Changing etiology of community-acquired bacterial meningitis in adults: a nationwide multicenter study in Korea.

Epidemiologic data on the etiologic organisms is important for appropriate empirical antibiotic treatment of bacterial meningitis. We identified the etiologies of community-acquired bacterial meningitis in Korean adults and the associated epidemiological factors. A retrospective, multicenter nationwide study was carried out. Patients 18 years of age or older with community-acquired bacterial meningitis with a confirmed pathogen were enrolled. Demographic, clinical, and microbiological data were collected. One hundred and ninety-five cases were collected. Streptococcus pneumoniae was the most common pathogen (50.8%), followed by Staphylococcus aureus (10.3%), Klebsiella pneumoniae (7.7%), Listeria monocytogenes (6.7%), and group B Streptococcus (3.1%). The penicillin resistance rate of the S. pneumoniae was 60.3%; 40.0% of the organisms were not susceptible to third-generation cephalosporins. The combination of third-generation cephalosporin with vancomycin was used in 76.3% of cases. Steroids were given before or with the first dose of antibiotics in 37.4% of patients. The 30-day mortality rate was 20.5% and neurological sequelae developed in 15.6% of cases. S. pneumoniae was the most common organism identified in community-acquired bacterial meningitis among Korean adults. S. aureus, K. pneumoniae, L. monocytogenes, and group B Streptococcus were also common. S. pneumoniae had high rates of resistance to penicillin and third-generation cephalosporins.

Quantification of emotion by nonlinear analysis of the chaotic dynamics of electroencephalograms during perception of 1/f music.

The goal of this study is to quantify and determine the way in which the emotional response to music is reflected in the electrical activities of the brain. When the power spectrum of sequences of musical notes is inversely proportional to the frequency on a log-log plot, we call it 1/f music. According to previous research, most listeners agree that 1/f music is much more pleasing than white (1/f0) or brown (1/f2) music. Based on these studies, we used nonlinear methods to investigate the chaotic dynamics of electroencephalograms (EEGs) elicited by computer-generated 1/f music, white music, and brown music. In this analysis, we used the correlation dimension and the largest Lyapunov exponent as measures of complexity and chaos. We developed a new method that is strikingly faster and more accurate than other algorithms for calculating the nonlinear invariant measures from limited noisy data. At the right temporal lobe, 1/f music elicited lower values of both the correlation dimension and the largest Lyapunov exponent than white or brown music. We observed that brains which feel more pleased show decreased chaotic electrophysiological behavior. By observing that the nonlinear invariant measures for the 1/f distribution of the rhythm with the melody kept constant are lower than those for the 1/f distribution of melody with the rhythm kept constant, we could conclude that the rhythm variations contribute much more to a pleasing response to music than the melody variations do. These results support the assumption that chaos plays an important role in brain function, especially emotion.