Research article

Genome evolution driven by host adaptations results in a more virulent and antimicrobial-resistant Streptococcus pneumoniae serotype 14

Feng Ding^1,2* , Petrus Tang^3* , Mei-Hua Hsu⁴ , Peng Cui^1,2 , Songnian Hu¹ , Jun Yu¹ and Cheng-Hsun Chiu⁴

¹  The CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, 100029 Beijing, PR China

²  Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, 100029 Beijing, PR China

³  Department of Parasitology, Chang Gung University College of Medicine, Kweishan 333, Taoyuan, Taiwan

⁴  Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung University College of Medicine, Kweishan 333, Taoyuan, Taiwan

author email corresponding author email* Contributed equally

BMC Genomics 2009, 10:158doi:10.1186/1471-2164-10-158

Published:	13 April 2009

Abstract

Background

Streptococcus pneumoniae serotype 14 is one of the most common pneumococcal serotypes that cause invasive pneumococcal diseases worldwide. Serotype 14 often expresses resistance to a variety of antimicrobial agents, resulting in difficulties in treatment. To gain insight into the evolution of virulence and antimicrobial resistance traits in S. pneumoniae from the genome level, we sequenced the entire genome of a serotype 14 isolate (CGSP14), and carried out comprehensive comparison with other pneumococcal genomes. Multiple serotype 14 clinical isolates were also genotyped by multilocus sequence typing (MLST).

Results

Comparative genomic analysis revealed that the CGSP14 acquired a number of new genes by horizontal gene transfer (HGT), most of which were associated with virulence and antimicrobial resistance and clustered in mobile genetic elements. The most remarkable feature is the acquisition of two conjugative transposons and one resistance island encoding eight resistance genes. Results of MLST suggested that the major driving force for the genome evolution is the environmental drug pressure.

Conclusion

The genome sequence of S. pneumoniae serotype 14 shows a bacterium with rapid adaptations to its lifecycle in human community. These include a versatile genome content, with a wide range of mobile elements, and chromosomal rearrangement; the latter re-balanced the genome after events of HGT.