Minimum inhibitory concentrations and resistance for selected antimicrobial agents (including imipenem, linezolid and tigecycline) of bacteria obtained from eye infections.

To determine bacteria obtained from eye infections, both resistance and minimal inhibitory concentration (MIC) to gatifloxacin, moxifloxacin, tigecycline, linezolid and imipenem, in vitro. A cross-sectional descriptive study was undergone with 50 samples from 50 eyes of patients diagnosed with keratitis or endophthalmitis, who came to a consultation at the Fundación Oftalmológica de Santander (Floridablanca, Colombia) from August to November 2014. The MICs of the isolated microorganisms were established through Etest® strips (BioMérieux SA, Marcy-l'Etoile - France). Of the 50 samples in total, 17 different bacteria species or groups were isolated. The main isolate for gram-positives was (17 samples), and for gram-negatives was (6 samples). The susceptibility percentages sorted from highest to lowest for gram-positive isolates (n=38) were: imipenem 90.3%, linezolid 87.9%, tigecycline 78.1%, gatifloxacin 68.8% and moxifloxacin 68.8%. For gram-negative isolates (n=12), they were: imipenem 72.7%, gatifloxacin 70%, moxifloxacin 66.7% (no reference cut-off points were found for ), tigecycline 22.2%, and linezolid 0% (as expected according to its inhibition spectrum). Although fourth generation fluoroquinolones are currently the preferred initial empirical monotherapy in our practice, given the increasing bacterial resistance, in cases in which gram-positive bacteria were isolated in the initial staining imipenem, linezolid or tigecycline could be used as an alternative. On the other hand, for cases of gram-negative bacteria, no antimicrobial susceptibility exceeded 80%, so using two antimicrobials looking for a synergy between them could be a better option. S = Susceptibility, IS = Intermediate susceptibility, R = Resistance.