Harold G. Jensen

The Comparative In Vitro Activity of Ofloxacin and Selected Ophthalmic Antimicrobial Agents Against Ocular Bacterial Isolates

The in vitro activity of ofloxacin, a new fluoroquinolone anti-infective agent, was evaluated against 419 ocular bacterial isolates of 55 species to determine its potential as a topical agent for the treatment of ocular infections. Other agents tested in this study, in which a modified tube-dilution procedure was used, include norfloxacin, gentamicin, tobramycin, chloramphenicol, and polymyxin B. Ofloxacin demonstrated good to excellent activity against a variety of gram-positive and gram-negative pathogens. The minimum inhibitory concentration against 90% of all bacterial strains tested (MIC90) of ofloxacin was 0.5 microgram/ml for Staphylococcus aureus and S. epidermidis, 2 micrograms/ml for Streptococcus pneumoniae, and 4 micrograms/ml for Pseudomonas aeruginosa. These species were more susceptible to ofloxacin than to any of the nonquinolones tested. The MIC90 of ofloxacin was lower than that of norfloxacin, another quinolone, against S. aureus, S. epidermidis, and St. pneumoniae and equal to that of norfloxacin against P. aeruginosa. Because of its broad spectrum of activity and excellent in vitro activity, we concluded that ofloxacin has the potential for development into a superior topical treatment for ocular infection.

Combined Treatment of Acanthamoeba Keratitis With Propamidine, Neomycin, and Polyhexamethylene Biguanide

We developed an intensive treatment regimen of topical neomycin, propamidine, and polyhexamethylene biguanide that was tapered to a maintenance level over a 14- to 28-day period as toxicity developed. Since July 1991, we used this treatment on six eyes of five patients in whom Acanthamoeba keratitis was diagnosed clinically. All patients had positive cultures for microorganisms from their corneas or contact lens cases or had pathognomonic findings of pseudodendritic subepithelial infiltrates and radial keratone-uritis. After therapy, all patients improved within two to four weeks, with regression or resolution of neuritis and infiltrates, healing of epithelial defects, and lessening of pain. By three to four months, visual acuity had returned to 20/20 in all eyes. We believe the addition of polyhexamethylene biguanide to our treatment regimen in Acanthamoeba keratitis dramatically aided and hastened the clinical improvement in five consecutive patients and may, with early diagnosis, increase the number of medical cures.

Ocular Infections Associated With Comamonas acidovorans

Comamonas acidovorans (Pseudomonas acidovorans) is a ubiquitous gram-negative rod. Although generally considered nonpathogenic, we found C. acidovorans to be associated with six cases of ocular infections. The organism was the only isolate in three cases, whereas an association of other organisms was present in three cases. The multiple resistance patterns of these strains to antibiotic susceptibility testing emphasizes the need for culturing ocular infections. We recommend the identification and susceptibility testing of all ocular gram-negative rod isolates.

Topical application of all-trans-retinoic acid. A look at the cornea and limbus.

A 0.1% all-trans-retinoic acid in petroleum-base ointment was applied daily in eight normal rabbit eyes. Epithelial samples were collected from the cornea and limbus of six rabbits by impression cytology at 3- to 4-day intervals. Cytological changes were followed for 21 days and the eyes subsequently harvested for histochemical, scanning electron microscopic (SEM), and transmission electron microscopic (TEM) analysis of corneal and limbal structures. Two rabbits were treated with 0.1% all-trans-retinoic acid for 24 days without impression cytology until the 21st day. On the 24th day these eyes were harvested for similar studies. Impression cytology studies of the corneal epithelium demonstrated perinuclear halos and vacuolization of the cytoplasm. Additionally, vacuolization of the cytoplasm was observed by TEM, with attendant extrusion of the cytoplasmic contents and a subjective increase in surface microvilli as seen by SEM. Histochemical analysis revealed mucinlike staining of the corneal epithelium.

An anterior limbal approach to vitrectomy for the surgical management of infectious endophthalmitis.

We present two cases illustrating a surgical approach to the diagnosis and treatment of infectious endophthalmitis following extracapsular cataract extraction with insertion of a posterior chamber lens. In both cases, a vitrectomy was initiated through a limbal approach after clearing the anterior chamber, thus allowing improved visualization of the vitreous cavity. The vitrectomy probe was then passed through a peripheral iridotomy, the peripheral posterior capsule and/or zonules, and into the anterior vitreous. The peripheral iridotomy allowed access to the vitreous cavity for an anterior vitrectomy. The entire anterior chamber and vitreous aspirate was then analyzed for culture and sensitivity. This technique minimizes the risks of pars plana vitrectomy for endophthalmitis by improving visualization and possibly decreasing the risk of retinal detachment.