[In vitro antibiotic susceptibility to fluoroquinolones]

Thymosin beta 4: A potential novel adjunct treatment for bacterial keratitis

Microbial keratitis is a rapidly progressing, visually debilitating infection of the cornea that can lead to corneal scarring, endophthalmitis, and perforation. Corneal opacification or scarring, a complication of keratitis, is among the leading causes of legal blindness worldwide, second to cataracts.Pseudomonas aeruginosaandStaphylococcus aureusare the two bacteria most commonly associated with this type of infection. Risk factors include patients who are immunocompromised, those who have undergone refractive corneal surgery, and those with prior penetrating keratoplasty, as well as extended wear contact lens users. Current treatment of microbial keratitis primarily addresses the pathogen using antibiotics. Bacterial clearance is of utmost importance yet does not guarantee good visual outcome. Clinicians are often left to rely upon the eye's innate ability to heal itself, as there are limited options beyond antibiotics and corticosteroids for treating patients with corneal infection. Beyond antibiotics, agents in use, such as lubricating ointments, artificial tears, and anti-inflammatory drops, do not fully accommodate clinical needs and have many potential harmful complications. To this end, treatments are needed that both regulate the inflammatory response and promote corneal wound healing to resolve visual disturbances and improve quality of life. Thymosin beta 4 is a small, naturally occurring 43-amino-acid protein that promotes wound healing and reduces corneal inflammation and is currently in Phase 3 human clinical trials for dry eye disease. Our previous work has shown that topical Tβ4 as an adjunct to ciprofloxacin treatment reduces inflammatory mediators and inflammatory cell infiltrates (neutrophils/PMN and macrophages) while enhancing bacterial killing and wound healing pathway activation in an experimental model ofP. aeruginosa-induced keratitis. Adjunctive thymosin beta 4 treatment holds novel therapeutic potential to regulate and, optimally, resolve disease pathogenesis in the cornea and perhaps other infectious and immune-based inflammatory disease. We plan to establish the importance of thymosin beta 4 as a therapeutic agent in conjunction with antibiotics with high impact for immediate clinical development.

Potentiation of Antibiotic Activity by a Meldrum's Acid Arylamino Methylene Derivative against Multidrug-Resistant Bacterial Strains

This study aimed to evaluate the intrinsic antibacterial activity and antibiotic-enhancing effect of an arylamino methylene derivative (MAD) in association with fluoroquinolones. The antibacterial activity against multiresistant Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli was analyzed by determining the minimum inhibitory concentration (MIC) using the broth micro dilution method. A reduction in the MIC of the fluoroquinolones against strains treated simultaneously with the MAD was interpreted as an enhanced antibiotic activity. While the MAD exhibited no clinically effective action (MIC ≥ 1.024 µg/mL), it was found to significantly potentiate the activity of norfloxacin, ofloxacin and lomefloxacin against all the strains, which may be related to structural similarities between the MAD and quinolones. Our findings suggest that Meldrum's acid arylamino derivatives may represent promising molecules in the elaboration of new drugs to reverse resistance to fluoroquinolones.

Antibiotic resistance profile in eye infections in a reference centre in Floridablanca, Colombia

BACKGROUND AND OBJECTIVE

In view of the increasing bacterial resistance to antibiotics, it is necessary to determine it locally in order to serve as a guide in clinical management. The purpose of this study was to characterise the pattern of antibiotic sensitivity in cases of eye infections in a third level ophthalmological institution in Floridablanca (Colombia).

MATERIALS AND METHODS

An observational cross-sectional study in which an analysis was made of the culture and antibiogram reports of specimens taken from cases of conjunctivitis, infectious keratitis, and endophthalmitis between January 2013 and June 2016.

RESULTS

A total of 833 specimens were positive for bacteria. Considering both gram-positive and gram-negative microorganisms gentamicin, tobramycin, and ciprofloxacin showed high resistance rates (64.4%, 40.3%, and 29.1%, respectively). Moxifloxacin, vancomycin, imipenem, and gatifloxacin showed low percentages of resistance: 2.6%, 2.1%, 0.6%, and 0.4%, respectively. When comparing the results with previous studies in our institution, there was a decrease in sensitivity to the fourth-generation quinolones and imipenem, especially within the gram-negative ones.

CONCLUSION

Fourth generation quinolones, imipenem and vancomycin continue to have a low in vitro resistance to bacteria that cause eye infections. However, there was a tendency to an increase in the resistance of gram-negative bacteria. Measures should be taken to try to control this phenomenon, and consider possible antimicrobial therapy alternatives to infections caused by these microorganisms.

