Antimicrobial activity of topical dyes used in clinical veterinary ophthalmology.

OBJECTIVE: To evaluate in vitro the antibacterial effects of fluorescein, rose bengal, and lissamine green topical ophthalmic dyes against selected Gram-positive and Gram-negative bacteria, and to evaluate whether preserved or preservative-free fluorescein solutions are able to inhibit or potentiate bacterial growth. PROCEDURES: Susceptibility testing was performed using the Kirby-Bauer disk diffusion method plated with clinical ocular isolates of Staphylococcus aureus, Staphylococcus pseudintermedius, Streptococcus spp., Escherichia coli, and Pseudomonas aeruginosa. Bacterial growth inhibition was evaluated 24 hours following the addition of commercially available fluorescein, rose bengal, and lissamine green sterile strips. Antimicrobial effectiveness testing was performed by inoculation of compounded 1% dye solutions, both with and without preservatives (fluorescein and lissamine contained thiomersal, and rose bengal contained nipagin and nepazol), with the five previously mentioned bacteria. Growth was evaluated at days 7, 14, and 28. RESULTS: All dyes showed antibacterial activity against Gram-positive organisms. Preservative-free compounded 1% fluorescein solution inhibited growth of Gram-positive organisms but not of Gram-negative organisms. Preservative-free rose bengal and lissamine green inhibited growth of both types of organisms. CONCLUSIONS: Preferably, ocular surface samples for antimicrobial culture should be taken prior to the administration of topical dyes, due to their potential antibacterial activity, particularly if undiluted strips are applied directly or commercial fluorescein solutions are used and not immediately rinsed. Ophthalmic dye solutions containing preservative are safe from bacterial growth for up to 28 days if properly handled and stored. The use of preservative-free fluorescein solutions should be avoided and preservative-free rose bengal and lissamine green should be handled carefully.

Effectiveness of clinical surface cleaning and disinfection: evaluation methods.

OBJECTIVE: To discuss the methods employed to evaluate the effectiveness of clinical surface cleaning and disinfection (C&D). METHOD: This is a theoretical reflection based on scientific studies and the experience of the authors. Knowledge and current gaps, the need for further studies, and practical application of the methods were approached. RESULTS: There are four main methods used to evaluate the effectiveness of clinical surface C&D: visual inspection, fluorescent markers, microbiological cultures, and adenosine triphosphate (ATP) bioluminescence. The first two are used to evaluate the process and to predict adherence to protocols by the staff, and the last two are employed to evaluate the results, therefore being the most relevant to assess the risk of infection. FINAL CONSIDERATIONS: The ideal method was not found, because all of them showed limitations. There is a need for strategies to optimize the precision of these methods.

Susceptibility of Candida albicans and Candida dubliniensis to erythrosine- and LED-mediated photodynamic therapy.

The effect of erythrosine- and LED-mediated photodynamic therapy (PDT) on planktonic cultures and biofilms of Candida albicans and Candida dubliniensis was evaluated. Planktonic cultures of standardized suspensions (10(6)cells/mL) of C. albicans and C. dubliniensis were treated with erythrosine concentrations of 0.39-200 µM and LEDs in a 96-well microtiter plate. Biofilms formed by C. albicans and C. dubliniensis in the bottom of a 96-well microtiter plate were treated with 400 µM erythrosine and LEDs. After PDT, the biofilms were analysed by scanning electron microscopy (SEM). The antimicrobial effect of PDT against planktonic cultures and biofilms was verified by counting colony-forming units (CFU/mL), and the data were submitted to analysis of variance and the Tukey test (P<0.05). C. albicans and C. dubliniensis were not detectable after PDT of planktonic cultures with erythrosine concentrations of 3.12 µM or higher. The CFU/mL values obtained from biofilms were reduced 0.74 log(10) for C. albicans and 0.21 log(10) for C. dubliniensis. SEM revealed a decrease in the quantity of yeasts and hyphae in the biofilm after PDT. In conclusion, C. albicans and C. dubliniensis were susceptible to erythrosine- and LED-mediated PDT, but the biofilms of both Candida species were more resistant than their planktonic counterparts.

Olho externo e filme pré-lacrimal / External eye and pre corneal film

A preservaçäo da transparência e regularidade da cornea dependem de um filme pré-lacrimal saudável. O exame do filme se faz principalmente pela observaçäo do menisco inferior, pela utilizaçäo de corantes como a fluoresceína ou a Rosa Bengala, o teste de Schirmer e o tempo de ruptura do filme pré-corneano. O exame da conjuntiva compreende a verificaçäo de alteraçöes de cor, relevo e secreçäo. É importante que ao exame clínico sejam associados o exame bacteriológico da secreçäo conjuntival e o exame citológico do raspado conjuntival. Um exame necessário para qualquer remoçäo de tecido é o anatomo-patológico, as vezes o único meio de diagnóstico tumoral. O exame da cornea deve incluir, além da cautelosa investigaçäo bio-microscópica, o exame da sensibilidade corneana