Bactericidal activity of besifloxacin against staphylococci, Streptococcus pneumoniae and Haemophilus influenzae

Multi-resistant organisms in burn patients: an end or a new beginning

Infections are a major cause of morbidity and mortality in burn patients, and the rise of multidrug-resistant organisms (MDROs) has made it more challenging to manage and prevent infections. This review examines the available treatment options for MDROs in burn patients and anticipates the future challenges posed by their increasing prevalence. The review covers new antibiotics, such as Eravacycline and Plazomicin, as well as non-antibiotic therapies, such as bacteriophages and nanoparticles. Future research should focus on examining the long-term efficacy, cost-effectiveness, and in vivo efficacy of different treatment modalities. The potential of alternative therapies, such as probiotics and low-frequency magnetic fields, should also be explored. Accurate and rapid diagnostic and monitoring tools for detecting MDROs in burn patients should be developed. The emergence of MDROs in burn care is a challenge and a new beginning in infection innovation and novel treatments.

Characterization of Polybacterial versus Monobacterial Conjunctivitis Infections in Pediatric Subjects Across Multiple Studies and Microbiological Outcomes with Besifloxacin Ophthalmic Suspension 0.6

Introduction

The choice of empiric therapy for bacterial conjunctivitis should be guided by an awareness of typical causative pathogen distributions. Bacterial conjunctivitis can be polybacterial, although pediatric-specific data are lacking.

Methods

This was a post-hoc analysis of data in pediatric subjects (1–17 years) from five bacterial conjunctivitis trials evaluating besifloxacin ophthalmic solution 0.6%.

Results

Of the 730 pediatric subjects with culture-confirmed conjunctivitis, nearly one-fourth (23.6%) had polybacterial infections and three-fourths (76.4%) had monobacterial infections at baseline. In both polybacterial and monobacterial infections, the most prevalent organisms were Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus, and Streptococcus mitis/S. mitis group. In polybacterial versus monobacterial infections, S. mitis/S. mitis group (8.7% vs 4.3%; P=0.032) and Moraxella catarrhalis (4.7% vs 0.5%; P<0.001) were identified more frequently, whereas S. pneumoniae (14.0% vs 28.1%; P<0.001) was identified less frequently, as the dominant infecting species. MICs for individual species were similar for tested antibiotics regardless of polybacterial or monobacterial infection, except Staphylococcus epidermidis for which fluoroquinolone MICs were ≥3 dilutions higher for isolates of this species sourced from polybacterial compared to monobacterial infections. Treatment with besifloxacin resulted in microbial eradication in 79.1% of polybacterial and 92.3% of monobacterial infections (P≤0.005 vs vehicle).

Discussion

One in four pediatric bacterial conjunctivitis infections is polybacterial, highlighting the need for a broad-spectrum antibiotic when choosing empiric therapy.

Antibacterial Activity and Membrane-Targeting Mechanism of Aloe-Emodin Against Staphylococcus epidermidis

The emergence of multidrug-resistant Staphylococcus epidermidis (S. epidermidis) dwarfs the current antibiotic development and calls for the discovery of new antibacterial agents. Aloe-emodin is a plant-derived compound that holds promise to battle against these strains. This work reports the antimicrobial activity of aloe-emodin against S. epidermidis and other Gram-positive pathogenic species, manifesting minimum inhibitory concentrations (MICs) and minimum bactericidal concentration (MBCs) around 4–32 and 32–128 μg/mL, respectively. For Gram-negative bacteria tested, the MICs and MBCs of aloe-emodin were 128–256 and above 1024 μg/mL, respectively. Aloe-emodin at the MBC for 4 h eradicated 96.9% of S. epidermidis cells. Aloe-emodin treatment led to deformities in the morphology of S. epidermidis cells and the destroy of the selective permeability of the cell membranes. Analysis of the transcriptional profiles of aloe-emodin-treated cells revealed changes of genes involved in sulfur metabolism, L-lysine and peptidoglycan biosynthesis, and biofilm formation. Aloe-emodin therefore can safely control Gram-positive bacterial infections and proves to target the bacterial outer membrane.

Characterization of baseline polybacterial versus monobacterial infections in three randomized controlled bacterial conjunctivitis trials and microbial outcomes with besifloxacin ophthalmic suspension 0.6

Background/Purpose

To date, studies examining polymicrobial infections in ocular disease have mostly been limited to keratitis or endophthalmitis. We characterized polybacterial infections compared to monobacterial infections in prior clinical studies evaluating besifloxacin ophthalmic suspension 0.6% for the treatment of bacterial conjunctivitis and report on associated microbiological outcomes.

Methods

In this post-hoc analysis, microbiological data for subjects with conjunctivitis due to one or more than one bacterial species in three previous studies (two vehicle-, one active-controlled) of besifloxacin were extracted. Bacterial species identified at baseline were deemed causative if their colony count equaled or exceeded species-specific prespecified threshold criteria. In subjects with polybacterial infections, the fold-increase over threshold was used to rank order the contribution of individual species. Baseline pathogens and their minimum inhibitory concentrations (MICs) for common ophthalmic antibiotics were compared by infection type, as were microbial eradication rates following treatment with besifloxacin.

Results

Of 1041 subjects with culture-confirmed conjunctivitis, 17% had polybacterial and 83% had monobacterial conjunctivitis at baseline. In polybacterial compared to monobacterial infections, Haemophilus influenzae and Streptococcus pneumoniae were identified less frequently as the dominant infecting species (P = 0.042 and P<0.001, respectively), whereas Streptococcus mitis/S. mitis group was identified more frequently as dominant (P<0.001). Viral coinfection was also identified more frequently in polybacterial infections (P<0.001). Staphylococcus aureus was the most common coinfecting species in polybacterial infections and the second most common dominant species in such infections. With few exceptions, MICs for individual species were comparable regardless of infection type. Clinical microbial eradication rates with besifloxacin were high regardless of infection type (P≤0.016 vs vehicle at follow-up visits).

Conclusions

Approximately one in five subjects with bacterial conjunctivitis are infected with more than one bacterial species underscoring the need for a broad-spectrum antibiotic for such infections. Besifloxacin treatment resulted in robust eradication rates of these infections comparable to monobacterial infections.

Trial registration

NCT000622908, NCT00347932, NCT00348348

Bactericidal Capacity of a Heterogeneous TiO2/ZnO Nanocomposite against Multidrug-Resistant and Non-Multidrug-Resistant Bacterial Strains Associated with Nosocomial Infections

The surge of medical devices associated with nosocomial infection (NI) cases, especially by multidrug-resistant (MDR) bacterial strains, is one of the pressing issues of present health care systems. Metal oxide nanoparticles (MNPs) have become promising antibacterial agents against a wide range of bacterial strains. This work study is on the bactericidal capacity of heterogeneous TiO₂/ZnO nanocomposites with different weight percentages and concentrations against common MDR and non-MDR bacterial strains. The profiles on disk diffusion, minimum inhibitory concentration, minimum bactericidal concentration, tolerance determination, time-kill, and biofilm inhibition assay were determined after 24 h of direct contact with the nanocomposite samples. Findings from this work revealed that the heterogeneous TiO₂/ZnO nanocomposite with a 25T75Z weight ratio showed an optimal tolerance ratio against Gram-positive and -negative bacteria, indicating their bactericidal capacity. Further observation suggests that higher molar ratio of Zn²⁺ may possibly involve generation of active ion species that enhance bactericidal effect against Gram-positive bacterial strains, especially for the MDR strains. Nano-based technology using MNPs may provide a promising solution for the prevention and control of NIs. Further work on biocompatibility and cytotoxicity profiles of this nanocomposite are needed.

