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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.

Objectives: 

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.

Methods: 

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.

Results: 

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.

Conclusions: 

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
Subject:
Location: Oxford, UK
Presentation type:
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