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J Clin Microbiol. 2002 Sep;40(9):3121-6.

Emergence of Klebsiella pneumoniae isolates producing inducible DHA-1 beta-lactamase in a university hospital in Taiwan.

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  • 1Department of Pathology, College of Medicine, National Cheng Kung University. Department of Pathology, Sinlau Christian Hospital, Tainan, Taiwan.

Abstract

Ten nonrepetitive clinical isolates of Klebsiella pneumoniae exhibiting an unusual inducible beta-lactam resistance phenotype were identified between January 1999 and September 2001 in a university hospital in Taiwan. In the presence of 2 micro g of clavulanic acid, the isolates showed a one to four twofold concentration increase in the MICs of ceftazidime, cefotaxime, and aztreonam but remained susceptible to cefepime (MICs, </=0.5 micro g/ml) and imipenem (MICs, </=0.5 micro g/ml). PCR, sequence analysis, and isoelectric focusing revealed production by these isolates of TEM-1, SHV-11, and DHA-1, a plasmid-encoded inducible AmpC beta-lactamase originally found in a Salmonella enterica serovar Enteritidis strain. Transfer of the resistance by conjugation experiments was not successful, but Southern hybridization showed that bla(DHA-1) was located on 70-kb plasmids, suggesting that the bla(DHA-1)-containing plasmids in the K. pneumoniae isolates were non-self-transmissible. Five isolates were recovered from patients in two surgery wards and two intensive care units. Acquisition of the DHA-1 producers could be traced back to previous hospitalizations 1 to 5 months earlier for the other five patients. Six and seven patterns among the isolates were demonstrated by plasmid analysis and ribotyping, respectively, indicating that the spread of the DHA-1 producers was due to both horizontal transfer of bla(DHA-1) and dissemination of endemic clones.

PMID:
12202541
[PubMed - indexed for MEDLINE]
PMCID:
PMC130748
Free PMC Article
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