• Cornea/External Disease

    This prospective study found a high prevalence and degree of fluoroquinolone resistance in patients with the Boston type 1 keratoprosthesis (KPro) who received once-daily moxifloxacin. These results likely demonstrate a causal relationship between antibiotic prophylaxis and increased resistance among these patients, and warrant further investigation.

    The authors characterized bacterial and fungal flora colonizing the ocular surface of eyes implanted with the KPro and determined the prevalence of antibiotic resistance among the isolates. They also compared their findings in KPro eyes with those of eyes with PKP that received chronic topical corticosteroids and control eyes given neither topical antibiotics nor corticosteroids. Each of the three groups had 25 patients.

    Although KPro, PKP and control eyes showed similar culture positivity rates and bacterial species composition, they varied significantly with respect to fluoroquinolone resistance. At least one bacterial isolate resistant to fourth-generation fluoroquinolones was found in 44 percent of eyes with KPro, compared to 24 percent of eyes with PKP and 8 percent of control eyes.

    They write that the results of this study confer valuable information for antibiotic selection. Because there was no resistance to cefazolin and vancomycin in any of the isolates, these antibiotics are probably better choices for the empiric treatment of bacterial keratitis in KPro and PKP patients. Also because topical ocular antibiotics can induce bacterial resistance at extraocular sites, KPro patients should perhaps be warned of the potential inefficacy of fluoroquinolones in the treatment of systemic infections. They add that evaluation of the nasopharyngeal flora should be considered in upcoming studies.

    They conclude that rational and evidence-based modifications to the current standard prophylaxis regimen for KPro eyes are needed to prevent further emergence of resistant organisms.