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 Original Articles |
| Antimicrobial Resistance of Streptococcus pneumoniae in Korea : Evidence for a Clonal Origin of Multidrug-resistant Strains |
| Jae-Hoon Song1), Ji Won Yang3), Nam Yong Lee2), Kyong Ran Peck1), Sungmin Kim1), Chik Hyun Pai4) |
| Division of Infectious Diseases1), Department of Clinical Pathology2), Samsung Medical Center, Samsung Biomedical Research Institute3), Department of Clinical Pathology4), Asan Medical Center, Seoul, Korea |
Vol.28 Num.5 (p393~404)
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Background : During recent three decades, the resistance of Streptococcus pneumoniae to penicillin has been rapidly increasing in many parts of the world. To characterize the epidemiology of multidrug-resistant S. pneumoniae as well as to investigate the possible spread of multiresistant clones which could partly explain the unusually high resistance rate in Korea, we conducted the antimicrobial susceptibility tests of pneumococcal isolates and performed pulsed-field gel electrophoresis (PFGE) and penicillin-binding protein (PBP) profile analysis of multiresistant strains from Korea.
Methods : A total of 174 pneumococcal isolates obtained from 153 patients who visited or were admitted to two tertiary care hospitals during the period from 1989 to 1995 were studied. Antimicrobial susceptibility tests for 173 isolates were performed using agar dilution method to determine minimal inhibitory concentrations of 11 antimicrobial agents. A total of 42 isolates with multidrug-resistance were subjected to PFGE and PBP profile analysis to investigate the genetic relatedness between multiresistant strains. SmaI and ApaI were used to digest the genomic DNAs in PFGE. For PBP profile analysis, 5 mCi 3H-benzylpenicillin were used to label PBPs of pneumococci.
Results : Antimicrobial susceptibility tests for 173 isolates showed that 67.8% of isolates were not susceptible to penicillin, exhibiting either intermediate (8.2%) or resistance (59.6%). Multidrug-resistance to three or more classes of antibiotics was observed in 25.4% of the isolates. Almost all isolates with resistance to penicillin were resistant to cephalosporins. PFGE showed that 29 of 35 Korean isolates with multidrug-resistance had an identical PFGE pattern. These strains also shared a common PBP profiles with decreased affinity of PBPs 1a, 2x, and 2b.
Conclusion : These data demonstrated the extremely high rates of penicillin- andmultidrug-resistance in pneumococcal isolates in Korea. Molecular epidemiologic studies suggest the spread of a single epidemic clone of resistant pneumococci within Korea, which could partly explain the unusually high rate of resistance in Korea. Future investigation with regards to source and mode of transmission is warranted.
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Keywords : Streptococcus pneumoniae, multidrug-resistance, pulsed-field gel electrophoresis, penicillin-binding protein analysis |
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