An Evaluation of Staphylococci from Ocular Surface Infections Treated Empirically with Topical Besifloxacin: Antibiotic Resistance, Molecular Characteristics, and Clinical Outcomes

Introduction

Understanding antibiotic resistance and toxin profiles among staphylococcal isolates in ocular infections can aid in therapeutic management and infection prevention strategies. We evaluated in vitro antibiotic resistance patterns and molecular traits of staphylococci isolated from patients with ocular surface infections. We also report on clinical outcomes for these patients following empirical treatment with topical besifloxacin ophthalmic suspension 0.6%.

Methods

This was a small observational study. Participating investigators from three clinical sites collected an initial ocular culture from the affected eye of patients presenting with ocular surface infections with presumed staphylococcal etiology. Clinical outcome data for patients with confirmed staphylococcal infections were collated later through retrospective review of patient medical records. Staphylococcal species identification in ocular cultures, in vitro antibiotic susceptibility testing, and PCR-based determination of methicillin resistance cassettes and toxin genotypes were conducted at a central laboratory. Isolates were categorized as susceptible or resistant based on systemic breakpoints, where available.

Results

Cultures were collected from 43 patients, and staphylococcal infections were confirmed in 25 patients. Two isolates of Staphylococcus aureus and 27 isolates of Staphylococcus epidermidis were identified. Both S. aureus isolates were methicillin-susceptible, lacked the gene encoding Panton-Valentine leukocidin, and carried few enterotoxin genes. Eight (30%) S. epidermidis were methicillin-resistant (MRSE), and 10 (37%) were ciprofloxacin-resistant. All but two MRSE isolates demonstrated multidrug resistance (MDR), and the staphylococcal cassette chromosome mec (SCCmec) type IVa was detected in five of the eight MRSE isolates. Clinical resolution of the ocular surface infection was reported in all 25 patients following treatment with besifloxacin.

Conclusions

In this study, S. aureus contained few toxins, while SCCmec IVa and MDR was predominant among MRSE from ocular surface infections. Despite significant in vitro fluoroquinolone resistance, there were no cases of treatment failure with topical besifloxacin ophthalmic suspension 0.6%.

Funding

Bausch Health US, LLC.

Novel Antibiotics for Multidrug-Resistant Gram-Positive Microorganisms

Increasing multidrug-resistance to Gram-positive pathogens, particularly to staphylococci, enterococci and streptococci, is a major problem, resulting in significant morbidity, mortality and healthcare costs. In recent years, only a small number of novel antibiotics effective against Gram-positive bacteria has been approved. This review will discuss the current evidence for novel branded antibiotics that are highly effective in the treatment of multidrug-resistant infections by Gram-positive pathogens, namely ceftobiprole, ceftaroline, telavancin, oritavancin, dalbavancin, tedizolid, besifloxacin, delafloxacin, ozenoxacin, and omadacycline. The mechanism of action, pharmacokinetics, microbiological spectrum, efficacy and safety profile will be concisely presented. As for any emerging antibiotic agent, resistance is likely to develop against these highly effective antibiotics. Only through appropriate dosing, utilization and careful resistance development monitoring will these novel antibiotics continue to treat Gram-positive pathogens in the future.

Microbial, phytochemical, toxicity analyses and antibacterial activity against multidrug resistant bacteria of some traditional remedies sold in Buea Southwest Cameroon

Background

Traditional medicine remedies are commonly used for treatment of diverse ailments including bacterial infections. The activity against resistant bacteria and safety of some remedies sold as anti-infective treatments in market places in Buea, Southwest Cameroon were investigated as potential alternative treatment to counter increasing antibiotic resistance.

Methods

Ten remedies were purchased, their components documented and microbial load estimated. Methanol extracts of the remedies were tested for antibacterial activity by disc diffusion and microdilution. Cytotoxicity was evaluated on monkey kidney epithelial cells (LLC-MK2) while acute oral toxicity was done in BALB/c mice for the bactericidal extract. Extracts were further analysed using phytochemical tests.

Results

All the remedies had microbial loads above the acceptable limit of 10⁵ CFU/g. The highest activity was produced by extracts of four remedies (TP 1, 2, 4, 6a, 6b) against all clinical isolates among which three were active against four control strains. Zones of inhibition ranged from 8 to 27 mm. Two of the four extracts produced zones ≥20 mm against multidrug resistant clinical isolates of Citrobacter freundii and Escherichia coli but were less active compared to Gentamycin positive control (P < 0.0001–0.0014). The most active extracts also recorded minimum inhibitory concentrations of 1 to 4 mg/mL. One of them (TP2) was bactericidal against a clinical isolate of methicillin–resistant Staphylococcus aureus with a minimum bactericidal concentration of 8 mg/mL. Extracts of six remedies did not show cytotoxicity and no mortality or adverse effect was recorded in the acute oral toxicity test. Phytochemical screening showed the most active extracts contained relatively high amounts of alkaloids and flavonoids.

Conclusion

Only four of the eight remedies tested showed activity against multidrug resistant bacteria suggesting some of these remedies may not be effective against bacterial infections. Production and handling methods should be improved and the product quality controlled to ensure biosecurity. The remedies which were both active and non-toxic should be further investigated including in vivo experiments to assess their efficacy.

A small mycobacteriophage-derived peptide and its improved isomer restrict mycobacterial infection via dual mycobactericidal-immunoregulatory activities

Mycobacteriophages express various peptides/proteins to infect Mycobacterium tuberculosis (M. tb). Particular attention has been paid to mycobacteriophage-derived endolysin proteins. We herein characterized a small mycobacteriophage-derived peptide designated AK15 with potent anti-M. tb activity. AK15 adopted cationic amphiphilic α-helical structure, and on the basis of this structure, we designed six isomers with increased hydrophobic moment by rearranging amino acid residues of the helix. We found that one of these isomers, AK15-6, exhibits enhanced anti-mycobacterial efficiency. Both AK15 and AK15-6 directly inhibited M. tb by trehalose 6,6'-dimycolate (TDM) binding and membrane disruption. They both exhibited bactericidal activity, cell selectivity, and synergistic effects with rifampicin, and neither induced drug resistance to M. tb They efficiently attenuated mycobacterial load in the lungs of M. tb-infected mice. We observed that lysine, arginine, tryptophan, and an α-helix are key structural requirements for their direct anti-mycobacterial action. Of note, they also exhibited immunomodulatory effects, including inhibition of proinflammatory response in TDM-stimulated or M. tb-infected murine bone marrow-derived macrophages (BMDMs) and M.tb-infected mice and induction of only a modest level of cytokine (tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6)) production in murine BMDMs and a T-cell cytokine (interferin-γ (IFN-γ) and TNF-α) response in murine lung and spleen. In summary, characterization of a small mycobacteriophage-derived peptide and its improved isomer revealed that both efficiently restrain M. tb infection via dual mycobactericidal-immunoregulatory activities. Our work provides clues for identifying small mycobacteriophage-derived anti-mycobacterial peptides and improving those that have cationic amphiphilic α-helices.

