and epidemiological analysis of glaucoma-filtering bleb infections in a tertiary eye care hospital in South India

Purpose:

To evaluate the microbial etiology and associated risk factors among patients with blebitis following trabeculectomy.

Materials and Methods:

A retrospective analysis of all culture-proven blebitis was performed in patients who underwent trabeculectomy between January 2004 and December 2008. A standardized form was filled out for each patient, documenting sociodemographic features and information pertaining to risk factors. Swabbing of the infected bleb surface was performed for all suspected cases and further subjected to microbiological analysis.

Results:

A total of 23 patients with culture-proven blebitis were treated during the study period, with a mean age of 59.2 years (59.2 ± SD: 12.8; range, 30-81 years). Duration of onset was early (≤36 months) in six (26%) cases and late (> 36 months) in 17 (74%) cases with a range between 15 and 144 months (mean, 82.91 months; SD: 41.89). All 23 blebs were located superiorly and of which, 21 (91%) were microcystic avascular, 1 (4%) diffuse avascular, and 1 (4%) vascular flattened. The predominant risk factor identified was bleb leak (35%; 8 of 23) followed by thin bleb (22%; 5 of 23) and blepharitis (17%; 4 of 23). Bleb leaks (100%) were recorded only in patients with late onset (≥ 9 years) of infection (P< 0.001), while the incidence of ocular surface disease (100%) occurred early (≤3 years) (P< 0.001). Use of topical steroids was associated frequently with cases of thin blebs (80%; 4 of 5) (P< 0.001), while topical antibiotics showed bleb leaks (88%; 7 of 8) (P< 0.001). Coagulase-positive staphylococci were frequently recovered from blebitis with thin blebs (71%; 5 of 7) (P = 0.001), Coagulase-negative staphylococci (CoNS) with bleb leak (100%; 8 of 8) (P< 0.001), Corynebacterium with blepharitis (100%; 3 of 3) (P = 0.001), and Streptococci with releasable sutures (75%; 3 of 4) (P = 0.001).

Conclusion

Bleb leak is the principal risk factor responsible for late-onset blebitis, while early-onset blebitis could be ascribed to ocular surface diseases. Streptococci were mainly responsible for early onset of infection, while the late onset was due to CoNS.

A novel cell-associated protection assay demonstrates the ability of certain antibiotics to protect ocular surface cell lines from subsequent clinical Staphylococcus aureus challenge

In vivo effectiveness of topical antibiotics may depend on their ability to associate with epithelial cells to provide continued protection, but this contribution is not measured by standard antibiotic susceptibility tests. We report a new in vitro method that measures the ability of test antibiotics azithromycin (AZM), erythromycin (ERY), tetracycline (TET), and bacitracin (BAC) to associate with mammalian cells and to protect these cells from destruction by bacteria. Mammalian cell lines were grown to confluence using antibiotic-free medium and then incubated in medium containing a single antibiotic (0 to 512 μg/ml). After incubation, the cells were challenged with Staphylococcus aureus ocular isolates, without antibiotics added to the culture medium. Epithelial cell layer integrity was assessed by gentian violet staining, and the minimum cell layer protective concentration (MCPC) of an antibiotic sufficient to protect the mammalian cells from S. aureus was determined. Staining was also quantified and analyzed. Bacterial viability was determined by culture turbidity and growth on agar plates. Preincubation of Chang and human corneal limbal epithelial cells with AZM, ERY, and TET at ≥64 μg/ml provided protection against AZM-susceptible S. aureus strains, with increasing protection at higher concentrations. TET toxicity was demonstrated at >64 μg/ml, whereas AZM displayed toxicity to one cell line at 512 μg/ml. BAC failed to show consistent protection at any dose, despite bacterial susceptibility to BAC as determined by traditional antibiotic susceptibility testing. A range of antibiotic effectiveness was displayed in this cell association assay, providing data that may be considered in addition to traditional testing when determining therapeutic dosing regimens.

