Micrococcus keratitis following microkeratome-assisted laser in situ keratomileusis.

We hereby report a case of infectious keratitis after laser in situ keratomileusis (LASIK) caused by Micrococcus luteus, a commensal, managed successfully in a nonimmunocompromised individual. A 25-year-old healthy male underwent uneventful bilateral simultaneous LASIK for myopia using disposable blades. Postoperatively, topical antibiotic and steroids were advised; he discontinued antibiotic on his own after using for a day. On the 5th postoperative day, he had pain, redness, decreased vision, and white spot in the left eye (LE) for 1-day duration. Uncorrected visual acuity (UCVA) of LE reduced to 20/80 from postoperative 20/20. Slit-lamp biomicroscopy revealed tiny infiltrate in the interface with reticular haze in the flap and stroma. Gram-positive cocci in pairs and tetrads were found on corneal smears that were collected after lifting the flap from infiltrate, stromal bed, and undersurface of the flap. M. luteus was isolated on culture. The infiltrate resolved with scarring with intensive topical antibiotics. UCVA was 20/25. To the best of our knowledge, this is a first case report of post-LASIK infectious keratitis caused by M. luteus. Copyright:

Introduction

Infectious keratitis after laser in situ keratomileusis (LASIK) is a rare sight-threatening complication.[12] Prompt diagnosis and appropriate management in such cases may prevent visual loss.[13] Gram-positive organisms are the most common microorganisms when infection occurs in early postoperative period within 7-day post-LASIK.[1] We report a case of infectious keratitis caused by Micrococcus luteus in the left eye (LE) of a patient who underwent simultaneous LASIK for myopia. To the best of our knowledge, we report the first case of Micrococcus keratitis after LASIK.

Case Report

A 25-year-old healthy male underwent bilateral, uneventful, simultaneous microkeratome-assisted, wavefront-guided LASIK (Bausch and Lomb Technolas 217z excimer laser machine) for −7.5 DS in the right eye (RE) and −8.0 DS in LE. Disposable blades were used for either eye for performing LASIK. Postoperatively, moxifloxacin (0.5%), fluorometholone (0.1%), and lubricating eye drops four times daily in both eyes (BE) were prescribed.

On the 1st postoperative day, he was comfortable, and uncorrected visual acuity (UCVA) was 20/20 in BE. The flaps were well apposed, with clear interface; the same treatment was continued. On the 5th postoperative day, he complained of redness, pain, decreased vision, and white opacity in his LE, commencing a day before. He had discontinued moxifloxacin on his own after using only for a day postoperatively. UCVA was 20/80 in LE. RE examination was essentially unremarkable. LE examination revealed eyelid edema and mild conjunctival congestion. Slit-lamp biomicroscopy revealed a dot infiltrate in the interface with diffuse reticular haze in visual axis and no epithelial defect [Figure 1a]. The anterior chamber was quiet. Intraocular pressure was digitally normal.

Figure 1

(a) Dot-like infiltrate with reticular haze in the flap at the time of first presentation. (b) Gram staining of the smears showing Gram-positive cocci in tetrads (black arrow). (c) Slit-lamp examination under diffuse illumination – Cornea showing diffuse stromal haze and flap edema and a small central infiltrate 1 day after flap lifting and scraping. (d) Slit view showing interface fluid

With a diagnosis of post-LASIK infectious keratitis, we obtained corneal scrapings, after lifting the corneal flap in operating room, using a 15-number sterile surgical blade on Bard-Parker handle from the undersurface of the flap and the stromal bed for Grams, Giemsa and 20% acid-fast stain, and potassium hydroxide with calcofluor white preparation. Direct inoculation onto sheep blood agar, chocolate agar, Sabouraud dextrose agar, and Lowenstein–Jensen medium was done. A bandage contact lens (BCL, PureVision, Bausch + Lomb) was placed on LE. Figure 1b shows Gram-positive cocci in tetrads and pairs on smears. Half-hourly fortified cefazolin (5%), ciprofloxacin (0.3%), and homatropine bromide (2%) thrice daily were prescribed.

Day 1 after scrapings, UCVA reduced to hand movements close to the face. The flap was edematous with diffuse stromal haze, and central infiltrate was tiny [Figure 1c]. The presence of minimal fluid in the interface [Figure 1d] and normal digital intraocular pressure were noted.

