Abstract
Abstract: :
Purpose: To determine changing trends over the past 12 years of microbiologic isolates and their antibiotic susceptibilities in vitreous cultures of patients with suspected endophthalmitis. Methods: A retrospective study of all vitreous cultures performed between 1991 and 2002 at the Yale University Eye Center. Results: One hundred and forty-two cultures were performed and 75 were positive. Fifty (66.6%) were gram-positive bacteria, 21 (28%) were gram-negative bacteria and 4 (5.3%) were fungal species. Of the gram-positive cultures, 22 (29.3%) isolates were coagulate-negative Staphylococcus, 6 (8.0%) were Staphylococcus aureus, and 6 (8.0%) were Streptococcus pneumoniae. Of the gram-negative organisms, the 3 most common isolates were 4 (5.3%) Propionibacterium acnes, 4 (5.3%) Klebsiella oxytoca and 4 (5.3%) Moraxella species. Coagulase-negative Staphylococcus remained the most common pathogen throughout the duration of the study. The antibiotic resistance of coagulase-negative Staphylococcus increased in later years. In Group I (1991-1994), 1 of 3 was resistant to a single antibiotic. In Group II (1995-1998), 1 of the 8 had resistance to multiple antibiotics. In Group III (1999-2002), 5 of the 8 (62.5%) had resistance to multiple antibiotics. All gram-positive isolates were sensitive to vancomycin, rifampin, and chloramphenicol. All gram-negative organisms were sensitive to ciprofloxacin, ampicillin/sulbactam, ceftriaxone, ceftazidime, mezlocillin and ticarcillin/clavulanate. One of the four fungal cases was resistant to multiple antifungals. Conclusions: Gram-positive organisms remain the most common isolate in cases of suspected endophthalmitis. Compared to previous studies, the incidence of coagulase-negative Staphylococcus is lower, while a variety of other gram-positive and gram-negative organisms are greater in frequency. This study demonstrates a higher incidence (28%) of gram-negative organisms than the Endophthalmitis Vitrectomy Study (5.9%). Multi-antibiotic resistance may be increasing for coagulase-negative Staphylococcus, the most common endophthalmitis pathogen. Fortunately, vancomycin remains active against all gram-positive isolates.
Keywords: endophthalmitis • microbial pathogenesis: clinical studies • antibiotics/antifungals/antiparasitics