A comparison of antibacterial activity against Methicillin-Resistant Staphylococcus aureus and gram-negative organisms for antimicrobial compounds in a unique composite wound dressing

OBJECTIVE

Antibiotic resistance is increasing among organisms that commonly cause wound infections. Therefore, it becomes increasingly desirable to prevent wound infections as systemic antibiotic treatment of established wound infections becomes more difficult, more expensive, and potentially more toxic. The ability to incorporate antimicrobial compounds into modern wound dressings provides an opportunity to prevent wound infections without the risk of systemic toxicity, thus diminishing morbidity, mortality, and cost to the healthcare system.

DESIGN

In these studies, the authors tested 16 antimicrobial agents in a unique composite wound dressing (TheraGauze; Soluble Systems, LLC, Newport News, Virginia) against clinical methicillin-resistant Staphylococcus aureus isolates and Gram-negative organisms commonly associated with wound infections and antibiotic resistance. Disk diffusion susceptibility testing is used to quantify antimicrobial activity.

RESULTS

Broad-spectrum antimicrobial activity was found for the following agents in the composite wound dressing: hydrogen peroxide, tobramycin, chlorhexidine digluconate, chlorhexidine gluconate, levofloxacin, and silver.

CONCLUSION

These studies suggest that potent local antibacterial activity can be achieved with several antimicrobials in this wound dressing.

Ocular pharmacokinetics of besifloxacin following topical administration to rabbits, monkeys, and humans

PURPOSE

Studies were conducted to evaluate the ocular penetration and systemic exposure to besifloxacin, a fluoroquinolone antibiotic, following topical ocular administration to animals and humans.

METHODS

Besifloxacin ophthalmic suspension (0.6%) was administered as a topical ocular instillation to pigmented rabbits, cynomolgus monkeys, and human subjects. At predetermined intervals after dosing, samples of ocular tissues and plasma were collected and analyzed for besifloxacin levels using HPLC/MS/MS methods.

RESULTS

Besifloxacin demonstrated good ocular penetration in rabbits and monkeys, with rapid absorption and sustained concentrations observed in anterior ocular tissues through 24 h after a single administration. Maximum besifloxacin concentrations in conjunctiva, cornea, and aqueous humor of monkeys were 6.43 microg/g, 2.10 microg/g, and 0.796 microg/mL, respectively, after a single topical dose, and concentrations declined in these tissues with an apparent half-life of 5-14 h. Following a single topical ocular administration to humans, the maximum besifloxacin concentration in tears was 610 microg/g with concentrations decreasing to approximately 1.6 microg/g at 24 h. The resulting pharmacokinetic parameters for besifloxacin in human tears were evaluated relative to the MIC(90) values (microg/mL) for besifloxacin against Streptococcus pneumoniae (0.125), Staphylococcus aureus (0.25), Staphylococcus epidermidis (0.5), and Haemophilus influenzae (0.06). Following a single topical administration, the C(max)/MIC(90) ratios for besifloxacin in human tears were > or =1,220, and the AUC((0-24))/MIC(90) ratios were > or =2,500 for these relevant ocular pathogens. Following repeated 3-times daily (TID) topical ocular administration to human subjects with clinically diagnosed bacterial conjunctivitis, maximum besifloxacin concentrations in plasma were less than 0.5 ng/mL, on average.

CONCLUSIONS

Taken together, the results of the current investigation provide a PK/PD-based rationale that supports the use of besifloxacin for the safe and effective treatment of ocular infections.

Control of inflammation and prophylaxis of endophthalmitis after cataract surgery: a multicenter study

PURPOSE

To compare two different postcataract surgery antibiotic/steroid therapeutic combinations, for clinical results as well as patient satisfaction.

METHODS

Prospective randomized clinical trial of patients with bilateral operative cataract. Postoperatively, for 15 days one eye was randomly assigned to therapy with the combination chloramphenicol 0.25%-betamethasone 0.13% gel three times a day (Group 1) and the other to the combination tobramycin 0.3%-dexamethasone 0.1% eyedrops four times a day (Group 2).

RESULTS

A total of 142 patients (284 eyes) completed the study. The authors could not detect any significant difference between Group 1 and Group 2 concerning preoperative evaluation, surgical procedure, and complications. Pertaining to the two therapeutic regimens, efficacy, side effects, and clinical findings such as uncorrected visual acuity, intraocular pressure, edema or hyperemia of eyelids and/or conjunctiva, conjunctival and/or ciliary vessels congestion, decreased corneal transparency, corneal edema, Descemet folds, anterior chamber Tyndall and depth, and posterior synechiae were also comparable. Postoperative subjective pain and dry eye sensation were comparable between the two groups, while the gel preparation elicited a significantly more pleasant sensation in the patients (p=0.04).

