Tobramycin Drops Research Articles

Higher Efficacy of Shufeng Tongqiao Decoction in Treating Acute Suppurative Otitis Media with Tobramycin Compared to Levofloxacinor Drops

We have evaluated the effects of Shufeng Tongqiao decoction on the efficacy of tobramycin drops and levofloxacin drops in treating acute suppurative otitis media. To this end, 200 patients with acute suppurative otitis media were divided into 4 treatment groups (A, B, C, and D) of 50 patients per group. Patients in groups A and B received a combination of Shufeng Tongqiao decoction plus levofloxacinor and tobramycin drops, respectively. Patients in groups C and D received only levofloxacinor and tobramycin drops, respectively. Among these four groups, group B (Shufeng Tongqiao decoction + tobramycin) was the most effective in decreasing the time of tinnitus and ear pain, discharge of pus and hearing loss (P < 0.05), and serum levels of proinflammatory cytokines. Also, this group promoted the quality of life as well as the clearance rate of pathogenic bacteria much faster relative to other groups. In conclusion, Shufeng Tongqiao decoction in combination with tobramycin drops has a significant curative effect in treating acute suppurative otitis media, which can improve the clearance rate of pathogenic bacteria, shorten the recovery time of patients, and promote the quality of life of patients.

Efficacy of postoperative medication in the treatment of cataract with uveitis

Objective To evaluate the efficacy of postoperative application of diclofenac sodium combined with triamcinolone acetonide in the treatment of cataract with uveitis. Methods The data of 85 patients of cataract with uveitis from Jan. 2016 to Jun. 2018 in Luhe Hospital were studied retrospectively.According to the random number table, all patients were divided into the observation group and the control group.The two groups were performed phacoemulsification and intraocular lens implantation.The control group, 40 cases, received injection of triamcinolone subconjunctival postoperatively, and treated with Tobramycin and Dexamethasone ophthalmic suspension eye drops after injection.The observation group, 45 cases, received diclofenac sodium eye drops on the basis of eyes drops of the control group.The course of medication was 1 month. The changes after treatment were compared between the two groups. Results The aqueous humor sCD44, TGF-β2 and MCP-1 in the observation group at 1 month after treatment were significantly better than those in the control group (P 0.05). In the observation group, the visual acuity, the incidence of grade 0 anterior chamber reaction, the total incidence of corneal edema, macular edema and photophobia were significantly better than those in the control group (P 0.05). Conclusion Application of Diclofenac sodium combined with triamcinolone acetonide is effective for cataract with uveitis, can reduce the aqueous humor sCD44, TGF-β2 and MCP-1 levels, alleviate anterior chamber reaction, and reduce the complications. Key words: Cataract; Uveitis; Phacoemulsification; Triamcinolone acetonide; Factor, aqueous humor

Comparison between corneal cross-linking, topical antibiotic and combined therapy in experimental bacterial keratitis model

