Streptococcus sanguis survival in K-Sol. Comparison of gentamicin and the fluoroquinolone antibiotics.

Viridans streptococci are poorly covered by gentamicin sulfate in corneal storage medium. To evaluate possible antibiotic alternatives among the newer broad-spectrum fluoroquinolone antibiotics, we compared the survival of the viridans representative Streptococcus sanguis in K-Sol with gentamicin sulfate (100 mg/L), norfloxacin (250 mg/L), ciprofloxacin lactate (250 mg/L), ofloxacin (250 mg/L), or no antibiotic. At 23 degrees C, K-Sol with gentamicin produced a 2-log kill by 80 minutes. By comparison, only one of the others (norfloxacin) had achieved a 2-log kill by 4 hours. At 4 degrees C, all antibiotics differed little from the control, and none was superior to gentamicin.

Effects of epikeratoplasty on the host cornea. An experimental study.

The effects of epikeratoplasty on the host cornea was studied using albino rabbits. Eyes underwent midperipheral partial trephination alone (group I), midperipheral partial trephination and peripheral undermining (group II), midperipheral partial trephination and circular keratectomy (group III), and trephination, peripheral undermining, and circular keratectomy (group IV). Corneal topography was assessed weekly using keratometry and photokeratoscopy. All eyes showed central corneal steepening with enhancing effects of increased surgical manipulation. Results were stable by 4 weeks in all eyes. Histopathologic evaluation revealed a constant wound depth of approximately 0.1 mm, with an increased accumulation of glycosaminoglycan material at the base of the wound. This was stained with PAS and alcian blue. Steepening of the host cornea may be another reason for lack of predictability and refractive regression following epikeratoplasty.

Polytetrafluoroethylene as an interpositional graft material for the correction of lower eyelid retraction.

Polytetrafluoroethylene (PTFE), a nonantigenic, autoclavable, inert, woven synthetic graft material was used to correct ten lower eyelids with retraction secondary to either thyroid disease (7 eyelids) or surgically repaired maxillofacial trauma (3 eyelids). The material was well tolerated for postoperative periods ranging from 10 to 26 months. In two eyelids, a portion of the PTFE was removed to treat eyelid thickening and an infected meibomian gland. Results of histopathologic examination of the graft showed minimal inflammation and capillary and connective ingrowth into the graft matrix as well as a dense fibrous capsule around the graft. In selected cases, PTFE may be an acceptable substitute for other graft materials used in oculoplastic surgery.

Survival of Streptococcus viridans in gentamicin-supplemented McCarey-Kaufman medium.

Our experience with three cases of Streptococcus viridans endophthalmitis, following penetrating keratoplasty, prompted us to investigate the ability of gentamicin-supplemented McCarey-Kaufman (M-K) medium to kill S. viridans contaminants. After inoculation of 20 cc of gentamicin-supplemented M-K with S. viridans, the M-K was exposed to temperature conditions similar to those that would be encountered by a donor cornea during storage (4 degrees C) and preoperative warming prior to keratoplasty (23 degrees C). Colony counts were performed at regular intervals. After 1 h of warming, no reduction in the initial inoculum had occurred. This is in contrast to results from similar experiments with Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa in which more than 1 log unit of killing occurred after 1 h. While previously reported clinical experience has demonstrated an overall low incidence of postkeratoplasty endophthalmitis using gentamicin-supplemented M-K, our own recent clinical and laboratory data suggest that additional or alternate antibiotic coverage for S. viridans may be prudent.

Streptococcal endophthalmitis from contaminated donor corneas after keratoplasty. Clinical and laboratory investigations.

We report three cases of Streptococcus viridans endophthalmitis following penetrating keratoplasty in which S viridans was cultured from the recipient eye, McCarey-Kaufman (M-K) media, and corneoscleral rims. As a laboratory correlation, we investigated the ability of S viridans to survive in M-K medium supplemented with gentamicin. After M-K medium was inoculated with S viridans, it was stored overnight at 4 degrees C, after which the temperature was raised to 23 degrees C. Periodic colony counts were performed for up to 24 hours after warming. No killing occurred in the cold. Ten hours passed before there was one log reduction in the bacterial colony count. Organisms could still be cultured at 24 hours. We conclude that gentamicin alone may be inadequate prophlyaxis against S viridans contamination of donor corneas.