CONCLUSIONS

The motivation for use of a gel is to prolong the permanence of associated drugs on the ocular surface, increasing potency and decreasing concentration of the drug and rate of administration. This in order to improve compliance and decrease potential side effects. Chloramphenicol 0.25%-betamethasone 0.13% gel combination proved to have comparable efficacy, tolerance, and better acceptance by the patients than an aqueous tobramycin 0.3%-dexamethasone 0.1% preparation.

Evaluation of the in vivo behaviour of gentamicin sulphate ocular mini-tablets in ponies

The in vivo behaviour of 5% gentamicin sulphate ocular mini-tablets (2-mm diameter, 6.525 mg weight) was compared with gentamicin eye drops in six ponies. Two mini-tablets were inserted on the bulbar conjunctiva of the right eye while a similar dose of gentamicin was administered via eye drops in the left eye. Irritation induced by the mini-tablets and the eye drops was evaluated using a visual analogue scale (0-10). Tears were sampled with ophthalmologic absorption triangles for 1 min for the determination of the concentration of gentamicin sulphate using a microbiological plate diffusion method. Irritation induced by the tablets was minor and clinically acceptable (overall median score of 1.7 +/- 1.4). Eye drops induced a sharp increase in gentamicin sulphate concentration (364.4 microg/mL after 5 min) followed by a fast decline (10.8 microg/mL after 60 min). The increase in concentration induced by the ocular mini-tablets was less pronounced (up to 56.2 microg/mL after 30 min) and followed by a gradual decrease; the concentration remained above 15 microg/mL for 8 h. Ocular 5% gentamicin sulphate mini-tablets are clinically well-tolerated in ponies, assuring a constant concentration in the tears for at least 8 h.

Prescrire les collyres fortifiés

Fortified preparations of ophthalmic antibiotics are made with commercially available antibiotics (parenteral or lyophilized preparations). These fortified eyedrops have two main advantages: the increase in the antibiotic concentration in the corneal stroma and the wide choice of available antibiotics. Fortified ophthalmic solutions are used in severe keratitis (large diameter, stroma infiltration, inflammation of the anterior chamber, old patient). The following associations are recommended: ticarcillin+gentamicin+vancomycin or cephazolin+amikacin since they provide a broad-spectrum antibiotic activity against the wide range of bacteria that may cause keratitis. The main toxicity of these preparations is the retardation effect of the epithelial-healing rate (aminoglycosides, vancomycin) and the corneal and conjunctival toxic effects (aminoglycosides). However, fortified antibiotic drops remain the standard therapy for severe bacterial keratitis, given their corneal penetration and the possibility of the synergic and combined effect of an antibiotic association.

Fusidic acid viscous eyedrops - an evaluation of pharmacodynamics, pharmacokinetics and clinical use for UK optometrists

Recent changes in UK law have allowed UK-based optometrists to sell and supply fusidic acid viscous eyedrops, providing it is in the course of their professional activity and in an emergency. Alternatively, the optometrist may access fusidic acid viscous eyedrops, for a named patient, using a written order supplied to a pharmacy. This review provides details of the legal background to these changes, examines the common causes of a bacterial conjunctivitis, examines the mechanism of action of this narrow spectrum antibiotic as a bacteriostatic agent, reviews the susceptibility of common ocular isolates of bacteria to the drug and presents details of the expected pharmacokinetics of the viscous eyedrops. From this perspective, a systematic review is provided of the clinical studies which have investigated the use of fusidic acid viscous eyedrops and their outcome. The indicated use is generally for the treatment of bacterial conjunctivitis and/or blepharoconjunctivitis, especially that caused by Staphylococcus, but not Streptococcus or Haemophilus sp. (more likely associated with concurrent nasopharyngeal infections). The usual regimen for use is twice daily for 5-10 days, depending on severity, and can initially be used more intensively (four times per day). It may also be used for the management of corneal and conjunctival abrasions and foreign body injuries, or some cases of chronic blepharitis.

