Treatment Of Bacterial Keratitis Research Articles

Recent trends: Medical management of infectious keratitis.

This review article highlights the newer diagnostic modalities and approaches in the medical management of infectious keratitis. A Medline literature search conducted to March 2014 has been included. Recent studies or publications were selected from international indexed journals using suitable key words. Development of specular microscopy and polymerase chain reaction (PCR) has a promising role as diagnostic modalities in infectious keratitis, especially in refractory cases. Previously fortified antibiotics have been the mainstay of treatment for bacterial keratitis. Recently, the advent of fourth-generation fluoroquinolones monotherapy has shown promising results in the management of bacterial keratitis. Corneal collagen cross-linking is being considered in the refractory cases. Topical natamycin and amphotericin B should be considered as the first choice anti-fungal agents in suspected filamentous or yeast infection respectively. Voriconazole and newer routes of administration such as intrastromal and intracameral injection of conventional anti-fungal agents have demonstrated a positive clinical response. Ganciclovir is a newer anti-viral agent with promising results in herpes simplex keratitis. Thus, introduction of newer diagnostic modalities and collagen cross-linking along with fourth-generation fluoroquinolones and newer azoles have a promising role in the management of infectious keratitis.

Besifloxacin Ophthalmic Suspension 0.6% in the Treatment of Bacterial Keratitis: A Retrospective Safety Surveillance Study

The objective of this study was to collect and evaluate retrospective safety information about the use of besifloxacin ophthalmic suspension 0.6% for the treatment of bacterial keratitis. This was a retrospective, postmarketing surveillance study conducted at 10 clinical centers in the United States. The study population included 142 patients treated with besifloxacin ophthalmic suspension 0.6% for bacterial keratitis in one or both eyes. For perspective, data on 85 patients treated at these centers with moxifloxacin ophthalmic solution 0.5% for bacterial keratitis were also included. The analysis was designed to measure the types and rates of adverse events (AEs) reported during the treatment of bacterial keratitis with besifloxacin ophthalmic suspension 0.6%. Other treatment outcomes of interest included the development of corneal scarring and corneal neovascularization, measured or presumed bacterial eradication, ending visual acuity, and duration of pain before and after treatment. There was one reported AE of mild superficial punctate keratitis in a patient using besifloxacin ophthalmic suspension 0.6%. The difference in AE frequencies between groups was not significant (P>0.999). Additional treatment outcomes were similar for both groups. Limitations of this report include the retrospective nature of the study. These retrospective data suggest that besifloxacin ophthalmic suspension 0.6% was well tolerated when included in the treatment of bacterial keratitis; no serious AEs were reported. A prospective clinical trial is needed to better isolate the contribution of besifloxacin to the therapeutic outcome and to confirm these observations.

The treatment for bacterial keratitis by local debridement combined with povidone iodine solution

Objective To observe the clinical efficacy of treatment for bacterial keratitis by local debridement combined with 0.5％ povidone iodine solution used in conjunctival sac.Methods 103 eyes of 99 patients with bacterial keratitis were treated by local debridement combined with 0.5％ povidone iodine solution used in conjunctival sac and medication and the effects were observed.Results The cure rates of above mentioned treatment were as the follows:100.00％ in the mild cases,81.58％ in the moderate cases,39.29％ in the serious cases.Conclusion The local debridement combined with 0.5％ povidone iodine solution used in conjunctival sac and medication is effective for the mild and moderate bacterial keratitis,yet little effective for the serious cases. Key words: Debridement, local ; Povidone iodine, solution, 0.5 ％ ; Irrigation ; Keratitis, bacterial

The Steroids for Corneal Ulcers Trial (SCUT): Secondary 12-Month Clinical Outcomes of a Randomized Controlled Trial

