TY - JOUR
T1 - Characterization of carbapenem-nonsusceptible Klebsiella pneumoniae bloodstream isolates at a Taiwanese hospital
T2 - Clinical impacts of lowered breakpoints for carbapenems
AU - Lee, N. Y.
AU - Wu, J. J.
AU - Lin, S. H.
AU - Ko, W. C.
AU - Tsai, L. H.
AU - Yan, J. J.
N1 - Funding Information:
Acknowledgments The authors are grateful to the Research Center of Clinical Medicine, National Cheng Kung University Hospital, Tainan, Taiwan, for providing the statistical consulting services. This work was partially supported by grants DOH100-TD-B-111-002 (Multidisciplinary Center of Excellence for Clinical Trial and Research, Department of Health, Executive Yuan, Taiwan) and NSC 99-3112-B-006-015 and 100-2320-B-006-015 (National Science Council, Taiwan).
PY - 2012/8
Y1 - 2012/8
N2 - This study was conducted in order to characterize carbapenem-nonsusceptible Klebsiella pneumoniae isolates and to evaluate the impacts of recently lowered interpretative breakpoints for carbapenems for Enterobacteriaceae. Among 152K. pneumoniae bloodstream isolates suspected as AmpC or extended-spectrum β-lactamase (ESBL) producers, 58 (38.2%) isolates were currently interpreted as nonsusceptible to ertapenem, imipenem, or meropenem, and 42 (72.4%) of them were categorized as carbapenemsusceptible by the previous criteria. The high revision rate was associated with the predominance (79.3%) of DHA-1 among the carbapenem-nonsusceptible isolates due to both polyclonal and clonal spread. ESBLs were common (~57%) in both ertapenem-susceptible and -nonsusceptible isolates; however, 84.8% of the carbapenem-nonsusceptible isolates were also AmpC producers. The IMP-8 metallo-β-lactamase was detected in three isolates. Polyacrylamide gel electrophoresis suggested decreased OmpK35 expression in all but one ertapenem-nonsusceptible isolate, and genetic disruptions of ompK35 and ompK36 were detected in 30 and six ertapenemnonsusceptible isolates, respectively. A comparison between patients infected by AmpC- or ESBL-producing ertapenemsusceptible (n062) isolates and those with isolates revised as ertapenem-nonsusceptible (n041) revealed more cases of malignancies (36.6% versus 14.5%; p=0.01) and higher Charlson score (p=0.033) among the patients with ertapenemnonsusceptible isolates; however, the acquisition of an isolate revised as carbapenem-nonsusceptible was not identified as an independent mortality risk factor.
AB - This study was conducted in order to characterize carbapenem-nonsusceptible Klebsiella pneumoniae isolates and to evaluate the impacts of recently lowered interpretative breakpoints for carbapenems for Enterobacteriaceae. Among 152K. pneumoniae bloodstream isolates suspected as AmpC or extended-spectrum β-lactamase (ESBL) producers, 58 (38.2%) isolates were currently interpreted as nonsusceptible to ertapenem, imipenem, or meropenem, and 42 (72.4%) of them were categorized as carbapenemsusceptible by the previous criteria. The high revision rate was associated with the predominance (79.3%) of DHA-1 among the carbapenem-nonsusceptible isolates due to both polyclonal and clonal spread. ESBLs were common (~57%) in both ertapenem-susceptible and -nonsusceptible isolates; however, 84.8% of the carbapenem-nonsusceptible isolates were also AmpC producers. The IMP-8 metallo-β-lactamase was detected in three isolates. Polyacrylamide gel electrophoresis suggested decreased OmpK35 expression in all but one ertapenem-nonsusceptible isolate, and genetic disruptions of ompK35 and ompK36 were detected in 30 and six ertapenemnonsusceptible isolates, respectively. A comparison between patients infected by AmpC- or ESBL-producing ertapenemsusceptible (n062) isolates and those with isolates revised as ertapenem-nonsusceptible (n041) revealed more cases of malignancies (36.6% versus 14.5%; p=0.01) and higher Charlson score (p=0.033) among the patients with ertapenemnonsusceptible isolates; however, the acquisition of an isolate revised as carbapenem-nonsusceptible was not identified as an independent mortality risk factor.
UR - http://www.scopus.com/inward/record.url?scp=84866390559&partnerID=8YFLogxK
U2 - 10.1007/s10096-011-1525-2
DO - 10.1007/s10096-011-1525-2
M3 - Article
C2 - 22249422
AN - SCOPUS:84866390559
SN - 0934-9723
VL - 31
SP - 1941
EP - 1950
JO - European Journal of Clinical Microbiology and Infectious Diseases
JF - European Journal of Clinical Microbiology and Infectious Diseases
IS - 8
ER -