title: Differences in the evolution of imipenem susceptibility among Klebsiella pneumoniae and Escherichia coli isolates during a 6-year period in a tertiary care hospital.
abstract: The evolution of imipenem disk-diffusion susceptibility results of 2652 strains of Klebsiella pneumoniae and 7596 Escherichia coli isolated during the period 2000-2005 were analysed. Screening for production of metallo-beta-lactamases was performed using the EDTA-synergy method. The percentage rate of K. pneumoniae isolates having a zone diameter < or =25 mm increased from 20% in 2000 to 41% in 2005, whereas the respective rate of isolates having a zone diameter > or =30 mm decreased from 48 to 23%. These changes were more evident during 2000-2002, followed in 2003 by the isolation of the first imipenem-resistant strains. Regarding E. coli, a similar decrease was observed (the rates of isolates having a zone diameter < or =25 mm and > or =30 mm changed from 7% and 68% in 2000, to 32% and 36% in 2005, respectively) following the respective changes of K. pneumoniae. A total of 20 K. pneumoniae strains, but no E. coli, were confirmed as metallo-beta-lactamase producers. In conclusion, a decrease of the imipenem susceptibility prior to the isolation of the first resistant strains in a tertiary care hospital was detected, as well as differences in this decrease between the two species. These findings indicate that monitoring of the evolution of imipenem susceptibility in real-time may help in unveiling forthcoming resistance and in implementing the appropriate diagnostic techniques.
authors.affiliation: Department of Microbiology, Laikon General Hospital, 11527 Athens, Greece. ipapapar@med.uoa.gr
authors.forename: Joseph
authors.initials: J
authors.lastname: Papaparaskevas
authors.forename: Angeliki
authors.initials: A
authors.lastname: Pantazatou
authors.forename: Ioanna
authors.initials: I
authors.lastname: Stefanou
authors.forename: Victoria
authors.initials: V
authors.lastname: Mela
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Galatidis
authors.forename: Athina
authors.initials: A
authors.lastname: Avlamis
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004492:Edetic Acid / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects*; D006801:Humans; D015378:Imipenem / Q000494:pharmacology*; D007711:Klebsiella pneumoniae / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D001618:beta-Lactamases / Q000096:biosynthesis
chemical_list: D000900:Anti-Bacterial Agents; D015378:Imipenem; D004492:Edetic Acid; D001618:beta-Lactamases