Extended-spectrum β-lactamases (ESBL) - producing Escherichia coli strains in blood cultures

Introduction: Extended-spectrum beta-lactamase (ESBL)–producing Escherichia coli (E. coli), are major pathogens responsible for bacteraemia. The CTX-M types of ESBL are becomingdominant worldwide, particularly CTX-M-15. Bacteraemia caused by these strains is difficult to treatbecause the organisms are frequently resistant to the antimicrobials recommended for treatment ofpatients. Methods: We included in our study all consecutive episodes of bloodstream infection due toESBL-producing E. coli during the period January 2007 - December 2010. Strains were isolated, andtested for antimicrobial resistance using Vitek2 system and API Biomerieux. ESBLs were characterizedusing polymerase chain reaction (PCR). Results: 127 episodes of E. coli bacteraemia, 30 ESBL-producingE. coli (24%) were included; 90% (19 strains) of the molecular characterizated isolates produced aCTX-M type of ESBL. The most frequent origins of infection were urinary tract (24%) and intraabdominalinfections (11%). Coresistance to other antimicrobials was important between ESBLproducingstrains. The majority of isolates were resistant to ciprofloxacin 22 strains (73%) andgentamicin 21 strains (70%). Conclusions: ESBL-producing E. coli is a significant cause of bloodstreaminfection in the context of the emergence of CTX-M enzymes. Empirical treatment of sepsis potentiallycaused by E. coli may need special attention in areas where such ESBL-producing isolates are present.