a 47-year - old female presented to our institution with diminished vision on the left side and red eye for 2 months . her past history was not significant , except for partial penetrating keratoplasty of the left eye 18 months prior to treat a corneal ulcer . she experienced one episode of graft rejection 12 months prior to presentation , and since then had been using eyedrops containing levofloxacin ( cravit ; taejoon pharm , seoul , korea ) and 1% rimexolone ( vexol ; alcon laby inc . after the rejection , a 22 mm , round - shaped corneal haziness associated with mild superficial infiltration had been present at the suture site in the 2 o / c area . we thought that this was a suture - related infection , so we removed the suture 6 months prior to presentation . after removal of the suture , the corneal haziness improved . in order to prevent additional rejection , we recommended the use of eyedrops containing levofloxacin and 1% rimexolone , and artificial tears 4 times a day . when the patient visited us with the above symptoms , eyelid examination revealed a greasy appearance and meibomian gland plugs that were determined to be posterior blepharitis on the left upper and lower eyelids . on slit lamp examination , a 43 mm , round - shaped corneal haziness and epithelial defect associated with mild superficial stromal infiltration was found at the junction between the graft and donor site at the 2 to 3 o / c area . the corneal ulcer had progressed slowly and seemed to be chronic , so we performed a corneal gram stain and culture . we recommended warm massage and scrubbing of the upper lid and prescribed a lid cleanser ( blephasol ; samil pharm , seoul , korea ) in an effort to improve the eyelid hygiene . we also recommended use of eyedrops containing 5% moxifloxacin ( a 4th generation fluoroquinolone ) every 2 hours and 0.15% amphotericin 4 times a day , because we were unsure whether the infection was fungal or bacterial . we also recommended reducing the use of vexol , a steroid eyedrop she had been using , to once a day . there was no improvement after 4 weeks with this treatment . eventually , the corneal culture grew mrsa ( ofloxacin resistance was also shown ) . according to the antibiotic sensitivity testing , we prescribed fortified 2.5% vancomycin - containing eyedrops 6 times a day . after 4 weeks , the corneal ulcer decreased to 23 mm in size , and we recommended reducing the use of the 2.5% vancomycin - containing eyedrops to 4 times a day . after 8 weeks , the corneal epithelium was healed completely and the corneal thickness returned to normal ( 581 m ) ( fig . 2 ) . a 62-year - old man presented with red eye , ocular pain , and eyewax on his right eye . he had a history of brain surgery to treat a brain tumor 1 year prior to presentation . after the surgery , a right - sided facial nerve palsy was noted , which reduced his blinking reflex . postoperative exposure keratitis developed , and he began to use eyedrops containing ofloxacin ( ocuflox ; samil pharm ) and artificial tears 4 times a day . on examination of the eyelids , a greasy appearance and meibomian gland plugs , which resembled thick toothpaste upon compressing the upper lid , were found , and posterior blepharitis involving the right upper and lower eyelids was diagnosed . on slit lamp examination , mild ciliary injection at the conjunctiva , an 88 mm round - shaped corneal haziness and epithelial defect associated with mild superficial stromal infiltration , and a 1.5 mm high anterior chamber hypopyon we recommended warm massage and scrubbing the upper lid with a lid cleanser ( blephasol ) in order to improve the eyelid hygiene . we also recommended the use of eyedrops containing 5% moxifloxacin every 2 hours , alternating with 5% ceftazidime ( a 3rd generation cephalosporin ) every 2 hours . there was no improvement in the corneal ulcer or the hypopyon after 4 days of treatment . after this , as we believed the ulcer was neurotrophic and we decided to reduce the frequency of eyedrops to 6 times a day . mrsa was eventually detected in the initial corneal culture , which took 1 week to grow ( resistance to ofloxacin was also shown ) ( fig . 4 ) . based on the antibiotic sensitivity testing , we prescribed fortified 2.5% vancomycin - containing eyedrops 6 times a day . after 5 days , the corneal ulcer size , superficial stromal infiltration , and hypopyon all decreased ( fig . we then recommended a reduction in the use of the eyedrops containing 2.5% vancomycin to 4 times a day . by the 2 week follow - up visit a 47-year - old female presented to our institution with diminished vision on the left side and red eye for 2 months . her past history was not significant , except for partial penetrating keratoplasty of the left eye 18 months prior to treat a corneal ulcer . she experienced one episode of graft rejection 12 months prior to presentation , and since then had been using eyedrops containing levofloxacin ( cravit ; taejoon pharm , seoul , korea ) and 1% rimexolone ( vexol ; alcon laby inc . after the rejection , a 22 mm , round - shaped corneal haziness associated with mild superficial infiltration had been present at the suture site in the 2 o / c area . we thought that this was a suture - related infection , so we removed the suture 6 months prior to presentation . after removal of the suture , the corneal haziness improved . in order to prevent additional rejection , we recommended the use of eyedrops containing levofloxacin and 1% rimexolone , and artificial tears 4 times a day . when the patient visited us with the above symptoms , eyelid examination revealed a greasy appearance and meibomian gland plugs that were