Dominance of CTX-M beta-lactamases among Escherichia coli isolates in an Algerian hospital

Abstract number: p509

Ramdani-Bouguessa  N., Mendonça  N., Leitão  J., Ferreira  E., Tazir  M., Caniça  M.M.


Class A extended-spectrum beta-lactamases (ESBLs), as CTX-M, are rapidly expanding worldwide. The aim of this study was to establish the frequency of resistance to broad-spectrum cephalosporins of E. coli strains collected in Algeria, and to characterize the types of ESBL produced.


During January–June 2005, 279 E. coli strains were recovered consecutively from separate patients at the Mustapha Pacha Hospital of Algiers, Algeria. ESBL producing enzymes were detected by disc diffusion method; E-test ESBL with cefotaxime (CTX) and ceftazidime (CAZ) plus clavulanate was used to confirm strains as ESBL producers. MICs of 23 antibiotics were performed by microdilution broth method against ESBL-positive strains. Isoelectric focusing was used to characterise pI of beta-lactamases. PCR was performed with specific primers to type beta-lactamase genes in ESBL producer strains: blaTEM, blaOXA, blaSHV, blaCTX-M and ampC. Sequencing identified ESBL enzymes and pulsed-field gel electrophoresis (PFGE) with XbaI-digested genomic DNA established the diversity of ESBL-positive clones. Specific primers were used to screen for the presence of ISEcp1 upstream from blaCTX-M.


Sixteen of 279 (5.7%) strains were confirmed as ESBL producers among the following biological products: urine (n = 5), pus (n = 5), CSF (n = 1), blood (n = 4) and sputum (n = 1). All strains had the ubiquitary ampC gene plus blaTEM and blaCTX-M genes. Sequencing of blaTEM and blaCTX-M amplicons identified that all strains encode the TEM-1A enzyme, 13 the CTX-M-15 and 3 the CTX-M-3; these enzymes were characterized with pIs of 5.4, 8.9 and 8.0 respectively. ISEcp1 was detected in all E. coli strains producing CTX-M enzymes; and PFGE profiles of these strains indicated that only five clones were related. CTX-M producers showed diminished susceptibility to different antibiotics, such as CTX (94%), ceftriaxone (94%), CAZ (75%), aztreonam (94%), trimethoprim/sulfamethoxazole (88%), gentamicin (94%), amikacin (25%), ciprofloxacin (19%) among others; 81% of strains CTX-M producers were multidrug-resistant.


We showed a high frequency of policlonal dissemination of resistance to broad-spectrum beta-lactams in a hospital in Algeria through CTX-M ESBL, probably facilitated by mobile elements. Our results suggest that therapeutic options may be dramatically diminished if CTX-M enzymes continue spreading in hospital environment, as multidrug-resistance was demonstrated in a high frequency.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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