PurposeThis study was conducted to investigate the effects of an experimental bacterial keratitis model on the corneal collagen cross-linking treatment (CXL), and also to compare topical antibiotic treatment with the combined treatment. MethodsThe study involved 40 young adult female Sprague Dawley rats, which had a 2 mm scraped defect of the central corneal epithelium in both eyes. The rats were divided into two equal groups. The first group was inoculated in both eyes with standard Pseudomonas Aeruginosa (PA) from a strain suspension prepared from 0.05 ml (Group 1), and the second group was inoculated with standard Methicillin Resistance Staphylococcus Aureus (MRSA) strains from a suspension prepared from 0.05 ml (Group 2). Group 1 was divided into four sub-groups: Group 1A was treated by collagen cross-linking (CXL), Group 1C was treated with topical tobramycin drops CXL and also treated by collagen cross-linking (CXL), Group 1D was treated with topical tobramycin drops, and Group 1B was left untreated in order to create a control group. Similarly, Group 2 was also divided into four sub-groups: Group 2A was treated by CXL, Group 2C was treated with topical 5% fortified vancomycin drops CXL and also treated by CXL, Group 2D was treated with topical 5% fortified vancomycin drops, and Group 2B was left untreated in order to create a control group. CXL was performed on the third day following the inoculation and topical drop therapy. Biomicroscopy and microbiologic assessments were performed on the third and seventh days following the inoculation of microorganisms. ResultsIn the treatment, which compared baselines in all groups before treatment, the diameter of keratitis infiltrations, corneal clouding, and corneal swab samples were obtained from the reduction in reproduction. The results were statistically significant (p < 0.01). Keratitis infiltration groups were conducted on the seventh day for Groups 1C and 1D according to Group 1B, whilst Groups 2A, 2C and 2D were conducted according to Group 2B, which showed a significant statistical reduction (p < 0.01). On the seventh day, focal groups were conducted in corneal clouding Group 1D according to Group 1B and in Groups 2A, 2C and 2D according to Group 2B, which revealed a significant statistical reduction (p < 0.01). On the seventh day, reproduction in culture was obtained from corneal swab samples in Groups 1C and 1D according to Group 1B; in Groups 1C and 1D according to Group 1A; in Groups 2A, 2C and 2D according to Group 2B; and in Group 2C according to Group 2A, where a significant statistical reduction was observed (p < 0.01). ConclusionsThe clinical and microbiological efficacy of the CXL treatment is evaluated in our study. In accordance with the conclusion reached an effective reduction in the density and severity of (infection), occurred as a result of CXL treatment, CXL treatment combined with topical antibiotic treatment and topical antibiotic treatment of Pseudomonas Aeruginosa (PA) and Metisilin Rezistant Staphylococcus Aureus (MRSA) keratitis infections. From these results, it is shown that topical antibiotics and CXL potentiate each other’s effects in the treatment of resistant bacterial keratitis.

Efficacy of recombinant bovine basic fibroblast growth factor in treatment of dry eye following phacoemulsification with IOL implantation

Background The study on eye surface damage following phacoemulsification with intraocular lens (IOL) implantation is increasingly concerned, and these symptoms were associated with dry eye and often treated by polyethylene glycol eyedrops to remit the discomfortableness. Recombinant bovine basic fibroblast growth factor (rb-bFGF) eyedrops contains neurotrophic factors, but its effect on eye surface damage is worth researching. Objective This study was to evaluate the repair effects of rb-bFGF on ocular surface injury after phacoemulsification with IOL implantation. Methods A randomized controlled trail was designed. Ninety eyes of 72 consecutive patients with age-related cataract were enrolled in Fenyang Hospital of Shanxi Province from September 2010 to August 2013 under the informed consent. Phacoemulsification with IOL implantation was performed on all the eyes, and tobramycin and dexamethasone eye drops was used for 15 days as basis therapy. According to the treatment sequence, the operative eyes were assigned to rb-bFGF eyedrops group, polyethylene glycol eyedrops group and basis therapy group.rb-bFGF drops and polyethylene glycol drops were topically administered 4 times per day since the first day after surgery for consecutive 30 days in corresponding group, and only basis therapy was maintained in the basis therapy grouply. Corneal fluorescence (FL) staining scores, breakup time of tear film (BUT) and Schirmer Ⅰ test (SⅠt) without topical anesthesia were examined in 1 day before operation and 1 day, 7 days, 15 days and 30 days after operation. The efficacy was intergrouply compared. Results No significant differences were seen in the demography and the relevant surface examinational outcomes among the rb-bFGF group, polyethylene glycol drops group and the basis therapy group before surgery (age: F=1.50; gender: χ2=0.336, both at>0.05; FL: F=0.31; BUT: F=0.65; SⅠt: F=0.57; all at P>0.05). Compared with the before operation, FL scores were obviously increased, and BUT values were reduced and SⅠt values were elavated in all the eyes early stage of surgey and then gradually improved with the lapse of postoperative time, showing significant differences (Ftime=7.83, 7.32, 7.17, all at P 0.05). However, there were still significant differences between the before and after operation in the basis were closed to those of before surgery therapy group (all at P<0.05). In addition, significant differences were found in corneal FL scores, BUT and SⅠt among these three groups (Fgroup=5.08, 4.15, 4.61, all at P<0.05). In postoperative 15 days and 30 days, the SⅠt values were (12.32±1.18) and (11.32±1.98) mm/5 min, which were significantly lower than (14.36±1.77) and (13.36±2.32) mm/5 min in the polyethylene glycol drops group and (17.25±2.24) and (13.25±2.53) mm/5 min in the basis therapy group (all at P<0.05). Conclusions The topical application of rb-bFGF combined with tobramycin and dexamethasone eyedrops can improve the dry eye-related symptoms and promote the repair of the ocular surface injury after phacoemulsification with IOL implantation, and the clinical efficacy of rb-bFGF eyedrops is better than that of polyethylene glycol eyedrops or only tobramycin and dexamethasone eyedrops. Key words: [Key words] Dry eye/therapy; Cataract/surgery; Phacoemulsification; Comparative studies; Eyedrops; Recombinant bovine basic fibroblast growth factor; Polyethylene glycol