To determine whether topical corticosteroids as adjunctive therapy for bacterial keratitis improves long-term clinical outcomes. Randomized, placebo-controlled, double-masked clinical trial. This multicenter trial compared 1.0% prednisolone sodium phosphate to placebo in the treatment of bacterial keratitis among 500 patients with culture-positive ulcers receiving 48 hours of moxifloxacin before randomization. The primary endpoint was 3 months from enrollment, and 399 patients were evaluated at 12 months. The outcomes examined were best spectacle-corrected visual acuity (BSCVA) and scar size at 12 months. Based on previous results, regression models with adjustments for baseline status and/or causative organism were used for analysis. No significant differences in clinical outcomes by treatment group were seen with the prespecified regression models (BSCVA: -0.04 logMAR, 95% CI, -0.12 to 0.05, P = .39; scar size: 0.03 mm, 95% CI, -0.12 to 0.18, P = .69). A regression model including a Nocardia-treatment arm interaction found corticosteroid use associated with a mean 1-line improvement in BSCVA at 12 months among patients with non-Nocardia ulcers (-0.10 logMAR, 95% CI, -0.19 to -0.02, P = .02). No significant difference was observed in 12-month BSCVA for Nocardia ulcers (0.18 logMAR, 95% CI, -0.04 to 0.41, P = .16). Corticosteroids were associated with larger mean scar size at 12 months among Nocardia ulcers (0.47 mm, 95% CI, 0.06-0.88, P = .02) and no significant difference was identified by treatment for scar size for non-Nocardia ulcers (-0.06 mm, 95% CI, -0.21 to 0.10, P = .46). Adjunctive topical corticosteroid therapy may be associated with improved long-term clinical outcomes in bacterial corneal ulcers not caused by Nocardia species.

An Improvement of Efficacy of Moxifloxacin HCl for the Treatment of Bacterial Keratitis by Formulation of Ocular Mucoadhesive Microspheres

The aim of this study was to prepare novel ocular mucoadhesive microspheres of Moxifloxacin HCl to increase its residence time on the ocular surface and to enhance its therapeutic efficacy in ocular bacterial keratitis. Microspheres were fabricated with different grades of Methocel and Sodium CMC as polymers. Microspheres were evaluated for their particle size, morphology, encapsulation efficiency, mucoadhesion, antimicrobial efficacy, and in vitro drug release studies. In vivo studies were carried out for the promising formulation on eyes of albino rabbits by inducing bacterial keratitis. A sterile microspheres suspension in light mineral oil was applied to infected eyes twice a day. A marketed conventional eye drop was used as a positive control. Eyes were examined daily for improvement of clinical signs of bacterial keratitis by an ophthalmologist. The average particle size of microspheres was found to be less than 80 μm. Methocel microspheres were found to have a smoother surface than Sodium CMC. Entrapment efficiency was enhanced with an increased polymer concentration and viscosity. The formulation containing Methocel K100M with a drug: polymer ratio of 1:2 exerted longer corneal and conjunctival mucoadhesion time of 8.45±0.15 h and 9.40±0.53 h respectively. In vitro release of Moxifloxacin HCl from microspheres was retarded with increased viscosity and concentration of polymers, and was controlled by diffusion as well as polymer relaxation. All formulations showed comparable antimicrobial activity in comparison with conventional marketed eye drops. The formulation containing Methocel K100M with a drug: polymer ratio of 1:2 was found to be a promising formulation and was used for the in vivo studies. The in vivo studies revealed that microspheres demonstrated significantly lower clinical scores and reduced the total duration of therapy than the marketed Moxifloxacin HCl eye drops. In vitro and in vivo studies showed that ocular mucoadhesive microspheres of Moxifloxacin HCl were found to have an improved efficacy in the treatment of ocular bacterial keratitis in comparison with the marketed formulation.

Besifloxacin Ophthalmic Suspension, 0.6%: a Novel Topical Fluoroquinolone for Bacterial Conjunctivitis

Acute bacterial conjunctivitis, the most common cause of conjunctivitis, is responsible for approximately 1% of all primary-care consultations. Of the topical ophthalmic antibiotics used to treat acute bacterial conjunctivitis, fluoroquinolones are especially useful because they possess a broad antibacterial spectrum, are bactericidal in action, are generally well tolerated, and have been less prone to development of bacterial resistance. Besifloxacin, the latest advanced fluoroquinolone approved for treating bacterial conjunctivitis, is the first fluoroquinolone developed specifically for topical ophthalmic use. It has a C-8 chlorine substituent and is known as a chloro-fluoroquinolone. Besifloxacin possesses relatively balanced dual-targeting activity against bacterial topoisomerase IV and DNA gyrase (topoisomerse II), two essential enzymes involved in bacterial DNA replication, leading to increased potency and decreased likelihood of bacterial resistance developing to besifloxacin. Microbiological data suggest a relatively high potency and rapid bactericidal activity for besifloxacin against common ocular pathogens, including bacteria resistant to other fluoroquinolones, especially resistant staphylococcal species. Randomized, double-masked, controlled clinical studies demonstrated the clinical efficacy of besifloxacin ophthalmic suspension 0.6% administered three-times daily for 5 days to be superior to the vehicle alone and similar to moxifloxacin ophthalmic solution 0.5% for bacterial conjunctivitis. In addition, besifloxacin ophthalmic suspension 0.6% administered two-times daily for 3 days was clinically more effective than the vehicle alone for bacterial conjunctivitis. Besifloxacin has also been shown in preclinical animal studies to be potentially effective for the "off-label" treatment of infections following ocular surgery, prophylaxis of endophthalmitis, and the treatment of bacterial keratitis. Taken together, clinical and preclinical animal studies indicate that besifloxacin is an important new option for the treatment of ocular infections.

