Performance of Aneurysm Wall Enhancement Compared with Clinical Predictive Scales: PHASES, ELAPSS, and UIATS.

OBJECTIVE: To correlate the presence of objectively measured wall enhancement on high-resolution vessel wall imaging (HR-VWI) with the clinical predictive scales PHASES, ELAPSS, and UIATS. METHODS: Patients with unruptured intracranial aneurysm (UIAs) prospectively underwent HR-VWI on a 3-T magnetic resonance imaging scanner at diagnosis. Aneurysmal wall enhancement was objectively quantified on T1 postcontrast magnetic resonance imaging using signal intensity values adjusted for the pituitary stalk to calculate a contrast ratio (CRstalk). UIAs with CRstalk ≥0.60 were considered "enhancing." Patients' demographics, comorbidities, and aneurysm morphology were reviewed to calculate PHASES, ELAPSS, and UIATS scores. Pearson coefficients were applied for statistical correlation. Univariable and multivariable logistic regressions were performed to assess for confounders. RESULTS: One-hundred and twenty-three patients harboring 178 UIAs underwent HR-VWI. A total of 101 patients with 135 UIAs were analyzed. Enhancing UIAs were larger (8.4 ± 5.5 mm vs. 5.5 ± 2.3 mm; P < 0.001), had higher aspect ratio (2.3 ± 1.5 vs. 1.8 ± 0.7; P = 0.008), higher size ratio (3.0 ± 1.8 vs. 2.4 ± 1.1; P = 0.016), scored higher on PHASES (5.6 ± 3.9 vs. 4.4 ± 2.6; P = 0.04) and ELAPSS (19.4 ± 8.9 vs. 15.4 ± 7.3; P = 0.006) compared with nonenhancing UIAs. Treatment allocation as defined by UIATS was measured independently to enhancement status. No significant differences were found for UIATS between enhancing and nonenhancing UIAs (P = 0.63). Multivariable regression showed that size was the only independent factor significantly associated with UIA enhancement (odds ratio, 1.76; P = 0.005). CONCLUSIONS: Enhancing UIAs score higher in PHASES and ELAPSS scales. This association is largely explained by aneurysm size, aspect, and size ratios. Morphologic UIA features should be accounted for in clinical predictive scales of aneurysm instability.

Surveillance of the Activity of Aminoglycosides and Fluoroquinolones Against Ophthalmic Pathogens from Europe in 2010-2011.

PURPOSE/AIM: Bacterial infections of the ocular surface are commonly treated empirically with broad spectrum antibiotics. Due to concerns over increasing antibiotic resistance, we evaluated current susceptibility patterns of the ocular bacterial pathogens in Europe. MATERIALS AND METHODS: Non-consecutive ocular isolates of Staphylococcus aureus, coagulase-negative staphylococci (CoNS), Streptococcus pneumoniae, Haemophilus influenzae, and Pseudomonas aeruginosa were collected in 2011 from centers in France, Germany, Italy, Poland, Slovak Republic, Spain, and the United Kingdom. Centers were asked to provide similar numbers of methicillin-susceptible and -resistant staphylococcal isolates. Minimum inhibitory concentrations were determined for fluoroquinolones (besifloxacin, ciprofloxacin, moxifloxacin), aminoglycosides (tobramycin, gentamicin, netilmicin), oxacillin, chloramphenicol and erythromycin. Isolates were categorized as susceptible, intermediate, or resistant according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. RESULTS: A total of 741 ocular isolates were obtained. Antibiotic resistance rates depended not only on the antibiotic and species, but also varied greatly by the country of origin. Resistance to ciprofloxacin, tobramycin, erythromycin, and to a lesser extent, chloramphenicol, was a concern for all staphylococci. Multidrug resistance was common among methicillin-resistant S. aureus (MRSA) and MRCoNS and isolates of S. pneumoniae, H. influenzae, and P. aeruginosa were frequently non-susceptible to erythromycin, beta-lactams, and ciprofloxacin/tobramycin, respectively. Resistance rates showed substantial differences among the seven countries tested. Fluoroquinolones and aminoglycosides showed differences in antibacterial potency and resilience toward the antibiotic resistance mechanisms. CONCLUSIONS: Methicillin-resistant staphylococcal isolates were frequently non-susceptible to a multitude of other antibiotics, making MRSA and MRCoNS a potentially significant concern. The broad range of resistance rates observed across Europe in this study confirms the importance of considering current local resistance patterns when antibacterial agents are chosen for empiric management of ocular infections.

