Antibiotic Resistances of Bacteria Identified in an Endophthalmitis Prospective Study

Abstract

Purpose: : To assess the antibiotic susceptibility of microorganisms identified in the vitreous and/or the aqueous humor of patients suffering from endophthalmitis.

Methods: : A multicenter prospective study was conducted from January 2004 to June 2005 to evaluate panbacterial Polymerase Chain Reaction (PCR) versus culture. We determined the antibiotic susceptibility of microorganisms identified by conventional identification (Culture in Brain Heart Infusion). Antibiotic resistance testing was performed using the disk diffusion technique in Mueller–Hinton agar or the VITEK2 system. We divided identified organisms into two groups, wild strain (WS) or with acquired antibiotic resistance (AAR).

Results: : We included 71 organisms from 64 endophthalmitis; twenty eight different microorganisms were identified. Among them, 84.5% were gram–positive Cocci ((staphylococcus 38/71, (53.5%), streptococcus 14/71, (19.7%)). We found 53.5% (38/71) of WS organisms and 46.5% of AAR (33/71) with 7 multiresistant strains. Resistances to fluoroquinolone (FQ) were 13.2%, and vancomycin was still effective against 100% of all tested bacteria.

Conclusions: : This study about antibiotic resistances of microorganisms isolated in endophthalmitis finds an important part of them (46,5%) with AAR. Sensibilities to FQ are higher than in the literature. Micro–organism diversity is important and despite the predominance of gram–positive Cocci, a combination of intravitreous antibiotics is still recommended as the initial empiric treatment of endophthalmitis.

Keywords: antibiotics/antifungals/antiparasitics • endophthalmitis