MOLECULAR EPIDEMIOLOGY OF DRUG-RESISTANT PNEUMOCOCCI - TOWARD AN INTERNATIONAL APPROACH

An international multicenter study was undertaken to investigate the e pidemiological dynamics of penicillin-resistant pneumococci. We compar ed the molecular epidemiological characteristics of 205 penicillin-res istant isolates originating from The Netherlands, Thailand, United Sta tes, Spain, Greece, Poland, Cuba, Germany, Finland, United Kingdom, So uth Africa, Hungary, Portugal, Croatia, and the Czech Republic, Eighty -four distinct restriction fragment end labeling (RFEL) types were obs erved, Twenty-eight genetic types were shared by two or more strains, Five genetic clusters consisted of strains originating from different countries, illustrating dissemination of penicillin-resistant pneumoco cci among countries, The strains displaying the two predominant RFEL t ypes corresponding with the pandemic clones 23F and 9V were found in 1 0 and 6 different countries, respectively, This clearly demonstrates t he pandemic behavior of these two clones, Twelve out of the 28 genetic clusters contained two or more serotypes, This finding indicates freq uent horizontal transfer of capsular genes, Within distinct RFEL types , identical penicillin binding protein (PBP) genotypes were often obse rved, suggesting a high frequency of horizontal transfer of penicillin resistance genes, The most predominant PBP type was found in 15 disti nct RFEL types, comprised 44% of the entire collection, and was observ ed in 11 countries, The vast majority of the strains belonging to the pandemic clones 23F and 9V shared this predominant PBP type, We hypoth esize that the clones 23F and 9V are responsible for the worldwide inc rease of penicillin-resistance, because they serve as a genetic reserv oir for susceptible pneumococci to acquire penicillin resistance.