Acanthamoeba encystment: multifactorial effects of buffers, biocides, and demulcents present in contact lens care solutions.

PURPOSE: To determine whether agents which are purportedly capable of inducing encystment of Acanthamoeba can recapitulate the signal when tested in differing formulations. METHODS: In accordance with the International Standard ISO 19045, Acanthamoeba castellanii ATCC 50370 trophozoites were cultured in antibiotic-free axenic medium, treated with test solutions, and encystment rates plus viability were measured via bright field and fluorescent microscopy. Test solutions included phosphate-buffered saline (PBS), borate-buffered saline, biguanide- and hydrogen peroxide (H2O2)-based biocides, propylene glycol (PG) and povidone (POV) ophthalmic demulcents, and one-step H2O2-based contact lens disinfection systems. RESULTS: Only PBS solutions with 0.25 ppm polyaminopropyl biguanide (PAPB) and increasing concentrations of PG and POV stimulated A. castellanii encystment in a dose-dependent manner, whereas PBS solutions containing 3% H2O2 and increasing concentrations of PG and POV did not stimulate encystment. Borate-buffered saline and PBS/citrate solutions containing PG also did not stimulate encystment. In addition, no encystment was observed after 24 hours, 7 days, or 14 days of exposures of trophozoites to one-step H2O2 contact lens disinfection products or related solutions. CONCLUSION: The lack of any encystment observed when trophozoites were treated with existing or new one-step H2O2 contact lens care products, as well as when trophozoites were exposed to various related test solutions, confirms that Acanthamoeba encystment is a complex process which depends upon simultaneous contributions of multiple factors including buffers, biocides, and demulcents.

Antibiotic Resistance Among Ocular Pathogens in the United States: Five-Year Results From the Antibiotic Resistance Monitoring in Ocular Microorganisms (ARMOR) Surveillance Study.

IMPORTANCE: The Antibiotic Resistance Monitoring in Ocular Microorganisms (ARMOR) study is the only ongoing nationwide antibiotic resistance surveillance program specific to ocular pathogens. OBJECTIVE: To report resistance rates and trends among common ocular isolates collected during the first 5 years of the ARMOR study. DESIGN, SETTING, AND PARTICIPANTS: This antibiotic resistance surveillance study was performed at an independent central laboratory. 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. Isolates were collected from January 1, 2009, through December 31, 2013, and analyzed from January 16 to May 15, 2015. MAIN OUTCOMES AND MEASURES: Minimum inhibitory concentrations for various antibiotic classes were determined by broth microdilution according to the guidelines of the Clinical and Laboratory Standards Institute. Minimum inhibitory concentrations were interpreted as susceptible, intermediate, or resistant based on established break points. RESULTS: A total of 3237 ocular isolates (1169 S aureus, 992 CoNS, 330 S pneumoniae, 357 H influenzae, and 389 P aeruginosa) were collected from 72 centers. Methicillin resistance was found among 493 S aureus isolates (42.2%; 95% CI, 39.3%-45.1%) and 493 CoNS isolates (49.7%; 95% CI, 46.5%-52.9%), and methicillin-resistant (MR) isolates had a high probability of concurrent resistance to fluoroquinolones, aminoglycosides, or macrolides (P < .001). Multidrug resistance to at least 3 additional antibiotic classes was found in 428 MR S aureus isolates (86.8%) and 381 MRCoNS isolates (77.3%). All staphylococcal isolates were susceptible to vancomycin. Resistance among S pneumoniae isolates was highest for azithromycin (113 isolates [34.2%]) whereas resistance among P aeruginosa and H influenzae was low against the antibiotics tested. Staphylococcal isolates from elderly patients were more likely to be MR, as were S aureus isolates obtained from the southern United States (P < .001). Methicillin resistance among staphylococci did not increase during the 5-year study period (P ≤ .22), and small decreases in resistance to ciprofloxacin among CoNS and MRCoNS and to tobramycin among CoNS (P ≤ .03) were found. CONCLUSIONS AND RELEVANCE: Methicillin resistance was prevalent among staphylococcal isolates from ocular infections, with many strains demonstrating multidrug resistance. These findings are consistent with resistance trends reported for nonocular staphylococcal isolates. Overall ocular resistance did not increase during the 5-year study period. Continued surveillance of ocular isolates provides critical information to guide selection of topical antibacterials used for empirical management of ocular infections.