Significant growth of multiple, small, confluent, gray colonies with no zone of hemolysis was observed on the blood and chocolate agars [Figure 2a]. The bacterium was identified by conventional biochemical tests and by Mini API ID32 STAPH (BioMerieux, France) as M. luteus. Antimicrobial susceptibility testing was determined by Kirby–Bauer disk diffusion method. The organism was sensitive to cefazolin, amikacin, ofloxacin, gentamicin, vancomycin, chloramphenicol, and gatifloxacin and resistant to ciprofloxacin and oxacillin with intermediate sensitivity to moxifloxacin. Ciprofloxacin was discontinued and topical fortified cefazolin 5% was continued.

Figure 2

(a) Blood agar and chocolate agar showing significant growth of multiple, small, confluent, gray colonies with no zone of hemolysis. (b) Slit view of the cornea of the left eye – few flap striae and central scarring, 2 weeks following the infection

On the 5th day, patient's symptoms improved; UCVA was 20/120 and improved to 20/40 with pinhole. The slit-lamp biomicroscopy revealed a pinhead-sized infiltrate with surrounding corneal edema and flap striae. We reduced frequency of fortified cefazolin to every 2 h, and prednisolone acetate 1% was added six times daily. BCL was removed. On subsequent visits, the corneal infiltrate decreased and visual acuity improved. On day 15, UCVA was 20/30; central cornea showed few flap striae and scarring [Figure 2b]. Antibiotics were discontinued. Corticosteroids were tapered over a month. Fourteen months later, UCVA was 20/20 in RE and 20/25 in LE, improved to 20/20 with + 0.50 DS.

Discussion

M. luteus is a common saprophyte and contaminate exposed skin of the face, arms, hands, legs, and conjunctiva. Panhalkar et al. isolated Micrococcus from conjunctiva in 17.7% of healthy controls.[4] Ozkan et al. isolated Micrococcus from the lower eyelid margins of controls and cases when contact lenses were dispensed.[5] Liu et al. reported BCL contamination, without causing any infection, when used after LASIK.[6] Micrococcus may cause an opportunistic infection in immunocompromised. However, infectious keratitis and endophthalmitis are very rarely caused by Micrococcus.[7] To the best of our knowledge, Micrococcus has not been reported to be a causative agent in post-LASIK infections.

The incidence of infectious keratitis is 0.035%; 62.5% of eyes presented within the first 7 days of LASIK.[13] Chang et al. reported the incidence as 0%–1.5%.[1] Most common cause of infectious keratitis reported after LASIK is Mycobacterium before 2005 and Staphylococcus aureus after 2005.[8] Gram-positive infections within 7 days and infections with Mycobacterium 10 days after LASIK are reported.[1] Early infections following LASIK are most commonly due to S. aureus, Streptococcus pneumoniae, Streptococcus viridans, Staphylococcus epidermidis, and Nocardia. Late infections are due to Mycobacteria and fungus.[12] Although Gram-positive coagulase-negative cocci such as S. epidermidis are well-recognized pathogens in ocular infections, similar reports concerning Micrococci are lacking.

Kent et al. reported infectious keratitis (1/22 eyes) with Micrococcus with BCL use for bullous keratopathy in compromised ocular surface.[9] The patient in this study had no BCL in his eye after LASIK. Diec et al. reported isolation of Micrococcus species from corneal scrapings of a contact lens wearer who presented with infectious keratitis.[10] The authors later isolated Pseudomonas and treated it as infectious keratitis, with ciprofloxacin.[10]

Broad-spectrum fourth-generation fluoroquinolones are routinely advocated as antibiotic prophylaxis for LASIK. We routinely prescribe perioperative moxifloxacin. However, our patient discontinued after 1 day of use.

The presence of dot infiltrate and reticular haze involving the flap and interface tilted our diagnosis toward infectious keratitis. Flap lifting followed by corneal scraping and microbiological evaluation of the sample for direct microscopy and culture helps in providing a reliable diagnosis though negative sample does not rule out infectious keratitis.[1] Micrococcus is very rarely isolated from cases of infectious keratitis. Post-LASIK infections may be atypical, and commensals may be causative organisms. Strict adherence to antibiotic prophylaxis may reduce chances of infection. In conclusion, any case of post-LASIK interface keratitis must arouse a high index of suspicion for infection. Early recognition and culture-sensitivity-based treatment might help in timely control of infection and reduce visual morbidity.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

This study was financially supported by Hyderabad Eye Research Foundation, Hyderabad, India.

Conflicts of interest

There are no conflicts of interest.