Dynamic expression of interleukin-22 in grafts after allograft corneal transplantation and its relationship with graft rejection in rats

Background The rejection following keratoplasty still is a leading cause of corneal transplantation failure.Studies showed that the interleukin-22 (IL-22), one of the effector molecules of T helper cell 17 (Th17) participated on the rejection after heart, liver and bone marrow transplantation.However, the effect of IL-22 on corneal graft rejection is not well understood. Objective This study was to investigate the expression of IL-22 mRNA in the corneal grafts and the role of IL-22 in the immune rejection after corneal transplantation in rats. Methods Seventy-two Wistar rats were randomized into autologous keratoplasty group, allograft keratoplasty group and anti-rejection group, and other 4 normal Wistar rats served as normal control group.Autologous keratoplasty was operated on the Wistar rats of the autologous keratoplasty group, and allograft keratoplasty were carried out with the 24 SD rats as donors and 48 Wistar rats as recipients.Tobramycin and dexamethasone eye drops were topically administrated after autologous keratoplasty for 2 weeks in the anti-rejection group.The experimental eyes were examined by slit lamp microscope after surgery and graft survival was evaluated based on the rejection scoring criteria of Larkin.Intergroup accumulated survival rates of grafts were compared using Kaplan-Meier analysis.Histopathological examination of grafts was carried out in 5 and 14 days after operation respectively, and the related expression levels of IL-22 mRNA and aryl hydrocar-bon receptor (AhR) mRNA were carried out by real-time fluorescence quantitative PCR.The feeding and use of the experimental animals followed the Guangdong provincial regulations on the management of experimental animals.The experimental design was approved by the ethics committee of Southern Medical University. Results The median survival time of grafts in the allograft keratoplasty group was 10 days, and that in the anti-rejection group was 17 days, showing a significant survival extention in the anti-rejection group (χ2=16.442, P=0.000). Significant differences were found among the 4 groups in the related expression levels of IL-22 mRNA in both 5 days and 14 days after surgery (postoperative 5 days: F=2.44, P=0.00; postoperative 14 days: F=267.92, P=0.00), and the related expression levels of IL-22 mRNA were remarkably higher in the allograft keratoplasty group than those in the anti-rejection group at different time points (postoperative 5 days: 9.70±0.35 vs.0.46±0.21; postoperative 14 days: 23.12±1.89 vs.3.14±0.94 ) (both at P<0.05). The related expression levels of AhR mRNA in the grafts were considerably different among the 4 groups (postoperative 5 days: F=395.73, P=0.00; postoperative 14 days: F=942.37, P=0.00), and the expression levels were significantly elevated in the allograft keratoplasty group compared with the anti-rejection group at various time points (postoperative 5 days: 2.52±0.32 vs. 1.89±0.10; postoperative 14 days: 7.20±0.25 vs.2.60±0.17) (both at P<0.05). Conclusions The expression level of IL-22 RNA up-regulates in the grafts with immuno-rejection.Topical administration of tobramycin and dexamethasone eye drops inhibits the rejection after keratoplasty.AhR plays a regulative role to the expression of IL-22 in rats after keratoplasty. Key words: Corneal transplantation; Graft rejection/immunology; T-lymphocytes, helper-inducer/immunology; Interleukin-22; Receptors, aryl hydrocarbon; Eye drops, tobramycin and dexamethasone; Models, biological; Rats, Wistar

Penetrating trans-orbital injury from a brush handle lodged in the infra-temporal fossa.

