Molecular characterization of multidrug-resistant Streptococcus pneumoniae isolates in Korea. The Asian Network for Surveillance of Resistant Pathogens (ANSORP) Study Group

Abstract

Pulsed-field gel electrophoresis, ribotyping, and fingerprinting analysis of 22 invasive isolates of multidrug-resistant (MDR) pneumococci from Korea showed that 59 to 82% were genetically related. DNA sequencing of the PBP 2B gene showed relatively uniform alterations in nucleotides (5.4 to 7.8%) and amino acids (3.0 to 4. 3%), while Asn-276-->Lys, Arg-285-->Cys and Ser-305-->Phe substitutions were unique to Korean MDR strains, suggesting the spread of a few epidemic clones of resistant pneumococci within Korea.

FIG. 1

PFGE patterns of chromosomal DNA restriction fragments of MDR pneumococcal isolates from Korea digested with SmaI. The type A pattern (lanes 1 to 3) was the most common pattern among Korean MDR strains which was identical to that of the Spanish 23F clone (lane 1), while the type B pattern (lanes 4 to 5) was a pattern unique to Korean strains.

FIG. 2

Ribotyping patterns of MDR pneumococcal isolates from Korea digested with PvuII. Lane M is the DNA marker. Ribotype 1 is noted in MDR strains in lanes 3 to 8 with subtypes of ribotype 1 in lanes 1 to 2, while that of a penicillin-susceptible R6 (lane 9) is different from those of MDR strains.