Objectives: To determine the spectrum and susceptibility of bacteria in vitreous fluid from patients undergoing vitrectomy for endophthalmitis. Methods: Vitreous fluid samples (n = 177) were obtained from 150 patients (94 male, 56 female) undergoing vitrectomy for endophthalmitis between January 2001 and October 2005. Specimens of undiluted aqueous and vitreous fluid were cultured for aerobic, anaerobic bacteria and fungi by conventional methods. Identification and antibiotic susceptibility were performed by the API system, Vitek II system (BioMerieux) and the agar disk diffusion methods according to CLSI recommendations. Results: Ninety one isolates were recovered from the samples. Gram stain was positive in 133/177 (75.1%), while cultures were positive in 94/177 (53.2%) samples. Gram-positive bacteria were the most common isolates (71/91, 78%), followed by Gram-negative bacteria (11/91, 12%) and fungi (9/91, 10%). Staphylococci coagulase-negative were isolated in 41/91 (45%). The next most common species isolated among Gram-positive bacteria were S. aureus (6.6%), Streptococcus spp (9.9%), Propionibacterium acnes (9.9%), Bacillus spp (3.3%), Streptococcus. pneumoniae (1%) and Enterococcus faecalis (1%). Among Gram-negative bacteria eight isolates were Enterobacteriaceae, two were non fermenters and one was Haemophilus inlfuenzae. Two of the fungal isolates were Candida albicans, one Acremonium spp and six Aspergillus fumigatus. Polymicrobial growth was observed in six patients with two at least isolates. Of staphylococci coagulase-negative 10/41 (24%) were resistant to methicillin. Only one strain of Staphylococcus aureus was methicillin resistant. All Gram positive isolates were susceptible to vancomycin. All isolates were sensitive to amikacine and ceftazidime while resistance was observed in 9/177 (5%) isolates to fluoroquinolones. Conclusion: A variety of microorganisms was isolated from the vitreous fluid of patients. The predominant isolates were Gram-positive bacteria, especially staphylococci coagulase-negative with low resistance rate to methicillin. So, therapy should be based on the isolation and identification of the infecting agent and the in vitro antibiotic susceptibility to the appropriate antibiotics.
Full conference title:
16th European Congress of Clinical Microbiology and Infectious Diseases
- ECCMID 16th (2006)