Penetrating trans-orbital injury from a brush handle lodged in the infra-temporal fossa.

Achromobacter xylosoxidansKeratitis after Contact Lens Usage

To report on Achromobacter xylosoxidans keratitis in two healthy patients who had worn contact lenses foran extended period of time. A 36-year-old female and a 21-year-old female visited our hospital with ocular pain and blurred vision. Both patients had a history of wearing soft contact lenses for over fve years with occasional overnight wear. At the initial presentation, a slit lamp examination revealed corneal stromal infiltrations and epithelial defects with peripheral neovascularization in both patients. Microbiological examinations were performed from samples of corneal scrapings, contact lenses, contact lens cases, and solution. The culture resulting from the samples taken from the contact lenses, contact lens cases, and solution were all positive for Achromobacter xylosoxidans. Confrming that the direct cause of the keratitis was the contact lenses, the frst patient was prescribed ceftazidime and amikacin drops sensitive to Achromobacter xylosoxidans. The second patient was treated with 0.3% gatifoxacin and fortifed tobramycin drops. After treatment, the corneal epithelial defects were completely healed, and subepithelial corneal opacity was observed. Two cases of Achromobacter xylosoxidans keratitis were reported in healthy young females who wore soft contact lenses. Achromobacter xylosoxidans should be considered a rare but potentially harmful pathogen for lens-induced keratitis in healthy hosts.

Ototoxicity caused by topical administration of gentamicin versus tobramycin in rabbits

Aim To investigate the possible differences in cochleotoxic effects in rabbits between twice-daily administration of topical gentamicin and tobramycin throughout the perforated tympanic membrane with the use of distortion-product otoacoustic emissions (DPOAEs). Materials and methods Twenty female rabbits were studied prospectively daily for 21 days. The rabbits’ ears were divided into two groups: right and left ear groups. Twice-daily for 21 days after paracentesis, 0.3% gentamicin was administered topically in the left ears, and 0.3% tobramycin was administered topically in the right ears. For 21 days, the cochlear activity of the right and left ears of all rabbits was examined every 7 days using DPOAEs. The numerical values of the distortion product (DP) intensity recorded on days 7, 14 and 21 of drug administration were compared between the two groups. Results Cochlear activity was reduced earlier in the gentamicin group in the 2–4 kHz frequencies compared to the tobramycin group in the second DPOAE measurement (day 7 of the experiment). In two rabbits in the gentamicin group, the third DPOAE measurement showed that cochlear activity was reduced in all frequencies. In six rabbits in the tobramycin group, the third DPOAE measurement showed that cochlear activity was reduced in all frequencies. There was no statistical significance between the two groups except day 7 in the 2 and 3 kHz frequencies ( p < 0.05). Conclusion We concluded that low frequencies (2 and 3 kHz) are more sensitive to the administration of topical gentamicin than to topical tobramycin. Early cessation of tobramycin drops may be minimally cochlear toxic compared to gentamicin within the first 7 days when these drugs are misused in treating chronic otitis media.

