[Ecological studies on hemolytic streptococci in aged population].

The pattern of group distribution of hemolytic streptococci and the source of specimen, when these organisms were isolated from the clinical specimen of the aged, were quite different from that of streptococcosis among children. The isolation frequency from the upper respiratory tract was rather low in comparison to the other specimen, such as sputum, exudate and urine. Both groups B and G were predominant among isolates from sputum, B more prevailing than G from exudate, and the isolates from the urinary tract were consisted almost solely of group B. These trends have been unchanged in the past 3 years. Normal pharyngeal streptococcus flora among the aged also differ from that of healthy children, the carrier rate being rather low, and groups B and G, instead of A in the case of children, being predominant. This pattern of group distribution, among the isolates of normal pharyngeal streptococci of the aged, seemed to be reflected on that of isolates from clinical specimen, especially those from the sputum. The type distribution of group B isolates from normal throat swabs of the aged resemble that of clinical isolates from the same generation, types Ia and III dominating in both cases.