Limitations of current antibiotics for the treatment of bacterial conjunctivitis

Ultrasound-Mediated Ocular Drug Delivery: From Physics and Instrumentation to Future Directions

Drug delivery to the anterior and posterior segments of the eye is impeded by anatomical and physiological barriers. Increasingly, the bioeffects produced by ultrasound are being proven effective for mitigating the impact of these barriers on ocular drug delivery, though there does not appear to be a consensus on the most appropriate system configuration and operating parameters for this application. In this review, the fundamental aspects of ultrasound physics most pertinent to drug delivery are presented; the primary phenomena responsible for increased drug delivery efficacy under ultrasound sonication are discussed; an overview of common ocular drug administration routes and the associated ocular barriers is also given before reviewing the current state of the art of ultrasound-mediated ocular drug delivery and its potential future directions.

Polymeric Nanoparticles-Loaded Hydrogels for Biomedical Applications: A Systematic Review on In Vivo Findings

Clinically available medications face several hurdles that limit their therapeutic activity, including restricted access to the target tissues due to biological barriers, low bioavailability, and poor pharmacokinetic properties. Drug delivery systems (DDS), such as nanoparticles (NPs) and hydrogels, have been widely employed to address these issues. Furthermore, the DDS improves drugs’ therapeutic efficacy while reducing undesired side effects caused by the unspecific distribution over the different tissues. The integration of NPs into hydrogels has emerged to improve their performance when compared with each DDS individually. The combination of both DDS enhances the ability to deliver drugs in a localized and targeted manner, paired with a controlled and sustained drug release, resulting in increased drug therapeutic effectiveness. With the incorporation of the NPs into hydrogels, it is possible to apply the DDS locally and then provide a sustained release of the NPs in the site of action, allowing the drug uptake in the required location. Additionally, most of the materials used to produce the hydrogels and NPs present low toxicity. This article provides a systematic review of the polymeric NPs-loaded hydrogels developed for various biomedical applications, focusing on studies that present in vivo data.

Antimicrobial resistance of ocular microbes and the role of antimicrobial peptides

Isolation of antimicrobial-resistant microbes from ocular infections may be becoming more frequent. Infections caused by these microbes can be difficult to treat and lead to poor outcomes. However, new therapies are being developed which may help improve clinical outcomes. This review examines recent reports on the isolation of antibiotic-resistant microbes from ocular infections. In addition, an overview of the development of some new antibiotic therapies is given. The recent literature regarding antibiotic use and resistance, isolation of antibiotic-resistant microbes from ocular infections and the development of potential new antibiotics that can be used to treat these infections was reviewed. Ocular microbial infections are a global public health issue as they can result in vision loss which compromises quality of life. Approximately 70 per cent of ocular infections are caused by bacteria including Chlamydia trachomatis, Staphylococcus aureus, and Pseudomonas aeruginosa and fungi such as Candida albicans, Aspergillus spp. and Fusarium spp. Resistance to first-line antibiotics such as fluoroquinolones and azoles has increased, with resistance of S. aureus isolates from the USA to fluoroquinolones reaching 32 per cent of isolates and 35 per cent being methicillin-resistant (MRSA). Lower levels of MRSA (seven per cent) were isolated by an Australian study. Antimicrobial peptides, which are broad-spectrum alternatives to antibiotics, have been tested as possible new drugs. Several have shown promise in animal models of keratitis, especially treating P. aeruginosa, S. aureus or C. albicans infections. Reports of increasing resistance of ocular isolates to mainstay antibiotics are a concern, and there is evidence that for ocular surface disease this resistance translates into worse clinical outcomes. New antibiotics are being developed, but not by large pharmaceutical companies and mostly in university research laboratories and smaller biotech companies. Antimicrobial peptides show promise in treating keratitis.

Nano-MOFs as targeted drug delivery agents to combat antibiotic-resistant bacterial infections

