In addition to the indicated resistance genes, we have found that the clinical isolates of multiresistant E. coli in our health area carry different classes of integrons. Ec-MRnoB showed a higher presence of these AZD8186 elements in comparison with the isolates belonging to the Ec-ESBL collection but, in both cases, the class 1 integrons containing dfrA17-ant(3′)Ie or dfrA1-ant(3″)-Ia genes were the most frequent ones. The implication of these elements this website in the spread of resistance in Spain [33] has been previously documented. Conclusion In conclusion, this study
has shown that, in our area, multiresistant E. coli producing either ESBL or other mechanisms OICR-9429 order of resistance are clonally diverse, although small clusters of related strains are also found. While both Ec-ESBL and EcMRnoB frequently contained IncFI plasmids, plasmids usually related to the most frequently detected ESBL (CTX-M-14), are uncommonly found in strains lacking this enzyme. Methods Bacterial isolates, susceptibility testing and clonal relationship Two hundred multiresistant E. coli (one per patient) producing (n=100) or not producing ESBL (n=100), consecutively obtained between January 2004 and February 2005 at the Clinical Microbiology
Service of the University Hospital Marqués de Valdecilla (Santander, Spain) were initially considered for this study. The organisms
were obtained from urine Urease (n=158) or from other samples (n=42, including 17 wound exudates, 8 samples from blood, 6 sputum, 6 naso-pharyngeal lavage, 2 catheter, 2 ascitic liquid and 1 bronchoalveolar aspirate). One hundred and sixteen isolates were from samples of patients admitted to the hospital and 84 from outpatients (database from Hospital Universitario Marqués de Valdecilla). No relevant differences were observed in the distribution of these parameters when comparing Ec-ESBL and Ec-MRnoB. Identification and preliminary susceptibility testing (including ESBL production) of the isolates had been routinely performed with the WalkAway system (Dade Behring, Inc., West Sacramento, Ca., USA) using gram-negative MIC combo 1S panels. Confirmation of ESBL production and determination of MICs of imipenem, meropenem, aztreonam, piperacillin, cefoxitin, cefotetan, cefotaxime, cefotaxime-clavulanic acid, ceftazidime, ceftazidime-clavulanic acid and cefepime were performed using Dried MicroScan ESβL plus (Dade Behring, Inc., West Sacramento, Calif.) panels according to the manufacturer’s recommendations.