Emergence of Klebsiella pneumoniae isolates producing inducible DHA-1 beta-lactamase in a university hospital in Taiwan.
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.
Department of Pathology, College of Medicine, National Cheng Kung University. Department of Pathology, Sinlau Christian Hospital, Tainan, Taiwan.
Jing-Jou
JJ
Yan
Wen-Chien
WC
Ko
Yun-Chih
YC
Jung
Chin-Luan
CL
Chuang
Jiunn-Jong
JJ
Wu
D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins; D003227:Conjugation, Genetic; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004790:Enzyme Induction; D005260:Female; D006785:Hospitals, University; D006801:Humans; D007710:Klebsiella Infections / Q000453:epidemiology* / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000302:isolation & purification; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010957:Plasmids / Q000235:genetics; D021521:Ribotyping; D013624:Taiwan / Q000453:epidemiology; D001618:beta-Lactamases / Q000378:metabolism*; D047090:beta-Lactams
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D047090:beta-Lactams; C048795:AmpC beta-lactamases; D001618:beta-Lactamases; C000601045:beta-lactamase DHA-1, Klebsiella pneumoniae