Late-onset Klebsiella oxytoca flap-margin–related corneal ulcer following laser in situ keratomileusis

Klebsiella oxytoca Complex: Update on Taxonomy, Antimicrobial Resistance, and Virulence

Klebsiella oxytoca is actually a complex of nine species-Klebsiella grimontii, Klebsiella huaxiensis, Klebsiella michiganensis, K. oxytoca, Klebsiella pasteurii, Klebsiella spallanzanii, and three unnamed novel species. Phenotypic tests can assign isolates to the complex, but precise species identification requires genome-based analysis. The K. oxytoca complex is a human commensal but also an opportunistic pathogen causing various infections, such as antibiotic-associated hemorrhagic colitis (AAHC), urinary tract infection, and bacteremia, and has caused outbreaks. Production of the cytotoxins tilivalline and tilimycin lead to AAHC, while many virulence factors seen in Klebsiella pneumoniae, such as capsular polysaccharides and fimbriae, have been found in the complex; however, their association with pathogenicity remains unclear. Among the 5,724 K. oxytoca clinical isolates in the SENTRY surveillance system, the rates of nonsusceptibility to carbapenems, ceftriaxone, ciprofloxacin, colistin, and tigecycline were 1.8%, 12.5%, 7.1%, 0.8%, and 0.1%, respectively. Resistance to carbapenems is increasing alarmingly. In addition to the intrinsic bla_OXY, many genes encoding β-lactamases with varying spectra of hydrolysis, including extended-spectrum β-lactamases, such as a few CTX-M variants and several TEM and SHV variants, have been found. bla_KPC-2 is the most common carbapenemase gene found in the complex and is mainly seen on IncN or IncF plasmids. Due to the ability to acquire antimicrobial resistance and the carriage of multiple virulence genes, the K. oxytoca complex has the potential to become a major threat to human health.

Very late-onset flap margin corneal ulcer following laser in situ keratomileusis

PURPOSE

To report and characterize cases of very late onset (5 years or more after surgery) flap margin corneal ulcers after laser in situ keratomileusis (LASIK) procedure.

METHODS

A retrospective case series of consecutive patients who were diagnosed with very late flap margin corneal ulcers following LASIK, between January 2014 and July 2017. All patients were treated with topical antibiotics and were followed up until complete resolution.

RESULTS

A total of eight patients, with a mean age of 46.5 ± 11 years, (range 31-64 years), were included in this study. All patients underwent uneventful myopic LASIK 13.3 ± 3 (range 10-20) years before presentation. Patients best corrected visual acuity (BCVA) at presentation was 0.20 ± 0.15 logMAR compared to a final BCVA of 0.10 ± 0.10 logMAR (p = 0.28). The ulcer was located in the bottom two clock hours of the flap margin (5-7 o'clock) in six (75%) patients and superior (11 o'clock) in the remaining two patients (p = 0.048). Seven patients (87.5%) suffered from blepharitis, and only one did not.

CONCLUSIONS

LASIK may be associated with an increased risk of late-onset corneal ulcer occurring years after the procedure. Instability of the flap margin, blepharitis and dry eye are possible causes of epithelial disturbance and may account for this complication.