highly significantP < 0.0001
The remaining absorbance after 3 hours (OD 620 , 3 h) was greater than 100% relative to the initial absorbance in 29 (58%) of ESBL isolates and in 11 (22%) of non-ESBL isolates, so these isolates were designated serum resistant and the difference was highly significant ( P < 0.0001).