Release of Vancomycin and Gentamicin from a Contact Lens Versus a Fibrin Coating Applied to a Contact Lens

To develop a contact lens capable of releasing antibiotics for a minimum of 8 hours for the treatment of bacterial keratitis. Fibrin gel was loaded with vancomycin or gentamicin and then shaped into a curved disc. The disc was then used to coat the surface of a commercial contact lens or was sealed between two lenses. Separate contact lenses were soaked in solutions of vancomycin or gentamicin. The in vitro release kinetics for each system was determined using PBS at 37°C and a particle-enhanced turbidimetric inhibition immunoassay. The bioactivity of the antibiotics released from the fibrin was confirmed by using a microbiological assay. Vancomycin and gentamicin were released at similar rates from soaked contact lenses and a coating of fibrin gel; however, the amounts of antibiotic delivered by the two systems differed considerably. The fibrin coating released over three times more gentamicin but less than one-fifth that of the lenses soaked in vancomycin. When fibrin was encapsulated between two contact lenses, significantly more controlled release was observed. For all systems, bactericidal amounts of vancomycin and gentamicin were released throughout the three-day testing period. As a delivery system, fibrin gel loaded with gentamicin performs better than contact lenses soaked in gentamicin. The opposite is true for vancomycin, where soaked lenses outperform fibrin gel. These systems could potentially be used as a treatment for bacterial keratitis.

Исследование активности лизосомальных ферментов в слезной жидкости при лечении бактериальный кератитов с применением пиобактериофага

Исследование активности лизосомальных ферментов в слезной жидкости при лечении бактериальный кератитов с применением пиобактериофага

A case of suture-related bacterial keratitis and its treatment with topical imipenem

Risk factors for the development of corneal infection include loose or broken sutures, corticosteroid use, persistent epithelial defects, contact lens use, keratoconjunctivitis sicca, and a history of herpes simplex virus keratitis. Most of the data regarding suture-related keratitis come from literature on penetrating keratoplasty [1]. However, suture-related keratitis following cataract surgery appears to be a rare event [2]. The treatment of bacterial keratitis in patients with or without sutures is similar. In the treatment of serious suture-related corneal infections, topical fortified antibiotic combinations like vancomycin (50 mg/mL) and gentamicin (14 mg/mL) [3] or ceftazidime (50 mg/mL) and vancomycin (50 mg/mL) [3] have been used successfully. However, despite intensive topical, subconjunctival, and systemic antibiotics, corneal perforation can develop [2]. Therefore, selection of the appropriate agent and treatment planning are important for treatment of corneal infections. A beta-lactam antibiotic, imipenem, has often been used systemically and as an intravitreal therapy. However, no study has reported the topical use of imipenem as a monotherapy in the treatment of bacterial keratitis in patients with or without corneal sutures. This report presents the treatment of corneal infection with topical imipenem (50 mg/mL) as monotherapy in a patient who developed an infectious corneal complication due to a broken corneal suture after extracapsular cataract extraction with posterior chamber intraocular lens implantation.

