Purpose:
To assess the rate of resistance to fourth generation quinolones of coagulase-negative Staphylococcus (CoNS) isolated from endophthalmitis cases in 2006 at the Federal University of São Paulo, Brazil.
Methods:
Bacterial endophthalmitis was diagnosed on 18 cases in 2006, among these nine eyes of nine subjects had a positive culture with CoNS isolates. Previous ocular surgery and use of antibiotics were assessed. All isolates were tested for their susceptibility to gatifloxacin and moxifloxacin by Etest, which provided quantitative (minimal inhibitory concentration - MIC) and qualitative data. Sensitivity to oxacillin and vancomycin was assessed by disc diffusion. We also compared susceptibility rate in 2006 to previous years.
Results:
Eight eyes had been previously submitted to ocular surgery (Table). Six had undergone phacoemulsification; 1 trabeculectomy; 1 penetrating keratoplasty (PK); and 1 perforating trauma. At the time of diagnosis, five were in use of moxifloxacin and 3 of gatifloxacin. However, it was not possible to establish if they had been used prophilatically or after the onset the signs and symptoms of infection. MIC of gatifloxacin and moxifloxacin is displayed (Table). CoNS was intermediately or highly resistant to moxifloxacin and gatifloxacin in 44% of the cases. All of them were also oxacillin resistant CoNS, and none was resistant to vancomycin. These data contrast to those in previous years (2002-2005), when 57 isolates of CoNS were sensitive to either moxicloxacin or gatifloxacin
Conclusions:
CoNS has been isolated from endophthalmitis cases but for the first time resistance to either gatifloxacin or moxifloxacin was observed. In this series, the majority of the patients had been submitted to prior ocular surgery, mainly phacoemulsification, and were using antibiotic drops at the time of diagnosis. It still remains unanswered if prior fourth generation quinolone use is implicated in the number of resistant cases.
Keywords: endophthalmitis • antibiotics/antifungals/antiparasitics