Comparison of Five Methods for Detection of Extended Spectrum β-Lactamases in Gram Negative Enteric Bacteria

摘要

The presence of extended-spectrum β-lactamases in 55 isolates of Gram negative enteric bacteria isolated from lower respiratory tract infections, was investigated by using the Clinical Laboratory Standards Institute CLSI method which showed that 41.8% of the isolates produced this type of β-lactamases, and that Klebsiella pneumoniae isolates were the most producing species with a production rate of 61.1%, followed by Escherichia coli isolates 43.75%. Five confirmatory methods were used to detect these enzymes: ceftazidime agar method, double-disk synergy method, combination disk method, modified 3D extract method and enzymatic disks method. The study indicated that ceftazidime agar method was the best method in detecting extended-spectrum β-lactamases as it gave a detection rate of 95.7%, followed by the double-disk synergy method with a rate of 87%, then enzymatic disks method with a rate of 73.9%.