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.

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.

Unencapsulated Streptococcus pneumoniae from conjunctivitis encode variant traits and belong to a distinct phylogenetic cluster.

Streptococcus pneumoniae, an inhabitant of the upper respiratory mucosa, causes respiratory and invasive infections as well as conjunctivitis. Strains that lack the capsule, a main virulence factor and the target of current vaccines, are often isolated from conjunctivitis cases. Here we perform a comparative genomic analysis of 271 strains of conjunctivitis-causing S. pneumoniae from 72 postal codes in the United States. We find that the vast majority of conjunctivitis strains are members of a distinct cluster of closely related unencapsulated strains. These strains possess divergent forms of pneumococcal virulence factors (such as CbpA and neuraminidases) that are not shared with other unencapsulated nasopharyngeal S. pneumoniae. They also possess putative adhesins that have not been described in encapsulated pneumococci. These findings suggest that the unencapsulated strains capable of causing conjunctivitis utilize a pathogenesis strategy substantially different from that described for S. pneumoniae at other infection sites.

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.

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.

Besifloxacin ophthalmic suspension 0.6% in the treatment of bacterial conjunctivitis patients with Pseudomonas aeruginosa infections.

BACKGROUND: The purpose of this study was to determine the efficacy of besifloxacin ophthalmic suspension 0.6% when used in the treatment of bacterial conjunctivitis infections due to Pseudomonas aeruginosa. METHODS: We undertook a post hoc analysis of clinical outcomes in patients with bacterial conjunctivitis due to P. aeruginosa across four prospective, multicenter, double-masked, randomized, controlled, clinical studies of besifloxacin ophthalmic suspension 0.6%. Efficacy outcomes included bacterial eradication and clinical resolution of the baseline infection at follow-up visits. Bacterial eradication was defined as the absence of ocular bacterial species present at or above threshold at baseline, while clinical resolution was defined as grade 0 ocular discharge and bulbar conjunctival injection. Safety outcomes included the incidence of adverse events, changes in visual acuity, and biomicroscopy and ophthalmoscopy findings. Patient outcomes were summarized and bacterial eradication and clinical resolution rates integrated. RESULTS: Of 1317 patients with culture-confirmed bacterial conjunctivitis across four clinical studies, nine (0.7%) were infected with P. aeruginosa at baseline, and of these, five were randomized to treatment with besifloxacin ophthalmic suspension 0.6%. Bacterial eradication of the baseline infection was observed at both follow-up visits in all five patients. Clinical resolution was achieved in two of five patients by the first follow-up visit and four of five patients by the second follow-up visit. There were no adverse events reported in these patients. There were no clinically meaningful biomicroscopy findings or changes in ophthalmoscopy or visual acuity. CONCLUSION: The incidence of bacterial conjunctivitis due to P. aeruginosa was low. Treatment of patients with P. aeruginosa infections with besifloxacin ophthalmic suspension 0.6% led to bacterial eradication of P. aeruginosa by the first follow-up visit and high rates of clinical resolution.

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.

Besifloxacin ophthalmic suspension 0.6% administered twice daily for 3 days in the treatment of bacterial conjunctivitis in adults and children.