Antiseptic effect of natural teat dip containing lactic acid against mastitis-causing Escherichia coli

Aim:

This study aimed to estimate the enumeration of total bacteria and coliform on teat skin from dairy cows and evaluate the efficacy of the natural rice gel containing 5% v/v lactic acid (NGL) against Escherichia coli standard and field strains isolated from bovine teat skin.

Materials and Methods:

A total of 100 bacterial teat skin samples (25 cows) were collected from dairy cows in smallholder farm. The cows were housed in freestall barns. The colonization of total bacteria and E. coli on teat skin was measured by 3M Petrifilm method. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of lactic acid were evaluated for reference strain of E. coli ATCC 25922 and two field strains of E. coli. The natural teat sanitizer was formulated using 5% NGL with modified rice gel. In vitro antiseptic efficacy of 5% NGL was determined by time-kill kinetic assay. E. coli morphology after exposure with 5% NGL was examined under a scanning electron microscope (SEM).

Results:

The total bacteria and coliform counts from bovine teat skin were 2.11×10⁴ and 1.54×10¹ colony-forming units/ml, respectively. The MIC and MBC of lactic acid on the tested bacteria were 0.5% v/v. The natural teat dip was successfully prepared with minimum change in consistency after 1 year of storage at 4°C. The reduction rate of 5% NGL on E. coli ATCC 25922 and field strain showed 32.77% and 27.58%, respectively. An appearance under SEM of non-viable E. coli after being incubated with 5% NGL clearly showed atypical form and rough surface cell membrane.

Conclusion:

The rice gel containing 5% v/v lactic acid is a promising preparation as a natural teat antiseptic for reducing bacteria on teat skin. It was shown to be effective against E. coli causing bovine mastitis in dairy cows.

Antibiotic Resistance Among Pediatric-Sourced Ocular Pathogens: 8-Year Findings From the Antibiotic Resistance Monitoring in Ocular Microorganisms (ARMOR) Surveillance Study

BACKGROUND

The Antibiotic Resistance Monitoring in Ocular Microorganisms (ARMOR) study is a nationwide longitudinal antibiotic resistance surveillance program specific to bacterial pathogens commonly encountered in ocular infections. We evaluated in vitro resistance rates and trends among isolates obtained from pediatric patients (≤17 years of age).

METHODS

Clinical centers across the United States were invited to submit ocular isolates of Staphylococcus aureus, coagulase-negative staphylococci (CoNS), Streptococcus pneumoniae, Haemophilus influenzae and Pseudomonas aeruginosa to a central laboratory. Minimum inhibitory concentrations for various antibiotic classes were determined by broth microdilution per Clinical and Laboratory Standards Institute guidelines and interpreted as susceptible, intermediate or resistant based on available breakpoints. Longitudinal trends were analyzed using a Cochran-Armitage test for linear trends in a proportion.

RESULTS

Of 4829 isolates collected from January 2009 to December 2016, 995 isolates, sourced primarily from hospitals and referral centers, were obtained from pediatric patients (n = 286 H. influenzae, n = 284 S. aureus, n = 213 CoNS, n = 150 S. pneumoniae and n = 62 P. aeruginosa). With few exceptions, P. aeruginosa and H. influenzae were generally susceptible to the antibiotics tested. Of S. aureus and CoNS isolates, respectively, 56% and 72% were resistant to azithromycin and 24% and 47% were methicillin-resistant (MR); concurrent resistance to other drug classes and multidrug resistance (≥3 drug classes) were prevalent among MR staphylococci. Of S. pneumoniae isolates, 38% and 35% demonstrated resistance to azithromycin and penicillin, respectively. Besifloxacin had the lowest minimum inhibitory concentration against the Gram-positive isolates.

CONCLUSIONS

These in vitro data suggest antibiotic resistance is common among staphylococcal and pneumococcal isolates collected from pediatric patients with ocular infections. Methicillin resistance was prevalent among staphylococci with many strains demonstrating multidrug resistance. These findings may not be representative of resistance trends in community-based practices.

Inhibitory Effects and Killing Kinetics of Lactic Acid Rice Gel Against Pathogenic Bacteria Causing Bovine Mastitis

Staphylococcus aureus and S. epidermidis are the major teat skin bacteria and lead to severe bovine mastitis. Teat antiseptic is an important tool for controlling intramammary infection. The antibacterial activity of lactic acid (LA) against one reference strain of S. aureus ATCC 25923 and two field strains including S. aureus and S. epidermidis was investigated using the broth microdilution method. Its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were 0.5% for strains belonging to both species. An antiseptic preparation containing 5% LA with modified rice gel (LA-RG) was successfully prepared. Rheological behavior of LA-RG was found to be a pseudoplastic flow with thixotropy with viscosity of approximately 0.007 Pas. LA-RG exhibited a sufficient adhesive property in the rolling ball test with a length of 9.67 ± 0.04 cm. Killing kinetic studies of LA-RG showed that the killing rate of LA-RG was significantly faster than that of LA. After 32 min of exposure to LA-RG, approximately 86% and 60% of S. aureus and S. epidermidis were reduced, respectively. Abnormal bacterial cell surface after exposure to LA-RG was observed by scanning electron microscopy. It is concluded that LA-RG is a promising preparation as an alternative product for preventing mastitis in dairy cattle.

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: Efficacy and Safety in Treatment and Prevention of Ocular Bacterial Infections

This comprehensive review summarizes the mechanism of action, pharmacokinetics, efficacy, and safety of besifloxacin ophthalmic suspension, 0.6% and examines its role in the treatment of ocular surface bacterial infections. Besifloxacin possesses balanced activity against bacterial topoisomerase II (also called DNA gyrase) and topoisomerase IV. It has shown a low potential to select for bacterial resistance in vitro and demonstrated strong in vitro activity against many Gram-positive, Gram-negative, and anaerobic organisms, including methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis (MRSA and MRSE, respectively). Ocular pharmacokinetic studies have shown that besifloxacin achieves high, sustained concentrations in the tear fluid and conjunctiva following topical administration, with negligible systemic exposure. Large randomized, controlled clinical trials have established the efficacy and safety of besifloxacin administered three times daily for 5 days for treatment of acute bacterial conjunctivitis in both adults and children, with high rates of clinical resolution (up to more than 70% by day 5) and bacterial eradication (more than 90% by day 5), and a low incidence of adverse events. Additionally, besifloxacin applied twice daily for 3 days demonstrated greater efficacy than vehicle in treating bacterial conjunctivitis. Case reports, a large retrospective chart review, and animal studies have provided supporting evidence for the efficacy of besifloxacin in the management of acute bacterial keratitis. There is some evidence to suggest that besifloxacin may provide an advantage over other current-generation fluoroquinolones in antimicrobial prophylaxis for ocular surgery. Besifloxacin is an appropriate option for treatment of bacterial conjunctivitis, and its use in the treatment of bacterial keratitis and lid disorders, as well as for surgical prophylaxis, appears promising and warrants further evaluation.