In Vitro Effects of Fluoroquinolone and Aminoglycoside Antibiotics on Human Keratocytes

PURPOSE

The purpose of this study was to assess the cytotoxic effects of the fluoquinolone ofloxacin and the aminoglycoside netilmicin on stromal human keratocytes in vitro.

METHODS

Cultured human keratocytes were exposed to various concentrations of ofloxacin or netilmicin (0.16-5.0 mg/mL). Both cell proliferation (MTT assay) and cell morphology (phase-contrast microscopy) were evaluated after 1, 4, 12, and 24 hours of incubation. Measurement of annexin V binding performed in association with the dye exclusion test using propidium iodide (PI) was also performed by FACS analysis after 4 hours of exposure.

RESULTS

Both antimicrobials induced dose- and time-dependent morphologic changes in keratocytes, yet the effects of netilmicin were minimal. After 24 hours of exposure, both drugs induced a dose-dependent inhibition of cell proliferation; however, ofloxacin demonstrated significantly more toxic effects than netilmicin (t test for ED50 values, P < 0.0001). Statistical differences between 2 antibiotics start at concentrations above 1.25 mg/mL (ANOVA with post-hoc test, P < 0.01). Expression of the apoptotic marker annexin V was unaffected by antibiotic exposure, whereas the uptake of the necrotic marker PI was increased by ofloxacin (5 mg/mL) but not by netilmicin (ofloxacin versus netilmicin, ANOVA, P < 0.05).

CONCLUSIONS

Relative effects of aminoglycosides and fluoroquinolones on stromal keratocytes appear to be different: netilmicin was shown to be significantly less toxic than ofloxacin. This finding is particularly relevant in deciding the optimal antibiotic to be applied in clinical situations in which the epithelium is absent or compromised, as after photorefractive keratectomy, alkali burns, or ulcerative keratitis.

Gram-negative bacteria responsible for insoluble technetium formation and the fate of insoluble Tc in the water column above flooded paddy soil

We studied the characteristic gram-stain of Tc insolubilizing bacteria using various antibiotics, and the fate of insoluble Tc in a water column above flooded paddy soil to clarify Tc behavior in paddy fields. The formation of insoluble Tc in water column samples was inhibited by the addition of antibiotics, especially reagents against gram-negative bacteria. For a sample without antibiotics, insoluble Tc formation increased with time, and the maximum amount of insoluble Tc was observed on day 4 of incubation with (95m)Tc. In contrast, concentrations of ferrous ion decreased with time. These results suggested that gram-negative bacteria were mainly responsible for insoluble Tc formation, and that these bacteria were able to transform soluble Tc to insoluble forms under oxidizing conditions.

Systemic adverse effects of topical ocular treatments

Some eyedrops, gels or ointments may cause adverse effects as serious as those observed with systemic therapies. Because of their relatively poor penetration into eye tissue, ophthalmic drugs usually contain high concentrations of their active ingredient. Asking patients about these drugs to prevent interactions is useful when prescribing a new systemic treatment. Conversely, it is advisable to ask about ophthalmic drugs during the etiological investigation of possible iatrogenic effects.

Effect of ofloxacin and netilmicin on human corneal and conjunctival cells in vitro

The purpose of this study was to compare the cytotoxic effects of the fluoroquinolone ofloxacin with that of the aminoglycoside netilmicin. Human corneal epithelial cells (HCE-T) and human conjunctival epithelial cells (Wong-Kilbourne derivative of Chang conjunctiva) were exposed to antibiotics (0.08-5.0 mg/mL) for 4 or 24 hours. Cell proliferation and viability were assessed with the MTT assay, neutral red uptake, and bromo deoxy uridine incorporation. In both cell lines, ofloxacin inhibited cell proliferation and viability. These effects were time and dose dependent. Concentrations of ofloxacin ranging from 0.4 to 2.4 mg/mL (0.04% to 0.24%) produced a 50% inhibition of proliferation and viability. In contrast, netilmicin induced no toxic effect. The differences between ofloxacin and netilmicin were highly statistically significant (p < 0.001). This finding is particularly relevant in deciding the optimal antibiotic to be applied in clinical situations in which the epithelium is compromised.