Mycobacterium Chelonae Keratitis in a Patient with SjöGren's Syndrome

In this report a case of Mycobacterium chelonae keratitis in a patient without any previously described risk factors is described. The only risk factor found was a rheumatoid arthritis related Sjogren''s syndrome. Case report. A 60-year-old woman was referred to the hospital with an infectious keratitis of the left eye of 3 months duration, unresponsive to empirical therapy with ofloxacin and tobramycin drops. Her medical history included a longstanding rheumatoid arthritis and a secondary ocular surface syndrome. Upon arrival the left eye showed diffuse corneal edema and centrally several large infiltrates with fluffy edges, surrounded by several smaller satellite infiltrates. The cornea was scraped for culture and grew M chelonae and sensitivity testing showed sensitivity to ciprofloxacin, clofazimine, and clarithromycin. Systemically, ciprofloxacin 750 mg and clarithromycin 500 mg twice daily were prescribed orally. Topical therapy consisted of topical erythromycin 10 mg/mL and ofloxacin 3 mg/mL every 2 hours. Treatment was continued for a total of 10 months during which the infiltrates cleared completely, but the central cornea remained scarred. M chelonae can be a cause of infectious keratitis in patients without known risk factors for rapidly growing mycobacterium keratitis. Especially in the case of ocular infections that show no response to regular antibacterial treatment, mycobacterial infection should be considered. Good communication between the ophthalmologist and the microbiologist is crucial for a rapid diagnosis.

Protective effect of corticosteroid against the cytotoxicity of aminoglycoside otic drops on isolated cochlear outer hair cells.

Otic drops are commonly used not only for otitis externa but also for otorrhea in the presence of tympanic membrane perforation or tympanostomy tube. Many studies demonstrated the ototoxicity of aminoglycoside. In our previous study, we observed that gentamicin (GM), when activated with liver extract, demonstrated significant cytotoxicity. The purpose of this study was to assess the protective effect of corticosteroid against the cytotoxicity of GM and tobramycin drops using isolated cochlear outer hair cells (OHCs) in vitro with liver extract. OHCs from adult chinchilla cochleae were exposed to standard bathing solution, liver extract alone, and aminoglycoside otic drops with and without corticosteroid and liver extract. All experiments were performed at an osmolality of 305 +/- 5 mOsm, at room temperature, and for up to 60 minutes. The images of OHCs were recorded using an inverted microscope and analyzed on the Image Pro-Plus 3.0 program. Time to cell death and change of cell length were measured and analyzed. The time to cell death and percent change in cell length observed was significantly longer in the GM + liver extract + dexamethasone group than the GM + liver extract group (P <.05). The Tobradex + liver extract group showed an insignificant increase in percent change of cell length (P >.05) and significantly increased time to cell death than the tobramycin + liver extract group (P <.05). This study demonstrated that dexamethasone significantly reduced aminoglycoside cytotoxicity.

The use of otic powder in the treatment of acute external otitis

Background: Acute external otitis (AEO) is a painful condition that results as a secondary infection of macerated skin and subcutaneous tissues of the external auditory canal. The most commonly causative microorganisms are Pseudomonas aeruginosa and Staphylococcus aureus. Classic management strategies include moisture prevention, cleansing of the canal and administration of topical antimicrobial agents in drop form, such as aminoglycosides and quinolones, at times in combination with steroid solutions. The objective of this study was to evaluate and compare the efficacy of topical otic powder, tobramycin drops and ciprofloxacin drops in patients suffering from AEO. Materials and Measures: A randomized prospective trial was performed to determine the efficacy of Auricularum powder (dexamethasone 10 mg, oxytetracycline HCl 90,000 U, polymyxin B Sulfate 100,000 U, nystatin 1,000,000 U; Trima, Serolam Laboratories, Germany) compared with ciprofloxacin (Ciloxan, Alcon Laboratories, Fort Worth, TX) and tobramycin (Tobrex, Alcon Laboratories) drops for the treatment of AEO. One hundred twenty patients who presented with signs and symptoms of AEO were enrolled. Inclusion criteria were: AEO diagnosed by an otolaryngologist, patient age 18 years, no prior treatment with other drops or systemic antibiotics, no sensitivity to any of the drugs used or their contents, and no perforation of the tympanic membrane. All patients were instructed to avoid moisture and wetness of the ear during the course of their treatment. After we received informed consent, a swab culture was taken, and the patient was randomly assigned topical treatment for 14 days. Results: Eighty-six percent of those treated with Auricularum powder were cured at day 3-4 after initial treatment. Seventy-seven percent of those treated with ciprofloxacin drops, and fifty-six percent of those treated with tobramycin were cured at that time. All 120 patients were cured by day 14. Conclusion: The results show that topical treatment with Auricularum powder is an effective and rapid method for the treatment of AEO. Ciloxan also was effective in the treatment of AEO and relieved symptoms quickly and efficiently in a short period of time. Tobrex was effective in treating AEO, but our results show that relief of symptoms was slower than with the other drugs. (Am J Otolaryngol 2002;23:142-147. Copyright 2002, Elsevier Science (USA). All rights reserved.)

