[Identification of Salmonella typhi phage types 1991-1996 in the Slovak Republic].

A total of 102 strains of Salmonella typhi were received at the National Salmonella Phage Typing Centre at Bratislava during January 1991-December 1996 from various regions of the Slovak Republic. From these, 24 strains were isolated and confirmed by cultivation from patients with typhoid fever and 78 strains were isolated from chronic carriers. According to the results of Vi-phage typing the strains belonged to 9 phage types. A predominance of phage types E1/a (24.5%), D1 (18.6%), A (13.7%) and F1 (12.7%) was observed. Another three groups were formed by the strains described as I + IV, strains of with atypical lytic reaction (RDNC) and Vi-negative strains. In the case of three chronic carriers a change of the originally established phage type to another phage type was observed after many years. This genetical problem should be kept in view in epidemiological practice, especially in the study of the phage types of Salmonella typhi strains isolated from long-term carriers.