Efficacy and Safety of 0.6% Pazufloxacin Ophthalmic Solution Versus Moxifloxacin 0.5% and Gatifloxacin 0.5% in Subjects with Bacterial Conjunctivitis: A Randomized Clinical Trial

PURPOSE

The purpose of this study was to evaluate the clinical efficacy and safety of a novel ophthalmic solution of pazufloxacin on the ocular surface of patients with bacterial conjunctivitis after 7 days of intervention.

METHODS

This is a phase 2, double-blind, controlled, multicenter, clinical trial of 300 subjects, randomized to either a 3 dosing regimen of pazufloxacin 0.6% ophthalmic solution (twice a day [BID], n = 90; 3 times a day [TID], n = 76; 4 times a day [QID], n = 68), moxifloxacin 0.3% TID (n = 82), or gatifloxacin 0.5% TID (n = 72). Follow-up was set on days 0, 3, and 7. Assessments of ocular signs were performed, both anterior and posterior segments. The primary outcome measures included conjunctival culture and clinical signs. Safety variables included adverse events (AEs), lisamine green, fluorescein ocular surface stains, and clinical signs of tolerability.

RESULTS

After intervention, bacterial eradication was reported in all groups: pazufloxacin BID 79%, pazufloxacin TID 84%, pazufloxacin QID 84%, moxifloxacin 80%, and gatifloxacin 82%. There were no significant differences between treatments. Similar results were reported in clinical remission: pazufloxacin BID 89%, pazufloxacin TID 98%, pazufloxacin QID 92%, moxifloxacin 91%, and gatifloxacin 92% (P = 0.03 comparing pazufloxacin BID vs. TID). There were no differences between female and male responses. The AEs were not related to the interventions.

CONCLUSIONS

A simplified dosing regimen was selected to follow the development of ophthalmic pazufloxacin based on its efficacy and safety profile. Pazufloxacin, 1 drop 3 times daily, showed similar rates of bacterial eradication and clinical remission compared with other fluoroquinolones.

Clinical features and microbiological in bacterial keratitis in a tertiary referral hospital

OBJECTIVE

To describe the clinical features, bacterial agents, and antibiotic sensitivity of bacterial keratitis in the Ophthalmology Department at the University Hospital Fundación Jiménez Díaz (HUFJD) in Madrid.

MATERIALS AND METHODS

A retrospective observational descriptive study using clinical records and reports of corneal scrapings in patients with bacterial keratitis at the HUFJD conducted between 2009 and 2014.

RESULTS

In a sample of 160 patients, gram-positive bacteria were the most prevalent with 64.3% (n=103). Coagulase negative staphylococcus (20.6%), Staphylococcus aureus (19.4%), and Pseudomonas aeruginosa (12.5%) were the most frequent bacteria. The most common risk factor was the use of contact lenses, followed by disease of the ocular surface, and previous ocular surgeries. The antibiotics to which the bacteria were most commonly susceptible were gentamicin (n=114), cotrimoxazole (n=107), vancomycin (n=106), and ciprofloxacin (n=97). The antibiotics to which the bacteria were most commonly resistant were ampicillin (n=59) and erythromycin (n=45).

CONCLUSIONS

In the initial management of bacterial keratitis, the sensitivity and resistance of bacteria to antibiotics should be taken into account. Based on our findings, the use of aminoglycosides, vancomycin and fluoroquinolones is recommended, and, although widely used today, the discontinuation of erythromycin.

Safety of intravitreal quinupristin/dalfopristin in an animal model

AIM

To determine whether different intravitreal doses of quinupristin/dalfopristin lead to electroretinographic or histological changes in the rabbit retina over one month period after injection.

METHODS

Eighteen New Zealand white rabbits were divided into three treatment groups (groups 1 to 3) and different intravitreal doses of quinupristin/dalfopristin were tested in each group. The right eye was injected with the drug and the left eye received intravitreal injection of 5% dextrose water and served as control eye. The doses delivered to each group were 0.1 mg/0.1 mL, 1 mg/0.1 mL and 10 mg/0.1 mL. Simultaneous, bilateral, dark-adapted electroretinography and clinical images of both eyes were obtained in all groups before injection (baseline) and after 7, 14, 21 and 28d, followed by enucleation for histological examination.

RESULTS

Subjects in the group 1 showed no signs of toxicity in the electroretinogram when compared with groups 2 and 3 (Kruskall-Wallis test, P=0.000). By day 7, no electrical response to light stimuli was recorded in the treated eyes in groups 2 and 3, consistent with severe damage due to retinal toxicity. Light microscopy revealed no significant histopathological changes in the group 1, while rabbits in groups 2 and 3 had signs of granulomatous inflammation in most cases.

CONCLUSION

Intravitreal 0.1 mg/0.1 mL doses of quinupristin/dalfopristin do not lead to electroretinographic or histological signs of retinal toxicity compared with 1 mg/0.1 mL and 10 mg/0.1 mL in this rabbit model.