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.

Rapid, sensitive and selective HPLC-MS/MS method for the quantification of topically applied besifloxacin in rabbit plasma and ocular tissues: Application to a pharmacokinetic study

Besifloxacin is a fourth-generation broad-spectrum fluoroquinolone registered for the topical treatment of bacterial conjunctivitis. In this study, a rapid, sensitive and selective liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for quantification of besifloxacin in rabbit plasma and ocular tissues using nateglinide as the internal standard (IS). The analyte and IS were separated on a Sepax GP-Phenyl column by isocratic elution with methanol-acetonitrile-5 mM ammonium formate-formic acid (29:55:16:0.1, v/v/v/v) as the mobile phase at a flow rate of 1.2 mL/min, and the total run time was 3.0 min. An electrospray ionization (ESI) source was applied and operated in the positive ion mode; multiple reaction monitoring (MRM) mode was used for quantification, and the monitored transitions were 394.2→377.1 for besifloxacin and m/z 318.3→166.1 for the IS. The calibration curve was linear over the range of 0.103-206 ng/mL for plasma and 2.06-2060 ng/mL for tears, aqueous humor, conjunctiva and cornea with correlation coefficient (r) greater than 0.99. The lower limit of quantification (LLOQ) for besifloxacin was 0.103 ng/mL for plasma and 2.06 ng/mL for other ocular tissues with good accuracy and precision. Intra- and inter-batch precision were both lower than 15% and accuracy ranged from 85% to 115% at all QC levels. The method was successfully applied to the pharmacokinetic study of besifloxacin in rabbit plasma and ocular tissues after single and multiple topical administrations.

Antibacterial efficacy of prophylactic besifloxacin 0.6% and moxifloxacin 0.5% in patients undergoing cataract surgery

Background

The purpose of this study was to investigate the ocular bacterial flora in patients scheduled to undergo cataract surgery and compare the antibacterial effects of besifloxacin ophthalmic suspension 0.6% and moxifloxacin ophthalmic solution 0.5% in these patients.

Methods

This was a prospective, randomized, laboratory-masked clinical trial. Patients received besifloxacin or moxifloxacin “quater in die” or QID (four times a day) for 3 days before cataract surgery in the surgical eye and 1 hour before surgery in the nonsurgical fellow eye. Conjunctival and eyelid swabs were obtained from both eyes at baseline and after treatment, on the day of surgery (Visit 2). Swabs were processed for bacterial colony counts (in terms of colony-forming units) and species identification. In vitro antibiotic susceptibilities of isolates were determined using Clinical and Laboratory Standards Institute breakpoints.

Results

Fifty-nine patients (n=28 besifloxacin, n=31 moxifloxacin) completed the study. The majority (73%) of conjunctival samples were culture negative at baseline. The most frequent isolates were coagulase-negative staphylococci (CoNS, 89%), specifically Staphylococcus epidermidis (72%). Both fluoroquinolones reduced the lid CFU values when administered QID for 3 days (P≤0.019), but only besifloxacin reduced the lid CFU estimate 1 hour following instillation of a single drop (P=0.039). Fewer besifloxacin-treated eyes had lids that were culture positive for CoNS at Visit 2 compared with moxifloxacin-treated eyes regardless of dosing regimen (P≤0.03). The minimum inhibitory concentration (MIC₉₀) of besifloxacin against methicillin-resistant S. epidermidis (MRSE) was eightfold lower than that of moxifloxacin.

Conclusion

Besifloxacin appeared more effective in reducing bacterial counts on eyelids of patients undergoing cataract surgery, with significant reductions as early as 1 hour postdose, compared with moxifloxacin. Besifloxacin was more active in vitro against MRSE.

Besifloxacin ophthalmic suspension 0.6% in the treatment of bacterial keratitis: a retrospective safety surveillance study

PURPOSE

The objective of this study was to collect and evaluate retrospective safety information about the use of besifloxacin ophthalmic suspension 0.6% for the treatment of bacterial keratitis.

METHODS

This was a retrospective, postmarketing surveillance study conducted at 10 clinical centers in the United States. The study population included 142 patients treated with besifloxacin ophthalmic suspension 0.6% for bacterial keratitis in one or both eyes. For perspective, data on 85 patients treated at these centers with moxifloxacin ophthalmic solution 0.5% for bacterial keratitis were also included. The analysis was designed to measure the types and rates of adverse events (AEs) reported during the treatment of bacterial keratitis with besifloxacin ophthalmic suspension 0.6%. Other treatment outcomes of interest included the development of corneal scarring and corneal neovascularization, measured or presumed bacterial eradication, ending visual acuity, and duration of pain before and after treatment.

RESULTS

There was one reported AE of mild superficial punctate keratitis in a patient using besifloxacin ophthalmic suspension 0.6%. The difference in AE frequencies between groups was not significant (P>0.999). Additional treatment outcomes were similar for both groups. Limitations of this report include the retrospective nature of the study.

CONCLUSIONS

These retrospective data suggest that besifloxacin ophthalmic suspension 0.6% was well tolerated when included in the treatment of bacterial keratitis; no serious AEs were reported. A prospective clinical trial is needed to better isolate the contribution of besifloxacin to the therapeutic outcome and to confirm these observations.

The safety of besifloxacin ophthalmic suspension 0.6 % used three times daily for 7 days in the treatment of bacterial conjunctivitis

BACKGROUND

Besifloxacin ophthalmic suspension 0.6 % (Besivance(®); Bausch & Lomb, Rochester, NY, USA) was approved by the FDA in 2009 for the treatment of bacterial conjunctivitis, with a recommended 7-day dosing regimen.

OBJECTIVE

The objective of this study was to compare the safety of besifloxacin ophthalmic suspension 0.6 %, administered three times a day for 7 days, with that of its vehicle.

METHODS

This randomized, multicenter, double-masked, vehicle-controlled, parallel-group study involved 518 patients ≥1 year of age with a clinical diagnosis of bacterial conjunctivitis. Patients were randomized 2:1 to treatment with besifloxacin 0.6 % ophthalmic suspension or vehicle, one drop in the infected eye(s) TID for 7 days. Main outcomes included the incidence and types of adverse events reported by the subject or observed by the investigator at each study visit.

RESULTS

Thirty-one ocular treatment-emergent adverse events (TEAEs) were reported by 28 subjects in the study eye; 19 occurred in 17/344 (4.9 %) besifloxacin patients, and 12 occurred in 11/170 (6.5 %) vehicle patients (p = 0.5362). Only two ocular events (mild instillation site reaction, one case in each group) were considered "definitely related" to study treatment. One event of self-limited dysgeusia in the besifloxacin group was considered definitely related to treatment; there were no other nonocular TEAEs considered related to treatment. There were no serious adverse events, and other safety outcomes (visual acuity, biomicroscopy, ophthalmoscopy) were unremarkable.

CONCLUSION

These findings indicate that besifloxacin ophthalmic suspension 0.6 % is safe in patients aged 1 year and older when used TID for 7 days.

