New knowledge in the understanding of infection immunology and the development of more effective antibiotics will influence the therapeutic options for extra- and intraocular bacterial diseases. The role of mucin with its high sIgA content, the glycoconjugate-mediated bacterial adherence phenomena of the cornea and conjunctiva, and the exact biomicroscopic classification can be constrated with the highly effective topically and systemically applicable antibiotics (e.g., Cephalosporins, Aminoglycosides, New Quinolones and Carbapenems). Recognition of the fact that the amplification mechanisms of the immune system are already fully activated when the clinical features of a serpent ulcer appear and that the destructive phase only represents an unwanted side-effect of the host defense mechanisms towards its own structures has resulted in the application of corticosteroids with simultaneous antibiotic medication and early tectonic perforating keratoplasty. Many intraocular inflammations of heretofore unknown etiology may be detected by modern diagnostic approaches as being localized manifestations of a systemic disease that can be properly treated (e.g., borreliosis, atypical syphilis). The incidence of "metastatic" endophthalmitis could be diminished in high-risk inpatients by preventive measures, including the elimination of potentially pathogenic agents with antibiotics (and antifungal drugs). Infection-associated intraocular inflammations ("Reiter's syndrome") have been linked to persisting pathogenic organisms at distant sites, thereby rendering themselves etiologically treatable (e.g., infections from Yersinia, Campylobaster, Urea-plasma, and Chlamydia). Except for a very few cases (use of monoclonal antibodies, serological methods and immunoblots), the diagnosis of bacterial infections is based on isolation of the organism concerned, which also represents a requirement for antibiotic susceptibility testing and, consequently a specific medication. Close cooperation with microbiologists and the direct culturing of isolates within ophthalmology clinics have seen a revival since the days of Theodor Axenfeld.