Infectious and noninfectious keratitis after laser in situ keratomileusis

Outbreak of Nocardia keratitis after photorefractive keratectomy: clinical, microbiological, histopathological, and confocal scan study

Nocardia keratitis occurred in 4 eyes of 3 patients (2 women and 1 man) who had photorefractive keratectomy (PRK) by the same surgeon at the same center. Two eyes of the first 2 patients required lamellar keratectomy to debulk the involved stroma and obtain specimens for microbiological and histopathological evaluation. Light microscopic examination disclosed gram-positive and acid-fast filaments of Nocardia that were confirmed by the microbiological results. Diagnosis of Nocardia keratitis in the third case was not as challenging as in the first 2 cases because of a high index of suspicion. Confocal scans of all cases disclosed hyperreflective and slender, fibril-like structures in the corneal stroma. All eyes responded favorably to topical amikacin and the infection resolved without recurrence. The most probable cause of the outbreak was inadequate attention to sterility during surgery.

Antibiotic susceptibility of conjunctival bacterial isolates from refractive surgery patients

PURPOSE

To determine the in vitro antibiotic susceptibility patterns of conjunctival bacterial flora isolated before surgery from patients undergoing refractive surgery.

DESIGN

In vitro laboratory investigation.

PARTICIPANTS

One hundred five eyes from 105 patients scheduled for refractive surgery at Balgensesang Ophthalmology Clinic between September 2005 and January 2006 were studied. Among 105 patients, 71 (67.6%) underwent LASIK using a femtosecond laser, 24 (22.9%) underwent LASIK using an automated microkeratome, 8 (7.6%) underwent LASEK, and 2 (1.9%) patients underwent phakic intraocular lens implantation.

METHODS

Preoperative conjunctival swab samples were inoculated directly in culture media at the bedside before topical anesthetic or antibiotic application. Blood agar, chocolate agar, thioglycolate broth, Sabouraud dextrose agar, and Ogawa media were used for bacterial, fungal, and mycobacterial cultures.

MAIN OUTCOME MEASURES

Minimum inhibitory concentrations (MICs) of ofloxacin (OFX), levofloxacin (LEV), gatifloxacin (GAT), moxifloxacin (MOX), gemifloxacin (GEM), and other commonly used antibiotics were determined using an E test.

RESULTS

From 105 patients, 73 (85%) coagulase-negative staphylococci (CNS), 2 (2.3%) Staphylococcus aureus, 1 (1.2%) Streptococcus pneumoniae, and 5 (4.8%) gram-negative bacilli were isolated. No fungi or mycobacteria were isolated. The MIC that would inhibit the growth of 90% of the tested bacterial isolates (MIC(90)) of OFX, LEV, GAT, MOX, and GEM for methicillin-susceptible CNS (n = 46) were 0.5 microg/ml, 0.19 microg/ml, 0.094 microg/ml, 0.047 microg/ml, and 0.023 microg/ml, respectively. The MIC(90) values for methicillin-resistant CNS (n = 27) were 32 microg/ml, 4 microg/ml, 1 microg/ml, 0.5 microg/ml, and 0.25 microg/ml, respectively (P<0.001).

CONCLUSIONS

The most effective against conjunctival bacteria isolated from refractive surgery patients were GEM, MOX, and GAT; however, resistance to earlier-generation fluoroquinolones (OFX and LEV) is increasing among methicillin-resistant CNS. It may be a therapeutic option to use newer fluoroquinolones in patients undergoing refractive eye surgery to reduce such infections as methicillin-resistant CNS.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

[A case of Scedosporium apiospermum keratitis confirmed by a molecular genetic method]

A 54-yr-old male, who was treated by chemotherapy for gastric cancer 15 months ago, presented to Yongdong Severance Hospital, Seoul, with complaints of pain in his right eye caused by a foreign body from the ground in the previous week. He had been treated with topical and oral antibacterial in addition to antifungal agents, but did not show significant clinical improvement. After a positive corneal culture with mold, topical amphotericin B was added to the initial regimen. The mold was identified as Scedosporium apiospermum by macroscopic and microscopic morphologies and the nucleotide sequences of a fungal PCR product showing 99% homology with those of S. apiospermum (EF151349). He recovered with good results at 25 days after corneal epithelial debridement. The early diagnosis of S. apiospermum keratitis is very important for proper treatment. It is recommended that molecular diagnostic methods such as fungal PCR and sequencing be done with conventional cultures whenever a fungal infection is suspected.

Two cases of methicillin-resistant Staphylococcus aureus keratitis after Epi-LASIK

BACKGROUND

We describe two severe cases of methicillin-resistant Staphylococcus aureus (MRSA) keratitis following Epi-LASIK surgery.

CASES

One patient was a 23-year-old man who underwent Epi-LASIK surgery in both eyes. He developed an infectious corneal ulcer in one eye 2 days after surgery and was referred to us 7 days post-surgery with corneal perforation, for which we performed therapeutic penetrating keratoplasty. The other patient was a 32-year-old man who developed infectious keratitis in one eye 4 days after bilateral Epi-LASIK and was referred to us 2 days later.

OBSERVATIONS

Microbial testing revealed MRSA infection as the cause of the keratitis in both patients which was successfully treated with vancomycin eyedrops.

CONCLUSION

Infectious keratitis after refractive surgery is uncommon; it is important to diagnose this condition, identify the causative agent, and initiate treatment with appropriate antibiotics as soon as possible.

Basic knowledge of refractive surgery: correction of refractive errors using modern surgical procedures

INTRODUCTION

Refractive ophthalmic surgery allows refractive errors to be corrected permanently in a safe, effective, and reliable way with few complications.

METHODS

Selective literature review with special reference to the guidelines of the German Commission for Refractive Surgery.

RESULTS

With a total of almost 18 million treatments performed to date, laser in-situ keratomileusis (LASIK) is the most commonly used refractive surgical procedure worldwide. Alternatives to LASIK include surface ablation procedures (PRK, LASEK, Epi-LASIK) and phakic intraocular lens implantation. If ocular accommodation is lost, removal of the crystalline lens and implantation of modern multifocal intraocular lenses (refractive lens exchange) provide an alternative means of correcting myopia, hyperopia and presbyopia.

DISCUSSION

The treatment effect is maximized and complications kept to a minimum if strict inclusion criteria are applied and a high technical standard maintained during the procedure.