Safety of besifloxacin ophthalmic suspension 0.6% in cataract and LASIK surgery patients

PURPOSE

The aim of the study was to evaluate the safety of besifloxacin ophthalmic suspension 0.6% as antibacterial prophylaxis in the surgical setting.

METHODS

Two prospective safety surveillance studies were conducted-one in the cataract surgery setting and the other in the laser-assisted in situ keratomileusis (LASIK) surgery setting. Cases from patients aged 18 years and above were eligible for inclusion. In both surveillance studies, data were collected from consecutive cases of routine primary cataract surgery and LASIK surgery, respectively, in which besifloxacin ophthalmic suspension 0.6% or moxifloxacin ophthalmic solution 0.5% was used as the topical perioperative prophylactic antibacterial medication as part of the clinician's routine standard of care. The primary safety endpoint was the incidence of treatment-emergent adverse events (TEAEs).

RESULTS

The cataract surgery surveillance study included 485 cases/eyes (besifloxacin, n = 333; moxifloxacin, n = 152), whereas the LASIK surveillance study included 456 cases/eyes (besifloxacin, n = 344; moxifloxacin, n = 112). In the cataract study, only 1 TEAE was reported in a besifloxacin case (mild hypersensitivity/allergic reaction considered possibly related to besifloxacin). No TEAEs were reported in the LASIK study. In both studies, surgical outcomes were similar with both treatments. The frequency of preoperative and/or postoperative dosing was generally lower for besifloxacin than that for moxifloxacin.

CONCLUSIONS

In prospective safety surveillance studies of patients undergoing cataract extraction or LASIK, TEAEs associated with prophylactic use of besifloxacin ophthalmic suspension 0.6% were rare, and surgical outcomes with besifloxacin were similar to those with moxifloxacin ophthalmic solution 0.5%.

The role of besifloxacin in the treatment of bacterial conjunctivitis

OBJECTIVE

To evaluate the role of besifloxacin in bacterial conjunctivitis treatment.

DATA SOURCES

Searches were made on MEDLINE/PubMed and EMBASE (January 2007 to January 2014) using the terms besifloxacin and Besivance. References from these publications were reviewed for additional resources. Additional information was collected from Bausch & Lomb, the manufacturer of Besivance; www.clinicaltrials.gov; and American Academy of Ophthalmology.

STUDY SELECTION AND DATA EXTRACTION

English-language documents were reviewed for pharmacology, pharmacokinetics, efficacy, and safety, with priority on clinical trials.

DATA SYNTHESIS

Three large randomized controlled clinical trials established the safety and efficacy of besifloxacin ophthalmic suspension 0.6% compared with placebo or active comparator (moxifloxacin ophthalmic solution 0.5%) given 3 times a day for 5 days for acute bacterial conjunctivitis (BC) treatment. Compared with placebo, besifloxacin had clinically superior bacterial eradication rates and was noninferior to moxifloxacin. Besifloxacin was compared with placebo in 2 randomized, placebo-controlled trials, dosed twice a day for 3 days. Superior efficacy was seen compared with placebo, which supports the shorter dosing schedule. Ophthalmic besifloxacin is well tolerated; the most common adverse effect (conjunctival redness) occurred in 2% of patients. Adverse effects in 1% to 2% of patients included blurred vision, eye pain, eye irritation, eye pruritus, and headache.

CONCLUSION

Besifloxacin 0.6% ophthalmic suspension 3 times a day for 5 days is safe and effective for BC. Twice-a-day dosing for 3 days was also effective-a simplified regimen compared with other fluoroquinolones. Disadvantages include price and lack of a generic. Further evaluation is needed to evaluate comparative efficacy among other ocular fluoroquinolones and unlabeled uses.

Contribution of the R8 substituent to the in vitro antibacterial potency of besifloxacin and comparator ophthalmic fluoroquinolones

Introduction

Previous work has shown that besifloxacin, an 8-chloro-fluoroquinolone, has more potent activity against gram-positive pathogens than moxifloxacin and gatifloxacin, which carry an 8-methoxy group. This study was conducted to determine the contribution of the R7 and R8 substituent to fluoroquinolone antibacterial activity.

Materials and methods

Besifloxacin, moxifloxacin, gatifloxacin, their R8 structural analogs, and ciprofloxacin were tested against representative isolates of various gram-positive and gram-negative species and previously characterized fluoroquinolone-resistant mutants of Staphylococcus aureus. Minimum inhibitory and minimum bactericidal concentrations were determined according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Reserpine was used to determine the effect of efflux pumps on antibacterial activity.

Results

In general, exchanging the R8 residue in besifloxacin slightly reduced the molecule’s potency, while introducing an 8-chloro group in moxifloxacin increased its potency. A similar change in gatifloxacin had little to no effect. Substituting the R8 residues did not increase the susceptibility to the efflux pump inhibitor reserpine or result in a loss of bactericidal activity. In contrast, the positive control, ciprofloxacin, was shown to be a substrate for reserpine and lost bactericidal activity against some fluoroquinolone-resistant isolates of S. aureus.

Conclusion

The data presented here show that, depending on the R7 substituent, replacing an 8-methoxy group with an 8-chloro substituent can improve potency or can have little-to-no effect. These findings highlight the importance of the interplay between the R7 and R8 substituents in determining antibacterial potency.

Role of topical, subconjunctival, intracameral, and irrigative antibiotics in cataract surgery

PURPOSE OF REVIEW

To summarize current understanding of antibiotic prophylaxis in cataract surgery, with particular emphasis on available evidence and change in practice patterns over the past decade.

RECENT FINDINGS

Povidone-iodine application prior to cataract surgery remains a universal practice, and is backed by good quality evidence. Subsequent to the results of the European multicenter trial documenting decreased risk of endophthalmitis with intracameral cefuroxime injection at the end of surgery, similar benefit with intracameral antibiotic use has been reported in studies with large sample sizes from multiple centers around the world. There has been a distinct change in practice patterns in many countries, with intracameral antibiotic use becoming part of routine protocol. In the USA, topical fluoroquinolone application remains the most popular mode of antibiotic prophylaxis. A promising approach is the development of novel drug delivery methods like polymeric devices designed for sustained antibiotic release.

SUMMARY

Based on current evidence, the recommended measures for endophthalmitis prophylaxis are preoperative topical instillation of povidone-iodine and intracameral antibiotic injection at the end of cataract surgery.

Studies on the antimicrobial properties of N-acylated ciprofloxacins

Fluoroquinolone antibiotics have been a mainstay in the treatment of bacterial diseases. The most notable representative, ciprofloxacin, possesses potent antimicrobial activity; however, a rise in resistance to this agent necessitates development of novel derivatives to prolong the clinical lifespan of these antibiotics. Herein we have synthesized and analyzed the antimicrobial properties of a library of N-acylated ciprofloxacin analogues. We find that these compounds are broadly effective against Gram-positive and Gram-negative bacteria, with many proving more effective than the parental drug, and several possessing MICs ≤1.0 μg/ml against methicillin-resistant Staphylococcus aureus and Bartonella species. An analysis of spontaneous mutation frequencies reveals very low potential for resistance in MRSA compared to existing fluoroquinolones. Mode of action profiling reveals that modification of the piperazinyl nitrogen by acylation does not alter the effect of these molecules towards their bacterial target. We also present evidence that these N-acylated compounds are highly effective at killing intracellular bacteria, suggesting the suitability of these antibiotics for therapeutic treatment.

