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Aleksandra V. Rachitskaya, Harry W. Flynn, Jr., Darlene Miller; Comparison Of Membrane Filter System And Blood Culture Bottles For Culturing Vitrectomy Samples. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1674.
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To evaluate two methods of culturing vitreous samples obtained during vitrectomy: a membrane filter system and blood culture bottles
This is a prospective study of vitreous samples from patients who underwent vitrectomy for clinically suspected infectious endophthalmitis or open globe injuries. The microbiological outcomes were compared between the vitrectomy samples from the same patient, which were cultured both on a membrane filter system and in a blood culture bottle. The culture results were compared at 24 hours, 48 hours, 1 week, and 2 weeks.
From September 2009 to April 2011, a total of 92 patients underwent vitrectomy for clinically suspected endophthalmitis or open globe injuries and had their vitrectomy samples processed by the Bascom Palmer Eye Institute microbiology laboratory. Out of 92 samples, 29% were positive in the membrane filter group and 25% were positive in the blood culture bottle group. In the culture positive samples, the rates of positivity comparing the membrane filter group versus blood culture bottles group were the following: at 24 hours (44% versus 30%), at 48 hours (41% versus 44%), at 1 week (15% versus 26%). No culture positivity was observed at 2 weeks. At 24 hours, 7 samples had identical microbiological outcomes between the membrane filter and the blood culture bottle groups, 5 grew on the filter paper but not in the bottle. By 48 hours, 16 samples matched (9 Staphylococcus, 3 Streptococcus, 2 Candida, 1 Gram-negative, 1 Gram-positive species), 7 organisms (2 Gram-negative, 2 Staphylococcus, 1 Streptococcus, 1 Mycobacterium, 1 Aspergillus species) grew on filter paper only, and 1 organism (Streptococcus species) grew in the bottle only. Out of 8 organisms that grew at 1 week, three were Propionibacterium acnes and two of those grew both on filter paper and in the bottle.
The direct inoculation of blood culture bottles may be an acceptable adjunctive or alternative technique to more complicated membrane filter system for vitrectomy samples in infectious endophthalmitis. The outcomes of the two methods of vitrectomy sample culturing were similar at 48 hours. Blood culture bottle vitrectomy sample culturing is easy to perform as compared to membrane filter system that requires trained microbiology personnel to perform and evaluate.
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