The prevalence and pathogenicity of Propionibacterium acnes keratitis.

PURPOSE: To study the prevalence, pathogenicity, and virulence of Propionibacterium acnes keratitis. METHODS: All cases of infectious keratitis submitted to the microbiologic laboratory of the New York Eye and Ear Infirmary between January 1, 2003, and April 6, 2006, were reviewed. Those cases in which P. acnes was recovered from culture were collected, and the medical records studied in depth. RESULTS: Of 1555 cultures submitted to the microbiology laboratory, 1329 (85.5%) were positive for growth. One hundred twenty four (9.3%) of the 1329 cases yielded P. acnes in at least 1 culture medium. Seventy eight (62.9%) of 124 cases had not been pretreated with antibiotics before culture, and 66.7% of the nonpretreated ulcers were monomicrobial (P. acnes only). Fifty one (65.4%) of 78 cases of the nonpretreated corneal ulcers presented with a cellular reaction in anterior chamber, 12 (15.4%) with a hypopyon (6 were monomicrobial), 21 (26.9%) had stromal thinning (12 of which were monomicrobial), and 2 (2.6%) progressed to perforation (both polymicrobial). Corneal ulcers associated with P. acnes tended to be small (66.7%) and were widely distributed: central (n = 17, 21.8%), paracentral (n = 44, 56.4%), and peripheral (n = 17, 21.8%). The most common risk factors were contact lens wear and previous history of ocular surgery. Three of the 78 nonpretreated patients were unresponsive to medical treatment and required surgery for keratitis. CONCLUSION: This study provides evidence that P. acnes is a frequent cause of bacterial keratitis and may cause significant morbidity.

Proteomic analysis of exfoliation deposits.

PURPOSE: To increase knowledge of the biochemical composition of lenticular exfoliation material (XFM) by using proteomic approaches. METHODS: Anterior lens capsules from patients with and without exfoliation syndrome (XFS) were homogenized in formic acid and subjected to cyanogen bromide (CNBr) cleavage, and the pattern of chemically generated fragments was compared by SDS-PAGE after silver staining. Unique XFS bands not present in control cases were excised, digested with TPCK-trypsin, and the resultant peptides sequenced with quadrupole time-of-flight mass spectrometry (MS). In parallel experiments, CNBr-fragmented XFM was separately digested in solution with trypsin and elastase, and the resultant peptide mixture was analyzed by liquid chromatography coupled to tandem MS followed by identification through homology searches at nonredundant protein databases. Immunolocalization of the MS-identified components were performed in XFS versus control samples by using conventional immunohistochemical methods and light microscopy. RESULTS: In addition to fibrillin-1, fibronectin, vitronectin, laminin, and amyloid P-component, which are well-known extracellular matrix and basement membrane components of XFM, the proteomic approaches identified the multifunctional protein clusterin and tissue inhibitor of metalloprotease (TIMP)-3 as well as novel molecules, among them fibulin-2, desmocollin-2, the glycosaminoglycans syndecan-3, and versican, membrane metalloproteases of the ADAM family (a disintegrin and metalloprotease), and the initiation component of the classic complement activation pathway C1q. In all cases, classic immunohistochemistry confirmed their location in XFM. CONCLUSIONS: A novel solubilization strategy combined with sensitive proteomic analysis emphasizes the complexity of the XFS deposits and opens new avenues to study the molecular mechanisms involved in the pathogenesis and progression of XFS.