TABLE 1.

β-Lactamase classes detected by PCR grouped by results of ESBL confirmation test on screening-positive strainsa

β-Lactamase class(es) detectedNonconfirmed ESBL testConfirmed ESBL test
E. coliK. pneumoniaeE. coliK. pneumoniae
n%n%n%n%
AmpC only35.8917.6
TEM only1121.2710.4
SHV only11.959.846.01725.0
CTX-M only11.9913.468.8
TEM+SHV35.81319.41623.5
TEM+CTX-M2435.8
SHV+CTX-M913.2
AmpC+TEM2650.012.0
AmpC+SHV11.91937.311.568.8
TEM+SHV+CTX35.911.513.2
AmpC+TEM+SHV23.8917.634.5
AmpC+TEM+CTX23.011.5
AmpC+SHV+CTX-M11.511.5
AmpC+TEM+SHV+CTX-M
PCR negative47.759.823.034.4
Totals52516867
Any AmpC3261.53874.5710.4811.8
Any TEM4280.81325.55074.62638.2
Any SHV713.51733.32334.35885.3
Any CTX-M11.935.93655.22638.2
  • a n, Number of isolates.