Abstract
Purpose: :
To examine the different species of Streptococcus causing endophthalmitis and to report their sensitivities to commonly used antibiotics.
Methods: :
This study is a non-comparative case series. Microbiology laboratory data was analyzed to identify all streptococcal vitreous isolates and their sensitivities from January 1, 1990 to December 31, 2010, at a single institution.
Results: :
In total, 194 streptococcal organisms were isolated from endophthalmitis cases during the study period. The species identified include Streptococcus viridans (56%), Enterococcus (21%), Streptococcus pneumoniae (14%), Group B Streptococcus (GBS, 5%), and miscellaneous Streptococcus species (4%). Overall, in vitro, the streptococcal isolates were 95% sensitive to levofloxacin, 92% sensitive to cephalothin, 79% sensitive to ceftazidime, 52% sensitive to ciprofloxacin, and 42% sensitive to gentamicin sulfate. All isolates were sensitive to vancomycin, except one Enterococcus strain, which showed intermediate resistance. Less resistance was found to gentamicin among Enterococcus isolates (29%), than S. pneumoniae (92%), GBS (80%), and S. viridans (62%) isolates. Conversely, much greater resistance was found to ceftazidime and cephalothin among Enterococcus isolates (100%), than isolates from other streptococcus species (0-2%).
Conclusions: :
Streptococcal endophthalmitis is most commonly due to S.viridans and Enterococcus. In spite of reports of increasing resistance of Streptococcus species to vancomycin, all isolates were sensitive to vancomycin in the current study and only one isolate had intermediate resistance. Cephalothin and ceftazidime were variably effective, with 98-100% sensitivity observed in non-Enterococcus Streptococcus isolates and complete resistance in Enterococcus isolates. While the second generation fluoroquinolone, ciprofloxacin, had high rates of resistance (48%) among all Streptococcus isolates, the third generation fluoroquinolone, levofloxacin, had very low rates of resistance (5%).
Keywords: endophthalmitis • antibiotics/antifungals/antiparasitics