The Efficacy of Topical Ciprofloxacin and Norfloxacin in the Treatment of Experimental Pseudomonas Keratitis

An aminoglycoside-resistant strain of Pseudomonas aeruginosa was injected intrastromally into the corneas of rabbits, and keratitis was allowed to develop over a 22-h period. Rabbits were treated with either 0.75% ciprofloxacin, 1% norfloxacin, or 1.36% tobramycin administered topically every 15 min for 1 h and then every 30 min for the following 3 h. All therapy ceased 26 h postinoculation. Rabbits were killed 1 h after the treatment, and the number of bacteria per cornea were quantified in terms of bacterial colony-forming units. Aqueous humor specimens were obtained from rabbits receiving norfloxacin and ciprofloxacin, and bioassays were performed to determine drug concentration. Ciprofloxacin caused a 5 log reduction in the number of bacterial colony-forming units, as compared with untreated controls (p < 0.0001); it also produced a significantly greater reduction in bacterial colony-forming units than either norfloxacin or fortified tobramycin drops (p < 0.0001). Norfloxacin produced a 2 log reduction in bacterial colony-forming units, as compared with untreated controls (p < 0.0001). The mean aqueous concentration of norfloxacin (7.5 μg/ml) was substantially less than that achieved by ciprofloxacin (30.5 μg/ml). We conclude that ciprofloxacin may be a useful broad spectrum, topical chemotherapeutic agent in the therapy of aminoglycoside-resistant P. aeruginosa keratitis.

The Efficacy of Topical Ciprofloxacin and Norfloxacin in the Treatment of Experimental Pseudomonas Keratitis

An aminoglycoside-resistant strain of Pseudomonas aeruginosa was injected intrastromally into the corneas of rabbits, and keratitis was allowed to develop over a 22-h period. Rabbits were treated with either 0.75% ciprofloxacin, 1% norfloxacin, or 1.36% tobramycin administered topically every 15 min for 1 h and then every 30 min for the following 3 h. All therapy ceased 26 h postinoculation. Rabbits were killed 1 h after the treatment, and the number of bacteria per cornea were quantified in terms of bacterial colony-forming units. Aqueous humor specimens were obtained from rabbits receiving norfloxacin and ciprofloxacin, and bioassays were performed to determine drug concentration. Ciprofloxacin caused a 5 log reduction in the number of bacterial colony-forming units, as compared with untreated controls (p less than 0.0001); it also produced a significantly greater reduction in bacterial colony-forming units than either norfloxacin or fortified tobramycin drops (p less than 0.0001). Norfloxacin produced a 2 log reduction in bacterial colony-forming units, as compared with untreated controls (p less than 0.0001). The mean aqueous concentration of norfloxacin (7.5 micrograms/ml) was substantially less than that achieved by ciprofloxacin (30.5 micrograms/ml). We conclude that ciprofloxacin may be a useful broad spectrum, topical chemotherapeutic agent in the therapy of aminoglycoside-resistant P. aeruginosa keratitis.

Tobramycin iontophoresis into corneas infected with drug-resistant Pseudomonas aeruginosa

Iontophoretic application of tobramycin was used to deliver drug to the cornea of rabbit eyes infected with a tobramycin-resistant strain of Pseudomonas aeruginosa (MIC = 31.25 micrograms/ml). Corneas infected with P. aeruginosa 27853/pMG6 were treated 22 hours after infection with tobramycin delivered by either iontophoresis, mock iontophoresis (eye cup without current), or application of fortified topical drops. Corneal iontophoresis of tobramycin at 25 mg/ml caused more than a three log reduction in bacteria; yielding a significantly lower number of bacteria compared to untreated controls and all other treatments (P less than or equal to 0.0001). Corneal iontophoresis of tobramycin at 10 mg/ml showed a one log reduction in the number of bacteria per cornea, yielding a significantly lower number of bacteria compared to untreated controls (P less than or equal to 0.0001), corneas treated with nine topical applications of 1.36% tobramycin drops (P less than or equal to 0.0001), and corneas treated with mock iontophoresis (P less than or equal to 0.02). These results suggest that iontophoresis is a powerful ocular delivery system for tobramycin and may be suitable for use with other chemotherapeutic agents.

