Emergence of a new group CTX-M enzyme in Romania and risk factors for extended spectrum beta-lactamase producing E. coli infections.

Antibiotic resistance rates in E. coli are rapidly rising, with worrisome aspects especially regarding community--acquired resistance to third- and fourth-generation cephalosporins and fluoroquinolones. The objectives of this prospective cohort study was to determine the resistance profile of E. coli for two categories of patients (< 49 years and > or = 50 years), risk factors for ESBL positivity and to investigate the molecular epidemiology of ESBL type CTX-M enzymes. A total of 885 strains of E. coli were isolated in the Infectious Diseases Hospital laboratory between June 2008 and June 2011 and E. coli resistance due to ESBL production was noted in 17% of cases. We found that previous therapy with cephalosporins, hospitalization and urinary catheter were risk factors for ESBL positivity. We noted significant differences concerning resistance rate between patients under 49 years and aged more than 50 years for ciprofloxacin (19% and 38%, respectively, p = 0,0001), for gentamicin (15% and 23%, p = 0,008), ceftazidime (15% and 24%, p = 0,001) and ESBL positivity (14% and 20%, p = 0.009). This study highlights the predominance of CTX-M producing strains (92.5% of ESBLs-positive E. coli harboured bla CTX-M genes); CTX-M-15 producing isolates were the most common, accounting for 96% of isolates. Only 4% were belonging to CTX-M group-9, an emerging ESBL group which is newly described in Romania.