[Epidemiology and pathogenesis of streptococcal infection]

Abstract

The appearance of the "streptococcal toxic shock-like syndrome" led to a growing interest in infections caused by Streptococcus pyogenes (group-A-streptococci). Since 1987 some 800 cases with a lethality of 20% or more were observed. Contrary to toxic scarlet fever the site of primary infection are the lower respiratory tract or soft tissue infections. Erythrogenic toxins and low molecular weight mitogens, inducing cytokines (IL-2, IL-3, IL-6, TNF-alpha, IFN-gamma) seem to be involved in the pathogenesis of these severe infections. Morphologically and culturally the strains isolated from cases of toxic shock-like syndrome cannot be differentiated from isolates of epidemic scarlet fever or sporadic cases. At the same time, when in Scandinavia an epidemic by S.pyogenes type 1 with many cases of toxic shock was observed, the same type caused a scarlet fever epidemic without complications in eastern Germany. Erythrogenic toxin type A or its toxoid, respectively, can be used for successful immunizations of rabbits. Another--antibacterial-immunization can be done with the M-protein of S.pyogenes, which is limited by its type-specificity. Streptococcal vaccination is required especially for developing countries with a high incidence of rheumatic fever. Infections due to Streptococcus agalactiae (group-B streptococci) are often underestimated though they have a first position in septicemia and meningitis of newborns. Taxonomy and nomenclature of streptococci are often changing; a list of the presently known species is presented in table I.