Antimicrobial efficacy of in vitro and ex vivo photodynamic therapy using porphyrins against Moraxella spp. isolated from bovine keratoconjunctivitis.

Infectious bovine keratoconjunctivitis (IBK) is an ocular disease affecting bovine herds worldwide, and it causes significant economic loss. The etiologic agent of IBK is considered to be Moraxella bovis, but M. ovis and M. bovoculi are frequently recovered of animals presenting clinical signs of IBK. The therapeutic measures available for its control have limited efficacy. Antimicrobial photodynamic therapy (aPDT) using porphyrins as photosensitizing molecules is an alternative method that can be used to reduce microbial growth. We evaluated the antibacterial activity of aPDT using two water-soluble tetra-cationic porphyrins (H2TMeP and ZnTMeP) against 22 clinical isolates and standard strains of Moraxella spp. in vitro and in an ex vivo model. For the in vitro assay, 4.0 µM of porphyrin was incubated with approximately 1.0 × 104 CFU/mL of each Moraxella sp. isolate and exposed to artificial light for 0, 2.5, 5, and 7.5 min. Next, 50 µL of this solution was plated and incubated for 24 h until CFU measurement. For the ex vivo assay, corneas excised from the eyeballs of slaughtered cattle were irrigated with Moraxella spp. culture, followed by the addition of zinc(II) porphyrin ZnTMeP (4.0 µM). The corneal samples were irradiated for 0, 7.5, and 30 min, followed by swab collection, plating, and CFU count. The results demonstrated the in vitro inactivation of the strains and clinical isolates of Moraxella spp. after 2.5 min of irradiation using ZnTMeP, reaching complete inactivation until 7.5 min. In the ex vivo experiment, the use of ZnTMeP resulted in the most significant reduction in bacterial concentration after 30 min of irradiation. These results encourage future in vivo experiments to investigate the role of metalloporphyrin ZnTMeP in the inactivation of Moraxella spp. isolates causing IBK.

Efficacy of different dosage levels and administration routes of tilmicosin in a natural outbreak of infectious bovine keratoconjunctivitis (pinkeye).

A total of 120 purebred Hereford cattle were selected from a herd on a ranch in Argentina that had a severe outbreak of infectious bovine keratoconjunctivitis (IBK, pinkeye) caused by Moraxella bovis. The animals were separated into six treatment groups: a nonmedicated control group, a group that received oxytetracycline at 300 mg injected intrapalpebrally, and four groups that received tilmicosin (Micotil, Elanco Animal Health, Indianapolis, IN; one group injected intrapalpebrally at 300 mg and three groups injected subcutaneously at 2.5, 5, and 10 mg/kg body weight, respectively). Animals were individually observed for resolution of lesions associated with IBK (ocular discharge, blepharospasin, and corneal lesions) every 7 days for 3 weeks. Corneal improvement was significantly better (P< or = .05) for all doses and for either route of injection for tilmicosin compared with no treatment or treatment with oxytetracycline. Tilmicosin given subcutaneously demonstrated a significant (P < or = .05) dose response for overall improvement (one or more score improved, none worsened). Tilmicosin given subcutaneously at 10 mg/kg was significantly more effective than tilmicosin at 2.5 mg/kg, oxytetracycline, and no treatment. Results for tilmicosin at 5 mg/kg were numerically better than no treatment, and tilmicosin at 10 mg/kg was numerically better than the drug given by intrapalpebral injection. Tilmicosin given by subcutaneous injection at 5 or 10 mg/kg was effective against IBK under the conditions of this study.

Tratamiento de la blefaroconjuntivitis y queratoconjuntivitis con ciprofloxacina al 0.3 por ciento vs tobramicina al 0.3 por ciento en solucion oftálmica / Treatment of blepharoconjunctivitis and keratoconjunctivitis with ciprofloxinine 0.3 por ciento vs tobramicine 0.3 por ciento in ophtalmic solution

Se diseño un estudio doble ciego, prospectivo, longitudinal y experimental comparando la eficacia, tolerancia y toxicidad de la criprofloxacina y la tobramicina tópica al 0.3 por ciento en el tratamiento de las blefaroconjuntivitis y las queratoconjuntivitis. Se incluyeron 40 ojos en cada grupo, encontrando que ambos fármacos son igualmente efectivos para erradicar o reducir los gérmenes causantes de infección en un 95 por ciento. La ciprofloxacina dismuyó el lagrimeo y prurito en forma estadísticamente más importante (p<0.05) que la tombracina además de ser mejor tolerada y no haber provocado efectos tóxicos secundarios