determined to be posterior blepharitis on the left upper and lower eyelids . on slit lamp examination , a 43 mm , round - shaped corneal haziness and epithelial defect associated with mild superficial stromal infiltration was found at the junction between the graft and donor site at the 2 to 3 o / c area . the corneal ulcer had progressed slowly and seemed to be chronic , so we performed a corneal gram stain and culture . we recommended warm massage and scrubbing of the upper lid and prescribed a lid cleanser ( blephasol ; samil pharm , seoul , korea ) in an effort to improve the eyelid hygiene . we also recommended use of eyedrops containing 5% moxifloxacin ( a 4th generation fluoroquinolone ) every 2 hours and 0.15% amphotericin 4 times a day , because we were unsure whether the infection was fungal or bacterial . we also recommended reducing the use of vexol , a steroid eyedrop she had been using , to once a day . there was no improvement after 4 weeks with this treatment . eventually , the corneal culture grew mrsa ( ofloxacin resistance was also shown ) . according to the antibiotic sensitivity testing , we prescribed fortified 2.5% vancomycin - containing eyedrops 6 times a day . after 4 weeks , the corneal ulcer decreased to 23 mm in size , and we recommended reducing the use of the 2.5% vancomycin - containing eyedrops to 4 times a day . after 8 weeks , the corneal epithelium was healed completely and the corneal thickness returned to normal ( 581 m ) ( fig . a 62-year - old man presented with red eye , ocular pain , and eyewax on his right eye . he had a history of brain surgery to treat a brain tumor 1 year prior to presentation . after the surgery , a right - sided facial nerve palsy was noted , which reduced his blinking reflex . postoperative exposure keratitis developed , and he began to use eyedrops containing ofloxacin ( ocuflox ; samil pharm ) and artificial tears 4 times a day . on examination of the eyelids , a greasy appearance and meibomian gland plugs , which resembled thick toothpaste upon compressing the upper lid , were found , and posterior blepharitis involving the right upper and lower eyelids was diagnosed . on slit lamp examination , mild ciliary injection at the conjunctiva , an 88 mm round - shaped corneal haziness and epithelial defect associated with mild superficial stromal infiltration , and a 1.5 mm high anterior chamber hypopyon were found ( fig . we recommended warm massage and scrubbing the upper lid with a lid cleanser ( blephasol ) in order to improve the eyelid hygiene . we also recommended the use of eyedrops containing 5% moxifloxacin every 2 hours , alternating with 5% ceftazidime ( a 3rd generation cephalosporin ) every 2 hours . there was no improvement in the corneal ulcer or the hypopyon after 4 days of treatment . after this , as we believed the ulcer was neurotrophic and we decided to reduce the frequency of eyedrops to 6 times a day . mrsa was eventually detected in the initial corneal culture , which took 1 week to grow ( resistance to ofloxacin was also shown ) ( fig . 4 ) . based on the antibiotic sensitivity testing , we prescribed fortified 2.5% vancomycin - containing eyedrops 6 times a day . after 5 days , the corneal ulcer size , superficial stromal infiltration , and hypopyon all decreased ( fig . we then recommended a reduction in the use of the eyedrops containing 2.5% vancomycin to 4 times a day . by the 2 week follow - up visit the prevalence of mrsa differs depending on the group which is being studied ; for example , the prevalence of mrsa was reported to be 0.1% in geneva 's hospital , 2.8% in a san francisco nosocomial community in 2000 , and 6.8% in a homeless group in san francisco in 2003 . the prevalence of mrsa infection is quite different among societies , but it is almost universally increasing . mrsa infections have many different appearances in different sites , and also show multiple resistances to antibiotics making treatment quite difficult . infections in immunocompromised patients can cause severe life - threatening problems , such as necrotizing cellulitis , pneumonia , and sepsis . in hospital infections , mrsa can be transmitted from patient - to - patient , via clinical materials , physician 's hands , and hospital instruments . ocular mrsa infections manifest as blepharitis , conjunctivitis , keratitis , dacryocystitis , endophthalmitis , and orbital cellulitis . generally , mrsa ocular conditions do not respond to commercially - used eyedrops , which can cause a delay in treatment and can lead to severe complications , including permanent loss of vision [ 21 - 26 ] . according to the study by sotozono et al . the first step is the asymptomatic carrier state or the patient who shows only conjunctivitis . the second step is the patient who shows a corneal epithelial defect with superficial infiltration . the third step is the patient who shows superficial keratitis with a corneal ulcer which progresses slowly and causes corneal stromal infiltration . thus , mrsa corneal ulcers have many manifestations , and can be treated with vancomycin - containing eyedrops or ointment according to each step , while intravenous vancomycin can be used in severe cases . according to kato and hayasaka , mrsa exists as normal flora in the conjunctiva in 1.3% of the population . high - risk factors for ocular mrsa infection are known to be previous long - term use of antibiotic - containing eyedrops , long - term use of steroids , long - term hospitalization , systemic disease ( respiratory failure , diabetes , cancer , and hepatic failure ) , ocular immunocompromised states ( dry eyes , ocular surface diseases , and stevens - johnson syndrome ) , long - term use of contact lenses , and previous ocular surgery ( partial penetrating keratoplasty and refractive surgery ) . patients who have had a keratoplasty , as in case 1 , have multiple risk factors . not only do they have a history of previous ocular surgery , but they also likely have a history of long - term use of antibiotic- and steroid - containing eyedrops to prevent rejection and infection . donor rejection must be excluded when corneal irritation symptoms develop , and consequently proper treatment can be delayed . the clinical findings of the cornea in rejection are quite different when compared to bacterial keratitis , including round superficial stromal infiltration and chronicity . the use of steroid or antifungal eyedrops can aggravate the corneal ulcer and cause corneal toxicity , which can lead to severe complications , including corneal perforation . therefore , if a patient has a slowly progressive chronic corneal ulcer and has risk factors for a mrsa infection , they should be examined and a mrsa corneal ulcer should be suspected . corneal culture and antibiotic sensitivity testing must be performed to establish the exact diagnosis . in patients who have been hospitalized for a long time , as in case 2 , it is important to consider that mrsa could be a nosocomial infection . nosocomial mrsa infections can cause worsening of underlying diseases , and the prevention of nosocomial mrsa spread is becoming increasingly important . most transmission of mrsa in hospital inpatients is thought to be via transiently - colonized healthcare workers . found that 73% of hospital rooms with patients infected with mrsa and 69% of rooms with patients colonized with mrsa have some environmental contamination . in the same study , nurses contaminated their gloves 42% of the time in rooms with mrsa patients despite only touching environmental contamination . other potential environmental reservoirs include computer keyboards used by clinicians , blood pressure cuffs , showers , and bathtubs . .   found that mrsa can survive on the external surfaces of sterile goods packaged for over 38 weeks . therefore , hand hygiene may be the single most important measure for controlling transmission of mrsa . for that reason , in mrsa patients confirmed by bacterial culture and antibiotic sensitivity testing , isolation and sterilization of the patient 's medical materials and handwashing by healthcare workers are of the utmost importance . although mrsa keratoconjunctivitis can be treated with vancomycin - containing eyedrops or ointments , mrsa infections are of great concern to ophthalmologists because these ocular infections , including blepharitis , conjunctivitis , keratitis , or endophthalmitis , respond poorly to conventional antibiotic treatments and are sometimes sight - threatening . consequently they have to be prepared directly in the hospital , which means they can be easily contaminated , may have high toxicity to the corneal epithelium , and may have unstable acidity which makes long - term storage difficult . unfortunately , with the high rate that bacteria are now developing antibiotic resistance , we expect that vancomycin resistant staphylococcus will also become a problem . we should therefore choose antibiotics carefully using the results of bacterial culture and antibiotic sensitivity testing . in corneal ulcers with a round - shaped , mild superficial infiltration that have a slow progression and in lesions that do not improve with -lactam antibiotics , mrsa infection should be considered , especially in high - risk groups . these high - risk groups include patients who have had penetrating keratoplasty and exposure keratitis . in such cases , bacterial culture and antibiotic sensitivity testing must be performed and treatment decisions should be based on the results of these tests . also , healthcare workers should practice serial hand washing and careful isolation of medical materials from known mrsa patients in order to prevent transmission of mrsa . the prevalence and transmission of mrsa in the community are increasing and preventing mrsa infection is becoming an increasingly important consideration .
considering the popular use of antibiotic - containing eyedrops in korea , it is important to know the emerging antibiotic - resistant strains of bacteria before treating infectious eye diseases . 
 this is especially important in high - risk groups because of the high incidence of resistant infections and the subsequent treatment requirements . 
 we report two cases of methicillin - resistant staphylococcus aureus ( mrsa ) corneal ulcers in high - risk groups . the first case involved a patient who had keratitis after using antibiotic- and steroid - containing eyedrops to treat a corneal opacity that developed after repeated penetrating keratoplasty . the second case involved a patient who used antibiotic - containing eyedrops and a topical lubricant on a regular basis for > 1 month to treat exposure keratitis due to lagophthalmos . 
 the second patient 's problems , which included a persistent superficial infiltration , developed after brain tumor surgery . both cases showed mrsa on corneal culture , and the corneal ulcers improved in both patients after the application of vancomycin - containing eyedrops . in conclusion , 
 mrsa infection should be considered in corneal ulcers that have a round shape , mild superficial infiltration , and slow progression , especially in high - risk groups . 
 this report includes descriptions of the characteristic features , antibiotic sensitivities , prevention , and successful treatment with vancomycin - containing eyedrops for mrsa corneal ulcers .