Concentrations of levofloxacin, ofloxacin, and ciprofloxacin in human corneal stromal tissue and aqueous humor after topical administration

OBJECTIVE

To evaluate the penetration of commercially available levofloxacin 0.5%, ofloxacin 0.3%, and ciprofloxacin 0.3% topical ophthalmic solutions in human corneal stromal and aqueous humor tissues.

METHODS

A total of 67 patients scheduled to undergo penetrating keratoplasty for treatment of stromal scar or dystrophy, keratoconus, pellucid marginal degeneration, or endothelial disease were enrolled in this prospective, double-blind, 3-center study. To be considered for inclusion, patients had to have an intact corneal epithelium and minimal or no corneal edema (pachymetry < 650 microm). After informed consent was obtained, patients were randomized to receive 1 drop of levofloxacin 0.5%, ofloxacin 0.3%, or ciprofloxacin 0.3% topical ophthalmic solution at approximately 15 and 10 minutes before surgery. Approximately 0.1 mL of aqueous fluid was aspirated by paracentesis through the trephination wound at the onset of surgery, followed by excision of the affected cornea and removal of its epithelium. Specimens were stored frozen at -70 degrees C until assayed by high-performance liquid chromatography.

RESULTS

All 3 fluoroquinolones were well tolerated. A total of 65 corneas and 59 aqueous fluid samples were obtained and assayed. The mean +/- standard deviation corneal concentrations of ciprofloxacin, ofloxacin, and levofloxacin following a 2-drop administration were 9.92 +/- 10.99 microg/g (n = 18), 10.77 +/- 5.90 microg/g (n = 23), and 18.23 +/- 20.51 microg/g (n = 24), respectively. Although corneal stromal levels were highest in the levofloxacin group, the high degree of interpatient variability prevented demonstration of statistically significant differences when compared with ofloxacin (P = 0.377). In contrast, levofloxacin concentrations were approximately twice as high as ciprofloxacin, and this difference reached statistical significance (P = 0.014). The corresponding aqueous humor concentrations of ciprofloxacin, ofloxacin, and levofloxacin were 0.135 +/- 0.231 microg/mL (n = 15), 0.135 +/- 0.111 microg/mL (n = 20), and 0.372 +/- 0.546 microg/mL (n = 24, P < 0.001 versus ciprofloxacin and ofloxacin).

CONCLUSION

The topical administration of all 3 agents was well tolerated in patients undergoing penetrating keratoplasty. Two drops of levofloxacin 0.5% solution results in a 1.7- to 2.7-fold greater penetration into human corneal stromal and aqueous humor tissues than ofloxacin 0.3% or ciprofloxacin 0.3%. The mean intracorneal concentrations of all three agents following 2 drops exceeds the MIC90 for the majority of pathogens causing bacterial keratitis. Topical levofloxacin appears to offer pharmacokinetic and pharmacodynamic advantages over ofloxacin and ciprofloxacin in terms of enhanced transcorneal penetration; however, clinical comparative trials are needed to confirm these relative advantages.

An in vivo study comparing the ocular absorption of levofloxacin and ciprofloxacin prior to phacoemulsification

PURPOSE

To compare aqueous humor concentrations of levofloxacin vs ciprofloxacin when used as prophylactic medications before phacoemulsification.

DESIGN

Patients (n = 93) were randomly assigned to receive either 0.5% levofloxacin (Quixin) or 0.3% ciprofloxacin (Ciloxan) using one of the following dosing regimens: (A) 1 to 2 drops four times a day for 2 days preoperatively; (B) 5 doses (1 to 2 drops) delivered every 10 minutes in the hour immediately preceding surgery; or (C) the combination of A and B.

METHODS

Aqueous samples (0.1 ml) were obtained immediately before surgery, and drug concentrations were measured using high performance liquid chromatography/mass spectrometry.

RESULTS

The mean concentration of levofloxacin in the aqueous humor was significantly greater than that of ciprofloxacin in all treatment groups (P <.001): 284.8 vs 67.4 microg/ml (regimen A); 1,135.6 vs 185.6 microg/ml (regimen B); and 1,618.6 vs 241.5 (regimen C). Dosing regimen B delivered significantly more drug to the aqueous humor than regimen A for both levofloxacin (P < or =.001) and ciprofloxacin (P =.004). Dosing regimen C delivered significantly more drug to the aqueous humor than regimen B for levofloxacin (P =.05) but not for ciprofloxacin (P =.384).

