title: Raman spectroscopy for differential diagnosis of endophthalmitis and uveitis in rabbit iris in vitro.
abstract: We developed a diagnostic tool to differentiate between endophthalmitis and uveitis using Raman spectroscopy. Twenty-two New Zealand rabbits with endophthalmitis induced by Staphylococcus aureus (10 animals), noninfectious uveitis induced by lipopolysaccharide from Escherichia coli (10 animals) and controls (two animals) were analyzed. Twenty-four hours after the eyes were inoculated, iris tissue was dissected and subjected to dispersive Raman spectroscopy using an excitation source at 830 nm and a spectrograph/CCD camera to detect a Raman signal with an integration time of 50 s. With the collected spectra of endophthalmitis and uveitis, we developed a routine to classify spectra in each specimen using principal components analysis, using a leave-one-out cross-validation procedure. The mean Raman spectra of tissues with uveitis and endophthalmitis showed several bands in the region of 800-1800 cm(-1), which have been attributed to nucleic acids, amino acids, proteins, and lipids. The bands at 1004, 1339, and 1555 cm(-1) differed significantly (t-test, p<0.05) between diseases. The principal components PC3 and PC4 differed significantly (ANOVA, p<0.05) for the two tissue types, indicating that these PCs can be used to discriminate between the two diseases using Mahalanobis distance as a discriminator. This technique is useful for differentiating the spectral bands of uveitis and endophthalmitis, and the diagnostic model showed sensitivity of 89%, specificity of 100%, and accuracy of 92% using the leave-one-out cross-validation procedure. These results may be clinically relevant for differentiating endophthalmitis from uveitis, and this approach may become a noninvasive method to optimize the diagnosis of inflammatory and infectious vitreoretinal diseases.
authors.affiliation: Health Sciences Center - CCS, Universidade Comunitária Regional de Chapecó - UNOCHAPECO, Chapecó, SC 89809-000, Brazil.
authors.forename: Eglas Emanuel
authors.initials: EE
authors.lastname: Rossi
authors.forename: Landulfo
authors.initials: L
authors.lastname: Silveira
authors.forename: Antonio Luiz
authors.initials: AL
authors.lastname: Barbosa Pinheiro
authors.forename: Stella Regina
authors.initials: SR
authors.lastname: Zamuner
authors.forename: Flávio
authors.initials: F
authors.lastname: Aimbire
authors.forename: Mauricio
authors.initials: M
authors.lastname: Maia
authors.forename: Marcos Tadeu
authors.initials: MT
authors.lastname: Tavares Pacheco
mesh_terms: D000818:Animals; D003937:Diagnosis, Differential; D009877:Endophthalmitis / Q000175:diagnosis* / Q000382:microbiology; D004927:Escherichia coli Infections / Q000175:diagnosis* / Q000382:microbiology; D015818:Eye Infections, Bacterial / Q000175:diagnosis* / Q000382:microbiology; D007499:Iris Diseases / Q000175:diagnosis* / Q000382:microbiology; D011817:Rabbits; D012680:Sensitivity and Specificity; D013059:Spectrum Analysis, Raman; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D014605:Uveitis / Q000175:diagnosis* / Q000382:microbiology