Antimicrobial susceptibility and molecular epidemiology of Streptococcus pneumoniae isolated from Shanghai, China

In this study, the antimicrobial resistance profiles of pneumococci isolated from respiratory specimens of patients from Shanghai, China, in 2004 and 2005 are described. Non-susceptible rates to penicillin and erythromycin among paediatric isolates (n = 122) were 63.1% and 94.3%, respectively, whilst those of adult isolates (n = 39) were 20.5% and 69.2%, respectively (P < 0.0001 and P < 0.0002). Nineteen serotypes were identified among 103 tested strains, 73.8% of which belonged to 19F, 14, 23F, 6B and 19A. The erm(B) gene was detected in 51 erythromycin-resistant strains (52.6%), the mef(E) gene in 5 strains (5.2%) and both erm(B) and mef(E) in 41 strains (42.3%). Among 45 sequence types (STs) determined by multilocus sequence typing (MLST) in these 103 isolates, 25 STs were new assignments and 9 STs contained 10 new alleles. On the other hand, 46 (68.7%) of 67 penicillin-non-susceptible S. pneumoniae and 51 (52.6%) of 97 macrolide-resistant S. pneumoniae were characterised as belonging to four international resistant clonal complexes, Taiwan19F-14, Spain23F-1, Spain6B-2 and Taiwan23F-15. Our findings indicate that the spread of international resistant clones played a predominant role in the emergence and increase of resistance in Shanghai. Conjugate vaccination may be a promising method to prevent the increase in pneumococcal resistance.