Moxifloxacin and Cholesterol Combined Treatment of Pneumococcal Keratitis

Purpose: Compare the efficacy of treatment of pneumococcal keratitis with cholesterol, moxifloxacin, or a mixture of the two (moxifloxacin/cholesterol).Materials and Methods: New Zealand white rabbits were injected intrastromally with 106 colony-forming units (CFU) of a clinical keratitis strain of Streptococcus pneumoniae. Eyes were examined before and after treatment of topical drops every 2 hr from 25 to 47 hr post-infection (PI). Corneas were harvested to quantitate bacterial CFU, and myeloperoxidase (MPO) activity was measured at 48 hr PI. Eyes were extracted for histology. Minimal inhibitory concentrations (MICs) were determined for each compound.Results: Eyes treated with moxifloxacin/cholesterol had a significantly lower mean slit lamp examination (SLE) score than eyes treated with phosphate-buffered saline (PBS), moxifloxacin alone, or cholesterol alone (P ≤ 0.02). A significantly lower log10 CFU was recovered from corneas treated with moxifloxacin/cholesterol and moxifloxacin alone as compared to corneas of eyes treated with PBS or cholesterol alone (P < 0.01). At 48 hr PI, significantly lower MPO activity was quantitated from eyes treated with moxifloxacin/cholesterol as compared to eyes treated with cholesterol or moxifloxacin alone (P ≤ 0.046). Eyes treated with moxifloxacin/cholesterol had fewer immune cells and less corneal destruction than eyes from all other treatment groups. The MIC for moxifloxacin alone was 0.125 μg/mL, and cholesterol alone was unable to inhibit growth at any of the concentrations tested. The MIC for moxifloxacin when combined with 1% cholesterol was 0.0625 μg/mL.Conclusions: Treatment with a mixture of moxifloxacin and cholesterol significantly lowers the severity of infection caused by pneumococcal keratitis as compared to treatment with moxifloxacin alone, cholesterol alone, or PBS. This treatment mixture eradicates the bacteria in the cornea, unlike treatment with PBS or cholesterol alone. Using cholesterol with moxifloxacin as a treatment for bacterial keratitis could help lower the clinical severity of the infection.

Bioadhesive sulfacetamide sodium microspheres: Evaluation of their effectiveness in the treatment of bacterial keratitis caused by Staphylococcus aureus and Pseudomonas aeruginosa in a rabbit model

The aim of this study was to prepare bioadhesive sulfacetamide sodium (SA) microspheres to increase their residence time on the ocular surface and to enhance their treatment efficacy on ocular keratitis. Microspheres were fabricated by spray drying method using mixture of polymers such as pectin, polycarbophil and hydroxypropylmethyl cellulose (HPMC) at different ratios. The particle size and distribution, morphological characteristics, thermal behavior, encapsulation efficiency, mucoadhesion and in vitro drug release studies on formulations have been investigated. After optimisation studies, SA-loaded polycarbophil microsphere formulation with polymer:drug ratio of 2:1 was found to be the most suitable for ocular application and used in in vivo studies. In vivo studies were carried out on New Zealand male rabbit eyes with keratitis caused by Pseudomonas aeruginosa and Staphylococcus aureus. Sterile microsphere suspension in light mineral oil was applied to infected eyes twice a day. Plain SA suspension was used as a positive control. On 3rd and 6th days of the antimicrobial therapy, the eyes were examined in respect to clinical signs of infection (blepharitis, conjunctivitis, iritis, corneal oedema and corneal infiltrates) which are the main symptoms of bacterial keratitis and then cornea samples were counted microbiologically. The rabbit eyes treated with microspheres demonstrated significantly lower clinical scores than those treated with SA alone. A significant decrease in the number of viable bacteria in eyes treated with microspheres was observed in both infection models when compared to those treated with SA alone. In conclusion, in vitro and in vivo studies showed that SA-loaded microspheres were proven to be highly effective in the treatment of ocular keratitis.

The Case Against the Use of Steroids in the Treatment of Bacterial Keratitis

The Case Against the Use of Steroids in the Treatment of Bacterial Keratitis

Trends in Resistance to Ciprofloxacin, Cefazolin, and Gentamicin in the Treatment of Bacterial Keratitis

The aim of this study was to evaluate the microbial profile, resistance patterns, and antibiotic sensitivity of bacterial keratitis to three commonly used ocular antibiotics. All cases of bacterial keratitis referred to the Massachusetts Eye and Ear Infirmary Microbiology Laboratory from two consecutive annual 10-month periods were reviewed. The bacterial profile and resistance to ciprofloxacin, cefazolin, and gentamicin was evaluated within the two intervals. Of the 485 cultures analyzed, 66.4% (322) were positive for bacterial isolates. Of these, 19.2% were polymicrobial, 87.5% were gram-positive, and 12.5% were gram-negative. The most prevalent isolate was coagulase-negative Staphylococcus (45.5%), followed by S. aureus (15.2%). The resistance patterns for gram-positive bacteria for ciprofloxacin for the first versus second time interval were 12% and 22% (P = 0.04) respectively, for cefazolin 13% and 23% (P = 0.04), and for gentamicin 4% and 7% (P = 0.36). The resistance patterns for gram-negative bacteria for ciprofloxacin, cefazolin, and gentamicin were not significantly different in the two tested time periods (all P > 0.05). There was increased resistance of gram-positive organisms to ciprofloxacin and cefazolin, but not gentamicin, in the two examined time periods. Increased resistance to these commonly used antibiotics emphasizes the need for close follow-up after initial empiric treatment, and maintaining a low threshold for selecting alternative therapy.