The drug resistance of bacteria is a significant threat to human civilization while the action of antibiotics against drug-resistant bacteria is severely limited owing to the hydrophobic nature of drug molecules, which unquestionably inhibit its permanency for clinical applications. The antibacterial action of nanomaterials offers major modalities to combat drug resistance of bacteria. The current work reports the use of nano-metal-organic frameworks encapsulating drug molecules to enhance its antibacterial activity against model drug-resistant bacteria and biofilm of the bacteria. We have attached rifampicin (RF), a well-documented antituberculosis drug with tremendous pharmacological significance, into the pore surface of zeolitic imidazolate framework 8 (ZIF8) by a simple synthetic procedure. The synthesized ZIF8 has been characterized using the X-ray diffraction (XRD) method before and after drug encapsulation. The electron microscopic strategies such as scanning electron microscope and transmission electron microscope methods were performed to characterize the binding between ZIF8 and RF. We have also performed picosecond-resolved fluorescence spectroscopy to validate the formation of the ZIF8-RF nanohybrids (NHs). The drug release profile experiment demonstrates that ZIF8-RF depicts pH-responsive drug delivery and is ideal for targeting bacterial disease corresponding to its inherent acidic nature. Most remarkably, ZIF8-RF gives enhanced antibacterial activity against methicillin-resistant Staphylococcus aureus bacteria and also prompts entire damage of structurally robust bacterial biofilms. Overall, the present study depicts a detailed physical insight for manufactured antibiotic-encapsulated NHs presenting tremendous antimicrobial activity that can be beneficial for manifold practical applications.

Antibacterial effects of antibiotics and cell-free preparations of probiotics against Staphylococcus aureus and Staphylococcus epidermidis associated with conjunctivitis

Conjunctivitis, caused by bacterial infections, represents health concern and diagnosis of the disease is pivotal for the proper selection of the treatment. The main causes of bacterial conjunctivitis vary in different countries. The current study investigated the common bacterial causes of bacterial conjunctivitis from eye clinics' attendants and evaluated the effectiveness of different therapeutic approaches. Eye swabs from patients, diagnosed with conjunctivitis, were assessed microbiologically and the isolated bacteria were identified using the standard biochemical identification and sequencing of the 16S rRNA gene. Antibiotics' susceptibility of the conjunctivitis-associated bacterial pathogens was evaluated against nineteen broad-spectrum antibiotics. In the meanwhile, cell-free preparations from probiotic Lactobacillus and Bifidobacterium strains were used to evaluate their antagonistic activities. Findings from this study showed that out of 52 specimen, 17 eye swabs from patients with conjunctivitis were bacterial culture-positive. The identity of the bacterial species, using the biochemical identification system, was Staphylococcus aureus (4 isolates) and S. epidermidis (13 isolates). Staphylococcus spp. showed susceptibility to linezolid, vancomycin, novobiocin, and fluoroquinolones (norfloxacin, ofloxacin, ciprofloxacin and levofloxacin). However, isolates from the two Staphylococcus spp. expressed resistance to penicillin G, oxacillin, and cephalexin. As alternatives to antibiotics, the growth of Staphylococcus spp., including isolates with antibiotic resistance, was inhibited by cell-free preparations of the 4 probiotic Lactobacillus and the 2 Bifidobacterium strains. These findings provide evidence that topical antibiotics such as fluoroquinolones are still effective antimicrobial agents against staphylococci associated with conjunctivitis whereas probiotic preparations could be promising for further research to pave the way for their therapeutic applications against ophthalmic diseases.

Miniaturized turbidimetric assay: A green option for the analysis of besifloxacin in ophthalmic suspension

Besifloxacin is an important antimicrobial agent, belonging to the class of fluoroquinolones, used in the treatment of infectious conjunctivitis. Quality control of this active pharmaceutical ingredient is essential, since poor quality antimicrobials may contribute to the aggravation of the worrying picture of bacterial resistance. Thus, analytical methods need to be developed, validated and improved for that purpose. It is also important that these methods be environmentally friendly, as ensuring the quality of products without harming the environment meets the global needs. The aim of the study was the development and validation of a miniaturized turbidimetric microbiological method for the analysis of besifloxacin hydrochloride (BSF) in ophthalmic suspension. The analyzes were performed in 96-well microplates using Staphylococcus epidermidis ATCC 12228 as test microorganism and BHI broth. The method was validated according to ICH guidelines and showed to be linear (in a range of 0.5-8.0 μg mL^-1), precise, accurate, robust and selective. Study of photo-degradation kinetics of BSF sample showed a zero order reaction. A comparative study with a previously validated HPLC method showed that the methods are interchangeable. This work shows the great potential of the proposed method of being introduced in routine analyzes of quality control of BSF in ophthalmic suspension as an option in line with the principles of Green Chemistry.

The Effects of Amoxicillin, Cefazolin, and Gentamicin Antibiotics on the Antioxidant System in Mouse Heart Tissues

BACKGROUND

Free radicals lead to destruction in various organs of the organism. The improper use of antibiotics increases the formation of free radicals and causes oxidative stress.

