Currently, there is a proliferation of Escherichia coli strains producing extended spectrum beta-lactamases (BLRS), in particular CTX-M BLRS. This multi-drug resistant microorganism is increasingly becoming the cause of serious community-acquired infections. Bacteremia caused by BLRS-producing E. coli is a therapeutic problem because the pathogen is often resistant to antimicrobial agents used to treat patients with suspected septicemia caused by E. coli .

In a 900-bed clinical hospital serving a population of 550,000, analysis of the predisposing factors, clinical characteristics and results of bloodstream infections caused by E.coli producing strains BLRS has been completed. BLRS has been studied using isoelectric focusing, polymerase chain reaction and sequencing.

43 cases of BLRS-producing E. coli infections in the bloodstream were recorded, representing 8.8% of all cases of bacteremia caused by E. coli ; 70% of the strains produced CTX-M BLRS. The number of cases increased from 6 in 2001 to 16 in 2004. The focus of infection in most cases was located in the urinary tract (46%) or the bile ducts (21%). Twenty-one cases of infection (49%) were of nosocomial origin, 14 (32%) were associated with the provision of medical care and 8 (19%) were of community origin. Obstruction of the urinary or biliary tract was observed in 38% and 25% of patients, respectively. A recent medical history of antimicrobial therapy was observed in 38% of patients. Mortality was 21%. Lethal results have been noted only in patients with nosocomial and medicine-related infections.

Empirical antimicrobial therapy was only appropriate in 51% of patients. Empirical therapy with cephalosporins or fluoroquinolones compared to beta-lactam antibiotic / beta-lactamase inhibitor therapy or carbapenem was associated with higher mortality (35% vs 9%; p = 0.05) and more often required modification (78% vs 24%; p = 0.001).

Thus, E. coli producing extended spectrum beta-lactamases is a common cause of blood circulation infections in hospital and ambulatory patients in the presence of CTX-M beta-lactamases. In areas where broad spectrum beta-lactamase producing strains are common, empirical treatment for sepsis, presumably caused by E. coli, is necessary.