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Sander Dubovy, Nancy Buchser, Guillermo Amescua, Darlene Miller; Detection of Organisms by Microbiology vs. Histopathology in Corneal Biopsy and Penetrating Keratoplasty Specimens. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2887.
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Detection of the causative organism is important for successful prompt management of keratitis. Microbiologic culture is the conventional method used to identify organisms. However, histopathologic analysis can also detect organisms in patients who undergo corneal biopsy or therapeutic penetrating keratoplasty (TPK). The purpose of this study is to compare the detection of organisms by microbiology (culture) and histopathology (slides) in corneal biopsies and corneal buttons removed by TPK.
: Records from the Bascom Palmer Eye Institute microbiology and histopathology laboratories were retrospectively searched for patients who underwent TPK or corneal biopsy for keratitis and had specimens bisected and submitted for both microbiologic and histopathologic evaluation between January 1, 1996 and June 25, 2011. Detection of bacteria, fungi, acanthamoeba and mycobacteria by these two methods were compared using growth in culture or histologic stains such as Gomori methenamine silver, periodic acid-Schiff, Brown and Hopps, and Ziehl-Neilson stain.
No organisms were detected in either slides or culture in 54% of specimens. These tests both identified organisms in 17%. Cultures were positive, but slides did not reveal organisms in 20%. Organisms were identified on slides, but cultures were negative in 9%. Of the 193 cases in which organisms were identified, 43% were fungi, 40% bacteria, 14% acanthamoeba, and 3% mycobacteria. Cultures grew fungi, bacteria, mycobacteria, and acanthamoeba in 74, 73, 5, and 19 cases, respectively. Histology provided the additional detection of 19, 14, 2, and 11 cases of fungi, bacteria, mycobacteria, and acanthamoeba, respectively. Culture identified more bacteria than histopathology (p<0.001). Histopathology detected more acanthamoeba than culture (p=0.057). Both tests were similar in their detection of fungi and mycobacteria.
: Microbiology and histopathology are complimentary tests to detect organisms in corneal tissue. Bacteria are more frequently detected with microbiology. Acanthamoeba are more frequently detected with histopathology. Identification of fungi and mycobacteria is comparable for both tests. Submission of corneal tissue for both microbiologic and histopathologic analysis is recommended to identify the cause of infectious keratitis.
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