OBJECTIVE

In this study, it was aimed to determine the effects of gentamicin, amoxicillin, and cefazolin antibiotics on the mouse heart.

METHODS

20 male mice were divided into 4 groups (1st control, 2nd amoxicillin, 3rd cefazolin, and 4th gentamicin groups). The mice in the experimental groups were administered antibiotics intraperitoneally at a dose of 100 mg / kg for 6 days. The control group received normal saline in the same way. The gene expression levels and enzyme activities of SOD, CAT, GPx, GR, GST, and G6PD antioxidant enzymes were investigated.

RESULTS

GSH levels decreased in both the amoxicillin and cefazolin groups, while GR, CAT, and SOD enzyme activities increased. In the amoxicillin group, Gr, Gst, Cat, and Sod gene expression levels increased.

CONCLUSION

As a result, it was concluded that amoxicillin and cefazolin caused oxidative stress in the heart, however, gentamicin did not cause any effects.

Wide bandgap semiconductor-based novel nanohybrid for potential antibacterial activity: ultrafast spectroscopy and computational studies

The properties of nanomaterials generated by external stimuli are considered an innovative and promising replacement for the annihilation of bacterial infectious diseases.

Besifloxacin: A Critical Review of Its Characteristics, Properties, and Analytical Methods

Bacterial conjunctivitis has high impact on the health of the population, since it represents more than a third of ocular pathologies reported by health services worldwide. There is a high incidence of bacterial resistance to the antimicrobials most commonly used for the treatment of conjunctivitis. In this context, besifloxacin stands out, since it is a fluoroquinolone developed exclusively for topical ophthalmic use, presenting a low risk of developing resistance due to its reduced systemic exposure. Bausch & Lomb markets it as ophthalmic suspension, under the trade name Besivance™. Literature review on besifloxacin is presented, covering its pharmaceutical and clinical characteristics, and the analytical methods used to measure the drug in pharmaceutical products and biological samples. High performance liquid chromatography is the most used method for this purpose. A discussion on Green Chemistry is also presented, focusing the importance of the development of green analytical methods for the analysis of drugs.

Besifloxacin in the management of bacterial infections of the ocular surface

Acute bacterial conjunctivitis is a common infection of the ocular surface. Increasing rates of bacterial resistance have prompted the development of new antibiotics with improved activity against the bacterial species most often found in this disease. Besifloxacin is the first topical chlorofluoroquinolone developed solely for ophthalmic use. Studies have attested to its in vitro potency against a broad range of bacteria, as well as its efficacy in clinical studies of bacterial conjunctivitis when dosed 2 or 3 times a day. This review provides an up-to-date summary of studies on causative pathogens in acute bacterial conjunctivitis; recent geographic trends in bacterial resistance among ocular pathogens, including that of methicillin-resistant Staphylococcus aureus; the efficacy of besifloxacin in preclinical and clinical studies; its safety; and the role of besifloxacin in combating resistant strains. Further, this review provides a brief update on bacterial keratitis, causative pathogens, the development of resistance among those pathogens, and the potential role of besifloxacin in the treatment of bacterial keratitis.

Clinical and Antibacterial Efficacy and Safety of Besifloxacin Ophthalmic Suspension Compared With Moxifloxacin Ophthalmic Solution

PURPOSE

To evaluate the efficacy of besifloxacin ophthalmic suspension 0.6% compared with moxifloxacin ophthalmic solution 0.5% in the treatment of bacterial conjunctivitis in an Indian population.

DESIGN

Multicenter, randomized, double-masked, active-controlled, parallel-group, clinical trial, including 6 clinical sites in India.

METHODS

Patients were randomized to receive 1 drop of besifloxacin or moxifloxacin in the infected eye(s), 3 times daily, for 5 days. Primary efficacy end points included clinical resolution and bacterial eradication at day 5. Secondary efficacy end points included clinical resolution and bacterial eradication at day 8, ocular discharge, bulbar conjunctival injection, investigator's global assessment, and bacterial eradication by species. Efficacy was analyzed using the Cochran-Mantel-Haenszel and Pearson χ2 tests. Safety was assessed by the incidence of ocular and nonocular treatment-emergent adverse events (AEs), changes in visual acuity, and biomicroscopy and ophthalmoscopy findings. Data presented are that for the subset of patients from India.

