MOSTAFA M. FARAG, ALI K. ALZAHRANI, KARIM F. ABDALLAH, AYMAN K. ISMAIL, ISMAIL A. ISMAIL, FAROOQ A. GANAI AND WALAA F. ALSANIE
Abstract
Beta-lactam antibiotics have been discussed as options for the treatment of infections caused by multi resistant extended-spectrum beta-lactamase (ESBL)-producing bacteria. The objective of this study was to investigate the in vitro activity of different beta-lactam antibiotics against CTX-Mproducing Escherichia coli. Twenty isolates of 100 E. coli with the ESBL phenotype were studied. A large percentage of the E. coli was susceptible to meropenem (100%), imipenem (95%) and gentamicin (75%), but resistant to Ampicillin (95%), ceftazidime (90%) and cefepime (90%). Polymerase chain reaction (PCR) amplification of CTX-M genes was performed. These isolates were demonstrating resistance to either oxyimino-cephalosporin, and were found to harbor blaCTX-M genes by PCR. All the twenty isolates harboredbla CTX-M genes belonging to the blaCTX-M-1, blaCTX-M-2, blaCTX-M-3 and blaCTXM- 4 clusters, respectively. The antibiotics susceptibility of isolates was tested and fingerprinting of these isolates was done using fiverep-PCR primers, and Dendrogram based on rep-PCR was grouped the E. coli isolates into two different clusters with about 57% genetic similarity. The first cluster contained E. coli isolates E19 and E20, while the second cluster contained other E. coli isolates. This study shows significant differences insusceptibility to different beta-lactam antibiotics among the CTX-Mproducing E. coli isolates and a significant difference for many antibiotics tested between the CTXMproducing groups 1 and 5. The good in vitro activity of other beta-lactam antibiotics compared to carbapenems indicate that clinical studies are warranted in order to examine the potential role of these beta-lactam antibioticsin the treatment of infections caused by multiresistant ESBLproducing E. coli.