A total of 101 strains of K. pneumoniae and 100 strains of S. marcescens isolated from various clinical specimens in Taegu and Seoul between 1987 and 1994 was tested for the antimicrobial susceptibility to theβ-lactam antibiotics and then was
subjected
for molecular typing ofβ-lactamase genes including the characterization of plasmids and isoelectric focusing(IEF) followed by Southern hybridization with TEM or SHV gene probe.
Eighty up to hundred percents of tested strains of S. marcescens were resistant to Cefazolin(Cz), Cephalothin(Cl), Cefamandole(Cn) and 10-27% of strains to Cefoxitin(Cx), Cefoperazone(Cp), Cefotaxim(Ct). But, only twelve percents of K. pneumoniae
were
resistant to Cz, Cl, Cn, and Cx, Cp, Ct.
Antibiograln showed that twelve percents of S. marcescens strains were resistant to more than eight drugs. Whereas, thirteen percent of K. pneumoniae strains were resistant to more than three drugs. Isolectric focusing ofβ-lactamase confirmed
that
fifty-six percents of K. pneumoniae produced the TEM typeβ-lactamase(pI 5.2-6.5) and seventy-three percents produced the SHV typeβ-lactamase(pI 7.0-8.2). Sixty percents of S. marcescens produced the TEM typeβ-lactamase on the contrary to the
fact
that only two percents of K. percents of K. pneumoniae strains produced the SHV typeβ-lactamase. Besides, ninty-four percents of S marcescens and fifty-four percents of K. pneumoniae produced the peculiar type(pI 9.6) ofβ-lactamse. One strain
of
extraordinary S. marcescens which was multiply resistant to 11 drugs produced only one type of pI 9.6β-lactamase. Strains harbored TEM-1 gene were 19% in K. pneumoniae and 18% in S. marcescens. Southern hybridization revealed that strains
harbored
SHV-1 gene were 13% in K. pneumoniae and 6% in S. marcescens. The plasmids(4.7-7.6 Md) encoding TEM-1 gene of K. pneumoniae found to be markedly larger than those(7.4-57 Md) of S. marcescens strains.
Seven strains of K. pneumoniae carried the plasmids(18-111 Md) encoding SHV-1 gene. Whereas there was no plasmid encoding SHV-1 gene among S. marcescens strains. Two strains of K. pneumoniae carried plasmids(89, 79, 18, 19 Md) encoding both TEM-1
and
SHV-1 gene.
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