BACKGROUND AND OBJECTIVE: Besifloxacin ophthalmic suspension 0.6% given thrice daily for 5 days is safe and effective in the treatment of patients with bacterial conjunctivitis. This study evaluated the safety and efficacy of besifloxacin ophthalmic suspension 0.6% administered twice daily for 3 days compared with vehicle in the treatment of bacterial conjunctivitis. STUDY DESIGN: This was a multicenter, double-masked, randomized, vehicle-controlled, parallel-group study. METHODS: A total of 474 patients aged ≥1 year with bacterial conjunctivitis were randomized in a 1 : 1 ratio to receive either besifloxacin ophthalmic suspension 0.6% or vehicle administered twice daily for 3 days. There were three study visits: day 1 (the baseline visit), day 4/5 (visit 2), and day 7 ± 1 (visit 3). The co-primary efficacy endpoints were bacterial eradication and clinical resolution at day 4/5 in designated study eyes of patients with culture-confirmed bacterial conjunctivitis. Secondary efficacy endpoints were bacterial eradication and clinical resolution at day 7 ± 1, individual clinical outcomes of ocular discharge and bulbar conjunctival injection at all visits; and microbial and clinical outcomes for overall bacterial species and individual Gram-positive and Gram-negative bacterial species at each follow-up visit. Safety endpoints included adverse events (AEs), changes in visual acuity and biomicroscopy findings at each visit, and changes in ophthalmoscopy findings at day 7 ± 1. RESULTS: Bacterial eradication and clinical resolution rates were significantly higher in the besifloxacin group than in the vehicle group (115/135 [85.2%] vs 77/141 [54.6%], p < 0.001, and 89/135 [65.9%] vs 62/141 [44.0%], p < 0.001, respectively) at day 4/5. Rates of bacterial eradication continued to be significantly greater in the besifloxacin group (115/135 [85.2%] vs 91/141 [64.5%], respectively; p < 0.001) at day 7 ± 1; however, the rates of clinical resolution did not differ significantly between the groups (103/135 [76.3%] and 94/141 [66.7%], p = 0.209) at this visit. Ocular discharge and bulbar conjunctival injection at each visit were consistent with the primary outcomes. Clinical resolution and bacterial eradication with Gram-positive or Gram-negative organisms were consistent with the overall findings. All AEs in both groups were of mild or moderate severity and were considered unrelated to the treatment. CONCLUSION: Treatment with besifloxacin ophthalmic suspension 0.6% administered twice daily for 3 days was effective and safe in adults and children with bacterial conjunctivitis. CLINICAL TRIAL REGISTRATION: Registered at ClinicalTrials.gov as NCT00972777.

Integrated analysis of three bacterial conjunctivitis trials of besifloxacin ophthalmic suspension, 0.6%: microbiological eradication outcomes.

PURPOSE: To assess clinical antimicrobial efficacy results obtained with besifloxacin ophthalmic suspension, 0.6%, administered three times a day (TID) for 5 days, integrated across three clinical trials of bacterial conjunctivitis and to investigate any microbiological eradication failures. METHODS: Clinical microbiological eradication data from three randomized, double-masked, parallel group studies of patients with bacterial conjunctivitis (two vehicle controlled; one active controlled with moxifloxacin ophthalmic solution, 0.5%) were integrated. All bacterial samples isolated at baseline above the species-specific threshold value were subjected to antimicrobial susceptibility testing. Samples isolated at subsequent visits were subjected to susceptibility testing and pulsed-field gel electrophoresis (PFGE) to investigate the cause of eradication failures and the potential for drug resistance development. RESULTS: Visit 2 (day 4 or 5) and visit 3 (day 8) overall microbiological eradication rates were 92.2% and 88.4% for besifloxacin ophthalmic suspension compared with 61.4% and 72.5% for vehicle and 91.6% and 85.7% for moxifloxacin ophthalmic solution. Visit 2 and visit 3 microbiological eradication rates for Gram-positive and Gram-negative isolates and for individual species were consistent with the overall eradication rates. The majority of observed eradication failures in any treatment group were due to the persistence of the pathogen isolated at baseline. Eradication failures in the besifloxacin treatment group were not associated with lower antimicrobial susceptibility at baseline. PFGE data showed that the majority of bacterial strains in eyes with eradication failures were identical to the strain isolated at baseline; these eradication failures were not associated with a lower antimicrobial susceptibility at the follow-up visit. CONCLUSION: Treatment with besifloxacin ophthalmic suspension, 0.6%, administered TID for 5 days resulted in microbiological eradication rates that were ≥ 90% across the three clinical studies for the common pathogens of bacterial conjunctivitis. The few eradication failures were not due to fluoroquinolone resistance at baseline and/or resistance development during treatment.