Treatment of Experimental Pseudomonas Keratitis Using Collagen Shields Containing Tobramycin

To study the effectiveness of collagen shields containing tobramycin sulfate in the treatment of Pseudomonas keratitis, rabbits were infected via an intrastromal injection of Pseudomonas aeruginosa and treated 22 hours later with either collagen corneal shields rehydrated in 4% tobramycin and applied to the cornea or 4% tobramycin drops. Bacterial killing was quantitated by culturing corneal homogenates and calculating the number of viable bacteria (colony-forming units) per cornea. Corneas receiving shields rehydrated in 4% tobramycin and applied for four hours demonstrated significantly reduced numbers of bacteria compared with untreated control corneas. The collagen shields were as effective in reducing the number of viable bacteria per cornea as 4% tobramycin drops applied every 30 minutes over a four-hour period. Over a nine-hour treatment period, the addition of four drops of 4% tobramycin to shields in situ was as effective as exchange with a new shield rehydrated in 4% tobramycin. These results suggest that collagen shields rehydrated in a water-soluble antibiotic such as tobramycin may be an effective and convenient mode of therapy for Pseudomonas keratitis.

Collagen shield drug delivery: Therapeutic concentrations of tobramycin in the rabbit cornea and aqueous humor

Collagen shields made of porcine collagen were placed in a solution containing tobramycin sulfate (40 or 200 mg/ml) for five minutes, then applied to rabbit eyes. One, four, or eight hours after application, the corneas, aqueous humor samples, and shields were assayed for antibiotic. At all intervals, the concentration of antibiotic in the corneas and aqueous humor samples exceeded the mean inhibitory concentration for tobramycin, as determined for most strains of Pseudomonas. Shields immersed in 200 mg/ml tobramycin produced significantly higher concentrations of antibiotic in the cornea at one hour than subconjunctival injections of tobramycin (20 mg) (P .0001). Shields immersed in 40 mg/ml tobramycin produced higher, although not significantly higher, concentrations of antibiotic in the cornea at one hour than subconjunctival injections of tobramycin (20 mg) (P = .318). Shields immersed in commercially available tobramycin drops or injectable tobramycin solution (40 mg/ml) caused no epithelial damage visible by slitlamp examination. Collagen shields containing antibiotics can serve as a vehicle for drug delivery and may prove superior to current methods for preoperative and postoperative antibiotic prophylaxis and the initial treatment of bacterial keratitis.

Iontophoresis of tobramycin for the treatment of experimental Pseudomonas keratitis in the rabbit.

Iontophoresis of tobramycin sulfate was employed to treat bacterial keratitis induced in rabbits by an intrastromal injection of Pseudomonas aeruginosa. Quantitation of bacterial killing was achieved by culturing corneal homogenates and counting viable bacteria per cornea after treatment. When the rabbits received two iontophoretic treatments, iontophoresis significantly reduced the number of bacterial colony-forming units, compared with the use of an eyecup without current or two subconjunctival injections of 20 mg of tobramycin sulfate, and with untreated controls. The results of iontophoresis were not significantly different from those involving treatment with topical fortified drops (40 mg/mL). A single iontophoresis treatment was compared with the use of an eyecup without current or less fortified topical drops (13.6 mg/mL), as well as with untreated controls. Iontophoresis was significantly better than either the eyecup or the topical fortified tobramycin drops in reducing viable bacteria in the corneas. Iontophoresis may be a useful adjunct in the treatment of severe corneal bacterial infections.