RESULTS

Of the 123 patients randomized at clinical sites in India, 96.7% completed the study. Day 5 differences in microbial eradication (100% besifloxacin vs 96.3% moxifloxacin) and in clinical resolution (78.9% besifloxacin vs 71.4% moxifloxacin) were not statistically significant. No statistically significant between-group differences were observed for secondary end points. All ocular AEs in both groups were mild or moderate in severity. There were no drug-related ocular AEs with besifloxacin.

CONCLUSIONS

Treatment of bacterial conjunctivitis with besifloxacin 0.6% produces similar antibacterial and clinical efficacy as that with moxifloxacin 0.5% in an Indian population, with no clinically meaningful safety concerns.

Ocular surface infections in northeastern state of malaysia: a 10-year review of bacterial isolates and antimicrobial susceptibility

OBJECTIVE

Ocular surface infections that include infections of conjunctiva, adnexa, and cornea have the potential risk of causing blindness within a given population. Empirical antibiotic therapy is usually initiated based on epidemiological data of common causative agents. Thus, the aims of this study were to determine the bacterial agents and their susceptibility patterns of isolates from ocular surface specimens in our hospital.

METHODS

This is a retrospective analysis and records of bacterial isolates from ocular surface specimens in Hospital Universiti Sains Malaysia from January 2001 to December 2010 were examined. Specimens were processed according to standard laboratory procedures. Antimicrobial susceptibility testing was conducted based on Clinical and Laboratory Standards Institute recommendations. Only single, nonrepetitive isolates were included in the analysis.

RESULTS

A total of 1,267 isolates were obtained during the study period, which comprised Staphylococcus aureus (n = 299, 23.6%), Pseudomonas aeruginosa (n = 194, 15.3%), Streptococcus pneumoniae (n = 108, 8.5%), Haemophilus influenzae (n = 100, 7.9%), Haemophilus parainfluenzae (n = 84, 6.6%), and Enterobacter spp. (n = 81, 6.4%). Fungi contributed to 4.4% of the total isolates. The antimicrobial susceptibility testing demonstrated that gram-positive bacteria were generally resistant to gentamicin (19%-57%), whereas gram-negative bacteria were resistant to chloramphenicol (27%-58%).

CONCLUSIONS

Based on the above results, knowledge of the initial Gram stain findings is imperative before the commencement of empirical antibiotic therapy. Therefore, a simple Gram staining for all eye specimens is highly recommended.

[Bacteriological analysis in the management of conjunctivitis. Comparison of antibiotic resistance between 1982 and 2008]

OBJECTIVE

To demonstrate the need for bacteriological analysis for the rational treatment of infections of the corneal surface, including conjunctivitis.

METHODS

The results of 1,970 consecutive bacteriological analysis obtained from 2001 to 2008 in patients with ocular hyperemia and discharge were analysed and compared with a similar study done in 1982 in the same geographical area.

RESULTS

Bacterial growth was obtained in 1,044 cases (53%). The most frequent bacteria were Staphylococci spp. (56.6%), followed by Streptococci spp. (21.4%), Haemophili spp. (12.1%), and other gram-negative bacteria (9.9%). No antibiotic was effective against all the bacteria isolated. The frequency of resistant bacteria against neomycin, tobramycin, erythromycin and gentamicin was significantly increased with respect to the study of 1982.

CONCLUSIONS

Bacteriological analysis of conjunctival specimens are necessary to ensure the choice of an effective antibiotic against bacteria of the ocular surface when the initial treatment fails.

Besifloxacin ophthalmic suspension: emerging evidence of its therapeutic value in bacterial conjunctivitis

Objective

To outline the pharmacodynamics, efficacy and safety of besifloxacin ophthalmic suspension 0.6% in the treatment of bacterial conjunctivitis.

Quality of Evidence

MEDLINE database was searched to review recent pharmacodynamic and clinical studies evaluating besifloxacin and comparing besifloxacin to other topical antibiotics for ophthalmic use. Findings were limited to full-text articles from clinical journals in the English language.

Main Message

Bacterial resistance is a common source for treatment failure in bacterial conjunctivis. Besifloxacin, a novel fourth generation synthetic fluoroquinolone is likely to show lower resistance rates due to its mechanism of action and its short-term use for ocular infections only (decreased systemic exposure). Besifloxacin displays improved pharmacodynamic properties compared to other commonly used fluoroquinolones and has shown to be efficacious and safe in clinical studies.

Conclusion

Besifloxacin ophthalmic suspension 0.6% provides safe and efficacious treatment for bacterial conjunctivitis. The factors leading to bacterial resistance are diminished, which allows besifloxacin to be a favorable treatment option.