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 ß-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 ß-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.

High proportion of nontypeable Streptococcus pneumoniae isolates among sporadic, nonoutbreak cases of bacterial conjunctivitis.

PURPOSE: Outbreaks of bacterial conjunctivitis have been linked to nontypeable strains of Streptococcus pneumoniae that lack a capsule, a key virulence factor for invasive infections. In contrast, isolates from sporadic, nonoutbreak cases of conjunctivitis were thought to be similar to invasive or nasopharyngeal isolates with respect to their capsular serotype and antibiotic resistance profile. This hypothesis was tested for 302 strains isolated during three prospective, multicenter clinical studies of bacterial conjunctivitis. MATERIALS AND METHODS: S. pneumoniae capsular serotypes were determined by agglutination assay and confirmed by the Statens Serum Institute. The presence of the cpsAB capsule genes was determined by polymerase chain reaction (PCR). Minimum inhibitory concentrations were measured for 17 antibacterial drugs by the broth microdilution method. RESULTS: Only 25 (8.3%) isolates reacted with the capsule-specific antisera and only one (0.3%) of these serotypes was covered by the capsule-specific PCV7 vaccine. The remaining 277 (91.7%) isolates were nontypeable, suggesting that they did not produce a capsule. PCR analysis indicated the loss of the capsule operon in 24/25 randomly selected nontypeable strains. Resistance rates were highest for azithromycin, trimethoprim, and tetracycline, while no resistance was detected for the fluoroquinolones, linezolid, and vancomycin. Antibiotic resistance rates were generally lower than those reported for invasive isolates, although some highly resistant or multidrug-resistant isolates were identified. CONCLUSIONS: The prevalence of nontypeable strains of S. pneumoniae was higher than expected, while the number of isolates responsive to the PCV7 vaccine was surprisingly low. These results highlight the need for new vaccines that can target all S. pneumoniae strains regardless of the presence or nature of a capsule. In addition, resistance to azithromycin, erythromycin, tetracycline, and trimethoprim was greater than 10%, which may be relevant when selecting empiric treatments for ocular surface infections.

Topoisomerase mutations that are associated with high-level resistance to earlier fluoroquinolones in Staphylococcus aureus have less effect on the antibacterial activity of besifloxacin.

BACKGROUND: The impact of mutations in DNA gyrase and topoisomerase IV on minimum inhibitory concentrations (MICs) was investigated to better understand why besifloxacin has a higher potency against Staphylococcus aureus when compared to other fluoroquinolones, which was especially pronounced against ciprofloxacin-resistant isolates. METHODS: MICs were determined for 52 clinical isolates against besifloxacin, moxifloxacin, gatifloxacin, ciprofloxacin, and levofloxacin. The genes encoding GyrA, GyrB, ParC, and ParE were sequenced and the potential impact of mutations assessed in light of recent structural data. RESULTS: For all fluoroquinolones tested, the MICs increased with the number of mutations in the quinolone resistance-determining regions. However, this increase was the smallest for besifloxacin and the largest for ciprofloxacin and levofloxacin. In addition to the commonly observed mutations in ParC and GyrA, more unusual mutations in ParE, such as Asp-432→His or Pro-585→Ser, were also detected. CONCLUSIONS: Compared to earlier fluoroquinolones, the higher potency of besifloxacin suggests that the drug's unique combination of a 7-azepinyl ring and an 8-chloro-substituent results in unique interactions with DNA gyrase and topoisomerase IV.