CONCLUSIONS

Although the concentration of active drug in levofloxacin is approximately 1.7-fold higher than that in ciprofloxacin, the aqueous concentration of levofloxacin after topical administration was four to seven times greater than ciprofloxacin; these differences were statistically significant. With dosing regimens B and C, levofloxacin concentrations in the aqueous humor were above the MIC90 for most common ocular pathogens, including Staphylococcus and Streptococcus species. Ciprofloxacin did not reach such concentrations in any treatment group.

What type of eye drops should be given to a toddler with conjunctivitis?

This mini-review describes a parent's search for evidence on the relative merits of two commonly used treatments for conjunctivitis. It was conducted in a very limited period of time with access to free databases (Pub Med, Cochrane Library) and only the abstracts of papers. Five relevant studies were identified that compared fusidic acid eye drops to chloramphenicol. Three of the five studies reported no difference in effectiveness between the two preparations with both drugs performing equally well. Two studies undertaken in less-developed countries showed fusidic acid to be far more effective but the cure rate with chloramphenicol was low, suggesting resistance or different causal agents. However, there was some evidence that chloramphenicol was less well tolerated and so fusidic acid may be the drug of choice. The review illustrates that evidence for practice can be found rapidly with access to limited facilities by an appropriately skilled practitioner.

Treatment of acute bacterial conjunctivitis: 1% fusidic acid viscous drops vs. 0.3% tobramycin drops

BACKGROUND

A frequent cause of conjunctivitis is an acute bacterial infection, presenting with mucopurulent discharge and conjunctival hyperemia. The authors compared the clinical and microbiologic efficacy, safety and acceptability of 1% fusidic acid viscous drops (Fucithalmic) with 0.3% tobramycin ophthalmic solution (Tobrex) in the treatment of suspected bacterial conjunctivitis.

METHODS

Patients were recruited at 20 sites in Ontario, Saskatchewan and Alberta from October 1995 to December 1998. Patients who presented to their primary care physician with suspected bacterial conjunctivitis, as identified by conjunctival hyperemia and purulent or mucopurulent discharge, were eligible for the study. Patients were randomly assigned to receive 7 days of treatment with either 1% fusidic acid (one drop applied twice daily) or 0.3% tobramycin (one to two drops applied four to six times daily). The investigators were blinded as to treatment status. Bacteriologic samples were taken from the inferior conjunctival cul-de-sac on day 0 and at the end of treatment. Signs and symptoms of conjunctivitis were assessed at baseline and after 3 and 7 days of treatment. The acceptability of treatment was assessed by having the patient or the parent or guardian complete a questionnaire on degree of compliance and ease of use after 3 and 7 days of treatment.

RESULTS

Conjunctival swabs were obtained from 484 patients (410 over 9 years of age and 74 aged 2 to 9 years) to determine baseline bacteriology. Of the 484, 319 (65.9%) (63% of the older patients and 80% of those aged 2 to 9 years) had positive results of culture for bacteria. Ninety-four patients (19%) (63 [15%] of the older patients and 31 [42%] of those aged 2 to 9 years) had per-protocol pathogens as defined by quantitative bacteriology criteria. There was a direct correlation between the presence of mucopurulent discharge and the presence of per-protocol pathogens. There were no significant differences in clinical or bacteriologic efficacy between the treatment groups. Treatment compliance was similar between the treatment groups for the older patients; however, for those aged 2 to 9 years, compliance was significantly better in the fusidic acid group than in the tobramycin group (85% vs. 47%) (p < 0.001). Significantly more patients in the fusidic acid group than in the tobramycin group rated treatment as convenient or very convenient, particularly among younger patients (97% vs. 54%) (p < 0.001).

INTERPRETATION

The clinical and bacteriologic efficacy of fusidic acid viscous drops combined with the convenience of a twice-daily dosage regimen establishes this antibiotic as first-line treatment for suspected acute bacterial conjunctivitis and a favourable alternative to other broad-spectrum antibiotics.