The epidemiology, phylogeny, and biology of nonencapsulated Streptococcus pneumoniae are largely unknown. Increased colonization capacity and transformability are, however, intriguing features of these pneumococci and play an important role. Twenty-seven nonencapsulated pneumococci were identified in a nationwide collection of 1,980 nasopharyngeal samples and 215 blood samples obtained between ...

1. Immunization of rabbits with Type III pneumococci is effective in producing active immunity against infection with a virulent strain of the homologous organism. 2. Immunization of rabbits with Type I or II pneumococci, and with R forms derived from any of the fixed types, is equally effective in producing active immunity against Type III infection. 3. Immunization of rabbits with nucleoprote...

1. Following repeated inhalations of the degenerated non-virulent "R" forms of Type II pneumococcus, no type specific antibodies can be demonstrated in the serum of rabbits. 2. Following repeated inhalations of slightly virulent Type II (SAv) pneumococci, only protective antibodies can be demonstrated in the serum of rabbits. 3. Following repeated inhalations of virulent Type II (Sv) pneumococc...

Pneumococcal adherence to alveolar epithelial cells and nasopharyngeal epithelial cells has been well characterized. However, the interaction of Streptococcus pneumoniae with bronchial epithelial cells has not been studied. We have now shown that pneumococci bind specifically to a human bronchial epithelial cell line (BEAS-2B cells). Pneumococci adhered to BEAS-2B cells in a time- and dose-depe...

Ciliated ependymal cells line the ventricular surfaces and aqueducts of the brain. In ex vivo experiments, pneumolysin caused rapid inhibition of the ependymal ciliary beat frequency and caused ependymal cell disruption. Wild-type pneumococci and pneumococci deficient in pneumolysin caused ciliary slowing, but penicillin lysis of wild-type, not pneumolysin-deficient, pneumococci increased the e...

1. Pneumococci contain an intracellular enzyme of marked lipolytic activity as measured by the acid liberated by its action on tributyrin. 2. Enzyme-containing solutions may be prepared by dissolving pneumococci in bile, or by extraction by other means. 3. The optimum reaction for maximum activity of the endolipase is about pH 7.8, which coincides with the optimum hydrogen ion concentration for...

The incidence of penicillin resistance in pneumococci is increasing in the USA, having risen from <5% before 1989 to >35% in 1997. There has also been a shift in the ratio of intermediate to high-level resistance from 3 or 4:1 to 2 or 1:1. Multidrug resistance and resistance to macrolides and fluoroquinolones in pneumococci is also a matter of concern. The implications for empirical treatment o...

Although virulence of Streptococcus pneumoniae is associated with its capsule, some pathogenic S. pneumoniae isolates lack capsules and are serologically nontypeable (NT). We obtained 64 isolates that were identified as NT "pneumococci" (i.e., bacteria satisfying the conventional definition but without the multilocus sequence typing [MLST]-based definition of S. pneumoniae) by the traditional c...

Intracellular killing of Staphylococcus aureus by alveolar macrophages is known to be enhanced by exposure to alveolar lining material. Because this material may have a role in pulmonary host defenses, we have studied its effect on pneumococci and other nonstaphylococcal organisms. Alveolar lining material from rats caused rapid killing and lysis of pneumococci. The antipneumococcal activity wa...

1. Rabbits are very susceptible to infection by inhalation of Type I pneumococci. 2. When rabbits are exposed to a pneumococcus spray the bacteria readily penetrate into the lower respiratory tract. The pneumococci which reach the periphery of the lungs as a result of this procedure usually disappear within a few hours but a generalized and fatal septicemia frequently later appears. Pneumococci...