Besifloxacin ophthalmic suspension, 0.6%: a novel topical fluoroquinolone for bacterial conjunctivitis

Acute bacterial conjunctivitis, the most common cause of conjunctivitis, is responsible for approximately 1% of all primary-care consultations. Of the topical ophthalmic antibiotics used to treat acute bacterial conjunctivitis, fluoroquinolones are especially useful because they possess a broad antibacterial spectrum, are bactericidal in action, are generally well tolerated, and have been less prone to development of bacterial resistance. Besifloxacin, the latest advanced fluoroquinolone approved for treating bacterial conjunctivitis, is the first fluoroquinolone developed specifically for topical ophthalmic use. It has a C-8 chlorine substituent and is known as a chloro-fluoroquinolone. Besifloxacin possesses relatively balanced dual-targeting activity against bacterial topoisomerase IV and DNA gyrase (topoisomerse II), two essential enzymes involved in bacterial DNA replication, leading to increased potency and decreased likelihood of bacterial resistance developing to besifloxacin. Microbiological data suggest a relatively high potency and rapid bactericidal activity for besifloxacin against common ocular pathogens, including bacteria resistant to other fluoroquinolones, especially resistant staphylococcal species. Randomized, double-masked, controlled clinical studies demonstrated the clinical efficacy of besifloxacin ophthalmic suspension 0.6% administered three-times daily for 5 days to be superior to the vehicle alone and similar to moxifloxacin ophthalmic solution 0.5% for bacterial conjunctivitis. In addition, besifloxacin ophthalmic suspension 0.6% administered two-times daily for 3 days was clinically more effective than the vehicle alone for bacterial conjunctivitis. Besifloxacin has also been shown in preclinical animal studies to be potentially effective for the "off-label" treatment of infections following ocular surgery, prophylaxis of endophthalmitis, and the treatment of bacterial keratitis. Taken together, clinical and preclinical animal studies indicate that besifloxacin is an important new option for the treatment of ocular infections.

Microbiological etiology and susceptibility of bacterial conjunctivitis isolates from clinical trials with ophthalmic, twice-daily besifloxacin

INTRODUCTION

Bacterial conjunctivitis is a contagious infection of the surface of the eye usually treated empirically with topical antibiotics. Since the etiologic agent is rarely identified, it is important to monitor which bacteria cause conjunctivitis and determine their antibacterial resistance profiles.

METHODS

A total of 496 bacterial samples were isolated during a randomized, double-masked, vehicle-controlled, parallel-group study conducted in the United States with besifloxacin ophthalmic suspension 0.6% dosed twice daily. Species were determined by standard biochemical and/or molecular identification methods. Minimum inhibitory concentrations were determined according to Clinical and Laboratory Standards Institute standards.

RESULTS

The most prevalent species was Haemophilus influenzae, followed by Staphylococcus epidermidis, Staphylococcus aureus, the Streptococcus mitis group, and Streptococcus pneumoniae. One species identified in this study, which was not previously noted as a common cause of bacterial conjunctivitis, was Dolosigranulum pigrum. Ampicillin resistance was common among H. influenzae isolates, while macrolide resistance was high among S. pneumoniae, S. epidermidis, and S. aureus. The latter two species also included a number of isolates resistant to methicillin and ciprofloxacin.

CONCLUSION

Antibiotic resistance among isolates remains a concern and the appearance of an emerging ocular pathogen, D. pigrum, suggests the need for continued observation. The topical ophthalmic fluoroquinolones continue to provide a good balance of low to moderate (i.e., manageable) levels of resistance plus broad-spectrum coverage for empiric treatment of ocular infections.

Prevention of postcataract endophthalmitis: evidence-based medicine

PURPOSE OF REVIEW

To provide a summary of current peer-reviewed publications on the methods of prophylaxis against postcataract endophthalmitis.

RECENT FINDINGS

Preoperative application of povidone-iodine remains the standard protocol for the prevention of postoperative endophthalmitis. More recent evidence suggests that intracameral cefuroxime administered at the conclusion of surgery significantly reduces the risk of endophthalmitis. However, its clinical use has been limited because of a lack of commercially available antibiotic indicated for intraocular injection. Although topical antibiotic application continues to be a controversial topic with respect to the types of antibiotic prescribed and dosage, most ophthalmologists do prescribe an antibiotic for the perioperative period. Resistance against antibiotics, including the very popular classes of fluoroquinolones, is rising. Most notably, methicillin resistance continues to increase over time.

SUMMARY

Prevention of postcataract endophthalmitis remains a difficult topic to study given the low incidence. In addition to appropriate wound construction, a combination of povidone-iodine and antibiotics provide a reasonable approach in reducing the risk of this rare but serious infection.

The role of topical moxifloxacin, a new antibacterial in Europe, in the treatment of bacterial conjunctivitis

This article discusses current practice in the treatment of conjunctivitis and how the use of topical moxifloxacin can increase therapeutic effectiveness, reduce treatment failures and, consequently, be cost effective and reduce the societal burden of the disorder. Current practice and effectiveness data were derived from the literature. Data on healthcare utilization as a result of treatment failure were collected by survey and the cost of treatment was defined using national costings. A decision-analytic model to assess cost effectiveness was developed and the impact on the healthcare budget was calculated to define the health economic impact. Bacterial conjunctivitis represents a significant health problem and accounts for an estimated 1-1.5% of primary-care consultations. The disorder is highly contagious and causes a substantial healthcare and societal burden. Bacterial conjunctivitis is generally self-limiting, resolving within 1-2 weeks. However, the use of antibacterials significantly improves clinical and microbiological remission, shortens symptom duration, and enables more effective use of healthcare resources, compared with placebo. From a health economic perspective this benefits the healthcare system and society, since fewer healthcare resources are needed and the adult affected, or the parent/caregiver of the child affected, can return to full work capacity sooner, reducing loss of productivity. Treatment strategies vary significantly between countries. Most patients are first seen in primary care, where 'wait-and-see', lubrification and antiseptic or antibacterial treatment is provided. In Europe, when antibacterials are prescribed most general practitioners (GPs) prescribe a broad-spectrum topical antibacterial. The most commonly used drugs are chloramphenicol and fusidic acid, with fluoroquinolones rarely reported as first-line treatment by GPs. At the specialist (ophthalmologist) level, or for second-line treatment at the GP level, topical antibacterials are frequently used. However, in most countries, topical fluoroquinolones, particularly those recently approved by the European Medicines Agency, such as topical levofloxacin and topical moxifloxacin, are rarely used and instead are reserved for use as a last resort. In other parts of the world topical lomefloxacin, gatifloxacin and/or besifloxacin are also available. The strategy of using novel topical fluoroquinolones as a last resort reflects a belief that the use of topical fluoroquinolones may enhance the development of resistance, jeopardizing future availability of antibacterial treatment for ocular infections. In fact, most cases of bacterial resistance arise as a result of systemic treatment. Thus, this concern should not be extrapolated to topical use of fluoroquinolones, which results in antibacterial concentrations at the ocular surface that can significantly exceed mutant prevention concentrations. In addition, with products such as topical moxifloxacin, a dual-step mutation is required for resistance to emerge. Moxifloxacin restricts the selection of resistant mutants, meaning that emergence of resistance is unlikely. The strategy of not using the most effective fluoroquinolones such as topical moxifloxacin may lead to more patients with no improvement or worsening of symptoms, requiring re-intervention, additional examination and new treatment; these outcomes are defined as 'treatment failures'. Treatment failures cause an extra societal burden and increased costs due to the extra healthcare resources required (additional GP/specialist visits, laboratory tests, additional treatment, etc.). Compared with non-fluoroquinolones, topical moxifloxacin has a higher potency and faster in vitro 'speed-to-kill'. It has also been shown that, within the fluoroquinolone class, topical moxifloxacin and besifloxacin achieve the highest mean concentrations in conjunctival tissue, have the longest residence times and display favourable area under the concentration-time curve from time zero to 24 hours (AUC(24))/minimum inhibitory concentration ratio required to inhibit the growth of 90% of organisms (MIC(90)) and thus favourable pharmacokinetic/pharmacodynamic characteristics. This can result in reduced time-to-cure and a lower number of treatment failures, leading to better disease management and a healthcare-economic benefit arising from the associated reduction in utilization of healthcare resources. The high potency and mean concentration in conjunctival tissue combined with the long residence time of topical moxifloxacin enables a dosing strategy of three times daily for 5 days. Topical moxifloxacin is also the first ophthalmic antibacterial in Europe provided as a multidose, self-preserved, topical solution, thus avoiding the risk of benzalkonium chloride preservative-related allergic reactions and swelling. In addition, topical moxifloxacin has a near neutral pH (6.8) and is well tolerated by patients. Given the characteristics of the novel topical fluoroquinolones, a change in the healthcare treatment strategy for acute infectious conjunctivitis is to be recommended. Topical application of fluoroquinolones, such as moxifloxacin multidose self-preserved solution, should be considered earlier in the treatment path for conjunctivitis. Notwithstanding the premium price attached to this novel topical antibacterial, use of topical moxifloxacin for bacterial conjunctivitis can be cost effective and even generate total healthcare budget savings by reducing both the costs of managing treatment failures and the use of clinicians' time to manage such failures.

