Detection of Klebsiella pneumoniae and Escherichia coli strains producing extended-spectrum beta-lactamases.
Plasmids encoding extended-spectrum beta-lactamases of the TEM, SHV, and AmpC families were introduced into common Escherichia coli and Klebsiella pneumoniae hosts to create a homogeneous panel for evaluating the abilities of five test systems to detect resistance to eight beta-lactam antibiotics. Although MICs, as determined by agar dilution or E test strips, were increased and disk diffusion zone diameters were diminished, breakpoints for resistance were often not reached, and neither approach was sensitive in detecting resistance to oxyimino-beta-lactams. The MicroScan 18-h microdilution or Vitek rapid automated procedures were similarly insensitive. Ceftazidime was the best single test antibiotic for detecting extended-spectrum beta-lactamase production. beta-Lactamases TEM-7 and TEM-12 were particularly difficult to detect. Because of such difficulties, the prevalence of extended-spectrum beta-lactamases is likely to be greater than is currently appreciated.
Katsanis
G P
GP
Infectious Disease Unit, Massachusetts General Hospital, Boston 02114.
Spargo
J
J
Ferraro
M J
MJ
Sutton
L
L
Jacoby
G A
GA
D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology; D005069:Evaluation Studies as Topic; D006801:Humans; D007710:Klebsiella Infections / Q000188:drug therapy / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000706:statistics & numerical data; D009154:Mutation; D010957:Plasmids / Q000235:genetics; D012680:Sensitivity and Specificity; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000235:genetics
D001618:beta-Lactamases