Monitoring antibiotic resistance in ocular microorganisms: results from the Antibiotic Resistance Monitoring in Ocular micRorganisms (ARMOR) 2009 surveillance study.

PURPOSE: To determine the antibacterial susceptibility profile of bacterial pathogens from ocular infections against relevant aminoglycoside, ß-lactam, cephalosporin, chloramphenicol, fluoroquinolone, glycopeptide, lincosamide, and macrolide antibacterial agents. DESIGN: Laboratory investigation. METHODS: Isolates from patients with bacterial eye infections were collected prospectively by 34 institutions across the United States and were submitted to a central laboratory for inclusion in the Antibiotic Resistance Monitoring in Ocular micRorganisms (ARMOR) study. Minimum inhibitory concentrations were determined by microbroth dilution for 200 Staphylococcus aureus (S. aureus), 144 coagulase-negative staphylococci, 75 Streptococcus pneumoniae (S. pneumoniae), 73 Haemophilus influenzae (H. influenzae), and 100 Pseudomonas aeruginosa (P. aeruginosa) isolates. RESULTS: A large proportion of S. aureus and coagulase-negative staphylococci isolates were resistant to oxacillin/methicillin, azithromycin, or fluoroquinolones; 46.5% of S. aureus, 58.3% of coagulase-negative staphylococci, 9.0% of P. aeruginosa, and 9.3% of pneumococcal isolates were nonsusceptible to 2 or more antibacterial drug classes. Only 2.7% of H. influenzae isolates were nonsusceptible to 1 of the agents tested. Methicillin-resistant staphylococci were statistically more likely (all P < .0038) also to be resistant to fluoroquinolones, aminoglycosides, and macrolides. CONCLUSIONS: Resistance to 1 or more antibiotics is prevalent among ocular bacterial pathogens. Current resistance trends should be considered before initiating empiric treatment of common eye infections.

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.

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].

Molecular epidemiology of methicillin-resistant and methicillin-susceptible Staphylococcus aureus isolated from the eye.

PURPOSE: Methicillin-resistant Staphylococcus aureus (MRSA) strains are commonly classified as hospital-acquired (HA) or community-acquired (CA). Typical HA-MRSA isolates are characterized by multidrug resistance and the SCCmec type II cassette, while CA-MRSA isolates are generally susceptible to more drug classes, are often of SCCmec type IV, and frequently carry the Panton-Valentine leukocidin (PVL) genes. This study determined the presence of traits characteristic for CA and HA strains in ocular MRSA isolates. MATERIALS AND METHODS: Fifty-six recent ocular isolates, consisting of 40 MRSA and 16 methicillin-susceptible Staphylococcus aureus (MSSA) comparator strains, were characterized. Minimum inhibitory concentration (MIC) testing was done according to current Clinical and Laboratory Standards Institute guidelines. Detection of the PVL encoding genes and determination of the SCCmec type was done by polymerase chain reaction (PCR), while spa typing and cluster analysis was performed following DNA sequencing. RESULTS: Of the 38 typeable MRSA isolates, 22 were of SCCmec type II and 16 were of SCCmec type IV. All SCCmec type II isolates were multidrug-resistant, lacked the PVL genes, and were of spa type t002 or closely related spa types. In contrast, the SCCmec type IV isolates were resistant to fewer classes of antimicrobial agents, often possessed the PVL genes (75.0%), and were of spa type t008 or closely related spa types. CONCLUSIONS: While the majority of ocular MRSA strains in this study fit the classical profile of HA- and CA-MRSA, some CA-MRSA isolates exhibited higher levels of antimicrobial resistance, which should be of particular concern to eye-care professionals. Furthermore, the apparent association of spa types and SCCmec types observed here warrants further investigation and suggests that spa typing may be useful in future HA- and CA-MRSA characterization studies.