Challenges in assessing microbial susceptibility and predicting clinical response to newer-generation fluoroquinolones

PURPOSE

To determine the most appropriate methods for assessing the potential effectiveness of the newer topical fluoroquinolones gatifloxacin, moxifloxacin, and besifloxacin.

METHODS

This article is based on a literature search for published articles about the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics of and measure of bacterial susceptibility to topical ophthalmic fluoroquinolones. Search terms included fluoroquinolones, susceptibility, resistance, minimal/minimum inhibitory concentration (MIC), PDs, PKs, and ocular, ophthalmic, or topical antibiotics.

RESULTS

Topical fluoroquinolones, particularly besifloxacin, gatifloxacin, and moxifloxacin, have become important treatment options for common ocular bacterial infections due to their broad-spectrum bactericidal activity and low toxicity. An important challenge in ophthalmology is identifying the most accurate in vivo and in vitro methods for evaluating the efficacy of these topical fluoroquinolones. The MIC is the most commonly used measure of in vitro susceptibility. In systemic therapy, this measure is combined with PK data of antibiotics to generate PD indices PK/PD whose breakpoints differentiate clinically susceptible from nonsusceptible bacterial pathogen populations. PD breakpoints are further tested in prospective studies for their ability to predict clinical efficacy. However, it is not known whether systemically derived breakpoints apply to the assessment of clinical susceptibility to ocular agents. Topical ocular antibiotics likely achieve higher concentrations at the target site than do systemically administered antibiotics, but these higher concentrations can be quickly reduced by reflex tearing and blinking induced by instillation. Hence, studies have been conducted in animals and humans to determine the PK concentrations of topically administered antibiotics in ocular compartments. When combined with MIC values for topical pathogens, the results have the potential to predict clinical efficacy after identification of the appropriate PK/PD target. Ocular studies incorporating PK/PD assessments have recently begun to be reported with newer fluoroquinolones, including besifloxacin, gatifloxacin, and moxifloxacin, whose prolonged contact time and potent bactericidal activity have translated into some of the most favorable PK/PD target values. However, the clinical relevance of these studies has yet to be determined.

CONCLUSION

There is still a clear need for predictive models to extend our understanding of the clinical susceptibility of ocular pathogens.

Integrated analysis of three bacterial conjunctivitis trials of besifloxacin ophthalmic suspension, 0.6%: etiology of bacterial conjunctivitis and antibacterial susceptibility profile

Background

The purpose of this paper is to report on the bacterial species isolated from patients with bacterial conjunctivitis participating in three clinical trials of besifloxacin ophthalmic suspension, 0.6%, and their in vitro antibacterial susceptibility profiles.

Methods

Microbial data from three clinical studies, conducted at multiple clinical sites in the US and Asia were integrated. Species were identified at a central laboratory, and minimum inhibitory concentrations were determined for various antibiotics, including β-lactams, fluoroquinolones, and macrolides.

Results

A total of 1324 bacterial pathogens representing more than 70 species were isolated. The most common species were Haemophilus influenzae (26.0%), Streptococcus pneumoniae (22.8%), Staphylococcus aureus (14.4%), and Staphylococcus epidermidis (8.4%). H. influenzae was most frequently isolated among patients aged 1–18 years, while S. aureus was most prevalent among those >65 years. Drug resistance was prevalent: Of H. influenzae isolates, 25.3% were β-lactamase positive and 27.2% of S. pneumoniae isolates were penicillin-intermediate/ resistant; of S. aureus isolates, 13.7% were methicillin-resistant (MRSA), and of these, 65.4% were ciprofloxacin-resistant, while 45.9% of S. epidermidis isolates were methicillin-resistant (MRSE), and, of these, 47.1% were ciprofloxacin-resistant. Besifloxacin was more potent than comparator fluoroquinolones overall, and particularly against Gram-positive bacteria. Against ciprofloxacin-resistant MRSA and MRSE, besifloxacin was four-fold to ≥ 128-fold more potent than other fluoroquinolones.

Conclusions

While the pathogen distribution in bacterial conjunctivitis has not changed, drug resistance is increasing. Patient age and local antibiotic resistance trends should be considered in the treatment of this ocular infection. Besifloxacin showed broad-spectrum in vitro activity and was particularly potent against multidrug-resistant staphylococcal isolates.

Acute and twenty-eight days repeated oral dose toxicity study of besifloxacin in Wistar albino rats

The purpose of this study was to investigate the potential acute and 28-day repeated oral toxicities of besifloxacin (BAF) in Wistar albino rats. In oral acute and repeated dose study, BAF was administered to both sex of rats, at dose levels of 0, 300, 600, 900 mg/kg/day and 0, 100, 200, 500 mg/kg/day, respectively. In the acute study, total white blood cell (WBC) (male, 43.74%; female, 42.60%) and total bilirubin (T-BIL) (male, 80%; female, 60%) were significantly increase, total protein (TP) (male, 23.24%; 27.80%) was significantly decreased, and significant incidence of pericholangitis (male, 83.33%; female, 75%) was shown in males and females of high-dose groups. In repeated oral dose toxicity study, similar type effects were also observed after serum hematological and serum biochemical analysis, whereas additionally sever hepatic injury and focal ulceration in gastric mucosa also observed in high dose groups of both sexes after histopathological analysis. However these toxic effects of besifloxacin were transient and reversible and no-observed adverse effect level (NOAEL) were 300 mg/kg/day for acute and 100 mg/kg/day for repeated dose toxicity study, respectively.