Gatifloxacin ophthalmic solution 0.3% in the treatment of bacterial keratitis

Infectious keratitis can be a medical emergency that can lead to a profound loss of vision if not treated promptly and appropriately. Although a shift in the etiology and predisposing factors has been reported within the past few years, bacteria still predominate as the causative organisms of infectious keratitis in temperate climates. The clinical outcome is greatly influenced by the rate of epithelial and stromal healing, which is affected by multiple factors, including the overall health of the patient, status of the ocular surface and selection of the topical ophthalmic preparations used during treatment. Fourth-generation fluoroquinolones, including gatifloxacin, have been widely adopted for an ‘off-label’ treatment of bacterial keratitis because of their broad-spectrum potency and effective penetration, as well as their minimal effects on corneal wound healing.

Clinical Efficacy of Moxifloxacin in the Treatment of Bacterial Keratitis: A Randomized Clinical Trial

Clinical Efficacy of Moxifloxacin in the Treatment of Bacterial Keratitis: A Randomized Clinical Trial

Stabilité à – 20°C des collyres antibiotiques renforcés (amikacine, ceftazidime, vancomycine)

Fortified antibiotic ophthalmic solutions are regularly administered as an immediate treatment for bacterial keratitis. Fortified antibiotics used to be self-prepared by nurses. To solve this problem, pharmacy staff studied the stability of three 5% solutions of vancomycin, amikacin, and ceftazidime prepared in aseptic conditions from parenteral antibiotic solutions. Solutions were frozen at -20 degrees C. Each solution were examined before storage and over a 75-day period. Ceftazidime and amikacin were diluted in 0.9% sodium chloride and vancomycin in 5% dextrose. Over a 75-day period, physical and pharmacological (absorbance spectra) properties and the sterility of each stock solution were studied. The pH of amikacin (6.51), ceftazidime (6.47), and vancomycin (3.77) remained stable during the 75-day period. Osmolarities also remained stable (367, 488, and 351 mOsm/L, respectively). There were no significant differences in the concentration, osmolarity, and pH of the three antibiotic solutions before storage and after 75 days of freezing. Over a 75-day period, the stability of amikacin, ceftazidime, and vancomycin remained constant; no contamination was detected before storage and after 75 days. Topical fortified antibiotic solutions can be stored for 75 days at -20 degrees C (15 days quarantine). After this time, these eye-drops should be stored at 4 degrees C and should be discarded after 3 days.

Frozen fortified antibiotic in ophthalmic solutions stability during 2 months

Abstract Purpose: Fortified antibiotic ophthalmic solutions are regularly administered as an immediate treatment for bacterial keratitis. The fortified antibiotics were used to be self‐prepared by nurses. To solve this problem, pharmacy staff studied the stability of three 5% solutions of vancomycin, amikacin and ceftazidim, prepared in aseptic conditions from parenteral antibiotic solutions. Methods: Solutions were frozen at ‐20°C. Portions of each solution were examined before storage and over a 75‐days period. Ceftazidim and amikacin were dilute in 0,9% sodium chloride and vancomycin in 5% dextrose. Over a 75 days period, physical, pharmacological (absorbance spectra) properties and sterility of each stock solution were studied. Results: The pH of amikacin (6,51), ceftazidim (6,47) and vancomycin (3,77) remained stable during the 75 days period. Osmolarities also remained stable (367, 488 and 351 mOsm/L). There were no significant differences in the concentration, osmolarity and pH of the three antibiotic solutions before storage and after 75 days of freezing. Over a 75 days period, stability of amikacin, ceftazidim and vancomycin remained constant; no contamination was detected before storage and after 75 days. Conclusions: Topical fortified antibiotic solutions can be stored 75 days at ‐20°C (15 days quarantine). After, these eye‐drops should be stored at 4°C and should be discarded after 3 days.

