Antibiyotik dirençli pnömokoklarin moleküler epidemiyolojisi

Antibiotic resistant Streptococcus pneumoniae strains have been isolated in increasing frequency worldwide and this creates a serious threat for current treatment strategies. The main cause of penicillin resistance in pneumococci is the genetic alterations seen in penicillin-binding proteins. These genetic changes are either due to chromosomal mutations or due to the formation of mosaic genes. Resistant pneumococci are spread clonally under the effect of selective antibiotic pressure, or horizontally by the transfer of resistance genes from related species. Several epidemiological markers are used currently in order to investigate the routes of spread of resistant pneumococci worldwide and also to undertake effective measures to prevent the increase in resistance rates of pneumococci. Among these epidemiological markers, molecular epidemiological ones are the most reliable and informative markers. The recent molecular epidemiological studies have shown that the resistance determinants are transferred to new strains by the way of horizontal gene transfer, and also it has been determined that the resistant pneumococcal clones, such as 23F, 19F, 6B and serogroup 9 spread intercontinentally.