Efficacy and tolerability of besifloxacin ophthalmic suspension 0.6% administered twice daily for 3 days in the treatment of bacterial conjunctivitis: a multicenter, randomized, double-masked, vehicle-controlled, parallel-group study in adults and children

BACKGROUND

Besifloxacin is a topical fluoroquinolone with potent in vitro activity against a broad spectrum of ocular pathogens, including drug-resistant strains. Besifloxacin ophthalmic suspension 0.6% given 3 times daily for 5 days has been reported to be more effective than its vehicle in the treatment of bacterial conjunctivitis. Pharmacokinetic/pharmacodynamic modeling suggests that besifloxacin might also be effective given twice daily.

OBJECTIVE

This study evaluated the efficacy and tolerability of besifloxacin ophthalmic suspension 0.6% administered twice daily for 3 days compared with vehicle (formulation without besifloxacin) in the treatment of adults and children with bacterial conjunctivitis.

METHODS

This was a multicenter, prospective, randomized, double-masked, vehicle-controlled, parallel-group study. Patients aged ≥1 year with bacterial conjunctivitis were randomized to receive besifloxacin ophthalmic suspension or vehicle administered twice daily for 3 days. There were 3 study visits: the baseline visit, visit 2 (day 4 or 5), and visit 3 (day 7±1). Participants recorded the times of medication instillation in a patient diary. The primary end points were clinical resolution and bacterial eradication of the baseline bacterial infection at visit 2 in patients with culture-confirmed bacterial conjunctivitis. Secondary end points were clinical resolution and bacterial eradication of the baseline bacterial infection at visit 3, individual clinical outcomes (ocular conjunctival discharge and bulbar conjunctival injection) at the follow-up visits, and microbial and clinical outcomes for overall bacterial species and individual gram-positive and gram-negative bacterial species. Tolerability assessments included ocular adverse events (AEs), changes in visual acuity, biomicroscopy and ophthalmoscopy findings, and nonocular AEs.

RESULTS

Of 202 patients randomized to treatment (mean [SD] age, 25.2 [24.3] years; 56.9% female; 76.7% white), 109 had culture-confirmed bacterial conjunctivitis (53 besifloxacin ophthalmic suspension, 56 vehicle). At visit 2, the besifloxacin ophthalmic suspension group had significantly greater rates of clinical resolution compared with the vehicle group (37/53 [69.8%] vs 21/56 [37.5%], respectively; P < 0.001), as well as significantly greater rates of bacterial eradication (46/53 [86.8%] vs 32/56 [57.1%]; P < 0.001). At visit 3, rates of bacterial eradication were also significantly greater in the besifloxacin ophthalmic suspension group compared with the vehicle group (46/53 [86.8%] vs 39/56 [69.6%]; P = 0.038). Results for the individual clinical outcomes and microbial and clinical outcomes by gram-positive and gram-negative species were consistent with the primary efficacy outcomes. The incidence of ocular AEs did not differ significantly between treatment groups (4/94 [4.3%] vs 8/98 [8.2%]). Ocular AEs in all treated eyes in the respective groups included bacterial conjunctivitis (3/157 [1.9%] and 5/154 [3.2%]), conjunctivitis (3/157 [1.9%] and 4/154 [2.6%]), and allergic conjunctivitis (2/157 [1.3%] and 1/154 [0.6%]). These events were of mild or moderate severity. Changes in visual acuity and biomicroscopy and ophthalmoscopy findings were comparable between groups. There were few nonocular AEs (2/94 [2.1%] vs 3/98 [3.1%]; P = NS), none of them considered treatment related.

CONCLUSION

In these adults and children with bacterial conjunctivitis, treatment with besifloxacin ophthalmic suspension 0.6% administered twice daily for 3 days was effective and well tolerated. ClinicalTrials.gov identifier: NCT00972777.

Limitations of current antibiotics for the treatment of bacterial conjunctivitis

Bacterial conjunctivitis is a common ocular infection that is generally treated empirically with a broad-spectrum antibiotic. The more common pathogens causing bacterial conjunctivitis include Staphylococcus aureus, Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus epidermidis, and Moraxella species. Several antibiotics traditionally used to treat bacterial conjunctivitis are no longer widely prescribed because of increased bacterial resistance and/or safety concerns. The introduction of the fluoroquinolone class of anti-infectives offered effective and better tolerated treatment options. Nonetheless, successful therapy for bacterial conjunctivitis continues to be limited by several factors. A primary concern is the development of bacterial resistance that may be impacted not only by widespread antibiotic use but also by antibacterial pharmacokinetics, such as maintenance of insufficient bactericidal concentrations at the site of infection. In addition, poor adherence to prescribed regimens that require frequent administration, along with undesirable adverse events, affects the development of bacterial resistance and the success of treatment regimens. This article reviews current antibacterial agents used to treat bacterial conjunctivitis, factors that limit their successful use in treatment, and options for future development of more effective topical ophthalmic anti-infective agents.

In vitro time-kill experiments with besifloxacin, moxifloxacin and gatifloxacin in the absence and presence of benzalkonium chloride

OBJECTIVES

To compare the bactericidal activity of besifloxacin, moxifloxacin and gatifloxacin and determine the contribution of the preservative benzalkonium chloride (BAK) to bactericidal activity.

METHODS

Time-kill experiments were performed against four species (n=12) with besifloxacin, moxifloxacin and gatifloxacin, in the presence or absence of BAK, at t=0, 5, 15, 30, 45, 60, 120 and 360 min, according to standard CLSI methods.

RESULTS

In the presence of BAK, bactericidal activity was observed within 5 min, regardless of the fluoroquinolone tested. The bactericidal activity of BAK was unaffected by the concurrent presence of besifloxacin and rapid killing (within 5 to 15 min) was not observed at BAK concentrations below 50 mg/L. However, when tested without BAK, besifloxacin was bactericidal in as little as 45 min, while moxifloxacin and gatifloxacin required at least 120 min; besifloxacin kill rates against fluoroquinolone-susceptible and -resistant strains were at least 2- to 4-fold faster than those of gatifloxacin or moxifloxacin.

CONCLUSIONS

Besifloxacin was the most rapidly bactericidal fluoroquinolone tested, followed by gatifloxacin and moxifloxacin, both of which had similar activity. Our studies demonstrate that the previously reported rapid in vitro killing by gatifloxacin formulations was probably due to the concurrent presence of 50 mg/L BAK, which is much higher than the 3.2 mg/L BAK observed in human tears 1 min after instillation of ophthalmic gatifloxacin solutions [Friedlaender MH, Breshears D, Amoozgar B et al. The dilution of benzalkonium chloride (BAK) in the tear film. Adv Ther 2006; 23: 835-41].