Clinical Efficacy of Moxifloxacin in the Treatment of Bacterial Keratitis: A Randomized Clinical Trial

To determine the clinical efficacy and safety of moxifloxacin (1.0%) in patients with bacterial keratitis compared with patients treated with ofloxacin (0.3%) or fortified tobramycin (1.33%)/cephazolin (5%). Prospective randomized trial. A total of 229 patients diagnosed with bacterial keratitis were enrolled in the study; 78 patients were randomized to the fortified tobramycin/cephazolin group, 77 patients to the moxifloxacin group, and 74 patients to the ofloxacin group. A total of 225 patients were evaluable for safety and 198 patients were included in the efficacy analysis. After corneal specimens were obtained, the assigned study medication was instilled every hour, day and night, for 48 hours and on the third day, every hour by day and every 2 hours at night. For days 4 and 5, 1 drop every 2 hours by day and every 4 hours at night, and for days 6 and 7, 1 drop every 4 hours. After day 7, the antibiotic was tapered to every 6 hours and stopped when appropriate. Resolution of keratitis and healing of ulcer, time to cure, mean time to discharge, clinical sign score, adverse reactions to study medication, and treatment failures. Of the 186 nonexiting patients, resolution of the keratitis and healing of the ulcer occurred in 175 (94%) nonexiting patients. In the 175 patients in whom the corneal ulcer was cured, there were no statistically significant differences between the treatment groups for the mean time to cure (P = 0.25). There were no statistically significant differences between the 3 treatment groups in the various sign parameters including the sign score. A positive bacterial corneal culture was obtained in 190 (83%) of the 229 enrolled patients. The distribution of the species of bacterial organisms was similar in each treatment group and no significant difference in the percentage of isolates between the groups was observed. Twelve (5.2%) of the treated patients had serious complications (perforation or enucleation). No serious events attributable to therapy occurred during the study and all treatments were safe and well tolerated. No difference in healing rate, cure rate, or complications between fortified cephazolin and tobramycin, ofloxacin, or moxifloxacin was seen in this study.

Corneal deposits and topical ofloxacin—the effect of polypharmacy in the management of microbial keratitis

To report six cases of corneal deposits after administration of topical ofloxacin in the treatment of bacterial keratitis. Six cases of microbial keratitis treated with multiple topical medications, including topical ofloxacin, resulted in corneal precipitates and poor wound healing. In five cases, the precipitates resolved with discontinuation of ofloxacin treatment. However, in one patient, some residual deposits persisted following discontinuation of ofloxacin. The cornea epithelialised, but deposits were identified subepithelially. Fluoroquinolone antibiotic drops have been extensively used in bacterial keratitis because of their ease of availability, broad spectrum of activity, and lack of toxicity. While corneal precipitates have been reported with cases of topical ciprofloxacin and norfloxacin, little has been documented on corneal deposits and topical ofloxacin in the treatment of bacterial keratitis. The predisposing factors resulting in corneal deposits and the role of polypharmacy are important features that may impair epithelialisation. Clinical management should be aimed at reducing the toxic environment and promoting ocular surface stability.

Evaluation of clinical characteristics and bacterial isolates in dogs with bacterial keratitis: 97 cases (1993–2003)

To evaluate clinical characteristics and breeds affected with bacterial keratitis and compare patterns of resistance in bacterial isolates over time in dogs. Retrospective cross-sectional study. 97 dogs with bacterial keratitis. Dogs with bacterial keratitis were identified from teaching hospital medical records at the Universities of Tennessee and Florida during the years 1993 to 2003. Data were collected pertaining to breed, Schirmer tear test results, treatments administered at the time of initial examination, bacterial species isolated, and resistance to selected antimicrobials. 66% of the dogs were brachycephalic, 54% had tear production < 15 mm/min, and 29% were receiving a corticosteroid at the time of initial examination. The most common bacteria isolated were Staphylococcus intermedius (29%), beta-hemolytic Streptococcus spp (17%), and Pseudomonas aeruginosa (21%). Staphylococcus intermedius isolates had limited resistance to certain antimicrobials. More than 80% of beta-hemolytic Streptococcus spp isolates were resistant to neomycin, polymyxin B, and tobramycin. Isolates of P aeruginosa were susceptible to tobramycin and gentamicin and had limited resistance to ciprofloxacin and enrofloxacin. Among bacterial species isolated, there was no evidence of development of antimicrobial resistance over time. Data suggested that administration of ciprofloxacin or a combination of a first-generation cephalosporin and tobramycin may be used in the treatment of bacterial keratitis while awaiting results of bacterial culture and susceptibility testing. Evidence suggests that current methods of medical management of bacterial keratitis are not associated with increased antimicrobial resistance.